Common Sense Loss Prevention
and Learning Experiences
Mark A. McCowan B.Sc.
Copyright 2008
You are encouraged to use this information to enhance the safety of
yourself, your colleagues, and your work site.
Use for commercial purposes requires specific permission.
An operator at the Carstairs Crossfield Gas Plant said “Please give me the benefit of
any incidents you are aware of as there are plenty of ways for me to get killed out
there without ignoring the ones I know about!” This is the best comment I have
received from an operator when presenting items pertaining to loss prevention.
Edited by Val Zacharias, M.A.
Executive Director, CMVA
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Foreword
Some of my colleagues have requested that I set down some of my life and work experiences so that
they could be used to assist those working in loss prevention or those interested in learning the basics
for the first time.
Most of what I have written is related from personal experience with some being obtained from
others who have given me the benefit of what they have learned and for those I am grateful.
Most information pertains to work with the oil and gas processing business with some pertaining to
chemical, manufacturing and service industries.
In today’s world of detailed high speed information transfer, we should be less likely to repeat
mistakes of the past if we make proper use of available historical data.
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The Benefit of Hindsight .................................................................................................................................................. 7
Heater Firebox Explosion ............................................................................................................................................. 7
Backhoe Line Strike...................................................................................................................................................... 7
Salt Bags Near Heater ................................................................................................................................................... 7
Hot Oil Spray ................................................................................................................................................................ 7
Seed Plant Fire .............................................................................................................................................................. 8
Plastic Pond Liners ....................................................................................................................................................... 8
Skids and Skid Spaces ...................................................................................................................................................... 9
Sub Floor Hazards ........................................................................................................................................................ 9
Skid Space Explosions .................................................................................................................................................. 9
Pollution ..................................................................................................................................................................... 10
Enclosed Skids ............................................................................................................................................................ 10
Pre-Cast Concrete ....................................................................................................................................................... 10
Low Pressure Fittings ..................................................................................................................................................... 10
Field Changes to Propane System ............................................................................................................................... 10
Hydraulic .................................................................................................................................................................... 10
High Pressure Gas....................................................................................................................................................... 10
Fire Extinguisher......................................................................................................................................................... 11
Chemical Reaction and Fire Hazards .............................................................................................................................. 12
Toluene Spray ............................................................................................................................................................. 12
Toluene Reaction ........................................................................................................................................................ 12
Methanol/Air............................................................................................................................................................... 12
Ether ........................................................................................................................................................................... 12
Sour Gas – two separate annual visits ......................................................................................................................... 13
Asbestos ...................................................................................................................................................................... 13
Fire Extinguishers - Chemical ..................................................................................................................................... 14
Nitrate Oil Mixture ..................................................................................................................................................... 14
Potassium Permanganate ............................................................................................................................................ 14
Salt Bath Heaters ........................................................................................................................................................ 15
Electroplating Plant .................................................................................................................................................... 17
Chemical Laboratory .................................................................................................................................................. 17
Incidents During Plant Surveys ....................................................................................................................................... 18
Furnace Fire ................................................................................................................................................................ 18
Aluminum Extrusion ................................................................................................................................................... 18
Hot Tubes of Heat Tracing ......................................................................................................................................... 18
Icy Slip ........................................................................................................................................................................ 18
Fire Training ............................................................................................................................................................... 18
Pit Fire ........................................................................................................................................................................ 19
Removed Hard Hat ..................................................................................................................................................... 19
Barrel Tipper .............................................................................................................................................................. 19
Man Lifts .................................................................................................................................................................... 19
Humphreys .................................................................................................................................................................. 20
Snoopervision ............................................................................................................................................................. 20
Hydrogen Sulphide (Sour Gas) Inexperience ............................................................................................................. 21
Dented Cab on LPG Tank........................................................................................................................................... 21
High Pressure Gas Cylinders near Fired Heaters ........................................................................................................ 22
Extension Cords .......................................................................................................................................................... 22
Incandescent Bulb Supports........................................................................................................................................ 22
Plastic Fire .................................................................................................................................................................. 23
Plugs Missing From Hazardous Area Boxes............................................................................................................... 23
Furniture Plant: Fire Protection Attitude Change ....................................................................................................... 23
Glycol Regenerator Condensate (natural gasoline) Carryover .................................................................................... 23
Cable Exposure Hazards ............................................................................................................................................. 24
Fire Detection ............................................................................................................................................................. 25
Need For Two Exits .................................................................................................................................................... 25
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Hollow Aluminum Pistons .......................................................................................................................................... 25
Powder Driven Studs .................................................................................................................................................. 26
Bolting ............................................................................................................................................................................ 26
Loose or Missing ........................................................................................................................................................ 26
Compressor Station ..................................................................................................................................................... 27
Hot Regeneration Gas ................................................................................................................................................. 27
High Pressure Gas Re-injection .................................................................................................................................. 27
Pressure Safety Valve ................................................................................................................................................. 27
Vibration Loosens Nuts .............................................................................................................................................. 27
Painted Bolt Hole........................................................................................................................................................ 28
Shaved Studs............................................................................................................................................................... 28
Design ............................................................................................................................................................................. 28
Standpipe Feed, No Back Check ................................................................................................................................ 28
Inexperience................................................................................................................................................................ 28
Gas Plant Layout......................................................................................................................................................... 29
Fire Pump Exposure ................................................................................................................................................... 29
Drawing Review ......................................................................................................................................................... 29
Relief Valve Setting .................................................................................................................................................... 29
Missing Valve on LPG Tank ...................................................................................................................................... 29
Two Losses in the Same Building ............................................................................................................................... 30
Bullseye Sight Gauge in Propane Service ................................................................................................................... 30
Criss-crossed Heat Exchanger .................................................................................................................................... 31
Gas Release and Loading Losses ................................................................................................................................ 31
Compressor Station Loss – Pendulum Effect .............................................................................................................. 31
Petrochemical Plants – Flare Knockout ...................................................................................................................... 32
Acetylene Reactor ....................................................................................................................................................... 32
Heater Layout ............................................................................................................................................................. 32
Tanks and Their Venting ................................................................................................................................................ 33
Explosion with No Warning ....................................................................................................................................... 33
Missing Building......................................................................................................................................................... 33
Exploding Kerosene Drum ......................................................................................................................................... 33
Unacceptable Application of Pressure ........................................................................................................................ 33
Oil Transfer By Air Pressure ...................................................................................................................................... 34
Ruptured Roof Seam................................................................................................................................................... 34
Bulged Diesel Fuel Tank ............................................................................................................................................ 34
Drums Are Not Pressure Vessels ................................................................................................................................ 35
Tank Roof Rupture ..................................................................................................................................................... 35
Tank Roof Rupture – Two Men Killed ....................................................................................................................... 35
Heating Tanks ............................................................................................................................................................. 36
Explosive Vapors ........................................................................................................................................................ 36
Tanks and Lightning ................................................................................................................................................... 36
Corroded Seams .......................................................................................................................................................... 36
Potential Lack of Oxygen ........................................................................................................................................... 37
Petrochemical Plants - Incidents ..................................................................................................................................... 37
Gas Release Boot ........................................................................................................................................................ 37
Steam Superheater Tube Rupture ............................................................................................................................... 37
Reaction Runaway ...................................................................................................................................................... 38
Shutdown When Wire Connector Fell Off .................................................................................................................. 38
Internal Fire in Compressor Station ............................................................................................................................ 38
Oil Fire Destroys Foam Plastic Insulation .................................................................................................................. 39
Plant Surveys .................................................................................................................................................................. 39
Forced Air Furnace Overheat...................................................................................................................................... 39
Genset Odorized Gas Leak ......................................................................................................................................... 40
Torch Used on Propane Tank ..................................................................................................................................... 40
Halon Suppression System Tests .................................................................................................................................... 40
Excessive Halon.......................................................................................................................................................... 40
Faulty Halon Alarm System ........................................................................................................................................ 41
Halon Discharge Damages Ceiling ............................................................................................................................. 41
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Button Release on Halon System ................................................................................................................................ 41
Lack of Visibility During Halon Discharge ................................................................................................................ 41
Battery Banks and UPS (uninterruptible power supply) ................................................................................................. 42
High Voltage Room .................................................................................................................................................... 42
Unsecured Cable ......................................................................................................................................................... 42
Battery Hydrogen Explosion....................................................................................................................................... 42
Gas Detectors and Gas Leakage ..................................................................................................................................... 43
Trust, or CHECK, the Instrument ............................................................................................................................... 43
Natural Gas is NOT Air .............................................................................................................................................. 44
Multi-Head Readings .................................................................................................................................................. 45
Steam Cleaning ........................................................................................................................................................... 45
Faulty Procedure ......................................................................................................................................................... 45
Fire Pump Tests .............................................................................................................................................................. 46
Broken Hydrant .......................................................................................................................................................... 46
Broken Monitor .......................................................................................................................................................... 46
Threaded Nipples........................................................................................................................................................ 46
Rocks and Pitots ......................................................................................................................................................... 47
Rock in Hydrant .......................................................................................................................................................... 47
Classic Sprinkler System Impairment ......................................................................................................................... 47
Water Thrust ............................................................................................................................................................... 47
Methanol in Hydrant ................................................................................................................................................... 48
Reversed Relief Valve ................................................................................................................................................ 48
Thermowells ................................................................................................................................................................... 48
Leak at a Weld ............................................................................................................................................................ 48
Alleged Leakage ......................................................................................................................................................... 49
Empty Fire Extinguishers............................................................................................................................................ 49
Propane Fire Loss ....................................................................................................................................................... 49
Drainage.......................................................................................................................................................................... 49
Modular Plant ............................................................................................................................................................. 49
Dried Out Trap ........................................................................................................................................................... 49
Backup of Flammable Vapours................................................................................................................................... 50
Backup of Gas to Air System ...................................................................................................................................... 50
Frozen Drain Line ....................................................................................................................................................... 50
Fireproofing .................................................................................................................................................................... 50
Powder Driven Fastners .............................................................................................................................................. 50
Corrosion Beneath Fire-Proofing Materials ................................................................................................................ 50
High Expansion Foam Test ............................................................................................................................................. 51
Frozen Foam Water Solution ...................................................................................................................................... 51
Debris in the System ................................................................................................................................................... 51
Relief Valves, Boilers, and Water Heaters ..................................................................................................................... 51
Relief Valves Have to Match Capacity Rating ........................................................................................................... 51
Do Not Restrict a Relief Valve ................................................................................................................................... 52
Understand the Implications ....................................................................................................................................... 52
Potential Blockage Due to Ice .................................................................................................................................... 52
Blind Flanges .............................................................................................................................................................. 52
Cost Benefit Attitude .................................................................................................................................................. 53
Out of Service PSV’s .................................................................................................................................................. 53
Waterflood Plant Fires and Explosions........................................................................................................................... 53
Welder’s Spark ........................................................................................................................................................... 53
Fractured Small Gas Line ........................................................................................................................................... 53
Failure of Tank Low Level Switch ............................................................................................................................. 54
Maintenance.................................................................................................................................................................... 54
Juxtaposition of Two Jobs Equals Loss ...................................................................................................................... 54
Solvent Heating By Trouble Light .............................................................................................................................. 55
Pressure Safety Valve – Air PSV Used in Gas Service .............................................................................................. 55
High Voltage Bug Killers ............................................................................................................................................... 55
Loss Incidents ................................................................................................................................................................. 55
Propane Blows Cladding ............................................................................................................................................ 55
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Old WKM Valve ........................................................................................................................................................ 56
Oil Line Vibration....................................................................................................................................................... 56
Starter Gas Release ..................................................................................................................................................... 56
Liquids in a Recip Compressor ................................................................................................................................... 57
Heater Loss/ Hydrate Plugging ................................................................................................................................... 57
Compressor Station huge amount of damage but what is the lesson? ......................................................................... 58
Common Sense ............................................................................................................................................................... 58
At a Compressor Station ............................................................................................................................................. 58
Service Station Vents .................................................................................................................................................. 59
Gas Pressure Regulator Vents ..................................................................................................................................... 59
Fire Blanket ................................................................................................................................................................ 60
Two Inch Drain Test ................................................................................................................................................... 60
PSV Block Valve Seals .............................................................................................................................................. 60
Shut Fire Protection Valves ........................................................................................................................................ 61
Deluge System Off ...................................................................................................................................................... 61
Frozen Supply Line ..................................................................................................................................................... 61
Temporary Lapse of Attention .................................................................................................................................... 62
Blocked System Marked OK ...................................................................................................................................... 62
Do Not Tinker Unless You Know What You Are Doing ........................................................................................... 62
Upside Down Start/Stop Switch ................................................................................................................................. 63
Electrical Fire Pump ................................................................................................................................................... 63
Incinerators and Recycling ......................................................................................................................................... 63
Sewers - Losses ........................................................................................................................................................... 64
Tanks - Diking ............................................................................................................................................................ 64
Truck Loading ................................................................................................................................................................ 65
Be Aware of Emergency Procedures .......................................................................................................................... 65
Be Aware of Hazards .................................................................................................................................................. 65
Quick Thinking ........................................................................................................................................................... 65
Instructions and Procedures ............................................................................................................................................ 65
Allen Screw Position Lock ......................................................................................................................................... 65
Body Bleed on Ball Valve .......................................................................................................................................... 66
Mis-Communication ................................................................................................................................................... 66
Freeze-Ups and Ice Damage ........................................................................................................................................... 66
Low Point Water After Hydro-Test ............................................................................................................................ 66
Nitrogen Compressor Water Jacket ............................................................................................................................ 67
Frozen Bolt Holes ....................................................................................................................................................... 67
Frozen Sprinkler Systems ........................................................................................................................................... 67
Still Column Vents...................................................................................................................................................... 67
Refinery Steam Tracing .............................................................................................................................................. 67
Hazards with Catalytic Space Heaters ............................................................................................................................ 67
Sour Gas ..................................................................................................................................................................... 67
Possibility of Igniting Oils .......................................................................................................................................... 68
Inoperable Safety Shutdown Bypass Button ............................................................................................................... 68
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The Benefit of Hindsight
Heater Firebox Explosion
Sid, the safety supervisor of a mid-west refinery, while training new operators, described a heater
operating incident in which a firebox explosion damaged the refractory by dislodging many bricks.
This shut down the heater for weeks. The class is fully apprised of what the operator did in an
attempt to provide a hot restart and get the heater back on line. Some of the class with the benefit of
the knowledge just obtained shook their heads and said “Who would do that?”
The instructor answered “I did!”, and the students all look surprised. After the original incident, Sid
said the refinery manager called him to his office. As he was heading to the office Sid was thinking,
“This is it, I’m down the road.”
Instead, the refinery manager said “Sid, we have an opening for someone to do safety training and
I’m offering you the job.” After his initial surprise, Sid agreed.
The refinery manager never regretted his decision because he ended up with one of the best safety
supervisors I have ever had the privilege of knowing. He learned and taught well in a very
conscientious manner. He dedicated his energies to becoming familiar with all types of process and
fire hazards as well as personnel safety.
Backhoe Line Strike
Something similar happened when a backhoe operator, going further than he was supposed to, struck
a gas line and there was a large leak. Fortunately, it did not ignite and the operator shut down the
machine as he escaped the area.
Head office wanted the operator fired immediately. The line supervisor had other ideas and said “No
way, this guy now knows the hazards better than anyone. He will be doing all the digs near pressured
lines that we need in future.”
As far as I know this tactic worked very well and that operator was not involved in any further
accidental line strikes.
Salt Bags Near Heater
In most instances those who have had a close call rarely take chances again as noted during a survey
of a gas plant which used a salt bath heater for process heat. As I started to explain some of the
hazards of the nitrate/nitrite salt mixtures and the fact they were strong oxidants, the operator
stopped me and said “You are talking to someone who knows!”
He then proceeded to describe an incident where they were in the process of starting up the heater
and had backed a semi-trailer up to the heater in order to facilitate the addition of salt. They were
tossing the bags to one side below the end gate of the trailer. Some of the bags came in contact with
the side of the hot fire tube and ignited.
The speed of the fire in the bags startled those in the truck and he said “If the truck box hadn’t had an
open side door, we would have been in real trouble!” They drove the truck away from the heater. The
bags burned quickly and because the exposure was of short duration, it caused little damage to the
heater flashing. A valuable lesson was learned -- that oxidizers and combustibles make for quick hot
fires which are very difficult to control.
Hot Oil Spray
In some cases the real hazards and possible consequences need some careful thought as the first
reactions of people sometimes miss the main points. In an oil production and treating facility which
was brand new and awaiting startup orders I pointed out that the body drain plug holes of the
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pressure safety valves in oil service were only fitted with plastic dust plugs and not the steel plugs
required. The first reaction of the operator was to state, “Oh man, would that ever make a mess!”
(referring to the heavy oil spray).
The supervisor, Art then said “And you are standing in just about the right place to get hit!” He had
correctly identified that probably the main hazard was to personnel, because in this instance it was
not only oil, but because the valves were on the treater it would be hot oil.
Seed Plant Fire
One interesting minor loss, but close call, I had the opportunity of looking into was at a seed cleaning
plant. At the point where the south annex roof slope meets the higher section a fire had started,
apparently by static sparking of a V belt. It progressed to where it actually burnt a hole through the
roof of the annex at the apex. The staff had discovered it and actually managed to put it out.
When I asked how they managed to accomplish this feat they replied they had used small pails of
water and plastic squeeze bottles so they could shoot the water up into the area of the fire.
When asked where they got the water the reply was, “Out of the sump in the basement!”
Considering where they got the water and how fast they must have reacted to put the water where it
was needed, these fellows probably should have considered Olympic competition. I told them I was
amazed by their feat. Then one of them said “Well, if this place burned down I wouldn’t have a job!”
I pointed out that it is not advisable to risk your life to save a building. They were told they should be
proud of what they had accomplished with so little in the way of resources at their disposal.
Static conductive V belts and static bonding seems to have solved the problem.
Plastic Pond Liners
Open reservoirs or ponds lined with plastic such as polyethylene or polyvinyl chloride are a very
significant hazard to personnel unless adequate safety measures are in place. Such ponds should have
security fencing with warning signs, safety lines and life buoys. When there is water or mud in these
ponds the slippery surface makes them virtually impossible to get out of without assistance. People
have drowned in these ponds and there are a number of cases where outside assistance was needed
for escape.
At a slurry test facility a dog became trapped in the pond and the dog’s owner also became trapped
when he went to assist the dog. The two were rescued by a second man who extended a ladder out to
assist them.
A man slipped into the firewater pond because the algal growth in the water made the plastic surface
as slippery as though it had been greased. That person was also rescued and now the pond has
knotted rot resistant ropes and life buoys around the perimeter.
Ropes and buoys need to be on a regular maintenance check list to assure they will remain in good
condition if needed. Work inside fences should require life jackets, harness and safety lines.
During the survey of a natural gas processing plant, an open pond with plastic liner was noted and
the hazards outlined. Interestingly enough it was not that far from the geographic location where the
dog and owner had a close call. Even more interesting was the fact that both facilities were owned by
the same parent company. One person at the gas plant had heard about the incident but had not
considered that virtually the same hazard existed at their plant.
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At another gas plant located where there were lots of deer in the area a pond fence was recommended
for that reason as well. Animals with sharp hooves such as deer have seriously damaged pond liners.
In talking to one pond liner installer he advised they had a major repair job on a pond liner when a
bunch of wild pigs went through the pond area before the fence was installed and fortunately well
before the pond was filled.
With respect to the hazard of slippery pond liners there was a case where a drilling rig worker ended
up in a foam covered mud pond and others were not even aware that he had slipped into the pond.
The foam was deep enough that it would have muffled any cry for help. Needless to say that one was
fatal.
Skids and Skid Spaces
Sub Floor Hazards
By the very nature of hydrocarbon vapors, when there is lack of good ventilation such as encountered
below many checkerplate covered steel skids, there is always a significant explosion hazard. This
issue has been raised at least since 1970. This concern was presented at a meeting with design
engineers. The design engineer did not appreciate the concern and with some irritation stated, “Show
me where someone has been killed and maybe I will do something about it!”
Unfortunately, someone had been killed in Alberta in April of 1981 but since I did not have the
information for release to the design group the issue was given no further consideration. Their
insurance manager who was also present agreed with my concern. The design engineer then said if
we could not show a dollar value cost saving for insurance with respect to design changes he was not
interested.
The insurance manager with a little irritation at this comment then said
“I could understand your view if we never had any losses, but during the last three years we have
been paid three times the annual premiums in loss payouts!” One of the group piped-up saying
“Great -- we are doing that right too!”
At this remark the insurance manager fell silent in disgust and said nothing further during that
meeting.
