Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
PROCESS DESIGN MANUAL
FOR
PROCESS ENGINEERING DESIGN
BASIS
Doc. No. OTV –00043, Page 1 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
Responsible Issuer:
Head of Department – Process Engineering
Table of Contents
Section
1.0 P&ID Engineering and Philosophy
2.0 Utility Battery Limit and Utility Header & Block Valves
3.0 Connection for Instruments
4.0 Equipment Sparing Philosophy
5.0 Equipment Duty Margin
6.0 Pressure Relief Philosophy
7.0 Insulation and Tracing Philosophy
8.0 Process Block Valves Philosophy
9.0 Utility Station Location Philosophy
10.0
Isolation Blinds / Spading Philosophy
11.0
Tank Fittings and Accessories Philosophy
12.0
Equipment Design Philosophy
13.0
Minimum Liquid Surge Requirement
14.0
Utility Conditions
15.0
Noise Control
16.0
Aromatics Handling
17.0
Corrosion Allowance
18.0
IBR requirements
Anoop Sharma,
Approval: Name, Date, Signature
Copying of this document, and giving it to others and the use or communication
of the contents thereof, are forbidden without express authority by Lurgi.
Doc. No. OTV –00043, Page 2 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
Dated : December 04, 2000
Foreword
We are pleased to note that Process Engineering Department is releasing the “Process Engineering Design
Basis” for use by its engineers.
In the past, it was seen that the engineers had to resort to repetitive use of uncompiled information required by
them in their day to day work. The need was therefore felt to compile all the design guidelines/data in one place.
The exercise carried out by the process engineers was therefore a fruitful one in the generation of this manual.
We are sure the manual will serve as a useful tool for the process engineers in their day to day work.
Dr. Sudhir Kapoor
Managing Director and CEO
Onkar Gupta
Director Operations
Doc. No. OTV –00043, Page 3 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
1.0
P&ID Engineering and Philosophies
1.1
General
Pressure drop and velocity criteria for the sizing of lines are outlined below. For revamped units higher
line velocities may be considered for existing lines.
1.2
Standard Line Sizes
The following non-standard line sizes will not be used unless approved by customer.
¼”, 2 ½”, 3 ½”, 5”, 7”, 9”.
1.3
Minimum Line Sizes
The following guidelines should be applied:
2”
2”
1½”
¾”
½”
1½”
4”
1.4
NB
NB
NB
NB
NB
NB
NB
Minimum nozzle size for vessels, tanks and heat exchangers.
Minimum process (hydrocarbon) line size.
Minimum utility line size.
Minimum bridle drain or pump casing vent / drain.
Minimum chemical injection. Tubing size to be 10 mm.
Minimum on pipe rack.
Minimum for underground lines (wrapped and coated)
Roughness Coefficient
The following roughness coefficients are to be used, unless stated otherwise:
Material
1.5
Roughness (Inches)
Carbon steel pipe
0.0018
Flare/vent headers (heavily corroded)
0.018
Stainless steel pipe
0.001
Glass reinforced epoxy pipe
0.0001
Pressure Drop Calculations
Design margins for two phase flow pressure drop calculations normally are 50% of the pressure drop
calculated at normal flow to allow for inherent inaccuracy in the calculation methodology, manufacturing
tolerances, deterioration of the new pipe with scale, etc.
It is important not to oversize pipe with vertical upward two-phase flow. The flow regime shall be
calculated for design, normal, and turndown. Every effort shall be made to avoid slug flow regime.
Doc. No. OTV –00043, Page 4 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
1.6
Pressure Drop Calculations for Vapour and Liquids
These margins are based on experience and range from 0% to 20% plus on the pressure drop at normal
flow, depending on the configuration of the system being designed. For most systems, 20 % pressure
drop margin is applied. However for very low pressure systems, margins are individually assessed, for
example in a tank to vent pipework.
1.7
Equivalent Lengths
Pipe fitting, contractions and enlargements are taken into account by utilising “equivalent lengths” as per
normal engineering practices.