Skid Space Explosions
Skid space explosions have been responsible for at least five deaths in the province of Alberta. At
one of the Gas Processor meetings George approached me and said “Am I ever glad we followed
your suggestion to fill the skid spaces with non combustible material.”
He then proceeded to tell me that they had filled the skid spaces at their liquids plant and thought
they had done a fairly good job. They had apparently missed one corner of the skid and some heavier
than air vapors had accumulated in the space. During subsequent hot work there was an explosion
and the corner of the steel plate flipped up giving people in the structure quite a fright. George said
he hated to think of the magnitude of the explosion if the whole skid space had been involved. There
was no insurable loss as a result of this incident so I would never have found out about it except for
our casual conversation.
One skid space explosion resulted in two deaths, very tragically a father and son. The explosion
lifted one end of the process refrigerant skid one and one half to two metres in the air as evidenced
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by piping. The degree of confinement provided by most skid spaces greatly increases the severity
because of the strength of the enclosure and the inertial effects.
Pollution
At another facility, the hazard of drain holes drilled through the steel floor plate was pointed out and
a request made to plug the holes using cold work procedures. The operator said “The plugs would
need to be removable to facilitate washdown.” He obviously missed the hazard potential and wasn’t
about to let anything I said change his mind. I also wondered what sort of environmental problem
they will find from chemicals and oil draining under the skid in years to come.
In another small facility, I entered a skid mounted building with holes drilled in the checkerplate
floor. Methanol leakage from a pump seal was running across the floor and down one of the holes
creating an explosion as well as an environmental concern.
Enclosed Skids
Elsewhere, the hazard of enclosed skids was pointed out and reference made to the National Fire
Protection Association Standard # 68 on Venting of Deflagrations. Some holes were made in the skid
but by the size and number they did not even comply with crankcase venting requirements of one
square inch for each thirty cubic inches of volume.
Pre-Cast Concrete
There are even hydrocarbon process and compressor buildings in the province where underfloor
spaces are covered by precast concrete slabs which could no doubt produce a very significant
pressure rise during an explosion simply due to the large inertial effects of the concrete.
Low Pressure Fittings
Continued vigilance is essential to prevent low pressure pipe fittings from being used in high
pressure service so many companies have a policy of not allowing them on site. In many cases it is
amazing what overpressures these fittings withstand without failure.
Field Changes to Propane System
In a small refrigeration plant, the local operator was having trouble with the piping configuration
when service work was required on the propane refrigeration compressor. He went to the hardware
store, picked up some pipe and fittings and made the changes needed to overcome his problem. Since
150# fittings and pipe were all that was available locally, that is what he used.
His comments were “It worked! What’s the problem?”
Hydraulic
Probably the most common area to see these fittings is in hydraulic systems with some even in the
control valving right beside the machine operator. In hydraulic systems these fittings often see
pressures exceeding 2000 psig. The farming community is an area where this is common because
low pressure fittings are relatively cheap and readily available.
High Pressure Gas
At a high pressure gas facility one of these fittings was noted downstream of a high pressure
regulator in a line operating at approximately 80 psig which was fine but I knew the company did not
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normally stock such fittings. I said to the District Supervisor “Hey, Tom, What’s this?” as I tapped
on the fitting with my pen.
Tom turned, looked and said “Geez!” as he backed up off the edge of the concrete pad, nearly falling
down from the slight elevation change. I apologized profusely as I suddenly realized he thought it
was under full line pressure and I was tapping on it, albeit with a plastic pen.
When I explained it was only at 80 psig he was much relieved.
It was against company policy to even have these fittings on site. It was determined a contractor had
installed the fitting for a temporary fuel gas system.
I am not sure if Tom ever forgave me for that fright even after I assured him that if it had been under
full line pressure I would not have tapped on it. I say this because I met him again many years later. I
immediately said “Hello!” and he returned the greeting. Our tour guide at the time said “Oh, you
know Tom?”
I said “Yes!”
Tom said “It was years ago but I remember him well!”
He obviously never forgot the low pressure fitting incident.
At a straddle plant the operator was asked what pressure was in the starting gas supplying an
emergency unit and he replied about 125 psig. A second operator said the pressure was more like 280
psig in the supply line.
They then asked the reason for the query.
It was pointed out that the piping system contained some 150# plumbing fittings. They were
surprised to see such fittings in the plant since this was against company policy. The fittings had
come with the skid mounted unit as part of the package. The package had not been reviewed for
compliance with plant standards prior to connection. The fittings had been in place for a number of
years.
A 150# reducer fitting was noted under a pressure gauge on the sales gas header. The gauge reading
was 1050 psig. The fitting had been in service for many years.
Changeout had to wait for a shutdown time when the sales gas header could be depressured.
Fire Extinguisher
A wheeled Ansul 350 D fire extinguishing unit had what appeared to be a 150# fitting in the power
gas supply piping from the 2200 psig nitrogen cylinder to the chemical tank.
Advice from the field indicated it was a 300# street elbow and ANSI (American National Standards
Institute) says street elbows in 300# rating should not be exposed to pressures above 600# gauge.
The extinguisher was a type which does not have a regulator between the cylinder and the chemical
tank. It works on a principle similar to a hand portable in that the pressure is correct when the small
high pressure cylinder equalizes into the larger powder container.
If any restriction or blockage were to occur in the gas supply dip tube the street elbow could see
pressures of 2200 psig, supply pressure.
The manufacturers representative stated they hadn’t had any failures yet.In addition the unit was
supposed to be rated for use at temperatures below -40 degrees and depressuring high pressure
nitrogen would drop the temperature even further.
ANSI standards say the fitting is not rated for use below -20 F.
A letter was later received from the supplier that there was no problem and that they had tested the
fittings to very high pressure. That being the case it seemed strange they requested an appointment to
go out to the site to change the fittings.
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Chemical Reaction and Fire Hazards
Toluene Spray
In the back corner of a tracked vehicle manufacturing facility there was an area with an overhead
track conveyor. An employee was using a spray gun to wash down or degrease parts for later coating
with primer and paint. The area was heated by an overhead natural gas fired forced air unit heater.
On entering the area a distinct odor of toluene was noted. When the worker was asked what he was
spraying he said he didn’t know but went on to explain he refilled the sprayer from “the big red drum
out at the back of the plant.” It was amazing to me there had not been a fire or explosion from this
practice.
Toluene Reaction
At another site of the same manufacturer a worker was washing parts in an open tank of toluene.
When asked if he got headaches or rashes he said “Is that what’s causing my headaches?” He also
had hands that were quite reddened and chapped. Needless to say many changes were recommended.
Methanol/Air
In a fairly large facility it was common practice to inject methanol into the compressed air line to
prevent icing and freeze-up in winter. The plant engineer felt that was okay and wasn’t concerned
about the potential for explosion.
When told that methanol can damage seals and other parts of pneumatic instruments this did not
convince him either. The health hazard of breathing vented air containing methanol didn’t help
convince him.
I was never able to convince Bill that he shouldn’t be adding methanol to air lines but should be
using a proper air dryer.
Ether
During a survey of a shopping centre, I entered the veterinary clinic in the north block. The vet
wasn’t busy so he toured me around his premises. When I asked “Do you use ether?”, because I was
concerned it might be stored in an ordinary refrigerator with a well known resultant explosion
hazard, he replied “No! I don’t have ether around here anymore!”
He then told me a story of his first year in practice. A lady had brought in her Budgie bird to have a
wart or growth removed from its leg. The vet carefully sedated the bird with ether until it lay quiet on
the table. He said without thinking further about it he picked up his little electric arc cauterizing pen
and went to touch it to the spot. He said the bird literally exploded in flame. The vet said he grabbed
a towel and used it as a fire blanket to snuff the flames. He said the bird was all singed because the
feathers must have been saturated with ether. The lungs must have exploded as well because the bird
died quickly on the table.
The vet said the worst part was having to explain to the lady that her bird was dead. He never
actually admitted to her exactly what happened. He resolved then and there to use a less hazardous
anaesthetic in future.
I explained that my concern was that he may have been storing ether for too long a time (which
allows formation of explosive peroxides) or storing it in a non-explosion proof refrigerator as that
had resulted in losses in the past. I had to explain this and remain as serious as he was at the time
about the whole incident.
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Sour Gas – two separate annual visits
A sour gas (containing poisonous hydrogen sulphide) separator building in northern B.C. had some
spaces under the wood sill foundation. When we opened the door of the building a rabbit ran out.
Since the rabbit was alive everyone figured it was safe to enter.
It was usual procedure to open both doors and wait for the wind to air the place out.
In a production area known as Bubbles the pit at one site was completely full of produced salt water.
Interestingly enough solution gas was bubbling up through the water in the centre of the pit.
The pit had overflowed in the past and you could see a strip of dead trees in the drainage ravine for
about one hundred yards.
Safety aspects have now changed to the point where a person wearing SCBA (self contained
breathing apparatus ) is required to do hazardous gas tests before entry.
However, in one case I know of a structure was declared safe. We entered although there was a slight
odor of hydrogen sulphide. I said “If it’s leaking from the same point it was last time we were here it
is the control case vent near the separator.”
The operator placed the tester near the vent and operated the pump. The tester went black
immediately and the operator yelled “Everybody out!”
We didn’t get to complete that survey. A work order was issued for repairs but the gas was no worse
than noted during a previous survey.
The attitude toward the hazard had improved to a great extent.
Asbestos
When touring some meter stations, some limpet asbestos insulation was noted on the ceiling of an
instrument room. There was a desk in the room and it was likely the operator was spending
considerable time in the area.
The operator was advised of the hazards of free asbestos fibres.
Some weeks later I received a call from Herb who wanted to know if I was the guy who had created
the big stir, telling the operators about asbestos.
I said I did mention the hazards of asbestos and had noted a desk in the room with a lunch box on it.
Herb then stated, “Well he shouldn’t be eating lunch in there!”
To this I replied, “Have you told him that?”
The answer was, “No but they knew about the asbestos and were working on it.”
They didn’t want to alarm the operators so had decided not to tell them. This would now be a clear
violation of OH&S (Occupational Health and Safety) standards but was common place for that time.
This was a little hard for me to understand. In this case letting someone work near a hazard without
telling them meant they could create an even worse hazard if they disturbed the material.
Corrective action was eventually taken to remove the material hazard.
I can also remember pointing out asbestos on piping and a boiler to a personnel safety advisor for a
company in the Swan Hills area and he said since I was working on the fire side of the survey I need
not mention it and he would take care of it.
I later heard a rumor their safety man had made big points for “discovering” the asbestos problem but
no matter -- at least the problem was corrected.
Before the hazards of asbestos fibre were well known I can certainly remember mixing asbestos fibre
with plaster to patch the insulation on the old steam boiler in our high school where my father
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worked as a steam engineer. Also, when I worked in a government laboratory we routinely used
asbestos gloves for handling hot materials and asbestos was routinely used in gaskets and hot pads.
Fire Extinguishers - Chemical
The hazard of accidental mixing of BC type and ABC type dry chemicals is referred to in National
Fire Protection Association Standard No. 10. This hazard has been encountered a number of times in
both production site and plant settings.
The hazards relate to the fact that ABC dry chemical is acidic (monoammonium phosphate) and BC
chemical is basic (potassium or sodium bicarbonate).
In the presence of even a small amount of moisture the chemicals react to release carbon dioxide
which can overpressure the shell of an extinguisher. The pressures are estimated to be in the region
of 800 psig (5500 kPa). There is of course no real hazard unless the chemicals are confined in a
pressure container such as an extinguisher since the gas can vent freely in the open.
In one plant, it was found that not only the hand units but the three hundred pound units had mixed
chemicals.
Dry chemical extinguishers must only be recharged with the chemical specified on the nameplate. To
alter the chemical or any component voids the listing or approval.
Nitrate Oil Mixture
During the review of a warehouse a number of bags of calcium nitrate were noted as being torn open.
Some was spilled on the floor and over wood pallets.
In the midst of this someone had been using a pipe threader and cutting oil had become mixed with
some of the nitrate.
A very careful cleanup was recommended. They were cautioned not to use any tools which cause
scraping or excess friction on the concrete floor.
Personnel using the nitrate for field fertilizer did not appear familiar with the fact it is a powerful
oxidizing agent and should not come in contact with oil or readily combustible material.
Potassium Permanganate
The well water at a rural compressor facility contained significant amounts of iron so
they had installed an iron removal system. This system was regenerated by using potassium
permanganate,
When an operator filled a plastic container with the purple crystals, he was surprised to find it burst
into flame. He quickly dropped it on the concrete floor.
An investigation was carried out. It appeared the container had not been thoroughly cleaned out and
some soap residue may have been present. A good amount of data on the hazards of potassium
permanganate and its reactivity was prepared for those at the station. The information was forwarded
to the site for their safety committee. The data was apparently discussed and filed.
On a tour of the same station six years later it was noted that someone had spilled permanganate over
some papers, cardboard boxes and a wood pallet in the warehouse.
The hazards were explained to the staff who seemed unaware of the potential. The site staff had all
changed in six years due to promotions and relocations. The information had not been brought to
their attention, in fact it could not be found at the station.
A copy of the original information was retrieved from our files and forwarded to the new group. The
area supervisor recalled the original incident when reminded.
At a later meeting when Dave was going to introduce me to the area supervisor
I said “Hello Bob” and Dave said “Oh you know him!”
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Bob said “Yes I know him and he has a memory like a f- - - ing elephant!” He was referring to the
incident six years earlier.
It is unfortunate but true that companies do not have long memories, only the individuals (who are
not there forever).
At a gas plant we found they were using a wood stick to break up lumps of permanganate in the
container. They said they even pounded on the stick with a hammer on occasion.
Sometimes you have to be somewhat wary of telling people about such reaction hazards due to their
inherent curiosity.
At a compressor station we were advised that the stain on the floor in the boiler room floor was
caused by accidental spillage of permanganate.
They were advised of the reaction hazards and told to make sure it never came in contact with glycol
such as contained in the boiler heat medium system or fire could result.
At our next survey of the station the staff said “You know what you told us last time about
permanganate and glycol?” to which I replied, “Yes” .
One fellow said “Well you were right, it takes about a minute to catch fire.”
They had mixed some in a small container way out in the yard to verify what I had told them.
They were told a person from B.C. had patented a device for back firing during forest fires. The
device consisted essentially of ping pong balls partly filled with permanganate. The balls were
injected with some glycol before being dropped from a helicopter. The balls would then burst into
flame shortly after hitting the ground.
Salt Bath Heaters
Salt Bath Heater Loss
John received a call from Don requesting a copy of a publication on Molten Salt Baths from the
National Board of Underwriters dated 1949. I was walking by his office at the time and heard him
say “No we don’t have it.” He then said “Just a moment.”
He called out to me asking if we had the publication. I said “Indeed we do, we even have the 1954
update.”
We were then asked if we would like to see the results of a salt bath heater loss at a gas plant about
one month previous. I expressed an interest in going and arrangements were made with Jan, the Plant
Superintendent. We checked in with the operators in the control room and headed out to the heater
area. The adjuster had been there in previous weeks and his report indicated it was likely a fuel gas
explosion.
As we rounded the end of the electrical and could see the heaters some distance away I said to Jan,
“One thing I can tell you right from here is that it wasn’t a fuel gas explosion.”
He said “What makes you so sure?”
I indicated the damage was far too severe for a fuel gas explosion so it must be a detonation.
There had been a wind baffle around the air inlet end of the heater which was blown away. The two
inch steel pipe support posts had not been bent over at the point where they entered the frozen
ground; they had been sheared off. Remains of the aluminum flame arrestor was scattered over a
wide area. There was a good sized hole out through the top of the heater opposite the air inlet end.
The fire tube had been blown open. The wall of the electrical building and metal aerial cooler
shrouds over twenty five metres away had been buckled by the blast. The half inch thick (12.7 mm)
bolt plate for the flame arrestor housing was located in the farmer’s field some four hundred and
thirty metres from its original location.
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Two Allan head screws from the heater light off and flame view port opening were found embedded
in the yellow jacket coating of a length of steel pipe about twenty seven metres in front of the heater.
The screws were partly flattened and the threads compressed in a mushroom effect. It was estimated
that the arc of trajectory was such that they dropped only about thirty centimetres (1 ft.) (if that) in
traveling the distance to the pipe. The screws were clearly moving like bullets.
Pieces of pipe and other objects were scattered across the plant site but amazingly did not pierce any
important equipment. One heavy piece of metal traveled either over or between an LPG sphere and a
condensate (natural gasoline) storage tank. There was a hole in one end of the gas tubes inside the
heater indicating a loss of regeneration gas circuit integrity.
As we returned to the control room Jan still wasn’t convinced and kept referring to my comments as
“your detonation theory”.
When we entered the control room an operator said to me, “Did you know one of these heaters could
explode like that?”
I replied, “Yes, if it overheats to a very high temperature and the nitrate/nitrite salts break through the
fire tube and come in contact with aluminum.”
His reply was, “Well I’ve been running those heaters for seventeen years and I never knew it. The
next time they ask me to check a salt bath heater I think I will use binoculars.!”
There had been no one near the heater at the time of the explosion and that was very fortunate.
It should be noted that this heater had been overheated at one time in the past. In that case the small
fuel gas bypass was found to be open. In this case when the bypass valve was located it was found in
the closed position.
Blocked Air Inlet
There are at least two other ways that very high temperatures could occur including the following:
This incident occurred during heavy blowing snow conditions and the air inlet could have become
partially blocked or choked resulting in soot buildup in the fire tube. If oxidizing salt leakage were to
occur it would contact hot carbon deposits in the fire tube.
The reaction between the hot carbon deposits and the oxidizing salt would create very high
temperatures. Once the temperature reached 1050 F it could destroy carbon steel such as used in fire
tubes fairly quickly.
Leak in Regeneration Gas Circuit
Secondly if a small leak were to occur in the regeneration gas circuit tube bundle the gas could
oxidize in the salt raising the temperature to the point where the hole would enlarge by oxidation of
the steel tube. In either case the normal temperature controls on the fuel gas supply would have little
or no effect on the end result.
Examination of the exfoliated arrestor fragments showed that some had reached the melting point
and others were still coated with the nitrate/nitrite salt mixture.
I discussed my findings with the insurance adjuster and he said whenever anyone else had any further
questions they would be told to contact our office.
This particular heater loss was considered unusual and it is fortunate that they are rare.
Weakened Steel Due to Overheating
A more common scenario for heaters is that when overheating occurs the steel near the middle
becomes weakened by the high temperature and the weight of the salt causes them to sag in the
middle like an old horse. This causes the inlet end to tip upward reducing the chance of salt leakage
reaching the aluminum arrestor. Often the sagging occurs below the temperature necessary for
detonation. To avoid the detonation potential it is possible to use stainless steel arrestors. If
aluminum is still the choice, then orienting the arrestor to minimize the chances of hot salt contact
will also help.
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Electroplating Plant
One of the plants on the survey list back in 1967 was an electroplating plant. Anyone familiar with
these facilities will know of the toxic and hazardous chemicals required in the processes.
I made a survey of the plant taking special note of the chemical storage including some stored near a
stairway leading up to a second level electrical room. I was to discuss any recommendations with the
manager who was familiar with the various chemicals they handled.
As we sat in his office we could see out across the plant through a plate glass window. As the first
item I said “See your chemical storage area out there by the stairway?”
He said “Yes”.
I then said “Do you see what is on the black drum beside that open black drum?”
He jumped up, departed his office and was across the plant in very short order. He picked up the lid
for the open drum, carefully placed it on the open drum, then slid the five gallon bottle off the top of
the adjacent drum and carefully moved it to a spot clear across the plant. He then returned to his
office where I was waiting and said “I came right past that spot on my way into the plant this
morning and it never even registered.”
He then said “Item number two?”
What we had been looking at was that someone had placed about half a glass carboy of sulphuric
acid on top of a drum of sodium cyanide eggs with a half used drum beside it. If the acid and cyanide
were ever to come in contact it would generate hydrogen cyanide gas which is exactly the
combination used in the gas chamber.
Chemical Laboratory
A very similar hazard but probably even more dangerous situation was noted in a west coast
chemical laboratory where the person in charge of the storage area thought it would be easy to find
everything if they stored it alphabetically.
It was pointed out that the glass bottle of cyanide was stored on a shelf directly above the glass
containers of sulphuric acid stored on the floor. In that case if a dropped bottle of cyanide smashed a
bottle of acid the results would be quickly fatal to anyone in the area.
Storing chemicals with due consideration for the hazards of reaction was recommended. In the
chemical storage area of a testing laboratory a can of anhydrous ether was noted. The broken seal
indicated it had been partially used so the lab technician was queried about the use of the ether.
The technician said it was only used on rare occasions and had been opened about a year and a half
to two years ago.
My recommendation was that they obey the directions on the manufacturers label.
The technician looked puzzled, picked up the container and read the label which said that due to its
tendency to form explosive peroxides any unused portion should be carefully disposed of within
thirty days. He had never read that part of the label.
A somewhat similar recommendation was made in an industrial housing manufacturing plant. They
were using turpentine for paint thinning and cleaning. They were leaving the soiled rags in a pile.
They were shown that the manufacturers clearly showed it was subject to spontaneous combustion.
They said they were aware of this property for linseed oil but were not advised it was also true of
turpentine.
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Incidents During Plant Surveys
Furnace Fire
During the survey of a steel foundry operation the tour guide and I had been standing in front of a
natural gas fired furnace. We turned and stepped a short distance away.
As I stopped to ask a question my attention was suddenly diverted. It definitely grabs your attention
to see your shadow outlined in flames on the wall in front of you.
An operator grabbed a wrench, rushed over and closed the gas supply valve like it was old hat. They
apparently did not have a high fuel gas pressure shutdown. By the speed and efficiency of the
operator this was not the first time it happened.
Aluminum Extrusion
While training a relatively new recruit to the underwriters organization I took him to an aluminum
molding extrusion plant. Before entering the premises I told Mike not to touch anything in process
because aluminum just below the melting point does not look much different than when it is cold.
About halfway through the tour I heard a ssst sound and turned to see Mike shaking his hand.
Unbelievably his comment was, “Well it didn’t look hot!”
He had touched a molding only about ten metres from the die of the extruder. Fortunately, he only
ended up with a blister on his thumb and index finger.
Hot Tubes of Heat Tracing
At one plant I saw two parallel three eighth inch stainless steel tubes that I thought were from a gas
meter orifice plate. They were vibrating rather vigorously. Thinking it was transmission from the
compressor I put my thumb on one of the tubes to dampen the vibration and see if it would restart
immediately. It turned out to be an uninsulated heat trace line and I pulled my thumb away rather
quickly. I was lucky and it didn’t even blister. The operator who was there then said “Oh by the way
we haven’t reinsulated all our heat tracing from the last turnaround so be careful.”
Nothing like stating what was now painfully obvious.
Icy Slip
Another time I was writing a note while walking as others had gone ahead a short distance to the
next building. I stepped in what I thought was shallow water on the concrete but under the water was
crystal clear ice on top of the concrete.
I ended up in an arched spread eagle on my hands and the toes of my boots. I never landed in the
water and didn’t get my clothes wet. I had bare hands and was able to get a little traction with my
fingernails. It was so slippery I was able to slide my feet up between my hands by arching my back. I
was then able to stand carefully and slide my way to the next building to join the others. They never
saw it and had no idea how close I came to getting soaked with very cold water. They didn’t notice
or didn’t ask how my notebook got so damp.
Fire Training
During the site tour of a foundry we came upon a fire training session being put on by the fire
extinguisher supplier. Staff members were being shown the proper use of a fire extinguisher. Their
fire was in a cut off drum containing solvent such as used for cleaning.
The supplier invited us to try to put out the fire. He handed me the extinguisher.
With about a two second burst I aimed and hit the far edge of the drum with the dry chemical. It
rolled beautifully snuffing the flame in an instant.
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One of the employees then said “(expletive deleted) pro!”
I never told him it was the very first time I ever used an extinguisher and was relying on what I had
learned from films on the subject.
Pit Fire
During our tour of a small gas plant, the operators had lit the on site open pit to burn off some waste.
A vehicle drove into the yard and out jumped a man putting on his white hard hat.
He was carrying a red book and I heard someone say, “I hope he’s not from the Board.” He was
from the Energy Resources Conservation Board and ordered the pit extinguished immediately. (He
had been watching from a nearby hill).
Two of the first three 30 pound extinguishers taken from vehicles malfunctioned and would not
discharge any chemical.
The fire was eventually extinguished with units brought from buildings in the plant.
They will likely be much more particular about maintaining their vehicle fire extinguishers in future
as that was obviously a little embarrassing.
Removed Hard Hat
One hot summer afternoon we were touring a plant when Tom, the safety supervisor I was with, took
off his hard hat inside the shop area to wipe the sweat off his brow and continued walking. He
promptly walked into the piping elbow of an overhead unit heater and banged his head.
He casually replaced his hard hat as other employees looked toward us on hearing the thunk.
We walked outside and headed across the yard as Tom said “After we get out here a ways I hope you
don’t mind if I yell, as that hurt like hell. I wasn’t going to let those guys know how much it hurt as
they wouldn’t let me forget it, if I took off my hard hat and walked into a pipe.”
Barrel Tipper
At a facility in 1980 a building unit heater of a type which was the subject of recall notices was seen
at a production building. Since we could not read the model or serial number from the floor our
guide Dwayne being the eager safety man decided to hop up on a horizontal barrel, which was on a
barrel tipper, to have a look.
Simultaneously with my saying, “Careful the barrel may be empty!”, he stepped more toward the
curved end of the barrel tipper. It started to tip up because the barrel was nearly empty.
He slipped off the barrel and landed on his feet in a crouched position, staggering backward to regain
his footing, which he would have done when he backed up against the wall of the building but he hit
an emergency release panel in the wall, (installed for emergency personnel exit) square in the centre.
He and the emergency panel ended up outside the building on the muskeg like ground.
After finding out he was okay, other than injured pride, I could not help but laugh. We refitted the
emergency release panel and completed the survey.
Dwayne was very concerned that I was going to mention the incident in my report to his company
but I assured him that would not be the case as we were supposed to confine our comments to fire
safety issues at the time. I am sure he warned others about the hazard of hopping up on horizontal
barrels, especially those located on barrel tippers.
Man Lifts
Man lifts in grain elevators should always be used with great care. Experience can be a great teacher
providing no harm is done.
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At Milk River I carefully balanced my weight with the various counterweights available for that
purpose. I released the brake and started up toward the head of the elevator. About half way up to the
top the man lift came off the tracks and swung sideways in the shaft.
By holding the rope and grabbing the side rails the platform was rotated back into position and
moved downward with braking control until it went back on the rails.
When I got back down to the bottom I advised the elevator operator what had happened. He just said
“Oh we must be getting full as when it loads up the rails bow and it comes off.” If you haven’
balanced the weight well it can be quite scary.”
I couldn’t agree more but was amazed he had not warned me at the start.
Humphreys
Humphrey (vertical belt with steps and hand holds) elevators used in flour mills and other industrial
occupancies should only be used after good instruction and supervision at least for the first few
times.
Many years ago while training Art at the old Robin Hood Mills, it was explained to him how to get
on and off safely. We started up the high section of the elevator on a humphrey which was in a
square open shaft. There were two belt elevators with a platform at the midway point because the
total height was something like one hundred and seventy feet which is too much for one stage.
When we stepped off on the platform half way up (about eighty feet) I looked at Art and he was
white as a sheet and so were his knuckles. We suggested he stay at the halfway point and wait for us
to come down and he readily agreed. On descent we stopped the lower level humphrey, letting Art
get on and hold the handle with both hands. It was started slowly and he descended to the bottom and
stepped off.
He was deathly afraid of heights and said he was never so frightened in his life as when he looked
down the open shaft from the eighty foot level half way up. In hindsight we should have asked him
first but he said nothing during the instructions of how to ride safely when we were at the bottom
looking up. As far as I know he never got on another humphrey elevator.
Snoopervision
One client with significant holdings in the U.S. sent their managers of loss prevention from two
different sites (Swede and Howard) up to Calgary to make plant site tours with us to see what we did
during the surveys. This certainly put the pressure on when you have two safety managers from the
U.S. as well as the local safety man (Larry) observing.
At their small plant the condensate (natural gasoline) loading spout was noted to be too short to
prevent hazardous splash filling during loading. A longer drop with proper end fitting was
recommended.
Swede then said “Well the trucker loads very slowly for the first half of the tank until the spout is
covered then increases the flow rate.”
This was a bit much so I turned and addressed others in the group saying, “Did you notice how he
managed to say that whole sentence and still keep a straight face?”
At this point Swede broke out in laughter saying “I wanted to see how much you would swallow!”
We both knew truckers are paid by how much they transport in as short a time as possible so they
usually flow full bore all the time.
The spout was later changed to mitigate the static hazard potential.
At the end of our surveys of their plants the managers expressed their appreciation for the job that
had been done. Swede said “We don’t get any good help like this from our broker representatives in
the States.”
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During follow up surveys either Swede or Howard made it a point to attend our surveys along with
the local representative.
Hydrogen Sulphide (Sour Gas) Inexperience
Respect Sour Gas
A company new to the sour gas industry had taken over a facility which was transporting gas which
was 30% hydrogen sulphide. Since additional facilities were being constructed on site a survey was
requested.
It became very apparent that they were not familiar with the properties or effects of sour gas. They
had brass or bronze pressure regulators, a copper base thermostat bulb, were using standard steel
studs and single valved solid piped sweet purge gas connections to mention some of the problems.
A report was prepared and submitted to the company Risk Manager.
A few weeks later the telephone rang and after stating my name, the voice at the other end said “Who
the hell are you and what are you doing in our facilities?”
I said “Excuse me, who’s calling?” He was so upset he had not identified himself or what company
he represented.
It turned out that Eric was the fellow who must have ended up with all the flak that resulted from my
report on the sour gas facility I had surveyed and he was to say the least not happy about this report.
When it was explained this was a confidential report between our company and his company and
would not be distributed to anyone else he came down a whole bunch of notches. After a 45 minute
conversation he seemed very satisfied that we were there to assist and to ensure as much as humanly
possible that employees return safe to their families each night. However, we did not get total
agreement to that level.
When visiting the same site two years later they had Glen in charge. He was very familiar with sour
gas, having lost a friend to it in the past. At first Glen was not going to let us on site until we donned
SCBA (self contained breathing apparatus). He was then asked if he could review the previous report
and I showed it to him. He said “Did you write that report?”
When I said “Yes I did” he became much more friendly and said he agreed with everything I had
said, but of course his comments were, “Unofficial”
During a follow-up survey another operator was our tour guide so I don’t know what transpired in
the interim.
However, I saw Glen across the yard at the site, approached him and asked, “How much pyrophoric
iron sulphide was in the catch tank on the site?”
He said “I’m not supposed to talk to you!”, but his horizontal hand about two feet off the ground told
me what I wanted to know.
Such are the tribulations of trying to be helpful. The setback or controversy couldn’t have hurt the
boss too much because last I heard he had risen to V.P. status.
I had carefully worded the recommendations to be advisory and not offend anyone or at least that’s
what I thought. This gave them room to respond saying we have checked industry practice and will
change or modify things to conform.
This property was later sold and as far as I know there were no serious losses or injury up to the time
of sale but all recommendations hadn’t been completed either.
Dented Cab on LPG Tank
During a mid-winter survey of a large gas plant in west central Alberta one of the operators drove me
out to the LPG storage tank area. After looking around at the facilities at least as much as you can
with deep snow conditions, we got back in the vehicle.
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The operator was attempting to turn the truck around in the deep snow and was rocking it back and
forth. In reverse the tires apparently went through the snow cover and grabbed on the frozen gravel
below. The half ton shot backward and as he braked there was a slight thump. I looked back to see a
dent in the cab behind our heads. The box had cleared the belly of the tank but the cab made contact
with the shell.
The truck was returned to the shop area.
I have no idea whether the incident was reported or if the smoothly rounded dent was ‘discovered’ at
a later date. However, you would think the tire tracks in the snow would have been a giveaway
unless the wind covered them in before anyone else saw them.
High Pressure Gas Cylinders near Fired Heaters
In 1991 a refinery site in Ontario was being surveyed with Willie. It was noted that high pressure gas
cylinders were secured to the concrete legs of fired heaters with nylon support straps.
Since heaters are a common source of fire from tube failure Willie wondered how they could have
missed that point during their surveys, especially the potential rocketing hazard to a responding fire
crew.
Hopefully they now have a safer place to locate their high pressure gas cylinders with steel support
straps or chains.
Extension Cords
During the survey of a large greenhouse operation we came across the twelve gallon per day water
still which was used to supply water for coffee and drinking water.
It was plugged in with the use of an extension cord.
Most ordinary extension cords are not designed to carry the amperage necessary for a distiller of this
size so it was carefully checked and found to be quite warm ,especially at the connection point
between the two cords.
I said to Reid “Here, touch it for yourself.”
He looked apprehensive and made some comment about not wanting to get burnt. He was assured it
wasn’t hot enough to burn or I wouldn’t have suggested he touch it. We did agree that direct plug-in
to a base receptacle was required for the still as heating problems only get worse with time.
I recall getting my fingertips burned by an extension cord when I was a teenager.
I had placed my hand on a moulding at the edge of a doorway. An extension cord had been run from
a plug-in along the outside edge of the moulding up and over a doorway and down the other side to
an electric kettle. The rubber cord cover got so hot by the time the kettle boiled that it was sticky to
the touch.
I had not even realized the cord was there until I touched it and got burned. I have made it a point to
check extension cords in high amperage service ever since.
In that case the cord heated up each time the kettle was used and cooled after it was disconnected. It
had been in service that way for some time.
Incandescent Bulb Supports
In greenhouse operations with fluorescent lighting there is a need to supply red spectrum from
incandescent bulbs. In one case this was done with a black and white twisted wire pair with drop or
pigtail sockets at intervals. The black and white wire ends were knotted then tied, in one case by a
fibre cord and in the other case a wire, then tied to the structural steel of the building for support. The
wires were open ended and had not even been taped or marred off. The support for the entire
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assembly was by tension on the current carrying wires. I don’t think Brad was too impressed with
this arrangement, especially when you consider the amount of watering and water misting that goes
on in a typical greenhouse.
Plastic Fire
A greenhouse operation had a close call but was successful in extinguishing a fire that started when
plastic air ducting ignited on incandescent light bulbs. Some of the lights had been fitted with
aluminum pie plate reflectors while others did not have any.
The potential hazard of the situation had been pointed out to the client at the time of our survey a few
weeks earlier but there had apparently not been enough time to implement the necessary changes.
Plugs Missing From Hazardous Area Boxes
A look through an inlet gas header building at a natural gas processing plant showed that both light
switch boxes located at either end of the building were missing bottom plugs negating their
explosion proof design.
An operator indicated the switches had been in use for at least three years. He appreciated the fact
that every time they operated the switch “It would be like striking a match in there!”
There was a realization that any hazardous concentration of vapor had not been at the switch at the
same time the switches had been operated. They felt fortunate that no explosion had occurred over
the years.
Proper plugs were promptly installed. Comments were made that they thought the electricals had all
been properly checked at the time of installation and approval.
Furniture Plant: Fire Protection Attitude Change
While working for what was previously known as the Canadian Underwriters Association I was sent
to inspect a furniture manufacturing operation. The contact person was less than enthusiastic about
loss prevention.
When I arrived there it was reflected in the housekeeping. He had no interest in testing or checking
any of the fire protection equipment including their Tyden Viking automatic dry pipe sprinkler valve.
Months later a fire occurred in the basement area and I was sent to investigate. Cardboard boxes and
other combustibles piled up near the waste incinerator had fallen over against the exposed metal part
of the operating incinerator which was hot enough to ignite the boxes. This incinerator was located
very close to the stairway which was the only exit from the basement woodworking operations.
The windows all had security bars across them on the outside. The fire developed very rapidly and
caused the operation of at least twelve automatic sprinkler heads. The dry valve tripped and the water
knocked back the fire to where they were able to finish extinguishment with a hand held
extinguisher.
On a return visit a few weeks later the housekeeping was excellent and the whole attitude to loss
prevention had changed. The person I usually had to talk to told me he had been in the basement at
the time of the fire and probably would have perished if the automatic sprinkler system had not
functioned correctly. It was never any problem checking fire protection after that incident and
housekeeping was always good at later surveys.
Glycol Regenerator Condensate (natural gasoline) Carryover
The evening before a scheduled survey a telephone call was received asking if postponement of the
survey was possible. We advised that it was part of a prescheduled multi location survey tour with
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the company aircraft that it had to be done on schedule provided their indicated problem was not too
serious.
When we arrived at the plant, across the yard I could see the glycol reconcentrator which was
obviously blackened and had been on fire.
I said to the operator “I see you had a condensate carryover into the dehydrator reconcentrator.”
The operator looking somewhat self conscious said “Yes, Has that happened before?”
I assured him it was fairly common and he seemed somewhat relieved to know his situation was not
unique and he should not be embarrassed about it.
It appeared likely that a sticking dump valve had caused the problem. He had not had it happen
before and thought he had done something wrong.
Years later I was at a plant when the still column vent on a reconcentrator started spewing
condensate but the vent was far enough away so that it did not catch fire before corrective action
could be taken.
Cable Exposure Hazards
At a methanol plant a new utility type metal shed was noted as having been installed since the
previous survey. The shed had been carefully installed on a concrete base pad. It was about half full
of glass bottles filled with methanol, all labeled as samples to be retained to verify purity of shipped
product in case they were needed for future reference. The glass bottles were necessary for reasons of
purity.
At the end of the survey the recommendations were being discussed. Mention was made of the
plant’s new sample storage shed.
The Plant Manager Ed said “What do you think of it?”
The answer was that it was of noncombustible construction on a concrete base and was fine until I
stood outside and looked up.
The Manager thought for a second and said “Oh you looked up!” There was a short pause and he said
“It will be moved!” The shed had been installed directly below the main cable and control runs
between the control building and the plant.
At the next survey the concrete pad was all that remained.
At a main compressor station site some large diesel fuel tanks on creosoted wood supports were
noted directly beneath the main cable runs. Some diesel leakage was evident. This arrangement was
temporary but represented a significant exposure potential. A wood frame enclosure with an electric
heater for keeping welding rods dry was also noted below the cables at that same site.
A sour gas processing plant had a diesel fuel tank under important control cable runs. In this case the
tank was on angle iron supports stabilized by a length of small cable between the tank and the
building. The sight gauge was an open ended plastic tube with the open end secured up to the support
cable between the tank and building by a length of wire.
In one plant a waste dumpster was located where it caused exposure to control cables. It was set up
so the waste pickup truck had to lift it slightly off the ground then back up before it could be dumped
so the dumpster would not hit the overhead control cables. It then had to be replaced using a reverse
procedure, an obvious potential for operator error. In addition, fires in waste dumpsters are fairly
common. It was recommended the dumpster be relocated.
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At a straddle plant, a propane fueled barbecue was located below important cables from a well
separated control structure and it had been used in that location. The exposure was greatly reduced
by moving it around the corner of the building which was actually a preferred location since it was
better protected from the prevailing winds.
Fire Detection
It is very logical to incorporate automatic fire detection into a safety shut down system for a plant
and this is the usual arrangement at most facilities.
At a heavy oil facility the operator was asked what sensitivity the detection modules were set at to
effect shutdown. Was it twenty five , fifty , seventy five or one hundred counts per second on the
ultraviolet detectors? To this the operator replied, “How do you tell?”
He was advised you can tell by checking the jumper wire on the internal circuit board but not to do it
until the system can be bypassed or jumpered out as pulling the module would likely cause a
shutdown due to fail safe circuit logic. He said he didn’t think so and it was merely an alarm
function.
He pulled the module to the sound of many alarms functioning as the pumps shut down. Other
operators scrambled to restart the pumps after the module was plugged back into the connections.
He then doubted that pulling the module had caused the shutdown so he pulled it out again to verify.
Everything went into crash shutdown again. When we came back through the control room the
operator who had caused the shutdowns was busy with the Dymo label maker. The tapes said
“Warning, pulling this module causes emergency shutdown!”
Need for Two Exits
Strong support for the idea that all compressor buildings no matter how small should have two exits
occurred at a site in the Brooks area.
During startup of a natural gas compressor a valve opening to atmosphere on the gas inlet line had
not been fully closed. This fact as well as an improper start sequence allowed air to be sucked in and
mixed with the gas.
The mechanism of ignition on the discharge side of the compressor was not certain but in any event
there was an explosion in the discharge line and outside at the gas cooler header. A chunk of the gas
cooler head blew off hitting the tubular pipe rail adjacent to the personnel door with such force it
bent the handrail over in front of the door so that exit from that door was not possible.
The second exit at the far end of the building remained operable. This loss pointed out that it is
almost impossible to predict some of the strange things that can occur.
Hollow Aluminum Pistons
Speaking of surprising things, a young welder eager to show his skills saw a damaged piston that had
been taken out of a propane compressor. He said he could rebuild it so that it could be machined for
use again. At first the plant person told him not to bother but eventually gave in and let the welder
take the piston to his shop.
When the welder started working on the hollow aluminum piston it exploded with such violence that
he was killed. The propane had migrated through the porous metal when it was in service under
pressure and a dangerous amount had remained in the hollow in the piston even after it had been
removed and stored for some time.