1.8
Limiting Velocities and Pressure Drops
ft/s
m/s
Press. Drop,
bar/100 m
4
5.2
10
4
7
4 to 6
10
API-RP14E
1.22
1.6
3.05
1.22
2.14
1.22 to 1.83
3.05
API-RP14E
0.1 to 0.06
0.05 to 0.22
0.2 to 0.5
0.06 to 0.1
-
250
200
150
100
75
60
45
30
20 to 40
40 to 80
6 to 12
12 to 25
50 √
15 √
Liquids
Pump Suction- boiling
Pump Suction- sub-cooled
Pump Discharge
Sidestream Draw-off
Amine, Carbonate, Sour Water
Sodium Hydroxide
Salt Water
Erosion Limits
Gases
General
Less than 1.03 bara
Upto
6.9 bara
Upto
69 bara
Over
69 bara
Compressor Suction
- Reciprocating
- Centrifugal
0.1 to 0.06
0.06 to 0.13
0.13 to 0.5
0.2% of
Pressure
0.02 to 0.6**
Steam General
High Velocity Flow (pressure let down)
0.1
0.1
d *
0.9 Mach
* d is in inches
** Depends if short or long line and steam pressure level
d *
0.9 Mach
1.9
Net positive Suction Head (NPSH)
1.10
A margin of at least 0.9 m between calculated NPSH and available NPSH has to be applied.
For positive displacement pumps, effect of acceleration head on NPSH will be taken into account.
Differential Head Calculations
Doc. No. OTV –00043, Page 5 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
Besides discharge piping loss, other losses taken into account are:
Orifice pressure drops
:
0.2 kg/cm2 assumed
Equipment drops; e.g. heat exchangers
:
fouled pressure drop
Control valve pressure drop
(for pump head calculations)
:
The greater of the following :
- 50 – 60% of the total frictional loss
excluding the control valve
- 0.7 kg/cm2
- 15% of the pump differential head
For valves installed in extremely long or high
pressure drop lines, the percentage drop cross
the valve may be somewhat lower, but at least
15% up to 25%, where possible, of the system
friction drop should be taken.
Head Loss
1.11
:
Based on low liquid level in suction
vessel and high liquid level in the discharge
vessel or discharge
nozzle elevation of
discharge vessel, which ever is higher.
Boiler Feed Water Pumps
BFW pumps will meet the requirements of ASME code section 1; i.e. be capable of supplying water to
boiler at a pressure of 3% higher than the highest setting of any safety valve on the boiler.
1.12
Vents, Drains and Steam out/Purge connections for Equipment:
a. Process Vessels
Process vessels (tower and drums) shall have vents, drains and steam-out or purge connections as
shown below:
Equipment Volume
m³
Vent Size
in
Drain Size
in
Steam out or Purge
Size, in
Upto 17 (600 ft3)
2
2
2
17 to 141.5 (600 – 5000 ft3)
2
3
2
141.5 to 283 (5000 – 10,000 ft3)
3
4
3
283 to 708 (10,000 – 25,000 ft3)
4
4
3
over 708 (over 25,000 ft3)
* To be located on opposite sides
6
6
Two 3 *
b. Exchangers (Shell and tube)
Doc. No. OTV –00043, Page 6 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
Provide 1” NB x 300 # (min.) flanged vents and drains at high and low points on Heat Exchangers. All
vents and drains are to be valved and blanked off.
Exchangers in total condensing service require a 2” vent connection at the opposite end of the shell inlet.
Sizes of Multi purpose connections and pressure gauge connections on exchanger nozzle shall be 1” NB
x 300 # (min.) for below 12 “ nozzles and 2” NB x 300 # (min) for 12” and over nozzles.
Multi purpose nozzles can be used for thermometer connections if required.
1.13
1.14
Piping
Pipe Size, in
Vent Size, in
Drain Size, in
4 and below
¾
¾
6 to 10
¾
1
12 and over
1
1½
Air Coolers
On Air Coolers one 2” vent shall be placed at the highest point on the inlet header and one 2” drain at the
lowest point in the outlet header. The exact locations of these vents and drains are dependent on the
actual cooler design. Connections are to be valved and blanked off.