A large plant was made aware of the hollow aluminum piston hazard so they decided to cold drill a
hole to vent any gas before working on one of their large hollow aluminum pistons.
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The worker was clad in protective gear and face shield and positioned himself to minimize exposure
from any vented gas. When the drill broke through to the hollow core a jet of gas was emitted. The
protected worker was not injured.
This is a job best suited to robot operated equipment.
Powder Driven Studs
Arriving at a compressor station, the operator was busy directing some contractors doing both field
and plant work so he asked me if I would mind looking around the site on my own and I said “No
problem, I’ll discuss anything I find when you have a minute later.”
In the compressor building there was a man in the floor trench working on some electrical conduits
as I walked around looking at other items. Suddenly, there was a Bang! I caught a flash of fire out of
the corner of my eye that made me jump even with the noisy compressor in operation. The electrician
was using powder driven studs to attach the supports for the conduits to the concrete side of the
trench.
I finished my survey of the compressor building as well as the other structures and went to the little
office where the operator was working.
While discussing loss prevention recommendations I asked about the issuance of a hot work permit.
The operator said that only cold work was being done on site.
I said “But the electrician is using powder driven studs in the floor trench!”
There was a very loud “What?!” as he took off out the door headed for the compressor building.
He was not even aware that the electrician had a powder driven nail gun.
Bolting
Many cases of poorly bolted flanges have been noted over the years. Loose or missing flange bolts
obviously raise a concern with respect to procedures for adequate stud preloading to assure leak free
joints.
It has been said that about eighty percent of the benefit of a loss prevention survey is achieved
shortly after arrangements are made with the operators so they know you are coming. They then go
about correcting deficiencies they otherwise seem to busy to look at in the daily routine.
It is of interest to note that operations personnel don’t seem to regard those in waterflood reinjection
lines as being as serious as those in gas service.
A jet of water at high pressure can cause serious injury the same way as hydraulic fluids by
penetration of the skin and flesh. Produced water often contains both salt and hydrocarbons.
Loose or Missing
One of the most astonished looks noted during surveys came when I leaned over toward a relief
valve normally retained by four studs, lifted one out and showed it to the operator. There was no nut
on the stud on the bottom side of the flange.
The other three studs were holding the 800 psig discharge pressure. A mechanic was summoned and
corrective action taken immediately.
There were some amazed looks when a pen was poked through an empty stud hole on the suction
flange of a reciprocating compressor which was in full operation at the time.
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When I found where a stud was missing at a piping flange attachment to a vessel, one operator
looked at the other and said “How come we didn’t see that yesterday during our tour?” This let me
know they were trying to stay at least one step ahead of us.
Compressor Station
At a compressor station the operator was very upset when we found a twenty four bolt explosion
proof electrical box under a floor plate with all of the bolts just standing loosely in the holes. They
had been operating that way for two weeks. The operator became downright upset, when on the
opposite side of the unit a space could be seen between a nut and a flange of the starting gas valve.
The operator then ordered all studs in the area be checked for proper torque before restart of the unit.
Hot Regeneration Gas
In 1974 we found an eight bolt hot gas flange on the side of the condensate stabilizer where all eight
studs were only engaged in the nuts by about the width of a washer. This hot gas line provided reboil
heat to the stabilizer so was quite hot. The operator was in a bit of a quandary as to whether he
should shut down the plant immediately or not. As far as I know it was upgraded later during a shut
down, as we strongly discouraged his first idea of doing one stud at a time while the flange was still
pressured.
High Pressure Gas Re-injection
Previous to a follow-up survey of one of the Brazeau plants we were given assurances that all items
from the last survey some three years previous had been completed, including correction of a very
badly secured four bolt flange on the discharge of a 3000 psig reinjection gas compressor.
The person who gave the assurances , because he had been advised by others, conducted the tour.
The compressor building was very noisy so voice communication was well nigh impossible.
The badly bolted flange which was the same as previous was merely pointed out to the operator. I
could lip read well enough to know he said “Holy (four letter expletive deleted)!” He was stunned to
realize that anyone would leave such a high pressure flange so poorly secured.
Later, I asked L.M. who was with us on the tour if she could read the operator’s lips when the flange
was pointed out. Her reply was “No!” to which I said “Good”.
Pressure Safety Valve
In 1994 at a central Alberta facility the contract turnaround crew had finished their job in September.
At the time of our tour in November one of four studs on the flange of a pressure safety valve for the
second stage discharge of the compressor was loose. In fact it was so loose that when the operator
touched the top nut the stud fell into the floor trench. The operator who was also the mechanic and
record keeper took immediate action to correct the situation.
However, the unit was not shut down during stud reinsertion and tightening. Pressure in the line was
over 800 psig.
This shows the pressure some people feel to maintain production no matter what.
Vibration Loosens Nuts
A back seated valve under the belly of an LPG tank had been subjected to so much vibration
transmitted from a pump that both packing stud nuts had fallen off. One was on the ground and the
other was stuck beside the valve stem in the yoke.
The nuts were replaced and tightened before the valve was operated.
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Painted Bolt Hole
At a mobile compressor station site a stud was noted to be missing on an eight bolt flange of a
pressuring line. Closer inspection revealed their summer student painter had even carefully painted
the inside of the bolt hole so there was no spot for rusting to occur.
When I showed this to Andy he said “Know what, I think you see everything the first time you come
around but you save a few items to show us the next year.”
I denied this of course and said “I probably had missed it on the previous tour simply because I like
to take a slightly different route each time and wasn’t at the right angle to see it before.”
Shaved Studs
At the point where a large multi-bolt flange connects to the suction side of a large centrifugal
compressor there was something I could not at first believe but closer inspection confirmed my
observation.
The assembly crew had found it impossible to get the flange bolts in place in the tight confines of the
working space so they shaved the studs so they could be slid in on an angle. This was visible because
the studs no longer filled the nut openings of at least four adjacent studs. This was put in the report
but after review by engineering they have made the decision that no changes are necessary.
Design
A logical review of drawings can prevent serious errors from occurring. Changes can be much more
expensive to make after a plant is complete. In fact changes may not even be practical after a plant is
complete.
Sometimes it is merely a failure to envision what actually happens in practice.
Standpipe Feed, No Back Check
An example was the installation for a standpipe and hose system at the Chinook Shopping Centre.
The usual fire department connection had been installed but no back check had been installed in the
normal water supply line to the system.
If the fire department had attempted to use the connection the higher pressure pumper discharge
would have flowed back out the normal supply line back to the yard main and back to the pumper
truck suction. This problem was not corrected until after our survey when the system had been in
service for a number of years. The system had been installed exactly as shown on the drawings.
Inexperience
Some problems have occurred when recent graduates eager to prove themselves have decided there
was no need to consult with others with more experience. A decision was made to review and
approve drawings without consultation. A case in point was that of a young engineer who reviewed
and commented on drawings of the contracting firm. It was a very important facility and when
construction was completed it was then decided we should be called in to review their facility, I
suppose to see just how well he had done the job.
When we entered the facility he advised us that would not find anything wrong because it had been
built with his input. The bottom line was that it took many thousands of dollars to correct
deficiencies and code violations. It also took years of scheduling so as not to interfere with the
operations of the facility. Costs had to be borne by his company (i.e. his employer) since construction
signoff had already been completed. At the time the engineer did not seem all that concerned about
the result.
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Gas Plant Layout
Layout and spacing of equipment is a design feature which is very beneficial in controlling the extent
of most potential losses.
A three unit compressor building was totalled but the process building some thirty metres (100 feet)
distant suffered no damage. Separation of compressor units into their own buildings can further
reduce loss potential as well as facilitate maintenance and safety.
Fire Pump Exposure
People who have been in the natural gas processing business for a time know that explosions and
fires are more common in compressor buildings. Imagine our surprise to find the plant fire pump
midway between two natural gas compressors in one compressor building. The pump was relocated
at considerable expense.
At first some of the senior engineers’ reaction was, “A fire pump in the compressor building? Come
on! get out of here, you are making this up!”
This may be one of those cases where truth is stranger than fiction.
Drawing Review
Drawing review may turn up items which are obvious mistakes and these should be carefully
documented and corrected as it is likely that construction supervision will see to it that plans are
followed to the letter.
A conversation with a tour guide at a new facility in the Stettler area went something like this, “What
is that valve for?”
Tour Guide “I don’t know, I’ll ask the foreman!”
Foreman “I don’t know but I will tell you one thing; if you close it you will create a hazard! I will
ask the Construction Supervisor.”
Construction Supervisor,“I have no idea but it was on the drawing so I put ‘er in!”
Tour Guide “Tell you what; it won’t be there next time you come here!”
The valve was on a gas compressor crosshead drain line to an underground tank teed into the engine
crankcase oil drain line. Closing the valve could have caused back pressure in the distance piece of
the compressor from any packing leakage.
Relief Valve Setting
While reviewing drawings a colleague found that a pressure relief valve setting was shown as twice
the design pressure of the vessel it was designed to protect.
Jack found it had been installed exactly as indicated during his field survey!
Missing Valve on LPG Tank
While discussing fire control measures at a small plant the operator was asked if there was a back
check at the LPG tank to prevent reverse flow to the process area in the event of fire in that area.
The operator was new to that facility and said he didn’t think so but we could go out to the tank and
look. He indicated he would likely have to close the tank valve.
I will always remember his look of dismay when we got out to the tank area. There wasn’t even a
valve at the tank!
He turned to me and said “All tanks have valves don’t they?”
At the next plant turnaround the system was drained and the valves were installed.
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Design had probably saved money by not installing a valve but this meant that a large volume of
liquids would have been able to reverse flow into the process area in the event of a break in the
piping in the process building.
Two Losses in the Same Building
Proper design management of seemingly small things is very important as evidenced by two losses in
the same compressor building within a six month time frame.
In the first loss a valve cover on an Ingersoll Rand compressor split. The valve chair adjustment
screw and lock nut were ejected resulting in an explosion and small fire.
A decision was made to check to see if liquid carryover from the suction scrubber was part of the
problem. A high pressure reflex style sight glass was attached to a threaded nipple under the suction
bottle of the compressor.
Due to the pendulum effect of the heavy sight gauge and the vibration from the reciprocating
compressor the nipple failed at the thread roots due to fatigue. This gas release resulted in a second
explosion and fire.
Fortunately no one was hurt in either case, if you discount pride.
A design review would probably have identified this arrangement was not a good idea, especially in
vibrating service.
At the time of the first loss someone had called the local newspaper reporter about the explosion,
telling him the compressor building had exploded. The reporter arrived at the plant to see the
superintendent to ask about the exploded compressor building.
The superintendent took him outside the office, pointing to the compressor building some distance
away and said “Does it look like it exploded to you?”
The reporter left thinking he had bad information but obviously did not notice the west wall sloped
outward toward the base. The entire back wall and part of the backside roof had been blown out and
were lying on the ground to the north of the building on the side away from the office but Andy was
not about to discuss it with the news media.
Bullseye Sight Gauge in Propane Service
Bullseye type sight glasses were noted in the propane accumulator in the process building. There was
no means to isolate them in the event of a crack or failure. You could look in and see the waves and
ripples in the liquid propane.
When the operator was asked what he would do if one of the sight glasses were to leak or crack he
started looking at the piping for isolation valves.
I then said “Hold it. I have a suggestion!”
He said “What?”
I replied, “If that ever happens there is so much liquid propane holdup that you get out of here as fast
as you can and maybe drive to town for coffee!”
He then said “That’s what I’d probably do!”
He was told no chunk of iron is worth risking your life for.
When this particular design feature was being reviewed with Hank and a group of design engineers,
he loudly announced that everyone designed them that way (i.e. with bullseye sight gauges).
It was the only time in my career that I said “BS!” right to a client’s face.
You could have heard a pin drop in the meeting room for a few seconds. He then said he would
telephone other companies to check it out. I told him he should do that.
At the next shut down the vessel was removed, shipped to the factory, fitted with reflex style high
pressure sight gauges and reinstalled at the plant.
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The next time I saw him on the street in Calgary Hank said “Hi, how are you doing?”, like an old
friend. I always suspected when he checked with other companies that the responses he got on his
design feature were less than favorable but he never said.
Criss-crossed Heat Exchanger
At a compressor station the operator and I were looking at the fuel gas heat exchanger near the end of
the day. It appeared that something wasn’t right but I mentally rejected someone had screwed up as
badly as it appeared. It looked like the fuel gas exchanger had been hooked up completely
backwards. It was late in the day and we didn’t pursue it any further as I knew the company was in
the process of reviewing the whole heat exchanger safety and isolation valving on a company wide
basis.
At the time of the following survey the operator I had toured with previously came up to me and said
“Remember, you didn’t think anybody could screw up that badly? Well they did including the
drawings!”
It was installed exactly as per drawings. High pressure gas at 840 psig. had been connected to the
shell designed for 150 psig. and tested to 225 psig. The glycol/water
was flowing through tubes designed for 1000 psig. and tested to 1500 psig. The glycol/water pressure
was normally 15 psig.
The operator said “the man who came to install the automatic valves just about backed up through
the wall when he saw how it was connected.”
I felt somewhat embarassed that I had not followed up the first time especially since the operator
reminded me of what we had discussed.
Gas Release and Loading Losses
On viewing the glycol reconcentration unit, it had no flame arrestor for the combustion air inlet and
was totally enclosed in a small building. I said “I don’t like this because if you have a gas leak in
here it will go into the burners and explode!”
Earl indicated it would be too expensive to change now. The natural gas condensate loading spot was
immediately outside the dike. It was indicated that insurance underwriters preferred it be located 100
feet (30.6 metres) away.
Earl again said “Well I can’t change it now!”
Within a year of commencement of operation two operators were in the reconcentrator building and
had connected a flexible hose to the fuel gas knockout drain. They were blowing off liquids with the
hose out through a hole in the wall. When the fluid was gone and the gas pressure started the hose
whipped back through the hole in the wall and started flailing around inside the building.
Instead of a ball valve it was an open stem and yoke type so before they got it closed the gas ignited
off the reconcentrator burners. The resultant explosion blew the walls off the building. Since the
weather was cold the operators had on heavy clothing and parkas. They received relatively minor
flash burns to the face.
The design changes were made and equipment deficiencies corrected.
Compressor Station Loss – Pendulum Effect
Loss information I was privy to but did not investigate personally involved a multi unit compressor building. An explosion blew out many of the external metal panels. A jet fire from
the leak source caused some further damage.
An automatic shut down system consisting of fusible sprinkler type plugs on the pneumatic
instrument system operated satisfactorily.
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The source of this loss was the failure of a nipple at the thread roots where a half inch connection
was made to the compressor discharge bottle. A heavy OS&Y (open stem and yoke) valve provided
the weight or pendulum effect to precipitate the fatigue type failure. The loss emphasized the fact
that only flanged and welded connections should be used where a substantial amount of vibration is
expected.
Petrochemical Plants – Flare Knockout
In preconstruction meetings for an olefins production facility Lloyd noted that the flare drum was to
be constructed of carbon steel. A stainless drum suited for use at very low temperatures was
recommended due to potential carryover of flashing liquids. The reply was that since there were
properly designed wet and dry knockout drums upstream of the flare drum this recommendation was
an unnecessary expense.
Plant designers and constructors treated the concern of possible carryover with a certain degree of
derision, and installed an ordinary steel drum.
After operating a number of years through a number of upsets, a crack appeared in the flare knockout
drum. The crack reached over one metre in length and in one area up to one centimetre in width.
There was a great scramble to keep the plant in production.
The crack in the drum was squeezed back together with steel tensioning bands and wood blocks
placed on either side of the crack to maximize pressure at that point.
A new stainless steel flare knockout drum was hastily fabricated, shipped to the plant and installed.
Acetylene Reactor
Another concern raised at the original design meeting for this olefins facility was that of the
possibility of an acetylene reactor runaway. The designer felt that since there were six levels of
temperature sensing there was no way this could happen.
It was pointed out that such a runaway had occurred in an overseas plant.
The designers then stated the plant operators could not have been very competent. Well, you
guessed it; this new plant also had a reactor runaway after some years, fortunately with relatively
little damage. I happened to be at the plant at the time.
So, do you think the original author of these concerns was ever officially contacted and told his
concerns were well founded?
Heater Layout
In the layout of plants the fact that fired heaters are an ignition source appears well known and
recognized. Large heaters are usually spaced at 30 metres (100 feet) or more from major hydrocarbon
potential leak sources.
What is not well recognized is the need to separate heaters from each other. In some plants where
there are multiple heaters there may be two heaters in one service to improve reliability. The benefit
of this feature can be lost if the two heaters are placed side by side.
A natural gas condensate heater suffered a tube rupture and fire during winter conditions. A wood
frame and plastic hoarding was installed to facilitate refractory repairs under the proper temperature
conditions.
During repairs, the second heater (which was being fired hard to maintain as much production as
possible) also blew a tube. The resultant fire burned off part of the wood frame and plastic hoarding
of the heater already under repair.
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Two vertical petrochem style heaters were in service adjacent to one another in a gas plant when one
was damaged by a tube rupture and fire. The contractor was asked to repair the heater while the
adjacent heater remained in service.
He stated, “You want me to have my people inside this heater while the adjacent heater remains in
operation? I don’t think so!”
The net result was that a whole new heater was built some distance away from the operating unit.
The previously damaged unit was eventually dismantled when the nearby heater could be shut down.
The plant now has two well separated heaters.
Tanks and Their Venting
Explosion with No Warning
Lack of consideration for proper fire exposure venting is one of the most common deficiencies noted
in field facilities.
Sealed drums of oil located inside gas process or compressor buildings present a serious threat to any
person attempting fire control since they explode with no warning. It is not unusual to find drums or
drum heads fifty yards (46 m) or more from their original location after they have been involved in
fire.
Advice given to personnel has been that if they know drums, sealed or poorly vented containers are
involved in a fire they should stay well clear of the area.
Missing Building
A field operator went out before sunrise to check on a small field facility. When he reached the area
where he knew the facility was located he was surprised that he could not see it. As dawn progressed
he could see what he knew to be part of a metal building near the farmer’s fence.
Investigation eventually revealed that a glycol injection line had failed near its point of entry into the
main process piping. The injection line had not been fitted with a backflow prevention device to
prevent the escape of natural gas. The gas jet caught fire and the jet flame impinged directly on the
250 gallon (1000 L) glycol tank.
The tank was of substantial construction, with flat sides, a rounded top and bottom, and flat ends, a
type often used for fuel oil storage. It had only a ¼ inch (6.3mm) breather vent.
The vapor generation from the jet flame on the tank could not escape through the small hole and the
tank ruptured with such violence that the structure and much of the equipment was blown away.
There was a rush program to check other company facilities to see if fire exposure venting had been
considered in the design.
Exploding Kerosene Drum
I watched from our downtown Calgary office when a drum of kerosene located in the on the
Stampede Grounds exploded producing a red hot mushroom cloud of flame that made people back
away from the windows.
Unacceptable Application of Pressure
Sometimes tanks that were never designed for pressure are exposed to pressure either intentionally or
accidentally. In one compressor building the transfer of bulk lubrication oil was facilitated by adding
compressed air to the tank vapor space (at one time a violation of the Alberta Fire Code but no
longer), to force oil out through an overhead line. The pressure had caused the tank ends to bulge and
the sight glass deflection snapped the sight glass.
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The response to this was to use plastic tube which would curve as the tank ends deflected. (Operator
Ingenuity?)
We expressed concerns about this arrangement for reasons already cited as well as the fact that
someone needing to refill the tank might forget the tank was pressured and remove the fill cap.
At this point in the conversation one operator looked over at the other and said “Oh we have already
done that!”
It must also be evident that fire exposure venting was not considered in this design.
Oil Transfer By Air Pressure
Another case, on a much smaller scale, of oil transfer by air occurred at a flour mill. An employee
was using this method to transfer lube oil from a standard steel drum out through a small line into a
container. The air pressure was supplied through a tee arrangement with one of the ends normally
open. The operator put his thumb over the open end of the tee with the apparent reasoning that the
drum would not overpressure with just thumb pressure.
In this case the pressure built up until suddenly both ends bulged. The drum jumped about three feet
(1 m) in the air jerking his hand off the connection releasing the pressure. The drum did not fail
completely and missed his feet when it came back down to the floor so that he was only startled. He
was surprised to learn that a person’s thumb over a half inch hole can easily hold back sufficient
pressure to rupture a drum. Again, the hazard of this procedure as well as the use of non inert gas
were lessons to be learned.
Ruptured Roof Seam
A serious fire occurred at a large gas plant from the rupture of the roof seam of an absorption oil
tank. Fortunately, the tank was designed using the weak roof to shell seam concept outlined in API
(American Petroleum Institute) standards. The roof of the tank returned to earth about fifty metres
from the tank. The roof was folded neatly in half with the appearance of a closed clam shell.
The bulk of the oil having characteristics approximating diesel fuel remained in the tank and burned
for some time.
We were advised that the operator seeing what he thought was an unusually high oil level in the
process vessel was dropping the level by manually dumping the liquid to the storage tank. There had
been a process upset and what he thought was absorption oil also contained considerable amounts of
LPG (liquefied petroleum gas).
When this liquid entered the tank the LPG flashed to vapor. The two inch (51mm) gooseneck vent
pipe could not handle the vapor pressure at the tank design pressure and the roof to shell seam failed
launching the roof skyward.
The flashing vapors flowed downhill to the fired heaters and ignited. The resultant fire damaged
much of the pumphouse and surrounding equipment. The location of fired heaters downslope from
where heavier than air vapors could escape is another point worthy of design change to avoid
ignition potential.
At another plant we had advocated removal of a similar tank from the process area for a number of
years but without much success. A few months after learning the circumstances of the above loss
because of joint venture participation the tank at this plant was removed from the process area block.
Bulged Diesel Fuel Tank
A diesel fuel tank in a high rise office building was bulged due to overpressure when it was
overfilled. By the time fuel exited the tank vent pipe, the pressure from the column of fuel was
enough to bulge the tank. Fortunately, it did not fail completely and the tank did not leak.
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This potential problem is identified in required codes but had not been picked up in the design or
installation. The height of the vent pipe has been lowered to ensure this will not happen again. The
original tank with its bulge remains in service.
Drums Are Not Pressure Vessels
On more than one occasion drums containing solvent dispensed by valved dip tubes with air pressure
applied to the vapor space have been noted during surveys.
In one case a relief valve was provided on the air supply with the setting at 15 psig. (about 103 kPa).
A reminder was issued that drums are not pressure vessels and many cannot withstand that pressure.
Tank Roof Rupture
After a second asphalt tank roof rupture at a refinery near Calgary we attended with the adjuster in
the afternoon for a review of the possible causes. The two tanks had partially separated roof to shell
seams. The two instances some weeks apart were very similar with very similar results. The effects
were like steam was generated in the heated tanks.
Hot product was designed to pass through a heat exchanger to limit temperatures so that steam
generation should not be possible. A review of the as built drawings showed this to be the
arrangement.
When the contact person at the refinery was asked if there was an exchanger bypass he said “No!,
There is nothing on the drawings.”
When he was asked if he had physically gone out into the plant and checked to see, he became angry
at the suggestion their as built drawings did not show everything.
It was now late in the day by the time the drawings were reviewed so Grant and I said we would
return the following morning.
Upon returning in the morning the refinery man seemed much more pleasant. He looked straight at
me and said “You knew didn’t you?” to which I replied “Knew what?” He then said “That there was
a bypass!”
I said that I have never toured your plant and did not “know” there was a bypass through which an
operator could dump hot product to the tank but it was the only logical explanation I had for the
events that took place.
We were advised the bypass is, “Now chained and locked shut!”
The tank ruptures had both occurred on the same shift with the same operator on duty. The cause of
the first loss was considered unknown up to this point.
Tank Roof Rupture – Two Men Killed
A tank roof ruptured, resulting in the death of two men who had been standing on the roof of the
tank. The tank supposedly contained what was referred to as dead oil (oil from which all the readily
volatile material had evaporated). Perhaps this assumption was made because the tank had not been
in active service for some time.
This tank was to be vented through a piping system. The two men had connected a mechanical joint
with piping attached to the top tank flange. They were lifting the free end of the pipe up to match up
with another section of pipe so the welder could connect the two pieces, standing near the edge of the
tank to accomplish this task.
The welder’s torch ignited the vapors which had migrated down the vent pipe and an explosion
resulted violently ejecting the roof of the tank.
One of the men who had been standing on the roof was found approximately fifty yards from the
tank in a stand of trees.
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The mechanical joint should have been the last connection but from available information it is likely
they used it as a fixed point to facilitate lineup of the free end of the heavy pipe for the welder.
Failure to respect the potential of a vapor/air explosion resulted in this tragic loss of life. It goes
without saying the term “dead oil” should never be used, especially when it comes to crude oil.
Heating Tanks
Numerous losses have occurred in heavy oil production where it is necessary to heat tanks to reduce
the viscosity to the point where it can be handled in a reasonable time. If the oil levels accidentally
fall below the top of the fire tubes in the tanks a vapor explosion can occur when the tube which is
no longer cooled by liquid becomes red hot. The explosion often sends the tank roof flying in various
directions. In one case the roof remained nearly horizontal and mowed down a number of small trees
as it sailed into the bush.
Explosive Vapors
A tank in the Lloydminster area was being fitted with a new manway. It had been ventilated all day
while work was in progress. At the end of the day the crew responsible for ventilation closed the
other openings telling the welder he could complete the external welding.
When the welder was nearly finished an explosion occurred which lifted the roof on the side away
from the welder. The roof swung overhead as though on a hinge with the first ruptured edge touching
the ground. The welder said he was left standing in a space under the roof which was much like a
leanto.
The welder was startled but otherwise unhurt. In this case it only took a few minutes for explosive
vapors to build up once ventilation was stopped.
Tanks and Lightning
There have been numerous losses from lightning strikes to tank equipped with open goose neck style
vent pipes. There seems to be great reliance on the fact that most tank vapor spaces have sufficient
vapors to keep them above the upper explosive limit of a gas/air mixture. On a warm day this may be
true.
Many vent fires have been snuffed with hand fire extinguishers.
However, depending on the volatiles present and the tank levels, explosion can result under
thunderstorm conditions. Rain falling on a warm tank, especially if the tank is at low level with lots
of vapor can provide sudden cooling which condenses some vapor allowing air to be drawn into the
vapor space thus generating an explosive mixture.
If a lightning strike then occurs it can propagate into the tank vapor space causing tank rupture and
fire.
The older Alberta Fire Code required the use of pressure vacuum vents to prevent such explosions
but in many cases the code was not followed or designers were simply not aware of the requirement.
The new code makes no such stipulation. It is therefore unlikely that such protection will be provided
unless a company experiences losses for themselves and realizes it is a good loss prevention feature.
Corroded Seams
In atmospheric storage tank areas it is important to keep the floor to shell seams clear of earth cover
to protect that joint from corrosion. If corrosion occurs at this seam over many years it is possible for
this seam to be weakened to the point where it can fail before the roof to shell seam if sudden
internal pressure such as from an explosion happens. Tanks have been known to rocket upward
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dumping their contents with such force that earth dikes are simply pushed aside by the wave of
flaming hydrocarbons.
Any firefighters anywhere near such a tank are in extreme danger.
Potential Lack of Oxygen
Tanks can present other hazards to the unwary, even tanks that have been drained and cleaned out. A
tank at a refinery had been cleaned out to repair some damage that had occurred. The large manway
was still open and some light was coming in through the damage hole at the top.
The client representative Dale that I was with wanted to go inside the tank for a closer look at the
damaged area. I indicated it was a confined space entry and the air in the tank should be tested. My
suggestion was ignored and he and another person ducked inside and walked clear across the tank.
They made it back outside okay as I waited outside the manway.
They seemed to ignore the hazard that wet steel can use up oxygen just by the oxidation process.
They must have also had a great deal of faith that the tank was totally clear of hazardous vapors. It
was also a clear violation of their company safety standards.
Petrochemical Plants - Incidents
Gas Release Boot
A recommendation was made that a gas release boot should be installed on the cooling tower return
line just before it enters the distribution deck of the cooling tower. The reply was that it would be too
expensive to retrofit.
Some months later a ¾ inch tube in 1500 psig service ruptured. The water/ gas surges did some
damage to the tower. The forces were so great that the return water riser was deflected away from the
tower about a foot and a half (45cm.). A spool piece had to be fabricated for the riser connection to
get the plant back on line quickly. Gas boots were then added.
At the next plant survey the manager said “I wish you had pounded your fist on my desk and said you
have to do it!” (Install gas boots).
I laughed and said “Ed, if I tried to tell you as manager what to do, you would probably thrown me
out of your plant!”
After thinking a moment Ed said “You are right I probably would have.”
I said “If I had, this may not have happened, then where would we be?”
However, a second incident at the plant proved the worth of the gas boots and the gas was vented
without damaging the tower.
It was also fortunate in the first instance that the released gas did not ignite so there was no fire or
explosion, just physical damage to the tower and piping.
Steam Superheater Tube Rupture
As we were driving around the process block of an olefins plant there was a loud bang and a white
cloud followed by a reddish brown cloud headed skyward. Our vehicle driver looked over at me with
a concerned look. I could see where the cloud was issuing from the stack and said “Looks like they
blew a tube in the steam superheater”.
At this comment Wayne looked more relaxed. The underwriter’s representative in the back seat said
“But what is that reddish dust?”
I explained it was likely refractory dust blown out by the high pressure steam escaping. Subsequent
investigation confirmed that was the case.
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At the next survey, when the underwriter asked about the investigation Wayne said
“Some people don’t need an investigation, they can tell what happened just by looking at it.” He was
looking at me when he said it.
I took it as kind of a backhand compliment on my quick assessment of the situation which dropped
his level of apprehension by an order of magnitude at the time.
Reaction Runaway
During a somewhat rainy survey of an ethylene plant we were advised the No. 1 Unit would be shut
down that day. Most of the survey had been completed and we were at the plant gatehouse when the
plant evacuation alarm sounded. We headed for the county road as per plant safety procedures.
About half way to the country road Garry of Risk Management approached me saying, “What do you
think is happening?”
I felt somewhat apprehensive about answering since the underwriter’s representative was standing
right there as well. I said “I can’t be sure, but since they are in the process of shutting down, I would
suspect an acetylene reactor runaway.”
After explaining to him what that was he said “What can they do to correct it?”
He was advised they would need to re-establish flow to provide cooling. Since the flare increased I
suspected that is what they were doing. The plant alarm soon dropped back to the alert level. We
slowly returned to the gatehouse a little damper but that was nothing to be concerned about.
During the incident the plant flare line had become so hot it slipped off one of the slide plates due to
the thermal expansion. The subsequent investigation confirmed my speculation so both the
underwriter and client seemed satisfied with my comments.
Subsequent investigation also revealed it is wiser to listen to knowledgeable people speaking calmly
about corrective action than it is to listen to those making a lot of noise and Jim was acting calmly
trying to get a point across.
Shutdown When Wire Connector Fell Off
While we were touring the loading rack area of a methanol plant the flare suddenly lit up. The plant
had gone into automatic emergency shut down.
Restart of the plant took a significant amount of time due to necessary precautions for restarting
reformers.
The shut down was caused by an open circuit on the low/low water level of the steam generation
system under the reformer. An instrument technician had been moving some wiring in the back of
the control panel. There was a loose screw on a terminal block and the open ended U shaped
connector fell off.
The wire end connectors were all changed to full encirclement types because of this incident.
Internal Fire in Compressor Station
When touring a large compressor station the operator Mickey turned to me and said
“I don’t know why you people even bother to come around and look at these stations. They have so
much instrumentation that nothing can go wrong! In fact, they have so many shutdowns they are hard
to keep running!”
About two weeks later I was at another station and heard some radio chatter about a problem at the
station operated by Mickey. On my road home there was an opportunity to drop into the site to ask a
few questions.
When I drove into the yard there were blackened combustor baskets and other parts lying in the yard.
Mickey was very surprised to see me and looked somewhat disillusioned.
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He told me there was an internal fire in the unit which was kept going by oil pumped in by the
auxiliary lubrication oil pump. The oil was the fire resistant synthetic type but burnt inside the unit as
the exhaust temperature indicator was over 1500 F for over an hour.
The turbine supplier had been trying some new impingement cooling blades and something went
wrong. The turbine supplier agreed to make all repairs so the company’s insurer was not even
notified. This was why he was so surprised to see me and asked how I found out about the loss.
Mickey had been under the impression that fire resistant synthetic oil would not burn because
supplier information showed no flashpoint in the data. As far as I know the operating company’s risk
management group has no record of the incident and since my drop in to the site was clearly
unofficial no follow up was ever done because the turbine suppliers didn’t want any mention of it.
Oil Fire Destroys Foam Plastic Insulation
A call came in that there was a fire in progress at a large gas processing plant so plans were made to
visit the following day. An absorption oil tank was still afire when we arrived at the site.
A process upset had occurred and an operator noting what appeared to be a high absorption oil level
had attempted to drain it back to the storage tank at the south end of the process area. However,
much of the liquid was in fact LPG which flash-vaporized overpressuring the tank and its roof
ruptured showering the south end of the pump building as well as equipment in the area with the
liquids. Heavy vapors had traveled downhill to the process heater area and ignition occurred.
The fire involved much of the pump building and adjacent outside equipment as well as a
maintenance truck and mobile crane that were close by.
This loss showed how quickly foam plastic insulation in low temperature service can be destroyed.
At the same time it showed how well ordinary calcium silicate block resists the effects of fire
exposure when secured in place by steel banding.
Some of the relief valves on vessels appeared to have been sized taking credit for the insulation even
when the insulation was foam plastic, quickly destroyed in the fire.
The fire climbed nearly to the top of towers under aluminum flashing on some that were insulated
with plastic foams.
In a couple of areas the fire was hot enough to partially melt some gray iron valve yokes.
Plant Surveys
Forced Air Furnace Overheat
At a gas facility, there had been two office building furnace fires resulting in damage. The fires
occurred about one year apart. A request was made for a site visit after the second loss.
The type of furnace was a low clearance type apparently installed to the one inch clearance to
combustibles specified on the name plate for side clearance. Part of the external wall of the structure
had been removed to achieve extinguishment of the burning wood material around the furnace.
Unknown to me at the time of my visit was the fact they had hired someone to look at the furnace
and could find no reason for the overheating.
On making inquiries it was found that both fires occurred when the ambient temperatures were
below minus twenty five degrees F. The underground fuel line from the compressor was shallow
buried from the compressor building a considerable distance away. There was no knockout pot at the
office end of the line to separate any liquids.
They were then asked “What is the hydrocarbon dew point of the gas at the compressor building?”
The reply was “Minus fifteen degrees F.”
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Along with auto refrigeration from pressure drop it appeared likely that liquids had entered the
burner system designed for vapor and subsequently caused overheating.
Genset Odorized Gas Leak
While touring a compressor station, the distinct odor of mercaptan was noted as I walked past the
emergency generator. A test of the air inlet showed a detectable level of natural gas leakage was
present.
Others in the group said they could smell nothing so a portable gas detection instrument was used to
verify the presence of gas. It was determined that the fuel gas solenoid valve was allowing gas to
seep past.
The operator at the station seemed pleased I had found the leak. I’m not sure it was because I found it
or the double time pay he would get to stay and fix it. At least that’s what he said he would get.
The latter was likely the case as when a plumber was installing a new water heater in our home I
detected some seepage at a joint in the factory tubing. The plumber said
“I am glad you have a sensitive nose as I get an extra half hour for that from the supplier!”
As you may have guessed, he didn’t have a combustible gas detector but verified the seepage with
his lighter before I could say anything! He then just blew it out.
Torch Used on Propane Tank
During a winter survey of new construction a propane tank with a soot blackened end was noted in
the construction area. I said that I wasn’t impressed by that and the tour guide facetiously said “What
do you mean?”
I said “Someone has been using a tiger torch on the end of the tank to vaporize the propane in cold
weather, haven’t they?”
The answer was, “Yes”. They felt that since the tank was nearly filled to capacity at the time that
there was little hazard.
This may have been partially true if the heat exposure was only on the liquid filled area but how
could they be sure of that or know what heat flux they were applying.
The soot indicated there was poor combustion with direct flame contact with the metal. They were
told it was a bad idea and a proper vaporizer should be provided.
The above idea is worse than those who use exhaust heat from pump jack engines to vaporize the
propane fuel supply but even that is not advised due to tank corrosion that can result.
Halon Suppression System Tests
Excessive Halon
The test of a large Halon suppression system was set up in the years before its ozone depleting
effects were known. All monitoring equipment was in place. Three people decided they wanted to be
in the room during the test.
The system was triggered and the monitoring equipment soon showed concentrations approaching
8% Halon and rising. We had to open the door and warn the occupants to leave thus voiding the test
but getting them to safety.
Investigation revealed that a cylinder for a much larger room had accidentally been connected to this
system. This was possible because the connection heads on the cylinders were exactly the same. The
cylinders containing the agent were physically the same size but contained different amounts of
Halon.
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This was not checked or verified prior to the test so the contractor had to pay for the replacement
Halon.
Faulty Halon Alarm System
A test was set up for the Halon system in the computer facility of an electronic equipment
manufacturing plant. The detection system heads went into alarm but there was no discharge of
Halon from the system.
After a review of the circuitry it was discovered that the polarity of the discharge solenoid was
accidentally reversed. The wiring was switched around and the system discharged successfully on the
second attempt.
Tony had originally wanted to be in the room during the test and was discouraged because of what I
said was needless exposure and the fact there was a good window for outside observation. Also, a
person would have to stay in the room at least the full ten minutes duration of the test to avoid
negating the test.
After the test Tony came up to me and thanked me for discouraging him from being in the room. He
said he had no idea how noisy it would be or how much of a blast effect there was from the high
pressure nozzles.
Halon Discharge Damages Ceiling
The discharge of a Halon system in a computer facility blew an unanchored suspended ceiling tile to
pieces sending mineral fibres and dust all over the room.
You can appreciate this was not good news in an area where a clean dust free environment is
standard.
Button Release on Halon System
During the survey of a Halon system for a gas turbine enclosure Carl the insurance underwriter’s
representative was advised the system was automatic as well as having a button release.
He looked at the electrical box and said “Where is the button?”
He was advised there was a spring loaded button under the slide plate which passed through the slots
in the side of the circular shield. He said that he wanted to see the button!
Don, the very helpful station operator squatted down and held the edge of the button with his
thumbnail while carefully removing the slide plate. He then moved slightly to one side to give Carl a
clear view of the red button.
Don momentarily lost his balance and his thumbnail slid off the edge of the spring loaded button
which popped out instantly discharging the system.
I couldn’t help but point to the button and emphatically say to Carl “There is the button!”
He just said “Oh” and walked away.
I certainly felt sorry for the operator who was trying to be extra accommodating
because his dumping the system cost hundreds of dollars for refill. Fortunately the turbine was not on
line at the time as it would have undergone automatic emergency shut down.
Lack of Visibility During Halon Discharge
The Halon test for a control room in a petrochemical product facility was to be videotaped for future
training sessions. It turned out to be a day when the atmospheric conditions and humidity were just
wrong for videotaping.
When the system discharged the room was filled with a dense fog that remained for at least fifteen
minutes. The video was fifteen minutes of whiteout.
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To think of this happening in an occupied control room where operators would need to see controls
and instrumentation is certainly worth considering.
This test was done prior to facility start up without anyone in the room.
Battery Banks and UPS (uninterruptible power supply)
High Voltage Room
About the only time I ever raised my voice at a client’s risk manager was to shout a warning. We had
entered a large battery room with supplied voltages up to 440 volts. The entrance door was properly
labeled, “High Voltage”.
When we were about half way along the end of the battery banks, the client took out a gold plated
pen and was moving it toward the battery post.
I have no idea whether he saw a speck of dirt or what but I yelled, “Don’t touch that!”
He stopped less than an inch from the post. He said “Well, it’s just like a big car battery isn’t it?” He
was told it was at least 240 volts where he was standing and the available amperage would be very
high. The person touring us through the facility motioned toward the door sign that said high voltage
and we continued on our way. I never appreciated the expression that it felt like your heart was in
your mouth as much as I did that day. It took a couple of minutes for the lump in my throat feeling to
pass.
Unsecured Cable
In the UPS room for a very important control system supplying pipe line operations, it was noted that
the main connecting cable had been inserted in the circular connector but the allen type clamping
screw had never been tightened down on the cable.
This was brought to the attention of the operations manager who at first couldn’t believe the cable
connection was not secured. He said “How do you know it was loose? Did you give it a pull to see if
it was loose?”
I said “You’ve got to be kidding!”
He then said“ Yes I am kidding!”
Arrangements were made to have it carefully tightened.
It was the main feed through the battery bank system and disconnection would likely have blanked
their whole control system.
Battery Hydrogen Explosion
At a structural steel sales yard, a welder was working in the area immediately adjacent to the engine
driven generator. There was a loud pop and he stopped welding, raised his helmet and said it was
like someone shot a small calibre rifle. He asked me if I had heard it.
I said I had but that it was not all that noticeable above the sound of the engine. We approached the
generator and noted the centres of half the battery caps were blown out with the threaded portion
remaining in place.