1.15
Pump Casings
For non-volatile services, casing vents and pumps drains shall be piped into a sewer or closed drain
system.
For volatile services, casing vents and drains are to be piped to the relief header and sewers.
1.16
Additional Notes
1.
2.
3.
4.
5.
6.
Valved and blanked off vent and drain connection shall be furnished on all equipment that is not
self-venting or self-draining. Connection shall be located on equipment, if practical, but may be
located on connected piping when there are no valves or blocks between the vent or drain
connections and the equipment.
Hydrostatic vents and drains for piping are to be provided and will not be shown on P&ID.
When soda ash neutralisation is required in shell and tube exchangers, standardise on 2” flange
connection.
At relief valves, a ¾” valve blanked off bleed shall be shown upstream of safety valve.
Vents from vessels that may chill and freeze during depressurising shall have double block valves
separated by at least 900 mm.
Steam out connections shall be located at minimum distance above the bottom head seam of
vertical vessels and the side or head of horizontal drums.
Doc. No. OTV –00043, Page 7 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
7.
Steam-out connections shall be located at minimum distance above the bottom head seam of
vertical vessels and the side or head of horizontal drums.
Blanked off vents shall be located on the top head of towers and vertical vessels. They shall be
located on the top of horizontal drums at the same end as the drain and the end opposite from the
steam out or purge connection.
A vessel drain shall be located in the bottom outlet line when the outlet line is located where it can
be used to drain the vessel. Consider adding downstream orifice for vessel drains under pressure
to limit drain velocity.
Minimum size vents for vessels having only one personnel access way shall be 4” for horizontal
vessels and 2” for vertical vessels.
Minimum manhole size shall be 20” internal diameter.
Large size manholes will be specified if required to accommodate internals. For underground
vessels the minimum manhole size is 30” internal diameter.
In trayed columns, manholes will be provided above top tray, below the bottom tray, at the feed
tray, at any other tray as identified on process data sheets. Maximum spacing of manholes does
not exceed 10 m. The minimum spacing of trays between manholes shall be 760 mm.
In horizontal vessels, equal or longer than 6 m, if an internal baffle is installed, two manholes will
be required, one manhole in every compartment.
8.
9.
10.
11.
12.
13.
14.
2.0
2.1
Unit Battery Limit and Utility Header & Block Valve
General
For new units and / or new storage, two block valves, blind and ¾” bleed or vent will be provided at
battery limits. When a second valve is located within the process unit, only one block valve is required.
2.2
Utility Header
At unit battery limit, provide isolation valves as below:
• For steam, fuel gas, steam condensate, boiler feed water & hydrogen, provide double block
valves, blind & ¾” bleed. For HP steam, also provide a 1” warm-up bypass.
• For instrument/plant air, service water, nitrogen, cooling water etc., provide a single valve, blind
and ¾” bleed.
Doc. No. OTV –00043, Page 8 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
3.0
Connection for Instruments
3.1
Instrument Connection Size (for guidance only)
S. No.
Instrument
1
Thermowell
2
Pressure
Instrument/Differential
Pressure (Direct Type, Pipe
Mounted)
Pressure
Instrument/Differential
Pressure (Direct Type, Equipment
Mounted)
Pressure Instrument
• Diaphragm Seal, Pipe
• Diaphragm Seal, Vessel
Differential Pressure (Diaphragm
Seal)
Standpipe
• Upto 330# Ratings
• 600# and above ratings
Level Gauge (On Vessel)
Level Gauge (On Standpipe)
Displacer Level TX (Vessel/Stand
Pipe External)
Displacer Level TX (Top, Internal)
Level
Switch
(Vessel,
S/P)
External
Annubar
O2 Analyser (On Stack)
Analysers (Others Except ‘B’)
Sample Probe
3
4
5
6
7
8
9
10
11
12
13
14
15
First
Isolation
Connection
(Piping / Vessels)
2” Flanged *
Instrument Connection
¾” Welded
2” Flanged
Temperature Element
Connection
to
Thermowel ½”.