The sparks from the welding had showered the top of the battery and the hydrogen had exploded
with enough force to blow the centres out of the caps.
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Gas Detectors and Gas Leakage
Trust, or CHECK, the Instrument
Small Leaks Can Cause Significant Problems
During a loss prevention survey, a gas detector module with readouts for the dehydrator building was
showing readings of 23% of the lower explosive limit and was fluctuating slightly. The site operator
said it had been that way for some time so he presumed the detector was malfunctioning.
Since it was moving at times to 26 % LEL it was suggested we do an experiment and the operator
said okay. We went out to the dehydrator building, opened both end doors and both side windows.
There was a slight breeze blowing so there was good cross ventilation.
Back we went to the control area and what do you know, the detector was now reading very close to
zero. Back to the dehydrator building to find the leak and sure enough, there near a small regulator
someone had bent a quarter inch tube over in a U shape and pinched it where an instrument had been
disconnected. They must have assumed the bend stopped the flow. However, there were small
openings on either side of the bent back tube where a small flow of low pressure gas continued.
The tubing line was then valved off, the tubing removed and the opening plugged with a solid bull
plug.
The windows and one personnel door were then closed and back we went to the control area. The gas
detector module reading now remained at 0 % LEL.
Gas Blowing from a Brass Fuel Gas Cock Valve
A tour was being conducted with an underwriter’s representative. In the control room a gas detector
module had a wavering reading of between 23 % and 26 % LEL. The module was for detectors
located in the compressor building.
The operator indicated the detector module was malfunctioning and had been that way for a week.
During the tour of the compressor building I checked what were known to be common leak sources.
On walking up to the brass fuel gas cock valve of the end compressor it was found to be blowing gas
so bad I could feel the draft on my pant legs.
Since we were all wearing hearing protection and the underwriter was at the far end of the building,
the operator was shown by hand signals and noted the draft for himself.
We signaled to the underwriter that we were leaving and we all exited the building. The operator
returned to the control building and advised the others the detector was not malfunctioning and there
was a leak requiring immediate attention.
We finished our tour without incident and left the plant. The underwriter seemed unaware of the
significance of what had transpired.
Wrong Alarm Setting
During a survey, it was noted that the high gas alarm levels were set at 100 % of the lower explosive
limit. It actually took some convincing before it was agreed that this setting was inappropriate. The
point was made that at this setting there could be a substantial volume of air/gas mixture between the
detection head and the leak source that could be well into the explosive range.
It is probably a good thing that settings for combustible gas detection equipment are now set out in
legislated codes. One such code is the Canadian Electrical Code which outlines requirements for
electrical equipment in hazardous locations.
Review of Shutdown Key
There are actually a substantial number of facilities where a review of the shutdown key shows
building ventilation fans starting at 20% of the lower explosive limit but tripping off at 40 % lower
explosive limit. This is apparently from the philosophy of disconnection of all ignition sources.
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However, odds are that simply due to numbers the gas leak is from a small diameter tube or fitting.
Stopping ventilation at 40 % LEL virtually assures that the whole structure will reach 100 % LEL in
a short time with the potential for a much larger and more damaging explosion. Ventilation fans can
also keep the hazardous conditions confined to one end of a building by a plume effect as an
example. This is especially true for lighter than air gases.
Ventilation fans should always be suited to Class I Division I hazardous electrical locations so the
can remain in operation on gas detection. This is true by the very nature of their operation in that they
are designed to remove hazardous gases which obviously must then flow directly past them.
Fans should shut down on indication of fire to avoid supplying combustion air to a fire scenario.
There are even cases where the shutdown key shows sour gas ventilation fans shutting down on high
concentration. Should there ever be an employee injured or knocked down during a sour gas release
event, shutting off the air supplied by ventilation fans could quickly lead to that person’s demise
caused by increased concentration of the poisonous gas.
Don’t Wait for Confirmation
A number of annual surveys of a gas plant were done on behalf of the interests of a client with local
representative as well as one from the U.S.
One year some significant gas detector reading were noted on the modules in the control room. We
asked if anyone had taken a portable detector unit out to verify if the readings were legitimate. The
answer was, “No”. They usually waited for them to alarm at the low alarm level or if a second head
showed a significant reading.
When this situation was brought to the attention of Roger the Plant Superintendent he was to say the
least “not amused”.
Use the Proper Instrument for the Service
The following year a 28% LEL was noted on the detection module for the area of the propane
compressor and was coming from a propane detection head. When asked if they were checking it out
they said ,“Yes”.
We then heard someone on the radio say he could get no reading on the Drager. Knowing the
Dragers they had were for hydrogen sulphide he was advised they should be checking with a proper
hydrocarbon detector since the head indicating gas was for propane. When asking about the portable
hydrocarbon detectors we were advised they were all in the instrument shop for repairs or calibration
so they decided to check with the hydrogen sulphide detector.
Natural Gas is NOT Air
I was touring with Gil the insurance department’s representative who had good knowledge of field
operations so was well aware of field practice. We entered the compressor building which housed
two units. One of the units was operating with the other being prepared for maintenance.
The engine spark plug areas of the shut down unit were being blown clear of dust and grit so no dirt
would enter the cylinders on spark plug removal.
I then turned to Gil and said “Geez, I don’t think much of that, let’s get out of here!”
He turned to me and said “What’s the matter with you? Everybody air blows dirt off like that.”
He must have thought I was concerned about flying grit.
“There is only one small problem, you don’t have an air compressor here!”
His eyes then followed the hose as mine had done and saw it went to a single stage regulator which
was supplied off the 900 psig gas line. At this point we both exited the building, walked over and
spoke to the supervisor who at first looked at us in disbelief.
The above was not the first instance of this kind as I also witnessed a mechanic using 150 psig gas in
an air wrench to install reciprocating compressor valve cover stud nuts to what torque is anybody’s
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guess. The gas in that case was literally blowing out in his face. When you see air type quick
connectors on gas lines you may be amazed at the reasons they are apparently in place.
Multi-Head Readings
In a large petrochemical plant control room significant readings on a gas detector module were
questioned and the operator replied, “Aw we don’t get excited until at least two heads show high
readings.”
When this comment was presented at the exit meeting, management responded in angry disbelief and
demanded the name of the operator. We refused to disclose the name because it appeared to be an
attitude problem that may be present on other shifts as well.
The management then agreed it would be looked into in training sessions. Another member of the
tour group from the plant site had heard the same words and backed up the statement. He also
refused to volunteer the name during the meeting.
I knew I had made the right decision in referring to it as a training problem when I looked over at the
most senior site manager and he was nodding his head with some chagrin.
A very similar situation developed at another petrochemical plant with similar reaction from
management. In that case the other person who backed up my statement was the plant engineer.
We actually became aware of a startup procedure for a natural gas compressor which called for
bypass of the combustible gas detection system since the starter gas exhaust was not properly vented
to a safe location and the starting gas would set off the combustible gas detectors and effect a unit
shutdown.
Fortunately this is a rarity.
When looking at a loss after a compressor building explosion, a one half inch fitting was still
blowing natural gas and condensate straight up in the air after the fire had been put out. The person
conducting the review walked over and put his boot on the fitting at an angle spraying the gas and
liquid out in a fan shape pattern from under the sole for a few seconds then turned and walked away.
This, to me indicated a complete lack of respect for hydrocarbons and their fire potential although
the compressor building in front of us was totaled.
Steam Cleaning
A combustible vapor test was done in the trench of a facility and no detectable levels of hazardous
vapors were noted. The steam cleaning of the trench was started. There was a flash fire which took
those doing the work by surprise , but there was a very logical explanation.
The steam provided the heat necessary to vaporize the liquid hydrocarbons in the trench then all that
was needed was for the hydrocarbons to migrate to a source of ignition which was present and the
fire ensued.
Steam clouds are a fairly well known generators of static electrical discharges.
Faulty Procedure
At an oil production facility the oil contained some hydrogen sulphide so sour gas detection and
shutdown tied to the detection had been provided. In the enclosure at the end of the heater treater
where test samples had to be drawn from the treater at various levels, the sour gas head was found to
be covered with a plastic cap.
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Their excuse for covering the head was that sour gas venting from the drawing of samples caused the
head to go into alarm and effect a shutdown so they simply covered the head to solve their operating
problem.
Fire Pump Tests
The importance of doing regular fire pump tests and system checks of equipment is illustrated by a
few examples.
Broken Hydrant
A fire hydrant was chosen for a flow test at a gas plant. Ralph proceeded to open the hydrant. A
distinct thunk was heard and water erupted in a rose pattern all around the fire hydrant. Undaunted,
Ralph jumped up on the hydrant with one foot on each butt, bowed his legs and slowly turned the
wrench between his legs until he had the valve closed again.
An examination revealed that water had frozen in the barrel and split the barrel all the way around. It
was held in place by the soil. Since the actual valve was below the frost line this would not show up
until someone opened the hydrant.
The quick response by Ralph minimized the outage to one fire hydrant. Thank goodness the valve
spindle held or Ralph might have reached a new altitude on a water jet. It was obvious he was very
familiar with the details of hydrant construction to know immediately that the situation was
controllable.
The thunk we heard was the hydrant barrel moving upward until the slack in the operating spindle
was suddenly taken up.
Broken Monitor
A fire hydrant monitor at the east end of the plant was chosen as the flow point. I approached the
monitor to move it to a different direction. Upon touching the monitor, it fell off on the ground much
to the surprise and chagrin of the operator.
The valve below the monitor was closed and it was likely that water seeped past the valve when the
hydrant barrel was pressured up, or the side butts had been in use for some purpose. The trapped
water did not drain when the hydrant was shut off because it was trapped above the valve. The water
later froze fracturing the cast iron valve.
The monitor was left balanced on the top when the ice thawed, and fell off when I attempted to move
it. It is usual good practice to leave monitor valves open so they will drain with the hydrant barrel. It
also means an operator need only open one valve to bring a monitor into play on a fire. Otherwise, it
is necessary to operate two valves and this can double the time required.
Threaded Nipples
During the test of a diesel engine driven pump at a straddle plant, a threaded nipple in the cooling
water line fractured, spraying water. During isolation of the leak I advised the operator to first open
the bypass line to avoid loss of coolant to the engine.
The bypass was opened and the leak isolated with no damage other than the need for a new pipe
nipple.
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Rocks and Pitots
Use caution when taking pitot readings for fire pump flow measurement especially when checking
maximum flow rates. Stones or other hard objects have lain in water mains for long periods of time
before suddenly moving into high velocity zones.
It is therefore wise to allow peak flows to stabilize before taking readings. By the time you hear the
tink , tink sound you may not have time to remove the flow device from the water stream before
impact occurs.
Speaking from experience even a walnut sized rock can cause severe damage to a pitot not to
mention stinging fingers. The pitot blade usually does a U turn of sorts. I thought I had seen damage
about as bad as it could get but the one that Chris was using handily beat my record for damage.
Thorough flushing of hydrant systems at recommended flow rates should minimize the rock problem
and should definitely be done after any fire main repairs.
Sand and grit can severely abrade the inside of nozzles the same way they can erode pump impellers.
Rock in Hydrant
During a flow test, a rock of sufficient size to stop in a fire hydrant butt came up the barrel with a
distinct thunk. Jim shut down the hydrant and the rock fell down the barrel. We then capped the butts
and opened the pumper connection and were able to blow it out through the pumper connection. It
was like a baseball in size.
The possible impact with respect to possible automatic sprinkler system blockage is self evident. In
fact I have had the experience of assisting in the removal of a pail full of rocks from a sprinkler valve
in a grocery store when city crews did not properly flush the mains after making repairs. The two
inch drain test caused sufficient velocity to bring the rocks into the system.
Needless to say hydro-pneumatic backflushing of the automatic sprinkler system was recommended.
Classic Sprinkler System Impairment
A four inch sprinkler system supply line was shown to have a severe restriction at a specific location.
Normal pressure was fine at no flow or very low flow but when drain tests were done the pressure
dropped very dramatically. They double checked all valves to no avail, and finally decided to dig up
the supply main.
They discovered a piece of wood four by four inside the pipe which they surmised had been used to
align joints in the pipe but had never been removed. The only space water could flow past the four by
four was along the flat sides out to the arc of the pipe wall. The piece of wood was extracted and the
piping was repaired. Water flow rates were then tested and went up to normal.
Water Thrust
Respect for the thrust of water discharging from fire pumps is essential. During the test of a large
diesel engine driven pump, the flow nozzles were lashed to a trailer with ropes. It was suggested the
trailer be braced or attached to a vehicle with brakes on. One skeptic said it was not a problem.
On high flow rate the trailer started to lift and move so the pump was immediately shut down. A
truck with brakes was quickly connected to the trailer and the test was then completed.
A ten inch flow meter leg and piping had to be anchored when thrust from an elbow made it lift off
its support which only considered gravity effects in its design. In this case the pumps were large high
flow types (4500 US gpm at 138 psig.)
This thrust effect is basically the same as that used in the design of jet boats.
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Methanol in Hydrant
Tom was going to demonstrate the extinguishment of Class A combustibles to the plant staff for
their fire training session. The small hose was connected to the hydrant and the hose pressured up.
The fire was then started and let burn for a while to simulate a real response.
Tom approached the fire and opened the nozzle. For a couple of seconds there was a huge fireball
but flow continued and the fire was brought under control. It was determined that to prevent winter
freeze-up someone had filled the hydrant barrels with methanol and this made the huge initial
fireball.
All the students were duly impressed. Tom had singed eyebrows but was otherwise okay. Filling
hydrant barrels with methanol is not a good idea and today it would be environmentally unacceptable
as well. It would also be illegal if the fire system was in any way used for potable water.
Methanol usually deteriorates gaskets and seals pretty quickly.
Reversed Relief Valve
A fire pump test at a distiller’s facility was scheduled with Jim of the IAO. The plant was nearing
construction completion and the test was needed for underwriter acceptance. Jim wanted to check the
relief valve setting. All pressure gauges were in place and the pump was running. Jim asked me to
watch for discharge of water outside the pump building.
He was backing off the setting for some time but there was still no discharge. Becoming impatient, I
went inside the building and noted some water coming out around the threaded stem of the relief
valve spindle which Jim now had very loose.
I advised him to stop saying, “It’s not much wonder there is no discharge!”
To this Jim said “Why?”
I showed him the relief valve had been installed backwards and could never have opened. If he had
unscrewed the stem any further he could have gotten very wet.
The contractor was summoned and laughed at my statement that the relief valve was installed
backwards. “Yeah right!”
When I explained both inlet and discharge flanges had identical configuration of bolt holes,
explained the function of the valve and showed him the valve arrangement he agreed to have the
necessary corrections completed.
Thermowells
It is essential that thermowells be of sturdy machined one piece construction with extra heavy wall
thickness to resist the effects of vibration induced by fluid harmonics.
Leak at a Weld
Hazards such as hydrate plugs have also been known to severely deform thermowells, in some cases
rendering removal impossible.
In one pipe line thermowells of welded construction were discovered when a leak at one of the welds
followed electrical conduits which were not adequately sealed. The gas entered the control area.
A person becoming aware of the presence of hydrocarbons turned on a ventilation fan. This resulted
in an explosion because the fans were designed for an ordinary hazard area, not contemplating the
presence of hazardous vapors because gas was not expected to get into the electrical control area.
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Alleged Leakage
In another case gas leakage from a thermowell was the ‘official’ cause of a loss in a control area for
an underground LPG storage facility. In reality the truth which came out years later was much more
bizarre.
The truth of the matter was that operations personnel were having fun freezing spiders with
discharge of propane from a small cylinder.
Electrical equipment switching in the control area was the ignition source. This part of the story was
true.
Empty Fire Extinguishers
A small fire that got away on a drilling rig and caused major damage. The fire extinguishers they had
in the area were carbon dioxide type and turned out to be mainly empty. Eventually the reason they
were empty came out.
It seems there is nothing much quicker for cooling a bottle of beverage on a hot day than putting the
cone of a carbon dioxide extinguisher over the bottle and giving it a shot.
Propane Fire Loss
In a propane refrigerant compressor building a thermowell eventually vibrated loose and blew out of
the discharge side of a turbo-driven compressor. The resultant explosion blew out the north wall of
the building and a fire ensued.
There were cellar type water spray nozzles positioned over the unit and the operators at significant
risk to themselves managed to get them operating. The cooling spray did not damage the hot turbine
as many had feared.
The insurance adjuster credited the operations staff with reducing the loss by “hundreds of
thousands of dollars” by their response.
Drainage
Modular Plant
During fast track construction of a modular refinery Tom noted the interconnection of subsurface
drains. He commented from his previous experience saying to the group,
“The insurance brokers will never agree to such an arrangement!”
Our office was contacted for an immediate meeting and a stop work order was issued at the
construction site. The plans showed drains from process blocks interconnected with ordinary hazard
areas such as electrical buildings and utility structures all without the benefit of liquid traps or other
safety measures.
The proper arrangement of drains was sorted out in a meeting under the pressure of knowing it was
costing thousands of dollars per hour while crews were basically told to sit and wait.
Dried Out Trap
An actual installation caused a problem when a trap in a floor drain in the motor control centre dried
out and flammable vapors backed up into the structure resulting in a flash fire when electrical arcing
occurred.
No one had thought of taking a pail of water and pouring some into the floor drain periodically. After
all, who would take a pail of water into a high voltage switchgear area?
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In large plants a good design feature is to make an automatic arrangement to send small amounts of
water to maintain floor traps when nearby water facilities are used.
When a utility room with gas fired water heater and other equipment was entered in Fairview ,
Alberta it was obvious from the odor that the floor drain had dried out.
It was fortunate that there had not been a flash fire from backup of sewer gas.
The tour guide said to write it up on the action list but an even more proactive employee Jim
immediately went and got a pail of water and filled the trap.
Backup of Flammable Vapours
An interesting incident involving back up of flammable vapors occurred at a large Fort
Saskatchewan plant. The vapors under pressure backed up into a laboratory adjacent to the control
area and when ignition occurred there was significant damage to both the lab and control area.
Details of this incident can be found in a paper presented to the American Institute of Chemical
Engineers called Sewers Can Pass On Problems.
Backup of Gas to Air System
Hydrocarbon dumps were routed to a collection header which also happened to be the box beams on
the side of the equipment skid. Freeze-off of the drain line to the pit made the box beams take on a
more spherical shape when pressure from dump valve operation built up.
Fortunately, it was noticed before rupture pressure was reached.
Frozen Drain Line
The water dump off the compressed air receiver was connected to a common line to the site flare pit.
Water froze in the drain line and hydrocarbon under pressure built up behind the plug.
When the water drain on the air receiver was opened the pressure differential was sufficient that
hydrocarbons backed up into the air receiver. This fact was picked up when an air line became nearly
red hot from internal combustion. The system was shut down, the drain line disconnected and the
whole air system carefully blown down and purged.
The air receiver drain line was then made completely independent.
Fireproofing
Powder Driven Fasteners
A fireproofing contractor was allowed to use powder driven fasteners to affix fireproofing supports
to steel vessel skirts in a modular refinery.
The worker was apparently not given detailed instructions as the skirt to vessel weld line was crossed
and steel studs were driven completely through the wall of the process vessels resulting in very
expensive corrective measures.
Corrosion Beneath Fire-Proofing Materials
There have been extensive problems with corrosion under fireproofing materials containing
chlorides.
In some cases it was poor preparation or improper protection of the base steel and in others it was
lack of proper weather flashing or sealing of joints.
I have seen a corrosion hole completely through large tower skirts and severe rust flaking of steel Ibeams.
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Chloride free formulations are now available but attention to exact details of installation remain very
important.
There is still nothing like good steel reinforced concrete for providing good fire resistance.
High Expansion Foam Test
High expansion foam generators were purchased for installation at a processing plant.
The units arrived in Calgary and Tim of the CUA was invited out to see the test along with a number
of other people. The vendor had the units positioned on the back of a large flat deck trailer attached
to a tractor trailer unit.
It turned out to be below freezing on the test day but since the water and foam tanks had been in a
warm building shortly before the test, the supplier suggested there would be no problem generating
the high expansion foam. Tim and I were somewhat skeptical.
Frozen Foam Water Solution
The water pumps were started and the fans rotated just fine but when the foam/water solution hit the
screen it froze instantly and all that issued from the unit was a plume of water vapor. The units were
taken to the plant as someone decided they would work inside the heated building where they were to
be installed.
Debris in the System
A test was arranged with Lou protesting there was no need for an actual test as the system would
work fine. He said he would be around to remind the Underwriters represented by Tim that a test was
a waste of time and money! The system was triggered and the foam/water pressure started to rotate
the fans which promptly came to a stop and dribbled water and very little foam.
Someone had forgotten to flush all the rust and mill scale out of the piping before connection. This
debris promptly plugged the generator nozzles.
The piping was disconnected and flushed and the unit nozzles cleared. A retest was scheduled for
the following day. The second test was successful but Lou was nowhere to found after the plug up.
Someone said he took the plane back to Calgary the first night.
The successful test dumped about an eight foot depth of foam in the building in six to seven minutes
and reached a maximum depth of eleven feet. Some people walked into the foam to verify the fact
they could breathe in the foam if necessary. They said however that it was difficult to control their
sense of panic at not being able to see as well as their feelings of disorientation. Of course if the
foam contained combustion products it would not be breathable without toxic effects.
The foam was cleared out of the building by opening the large doors and the wind blew most of it off
into the trees. From this you can surmise if an explosion preceded a fire and destroyed the integrity
of the structure the foam may not be confined as required. Extra foam generation capacity is also
needed to offset deleterious effects of products of combustion when inside building air is used.
Relief Valves, Boilers, and Water Heaters
Relief Valves Have to Match Capacity Rating
A check of some older style Crane natural gas fired water heaters of the 40 US gallon size revealed
the burner capacity was listed as 36,000 BTU/Hr. The half inch relief valves carried a label listing
their relief capacity at 15,000 BTU/Hr.
Today relief valves smaller than ¾ inch in size are not allowed by code.
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Do Not Restrict a Relief Valve
A ¾ inch outlet on a hot water tank relief valve was fitted with a swedge that cut the outlet size to
about 3/8 of an inch. This was pointed out to the Plant Superintendent, who immediately said “Why
on earth would anyone do that?”
A quick look around revealed the answer. There was a piece of hose, a mop and a scrub pail in the
area. There was no other hot water outlet near the tank. The clean up crew merely connected the hose
to the swedge and lifted the manual operating lever on the relief valve to get the hottest water for
cleanup.
It is not likely the danger of restricting the relief valve to a small fraction of its required capacity
even entered their mind.
Understand the Implications
A small boiler relief valve lifted and sprayed glycol/water against the wall of the enclosure, so site
personnel screwed a ¾ by ¼ bushing into the outlet and piped the ¼ inch outlet out through the wall
of the building. They saw it as a solution to their problem, not realizing that it created a far worse
danger of a boiler explosion capable of demolishing the entire structure.
In a second very similar arrangement the operator lifted the manual relief lever and the valve would
not reseat either due to back pressure effects or scale in the valve. A fair amount of glycol/water
solution was lost.
Swedging down relief valve outlets is not allowed because of loss of design capacity and the fact that
any solids capable of passing through the relief valve must be able to pass freely out the discharge
line.
Potential Blockage Due to Ice
At the top of a high rise building the discharge tail pipe off a steam boiler relief passes vertically
through the roof and has no frost protection above the roof. A small seep of steam could result in
formation of an ice plug in very cold weather. Seepage problems have occurred in the past.
A small weep hole is provided in the discharge line in the heated area to drain liquid from the line
but is no guarantee that condensation and blockage cannot occur further up the line where it could be
much colder.
Even if the piping held and blew out an ice plug, it could be launched upward from its 37 storey
starting point and when it returned to ground level it could be dangerous.
Blind Flanges
Blinds were noted in the discharge flanges of pressure safety valves in heavy oil service. I was
alarmed at this and telephoned the area supervisor to tell him there were blinds in the pump pressure
safety valve discharge flanges.
His casual comment was “Oh probably” indicating he was well aware of it.
When asked why they would do that, his reply was that when the valve lifts, the sand in the oil gets
under the valve seat and causes the valve to leak afterwards. Their solution was merely to blind off
the relief valves. His reasoning was that the pipe and fittings had 150 pound rating so they should be
capable of withstanding 300 pounds. Since in their opinion the pumps could not deliver more than
three hundred pounds they thought they were okay.
Considering sand also causes metal erosion it is likely only a matter of time before an accident
occurs.
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Incidentally the on site operator seemed unaware of the situation. The person making the decision to
blind was highly unlikely to be in the vicinity of the equipment in the event of failure. This appears
to be a construction at any cost mentality.
Cost Benefit Attitude
I have known risk management types who say if it costs 2X dollars to make all facilities safe, and
you only have to pay out X dollars to a man’s widow say every twenty years, then don’t spend the
money to correct the situation and you have a fifty percent profit.
As this approach does not sit well with me, I asked how he would like someone making that kind of
decision about his son. His reply to my comments were “That’s dirty pool!” He felt it unfair for me
to make such a comment.
However, it was pointed out that those kinds of decisions involve someone else’s family and are they
any less important?
Out of Service PSV’s
After touring a refinery we were discussing the fact that everything was on line and the chalkboard in
the control room showed there were eight pressure safety valves out of service for repair and
maintenance testing.
The client representative said “I know that is entirely too many and we are working on it!” Imagine
his chagrin when it was pointed out that there were six that were not even listed!
We had counted fourteen valves out of service on our tour and doubted that we had seen them all.
Waterflood Plant Fires and Explosions
Welder’s Spark
When a large waterflood pump building burned down due to solvent and oil in the floor trench being
ignited by a welder’s spark the owner thought they were the first to ever burn up a waterflood
building. They were advised that they were at least third in line by my recollection.
Their loss was the largest in value but was definitely not a first.
Massed electrical cables were also a contributing factor in their loss.
Fractured Small Gas Line
In a previous case, two operators starting cleanup decided to bring a barrel of solvent into the
building. They tipped it to one side and were rolling it on the bottom rim into the building.
When it rolled onto the steel floor grating the grating tipped out of place and the barrel fell into the
floor trench fracturing the small gas line that supplied an overhead unit heater. The rush of gas
ignited off the flame in the heater resulting in a torch like flame in the trench which directly
impinged on the solvent barrel.
They rushed outside to close the fuel gas isolation valve which was frozen and would not move. One
of the operators jumped in his truck and drove down the road to the battery to isolate the fuel gas line
from that end.
The operator who stayed at the site said the just as the gas flame in the trench started to diminish the
barrel of solvent ruptured violently and the resulting fire destroyed the water pump structure.
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Failure of Tank Low Level Switch
Another interesting loss at a waterflood plant occurred when a tank low level switch apparently
failed. As the booster pump ran dry the tanks blanket gas exited the water pump seals and entered the
pump building. The building also housed ordinary domestic water pumps for the residence on site.
The operator in the nearby residence flushed the toilet and the water pressure fell.
He noted it then increased with the start of the pump and simultaneously he heard a large explosion.
On looking outside he noticed the wall of the water pump building was about half way between the
house and the remainder of the pump building.
The call of Mother Nature saved the day and no one was injured.
Maintenance
Juxtaposition of Two Jobs Equals Loss
An interesting loss occurred in a synthesis gas compressor building as a result of two different jobs
being done at the same time. The most significant damage from the resultant fire was to a group of
electrical cables near the point where they exited the building. These power and instrument cables
took a significant amount of time to replace.
During a maintenance shut down a restricting orifice designed to prevent high differential pressure
damage was inadvertently left out of the oil piping during reassembly. This orifice plate was
discovered about the same time as a hot alignment check was to be carried out on the compressor
shaft.
It was decided to do both jobs at the same time. The compressor seal oil system had to be drained
back to the storage tank in order to replace the orifice. To do this safely it was necessary to
depressure the compressor barrel as well. The oil was all drained back to the storage tank before the
gas pressure in the compressor case was vented.
The gas pressure crossed the now dry seals and flowed down into the full seal oil storage tank. The
gas pressure blew oil back up the drain lines and out the partially open couplings of the compressor.
The coupling covers had been partially removed in preparation for the hot alignment checks. The
original tank venting design did not contemplate the volume of gas that could come through the seals
with the case under pressure.
The oil sprayed out from the coupling cover area and contacted the casing of a steam turbine which
powered one of the oil pumps and ignited.
One maintenance man even stomped on the upper half of the coupling cover in an effort to keep it in
place and stop the oil spray.
The subsequent oil fire damaged the building roof and electricals above a personnel door which was
open and allowed fresh air for combustion to enter.
Temperature readings were taken from hot steam turbine casings and it was questioned as an
ignition source because readings were below the oil’s autoignition temperature. Two witnesses said
they saw where it ignited and it was the turbine.
We did some background research work that showed rough castings can have a catalytic effect very
similar to fibrous insulations and ignition can occur well below the expected temperatures. In this
case there were two very credible witnesses as well. It was apparent that the juxtaposition of the two
jobs was necessary to create this loss scenario. Oil could not have sprayed from the coupling covers
if they had not been loosened for the hot alignment.
A much larger gas vent was installed on the oil drain tank so pressure would be much less likely to
build up to the point where oil could be blown back up drain lines.
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Solvent Heating By Trouble Light
On January 28, 1970 we were touring a southern Alberta plant during the maintenance season and
noticed a bright glow coming from a pail of liquid which turned out to be cleaning solvent.
The area where work was being performed was unheated and the solvent was very cold so the
mechanics had totally immersed an ordinary trouble light in the solvent to warm it up so it would not
be so cold on their hands.
The electrical hazard of breaking the bulb with a steel part did not appear to have been considered
much less the potential for accidental ignition if the light were lifted out of the solvent.
Personnel knew breakage of a totally submerged bulb would not cause ignition but had not given
much thought to the shock hazard.
A safer means of warming to a controlled temperature was suggested and a caution issued that the
solvent could reach the flash point if the temperature was not kept below 100 F.
Pressure Safety Valve – Air PSV Used in Gas Service
When working on pressure safety valves, (testing, cleaning and returning to service), the importance
of clear and complete labeling cannot be over emphasized.
At a natural gas processing plant, the tag on the pressure safety valve on the discharge bottle of a
natural gas compressor was checked. It indicated it was from the plant air receiver but identical
flanges and bolt holes allowed it to be accidentally installed on the natural gas compressor where the
required pressure setting was the same.
The flanges were both four bolt on the inlet and discharge sides.
Physically the two valves were interchangeable but this error clearly should not have happened if all
the labeling details had been checked.
High Voltage Bug Killers
During a survey of the lower silo storage area where sugar was handled in large quantities with its
inherent dust explosion potential a high voltage fly zapper had been installed for health reasons.
The potential for ignition from this unit had not been considered even though all lighting in the area
was of a dust tight type. It is sometimes amazing that resolution of one problem may ignore other
even more obvious hazards.
The high voltage discharge had plenty of ignition potential but that was not considered in their zeal
to eliminate those pesky flies.
Loss Incidents
Propane Blows Cladding
At a large gas plant maintenance work was being carried out on two large reciprocating compressors.
Two mechanics were actually inside the crankcase of one of the units when an explosion blew every
piece of metal off the structural steel frame of the building.
Neither of the men was hurt in the explosion. They said when they emerged from the crankcase you
could walk out of the structure in any direction since the building had no walls.
A one half inch nipple in propane service outside the building had broken near a personnel door. The
breeze mixed the propane with air and it was blown through the door into the building where the
maintenance work was progressing. It found an ignition source somewhere in the area resulting in
the explosion.
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A contractor asked to bid on the replacement of the metal building skin was heard to say, “Wow, I
doubt if my guys could have made that clean a job tearing it off! It looks like the building is just
under construction.”
Old WKM Valve
Another propane explosion and fire occurred when the stem of an older style WKM ball valve blew
out when the Allen screws of the retainer vibrated loose and fell out. The valve was in a partly open
position across the valve seats. If fully open or fully closed the leakage would not have occurred.
The design of newer valves has been changed to preclude this happening. In new ones, the stem
cannot blow out when the retainer screws are removed from the packing compressor.
This incident also pointed out the need to be able to automatically isolate significant quantities of
hydrocarbons at receiving vessels as pump valves may not be accessible during a fire.
Oil Line Vibration
Word was received of a fire and explosion at a natural gas compressor station along with a request
for an on site review as soon as possible. The fact that this site was involved did not come as a big
surprise since it had been surveyed some months earlier and oil leakage problems were evident at
that time.
During our previous site visit Dave had been so concerned about the oil situation that he wanted the
compressor unit shut down on the spot but the boss was not receptive to this idea so it never
happened. In my report I questioned the prudence of continued operation of the unit under those
conditions.
Upon arrival at the site the fire damage was the first thing evident but the structural steel building
was still standing with the exception of part of the south wall which had been blown out by an
explosion.
Damage to the gas generator section was so extensive some of the air compressor blading was visible
through melted gaps in the casing.
Subsequent investigation revealed that oil line vibration caused by control regulators had fatigued the
oil line at a connection to the point of failure. The coarse cut and fine cut regulators overlapping or
operating somehow alternately and together caused some sort of fluid dynamics induced vibration of
the right frequency to precipitate failure. Oil spray from the broken tubing likely ignited off the hot
power turbine or combustor section. This oil mist exploded with sufficient force to blow out the
south wall of the building.
Upgrades were needed in gas flows at other locations and this unit was not replaced at the site of the
loss.
Starter Gas Release
During startup of an Alison gas turbine at a compressor station, there was a low order natural gas
explosion that was only sufficient to bulge the south wall of the building. In fact it was not known
there was an explosion until the bulge in the wall was noted by someone walking from the control to
the compressor area.
The investigation determined that the assembly screws of the natural gas starter unit had come loose
over time allowing gas to escape across the gasket into the building atmosphere. The ignition source
was not determined with any degree of certainty.
Corrective measures were taken and the unit started up safely after checks were made for other
damage.
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At a subsequent loss prevention survey the opportunity was taken to look closely at the fastening
screws. It appeared that some had come loose again. This was brought to the attention of the station
operator who at first expressed disbelief but when he reached in and found he could turn some with
his fingers he agreed. The next fix involved the use of drilled screw heads and seal wires much like
usually seen in high risk operations.
No further incidents have been reported.
Liquids in a Recip Compressor
An explosion and fire occurred in a compressor building housing fourteen units. Five of the units
were lost in the ensuing fire.
Containment
Had it not been for the courageous efforts of employees who carried portable monitors into the
structure it is likely that all units would have been lost.
The water spray provided by the monitors confined the fire to one end of the building. The aluminum
sheeting on the roof of the building burned through quickly and this helped create a local chimney
effect controlling the spread of fire to some extent.
A problem arose when a flare line which ran above the compressors suffered a ductile failure from
heat exposure from a jet flame coming from a compressor suction bottle which had also failed from
flame exposure. A jet of gas coming from the flare line was forced down toward the floor as the
plant depressured. Operators had started to depressure other sections of the plant through the
common flare system. When operators determined this was adding to their problem they stopped
depressuring of the other plant.
Consequent Damage
The fire was also partially spread by the melting out of aluminum crankcase doors releasing oil from
the engine which exposed the next unit down the line.
Analysis
The cause of the initial gas release was determined to be fatigue or impact loading of the stud bolts
connecting the cylinder to the distance piece of one of the reciprocating compressors. There may
have been some impact loading caused by liquid carryover from a low point downstream of the
suction scrubber.
Solution
A special extra low point dump was installed on the low point of the piping downstream of the
suction scrubbers.
Low points downstream of suction scrubbers are not a good design arrangement, especially where
liquids are possible. Piping should be arranged to be self draining.
During rebuild the overhead flare line was removed and routed completely outside the building to
avoid any future exposure potential.
Heater Loss/ Hydrate Plugging
The fuel gas system of a natural draft oil heater developed a hydrate plug sufficient to cause
temporary obstruction or at least until the flame went out. The gas apparently started to flow again
because the operator who was approaching the heater with a lighted torch caused ignition of the gas
which blew out both ends of the heater firebox and bulged the sides. As far as known the operator
was not seriously injured.
The hydrates may have prevented the shutdown valve from sealing fully on flame failure.
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Compressor Station
One evening I received a telephone call from a rather excited Risk Manager advising me there was a
serious fire at their largest compressor station. He was talking about a loss that could reach their
policy limits.
During the course of a number of phone calls throughout the evening he advised me as much as he
knew about the progress of the fire. When he advised me the two operators on site had escaped and
were being treated for burns that were not life threatening I told him that was good news. I said “The
rest is just iron which we will sort out in the days to follow and not to worry about it.”
The last phone call at about 1:30 am was for arrangements for me to take their adjuster John and
their company photographer to the site before first light in the morning. I was elected because I
needed no directions on how to get there.
When we arrived at the site the fire had been out for some time. The station operator had been
advised by the RCMP that no one was to go on site until they had a chance to look around. The
adjuster’s comments were basically b.s. and he went on site anyway with the photographer who was
very excited about this big job. I shadowed the photographer to warn him of open pits where covers
had been blown off by the blast and jet fire since it was not yet light enough for him to see that some
of those shadows were deep holes.
We were pretty well through looking at what we wanted to by mid morning when the RCMP
arrived. They got out of their car and were looking in awe at the devastation. One of the Officers then
said “Wow! If you need any help with traffic control or anything, just give us a call.” They looked
around for a short time like they had no idea what to do, then left.
Damage
The fillet weld area adjacent to a bolt flange, which was attached to a gate valve by a pipe ring, had
fractured in the underground B station discharge emergency shut down valve area. The blast blew the
valve operator off the valve and it remained in a partially open position. The jet of flame had been
directed back alongside the two unit B buildings resulting in their destruction as well as severe
damage to a larger D unit building. The control building, shop and small garage building were also
heavily damaged. The asphalt and gravel roof of A station had ignited from the radiant heat. A
warehouse building was heavily damaged when the contents were ignited by radiant energy coming
in the windows. A plastic greenhouse about seven hundred feet away was melted. All the snow on
site and for a distance around had melted and the ditches had waves on the water. This looked out of
place in midwinter. The gravel on site crunched under your feet like cinders and the ground was
baked brown. The whole site had the dry brown appearance of summer but it was cold and windy.
The jet flame had been fed by about 28 miles of main line piping. This exposed a second line that
failed by ductile failure due to fire exposure.
Although the station was northeast of Brooks, Alberta there were reports that reflections on the
clouds could be seen as far away as the State of Montana.
Common Sense
At a Compressor Station
During the survey of a compressor station, our tour guide was Dick who had in excess of twenty five
years of service in the industry. The Calgary office representative from their company was Dale, who
would question every suggestion no matter how logical. It was very encouraging to receive backing
from Dick on virtually every suggestion presented.
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The entrance gate was almost directly in front of the station suction scrubber. A sharp right turn was
required immediately inside the gate. A recommendation was made to provide protective bollards for
the scrubber.
To this recommendation Dale retorted,“What damage would a vehicle do to such piping?”
He was advised that our concern wasn’t the large piping but the half inch gauge fittings and dump
valve connections. Dale then said “What would happen if a driver did break one off?”
Dick was quick with the answer saying, “It would probably be the last thing he ever did!”
Dale just said “Oh.” Dale then said “Well, drivers are supposed to stop at the gate and drive slowly
into the yard.”
Dick was again the one with the reply saying, “Do you think he is blind?”
Dale said “What do you mean?”
Dick said “He saw that guy from the telephone company whip through the gate.”
Dale looked over by the office and saw the yellow truck with a look of surprise.
It seemed the only one who had not seen the truck from across the yard was him.
Service Station Vents
This was not the first time to note the antagonism of people before they stop and evaluate the reason
for a recommendation. We had done surveys of many service stations and one of the most common
concerns was the location of gasoline storage tank vents under the eaves or soffits of the buildings.
The vents had probably no been properly extended so as not to interfere with the aesthetics of the
architecture.
Charlach had received a reply to one such recommendation for extension of the vent pipes for better
dissipation of hazardous vapors. Being a forthright honest person he passed it on to me verbatim and
requested a response.
The gist of the message was “The logistics of this recommendation are asinine!”
While the literal wording may have had some measure of truth because it was expensive to do after
construction compared to the original, it was still a sound recommendation.
Within three days of receiving the note the original author was in Charlach’s office asking him if he
still had the note because he wanted to rescind it. Charlach said it had been sent out for response
much to the chagrin of the author.
It seems that within a day of issuing his comment a tanker truck was filling a station’s tanks. The
vapors issuing from the vents had entered the service station where was a gas fired heater was
suspended from the ceiling just inside the wall.
The explosion damaged the concrete block walls and roof in the area. This information was relayed
to me by Charley along with a comment that a reply to the original memo was no longer necessary.
Gas Pressure Regulator Vents
Vent openings above diaphragms of natural gas regulators should be properly vented outside
buildings by means of full size self draining vent lines terminating in moisture and insect resistant
fittings.
This was recommended at a gas plant and was implemented by the operator. At a follow up survey a
year later the operator complained that one of the regulators he had vented was giving him trouble
two months after he had vented it. He was asked if he had checked the end of the vent pipe outside
the building to see if there was a problem. He said that he had not made any checks.