½” NPT
2” Flanged *
½” NPT
2” Flanged **
2” Flanged *
3” Flanged
2” Flanged **
2” Flanged *
3” Flanged
3”
4”
2” Flanged *
¾” Flanged *
2” Flanged *
¾” Flanged
¾” Flanged
2” Flanged *
4” Flanged *
2” Flanged *
4” Flanged *
2” Flanged *
2” Flanged *
4” Flanged **
3” Flanged **
2” Flanged **
½” NPT (Pressure Tap)
* Flange rating shall be min 300#
** Flange rating as per Pipe Specification
4.0
Equipment Sparing Philosophy
The Following equipments shall be provided with a spare:
•
•
•
•
Main Process Pumps viz. Feed Pumps, Product pumps, reflux pumps and transfer pumps
Reciprocating Compressors
All Control Valves shall be provided with manual bypass globe valve unless provided with
handwheel
Filters where duplex is specified or where additional Filter is required owing to process reasons.
Doc. No. OTV –00043, Page 9 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
5.0
Equipment Duty Margins
Equipment duty margins (between normal and design duties) are specified on the process data sheet.
In case of new equipment, duty margins are allowed as follows as minimum requirement.
5.1
Heat Exchanger (Shell and Tube)
A nominal over surface, based on either 10% on flow and / or duty will be used depending on if the
services is critical or non critical, in consultation with the Customer.
5.2
Air cooler
Use similar approach as above.
5.3
Fired Heaters
Use similar approach as above.
Notes:
•
For fuel fired heaters a maximum of 25% excess air is allowed.
•
For gas fired furnaces the excess air is 15%.
5.4
5.5
Pumps
Centrifugal Pumps
: For small process pumps and reflux pumps use 20% margin on
normal flow. For large pumps, use 10% of normal flow.
Reciprocating Pumps
: Use 10% of normal flow for both small and large pumps.
Compressor
For both centrifugal and reciprocating compressors, use 10% margin of normal flow.
For air blower use 10% margin on normal flow.
6.0
Pressure Relief Philosophy
All relief valves load and size shall be calculated according to the following mentioned codes:
•
•
•
•
•
API 520
API 521
API 526
API 527
API 2000
The size of relief valves are based on either over-pressure condition, fire exposure or vacuum situation
for a particular system.
Doc. No. OTV –00043, Page 10 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
6.1
Typical over pressure conditions is:













6.2
Typical vacuum considered would be:







6.3
Blocked Discharge
Inadvertent Valve Opening
Utility Failure
Cooling Water Failure
Electrical / Mechanical Failure
Loss of Air Cooler Fans
Loss of Heat in Fractionation
Loss of Instrument Air or Electric Power
Instrument Failure or Blow-by
Reflux Failure
Abnormal Heat Input From Reboilers
Heat Exchanger Tube Failure
Trapped Liquid Expansion
In-breathing due to pumps out and temperature variation
Steam condensation (Vacuum arising from steam out under maintenance conditions
not be considered for vacuum relief protection)
Equipment normally operating under vacuum
Equipment operating under vacuum conditions during start-up, shutdown, regeneration, or
evacuation
Liquid full vessels that can be blocked in, and cooled
Distillation columns and associated equipment that can be subjected to vacuum due to loss to heat
input.
Pressure vessels containing liquid having vapour pressure at minimum ambient temperature less
than atmospheric pressure.
Relief Valve Selection Type
Balanced bellow will be used for the cases where the built-up backpressure and the variable
superimposed backpressure exceeds 10%, but is below 50% of the set pressure.
Pilot operated relief valves may be used for systems when maximum set point accuracy is required. They
will be installed in equipment, which operate very close to set pressure. All above valves are also limited
by process considerations (i.e. H2S service etc.) and material.
Notes:
1.
Valve selection will be based on maximum operating temperature and relief valve set pressure.
2.
Where H2S is present, process data sheet will contain a note to indicate its presence.
3.
Safety valves on column circuits are preferred to be located at the highest point in the overhead
vapors lines. Alternatively, these safety valves can be located as per below provided that the
pressure drop in the inlet line is within 3% of set pressure.