We checked it a few minutes later and it was blowing a significant amount of gas from a ruptured
diaphragm. The vent had been doing what it was supposed to be doing by dumping gas outside the
building for about eight months.
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Comments have been received that if regulators vented inside the gas would be picked up on gas
detectors where these are provided. It is much better to prevent the formation of an explosive mixture
inside a building in the first place. From a health point of view it is better to prevent exposure to
hydrocarbon vapors whenever possible because things like benzene are known carcinogens.
For similar reasons, filter separator doors and pig traps should always be outside buildings.
Fire Blanket
At a compressor station tour with Marc, some rust was noted on a hinged vertical fire blanket
enclosure but more importantly, the pull ropes or straps had been placed inside during the last wash
down to prevent them getting wet.
My comment was, “Quick, I’m on fire I need a fire blanket!” Marc grabbed the enclosure with both
hands and attempted to pull it open but it wouldn’t budge. He had to go and get a slot head
screwdriver and pry the enclosure open to extend the ropes.
He said “Gee, this is ridiculous! We just went through our safety checklist but nobody actually
checked to see if they could open the enclosure or that the ropes were properly extended.” (Or in
retrospect that it actually even contained a blanket )
A few years later the same person was not impressed with shop personnel when it was discovered
they were continuing to use an acetylene cylinder when the cylinder valve would not close after it
was opened. They had just shut off the torch valve leaving the hose pressured up at night, which is a
clear violation of Alberta Occupational Health and Safety regulations. The unit was immediately
moved outside and the cylinder supplier contacted for corrective action.
Two Inch Drain Test
When doing a survey of a newspaper building, we were unable to complete the two inch drain test of
the supply line because drainage was inadequate and floor flooding would have been a problem. A
recommendation was made to that effect as this test is important in making sure the supply line is not
obstructed.
The reply forwarded was less than complimentary. The person in charge at the site complained the
valve had nothing whatever to do with the functioning of the system and was only for draining the
piping when necessary.
Our reply had to carefully explain the need for flow under pressure to check for pressure drop to
ensure there was no major restriction in the water supply such as a partially closed valve.
This was a case where the person in charge had a little knowledge but lacked a complete
understanding. (I had already had the experience of having to lift up and dry off furniture legs at
furniture store when Dan opened a two inch drain test valve and hundreds of gallons of water backed
up on the floor in the furniture storage area.
PSV Block Valve Seals
Most natural gas, oil and petrochemical plants have their own internal audit systems checking for
safety and loss prevention. It is very important to guard against apathy in what seems at times to be
repetitious drudgery. The following case is an example.
It was discovered there were properly identified car seals on OS&Y (open stem and yoke) valves
located under pressure safety valves on the liquefied petroleum gas filters. These were on a check list
and had been checked off as okay. However, they had failed to note the valves were actually in the
closed position when they were sealed.
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This was brought to the attention of Chris in the front office. He immediately contacted control by
radio. An operator went out, broke the seals, properly opened the valves and reinserted the seals
through the hand wheels to make it look like they had been open all the time.
When we got back out there, close examination revealed the broken seals. This action further
compounded the embarrassment of the situation. Chris then said to the operator “You will be writing
up a Class A incident report on this, won’t you?”
The operator looked rather pained but indicated that “Yes it will be written up.”
Shut Fire Protection Valves
There is nothing that seems to make an insurance underwriters’ representative’s day like finding a
shut fire protection system valve.
A group was on tour at a large plant and Stan was driving us around at a leisurely pace the yard to
look at the general yard fire hydrant system. We slowly drove into an area past a post indicator valve
that was clearly shut.
We toured around the area and came back out the same way, this time actually stopping very close to
the shut valve. I looked over at Stan and said “No one could accuse you of not being fair.”
Stan nodded and drove out of the area with no one else even figuring out what we were talking
about.
There were other shut valves with reasons recorded for each one but at least a query was expected.
Deluge System Off
One shut valve was noted on the supply to the sprinkler system in a large grocery store. When I
expressed concern about the shut valve the stock person said
“How do you know it’s shut off?”
I told him “Because the stem of the OS&Y valve is in.”, and I showed him.
He then told me he kept running into the spindle and found out that if he turned the wheel the stem
went in out of his way, so that’s what he did to solve his problem.
The fact that he had shut off the fire protection system for the entire building never crossed his mind.
Frozen Supply Line
One cold winter day what was the equivalent to a shut valve was discovered at a warehouse. The
sprinkler system pressure gauge showed 135 psig and the manager said “We have lots of pressure. It
must be the lower water use in winter.”
He watched as I carefully cracked open the two inch drain test valve and the pressure gauge dropped
smoothly right down to zero. I indicated there is either a shut supply valve, or more likely due to the
weather, the underground supply line was frozen.
It turned out that the underground supply line was frozen because the coarse glacial till backfill had
allowed frost penetration down to the line which was nine feet deep.
The line was thawed and more insulating type backfill provided.
Because this supply line had no domestic water take-off, the ice plug could form and no one would
notice until the flow test was made. The high pressure caused by ice plug expansion against the
confined water was a tip off. A small domestic take-off is beneficial as concern happens quickly if
the bathroom doesn’t work.
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Temporary Lapse of Attention
A young engineer was on the tour of a compressor site. He had worked on instrument design logic so
I can only assume he had a temporary lapse of attention when he noted a combustible gas detector
module had a reading of about 5% of the lower explosive limit. He reached out and turned the power
supply switch to off to see if the needle would return to the zero point. It went to zero along with the
sound of the opening of the station emergency vent valve discharge.
The Area Superintendent reacted immediately, resetting the system, reversing valve operation and
stopping the blowdown. The engineer covered his face and lowered his head in embarrassment. He
knew full well the system was designed to fail safe on loss of any of its safety systems. His first
reaction when he heard the blowdown operating was to say, “I didn’t do that!”.
The Supervisor was quick to contradict “You did so!”
As you can imagine news of this accidental blowdown spread rather quickly so when we finished the
tour of the next station the operator there said “So you managed to get through the site without
blowing her down?”
In this case he was looking toward me, so I was glad the Area Supervisor was still with us and
jumped into the conversation saying, “Hold it! That was one of our guys!”
I very much appreciated him saying that as I wasn’t about to say who was responsible because I
knew just how embarrassed he was about the incident.
After all, we are all human and we all make mistakes.
Blocked System Marked OK
A routine check at a petrochemical site showed that a deluge system had been blocked in for some
time, according to the dated tag on the hand-wheel. This had been noted on a few of the tick and
check sheets but then the check sheet showed comments like checked okay and subsequent reports
repeated the same words.
We made a comment that a blocked in system should not be shown as checked okay. They had done
this because the tank normally protected by the system was empty and they felt it was okay to leave
the system off.
It was pointed out that the adjacent tank was full and a fire there would have serious exposure
implications to the empty tank. In fact, the empty tank would likely collapse very quickly because
there was no liquid in it to provide a heat sink. They said they had not considered the exposure
potential and would restore the system to normal. They said they would also review their comment
and recording procedures.
Do Not Tinker Unless You Know What You Are Doing
It should go without saying but it is still necessary to remind people not to touch or tinker with things
they do not know about. It is much better to ask questions of an experienced operator.
Dave noted a lever on the side of a steel box attached to the yoke area of a gas control valve.
Assuming it was a latch to open the box, he lifted the lever as the operator said “Whoa - whoa!”
The operator then told Dave that he was lucky the valve was already in the position he had called for
it to travel so nothing happened. Dave had lifted the valve position control lever.
There was no harm done but it was a good lesson about making assumptions.
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Upside Down Start/Stop Switch
Fireproofing assessments were being reviewed for a methanol plant. We were looking at the liquids
pump area which was a key consideration.
One of the pump start/stop switches had the cover plate for the explosion proof box installed upside
down so the start /stop buttons were reversed relative to all other pumps in the plant. This was an
error waiting to happen so a recommendation was made to have it corrected for the sake of
consistency.
This had nothing to do with the fireproofing project but could not be ignored.
Electrical Fire Pump
At a heavy oil refinery the electrical fire pump was being tested. Near the end of the test the operator
was noted to be using the pump disconnect knife switch to start and stop the pump. When he was
advised this was a hazardous practice, he more or less scoffed saying that he used it all the time and
what would the commenter know about it anyway.
Seeing he was not easily convinced, I suggested he query the plant electrician about this practice and
he said he would. At the next survey a year later when I entered the meeting room and saw the
operator. He didn’t even say hello at first, he just looked at me and said “I don’t do that anymore!”
Others in the room looked puzzled as if to say “What’s he talking about?”
I knew exactly what he was talking about so I just replied “Good.”
He had obviously spoken with someone knowledgeable about the hazards of connecting and
disconnecting loads using a knife type disconnect switch. I would have appreciated knowing how
gently the electrician spoke to him but that is something I will never know.
The panel of the electrical controller was later noted to have proper warnings and labels as to good
operating procedure.
Incinerators and Recycling
In the late 1960’s a number of companies disposed of waste paper and other items by burning them
in incinerators.
It seemed no matter how many notices were posted about how to dispose of different materials, it
was impossible to get all people to follow simple guidelines such as not throwing supposedly empty
hair spray or pressurized paint cans in the paper waste.
A blackened and burst open pressure container was noted nailed to the employee bulletin board in
the downtown Eaton’s store as a reminder. When I say nailed, I mean nailed with a three inch nail
driven by a hammer.
The pressure can had exploded in the fire when the door of the incinerator was opened and it flew
out through the door causing a severe cut and burn to the side of the person’s face who was adding
more material to the incinerator.
Getting people to follow simple instructions is one of the biggest problems facing recyclers.
Packages of things like stale meat have shown up in recycle bins for paper.
In one case plastic supposedly for a special recycle project had to be disposed of in the sanitary land
fill because of the level of contamination in the bin. The instructions for that project called for
washed or clean plastic only. Instead among other things, leftover cottage cheese and a plastic bottle
still full of outdated Halibut liver oil capsules had been thrown in. Just imagine a cup of stale fish oil
being heated up and pressed through a plastic extruder.
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The project eventually had to be abandoned because of the amount of unacceptable contaminants that
sabotaged the work of those who were doing a proper job of sorting and cleaning their recycle
material.
Sewers - Losses
The 1992 Pemex explosion in Guadalajara, Mexico was the most spectacular sewer explosion of
gasoline known and resulted in over two hundred people being killed.
It brought back to mind a comparatively minor explosion that did not result in any deaths but startled
a lot of people and damaged storm sewer piping.
The paving crews had sprayed hot tar on the gravel road base preparatory to paving. The tar must
have contained enough volatile material to form an explosive mixture in the storm sewers over a
number of city blocks. A wick type kerosene road flare ignited the tar, and vapor flashed over and
down into the storm sewer system causing an explosion and column of smoke.
My first thought on hearing the boom and seeing the column of smoke was that a jet trainer from the
local air base had crashed in town but happily that was not the case.
One of the manhole covers that blew off sliced through power lines on the way up and came down
sideways imbedding itself in the concrete sidewalk.
Tanks - Diking
A new blade wash oil tank was installed at a large plant and was surrounded by a concrete dike wall.
It had been reviewed by the design group and all hazards taken care of in their opinion.
A few eyebrows were raised by my comment about their academic dike. They of course wanted
clarification. They had recognized the potential for spill from truck unloading and had installed a
wick drain system which ended up in the sump area inside the tank dike. It ran under the dike and
was wide open so I pointed out that a tank spill could run out as easily as the fluid from the drain
system could run in.
A pipe ran through the side of the dike and sealing of the annular space was uncertain.
A water drain valve from the tank dumped into an open cup about six inches above the floor of the
diked area so even if the wick drain system were closed, the dike would not hold more than a six
inch depth before oil ran out into the drain system which was not valved.
When the plant manager was asked how this could happen his answer was very straightforward.
“Somebody screwed up!”
At a heavy oil processing facility some large atmospheric tanks had high earth dikes surrounding
them. These were very impressive but of very little use since an open grated storm water drain
system went from inside the dike to outside without the benefit of shut off valving.
At a finished product storage terminal an open drain cup without a shutoff valve was noted near the
floor of the diked area. This had never before been brought to their attention. They had considered
their diked area as functional.
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Truck Loading
Be Aware of Emergency Procedures
Product loss occurred at a liquefied petroleum gas loading facility. A trucker was in the process of
loading his tanker when a severe leak occurred from a partially ruptured loading hose. The trucker
left the site and headed out to the highway abandoning his vehicle.
As the leak progressed an RCMP Officer stopped on the highway and assessed the situation. He
noticed a switch on a post labeled ESD (emergency shut down ) that the trucker had run past on his
way out of the station site. The Officer approached the switch and pushed it. The valves closed and
the leak eventually lessened and stopped.
The LPG cloud dispersed and there was no ignition.
Be Aware of Hazards
A tired trucker blocked open the dead man valve because he knew how long the natural gas
condensate took to load. He entered the cab and fell asleep while waiting.
He awoke to find his truck in the middle of a growing pool of natural gasoline.
Fortunately he had the presence of mind to carefully roll down his driver’s window and escape
realizing that the light switch that operates when the door is opened could easily be an ignition
source.
The valve was closed and the spill cleaned up.
Quick Thinking
Another instance of quick clear thinking after a hydrocarbon spill comes to mind when John and an
employee entered the area of a condensate spill from a pipe line where the ground was saturated.
A man in a small car stopped on the road and ran up to the two in the spill area saying, “Hey, I sell
dispersants could you use some?’
John approached the man carefully, then quickly reached up and removed a lit cigarette from the
man’s mouth, spit in the palm of his hand and doused the cigarette.
He then told the man in a rather impolite fashion that he didn’t care what he was selling and where
he could go.
John had realized instantly that if he said anything about the cigarette the man by habit would have
thrown it on the ground to step on it, and the ground was soaked with hydrocarbons.
Instructions and Procedures
The importance of giving step by step instruction paying proper attention to detail and confirming
understanding cannot be overemphasized as illustrated by the following examples.
Allen Screw Position Lock
During the rush of turnaround at an oil refinery, instructions were given for the removal of an
electrical junction box on the hydrocarbon detection probe on the boot of a natural gas condensate
vessel. The person was told to unscrew it off the connection. An hour or so after the task was
completed a fire erupted in the area. The fire caused severe damage and required a number of heavy
hose streams to bring under control and provide cooling.
The supervisor who had given the original order for removal of the box looked at what had been
brought into the office and recognized immediately what had happened. The person removing the
box had merely taken hold of it and unscrewed it because he had not been given the instruction that a
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small Allen screw had to first be loosened at the back of the box. The hex head bushing behind the
box then needed to be held in place with a wrench and the box unscrewed.
When the person removing the box turned the box for removal it unscrewed the hex bushing that
retained the hydrocarbon probe in the vessel boot. The probe actually remained in place for some
time before it vibrated loose and blew out, releasing the gasoline. This was fortunate because the
person who had unscrewed the bushing was clear of the area before the release and subsequent fire
occurred.
Body Bleed on Ball Valve
A natural gas pipe line ball valve had been cut out of a depressured section of underground pipe line
and was lying in the yard of the compressor station in the open position. The supervisor instructed a
summer student employee to remove the body bleed valve because they needed it for another
location.
The supervisor was later approached by the ashen faced student who said the valve had blown clean
across the yard when being removed. The supervisor was embarrassed because he had neglected to
tell the student to slowly and carefully open the valve to check for pressure before removal. The gas
pressure trapped between the valve seats of the ball valve was sufficient to cause violent ejection of
the valve when it was unscrewed.
The student who was not familiar with the construction of the valve was shocked because the large
valve was in the open position and he could see right through it. It was fortunate the flying valve
missed the student when it blew out of the opening. Had the valve been in the closed position the
volume of gas could have made it even more dangerous.
Mis-Communication
Due to extremely muddy conditions a supervisor and an employee of two months had walked into a
gas meter site to change the charts. The supervisor noted the ink pen on the end of the recording arm
had come loose. It was usual to merely crimp it slightly with a pair of pliers to tighten it on the arm.
Since the pliers were in the truck out at the main road, the supervisor figured he could fill the gap
with a small piece of paper or cardboard to tighten up the pen until their next visit. Knowing the new
employee was a smoker he thought of using a piece of the cardboard off a match so he said to the
employee, “Give me a match.”
Well you probably guessed it. The employee lit the match and there was an explosion. Both of them
survived but they suffered some flash burns.
He failed to communicate his need was just for a small piece of the cardboard.
Freeze-Ups and Ice Damage
Low Point Water After Hydro-Test
A natural gas condensate vessel had been hydrostatically tested at a small refinery and the vessel was
then drained. A two inch pipe attached to the side of the vessel formed a low point dead leg at a blind
flange and this was missed in the drainage operation.
The water froze in cold weather and split the pipe.
The vessel was placed back in service and as the warm hydrocarbon thawed the long
ice plug a leak developed at the pipe split which increased with rapid thawing caused by the flow.
Ignition from a hot surface or nearby heater caused a fire that was hot enough to spall some of the
concrete pipe stanchions.
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Nitrogen Compressor Water Jacket
Nitrogen compressors which had been hydrotested but not properly drained were left outside during
winter. The water jackets of the compressors were cracked by the ice formation. This resulted in a
delay of startup while new compressors were obtained.
Frozen Bolt Holes
A fairly significant regrouting job was necessary when bolt holes in large compressor pedestals filled
with water froze and split the concrete.
Frozen Sprinkler Systems
Freeze-up of sections of firewater sprinkler systems is fairly common during very cold weather with
high winds. When water pressure gauges at an alarm valve showed abnormally high pressure, checks
of the system were carried out.
Ice formation results in expansion which increases pressure in the hydraulically confined liquid.
When I opened a door to a poorly heated back stairwell the problem was located. A two and one half
inch pipe fitting was lying in pieces on the floor. I was looking at an ice plug that I knew had 130
psig water pressure behind it.
The system was shut off, drained and the ice plug thawed out. Repairs were made and any potential
water damage avoided.
I have seen sprinkler system freeze-ups that were so bad the sprinkler heads were pushed open and
the ice extruded in pig tail spirals out of each of the heads.
Still Column Vents
In natural gas dehydration processes a severe hazard can be created by ice formation in long still
column vent lines off the glycol reconcentrators. Proper emergency venting and freeze protection is
essential. This is partly due to the fact that the reconcentrator is only designed for atmospheric
pressure.
If freeze off of the vent occurs without proper auxiliary relief capacity, the steam pressure can cause
violent rupture of the vessel and great danger to any personnel in the area.
Refinery Steam Tracing
A very costly freeze-up at a refinery happened in very cold weather when all the plant boilers were
nearly fully loaded. A person working on the boiler control system cut a green wire with sidecutters.
The boiler tripped off line and the other boilers tripped off one after the other when they could not
pick up the load demand for steam.
Before they could get the boilers back on line a great amount of the steam tracing had frozen and was
damaged.
This turned out to be another case of “if you don’t know what it does, don’t mess with it”.
Hazards with Catalytic Space Heaters
Catalytic space heaters for hazardous locations are fairly often placed in inappropriate locations or
operated under conditions outside their design parameters.
Sour Gas
Sour gas either in the fuel or in the ambient air means catalytic heaters are not suitable for that
location. It is corrosive, and it ignites at a lower temperature than pure natural gas.
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Possibility of Igniting Oils
These heaters should not be located where oils such as crude oil could accidentally be dripped,
spilled or splashed on the unit, especially the face, because they are capable of igniting oils which
have auto-ignition temperatures which are much lower than natural gas in air. This often comes as a
surprise to many people as they have a tendency to think of oils as lower hazard.
At one crude oil production facility it was noted that heavy crude had dripped across the face of a
catalytic heater. The operator was told this was a serious ignition hazard but he found that hard to
believe. It was explained that the heaters were designed for a natural gas in air atmosphere which has
a much higher auto-ignition temperature. The operator was under the mistaken impression that oil
was much harder to ignite than gas in air. He was advised that oil will ignite at about half the autoignition temperature of natural gas in air.
I am sure the operator was still skeptical enough that he was about to do his own research but I think
that is great because he will probably remember it a lot better if he reads about it for himself.
Inoperable Safety Shutdown Bypass Button
One hazardous practice we have found on occasion is the tendency to wire down the safety shutdown
bypass button which should only be manually held down during startup operations. The hazard can
be considerable if fuel gas pressure is lost; the heater stops operating but when fuel gas pressure is
restored the gas will flow out into the building atmosphere creating an explosion hazard as well as a
health hazard.
Conclusion
Take responsibility for your own safety and the safety of your colleagues.
This information is an assemblage of some of my personal experiences and should not be considered
as comprehensive or extensive. For all matters pertaining to hazard identification and loss control
reference should be made to government requirements, industry standards and authorities having
jurisdiction for insurance purposes.
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