4.
PSV discharge to be free draining to flare header, and join at 45o angle for 2” and larger size and
90o and free draining towards flare header for 1 ½” and higher size.
Doc. No. OTV –00043, Page 11 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
5.
Inlet and outlet valve to be full port.
6.
Relief valves on highly viscous fluid lines to be steam jacketed.
7.
Relief valves, which are susceptible to plugging, shall be steam traced and have a rupture disc
installed under them.
8.
Staggered pressure setting may be specified to minimise losses.
9.
For atmospheric relief, the open end of discharge will be located 30m from any source of ignition.
Discharge is usually 3m higher than any equipment or manholes (Ladder, platform etc.) within 15m
radius
NO
POCKETS
FREE DRAINING
FREE DRAINING
COLUMN
FLARE HEADER
CONDENSER
REFLUX DRUM
SUFFICIENTLY HIGH TO AVOID LIQUID
ACCUMULATION. ALSO ENSURE SAFETY VALVES
ACCESSIBILITY FOR MAINTENANCE
7.0 Insulation and Tracing Philosophy
To reduce heat loss, piping, vessels, tanks and the equipment will be insulated where operating
temperature exceeds 70oC.
The table showing insulation thickness with temperature is below:
Doc. No. OTV –00043, Page 12 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
Table - 1
Insulation Thickness for Personal Protection
Insulation thickness in mm
Surface temperature of insulation less than 60°C
Nom
Dia. (in)
0.5
0.75
1
1.5
2
3
4
6
8
10
12
14
16
18
20
Flat
Surface
Upto
125
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
126 150
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
151 200
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
Operating Temperatures in ° C
201 251 –
301 351 250
300
350
400
25
25
25
40
25
25
25
40
25
25
40
40
25
25
40
50
25
25
40
50
25
40
50
50
25
40
50
65
25
50
50
65
40
50
50
75
40
50
50
75
40
50
65
75
40
50
65
75
40
50
65
80
40
50
65
80
40
50
65
80
40
50
65
80
401 450
50
50
50
50
65
65
75
75
80
80
90
90
90
90
90
90
451 500
50
50
65
65
75
75
80
90
100
105
115
115
115
115
115
115
501 550
65
65
65
75
80
90
105
105
115
125
125
130
130
140
140
140
Types of Insulation Materials
Bonded Mineral Wool pipe sections (MW)
Bonded Mineral Wool mattress (MW)
Cal. Silicate Pipe Sections (Cal. Sil)
Cal. Silicate Lags (Cal. Sil)
Doc. No. OTV –00043, Page 13 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
Table - 2
Insulation Thickness for Heat Conservation
Insulation thickness in mm
Heat Loss = 150 Kcal/hr-m2 (max)
Nom
Dia. (in)
0.5
0.75
1
1.5
2
3
4
6
8
10
12
14
16
18
20
Flat
Surface
Upto
125
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
126 150
25
30
30
30
30
35
35
35
40
40
40
40
40
40
40
40
151 200
35
40
40
45
45
50
50
55
55
55
60
60
60
60
60
60
Operating Temperatures in ° C
201 251 –
301 351 250
300
350
400
50
60
70
85
50
65
75
90
55
65
80
95
60
70
85
100
60
75
90
105
65
80
100
115
70
85
105
120
75
90
110
130
75
95
115
140
80
100
120
145
80
100
125
150
80
105
125
150
85
105
130
155
85
105
130
155
85
105
130
155
85
105
130
155
401 450
95
100
105
115
120
135
140
155
160
170
175
175
180
185
185
185
451 500
110
115
125
130
140
150
150
160
175
185
195
200
205
210
215
215
501 550
115
125
125
140
150
150
150
165
180
190
200
210
210
220
220
220
Types of Insulation Materials
Bonded Mineral Wool pipe sections (MW)
Bonded Mineral Wool mattress (MW)
Cal. Silicate Pipe Sections (Cal. Sil)
Foam Glass pipe sections (upto 125 °C only) (FG)
Notes:
1. Applicability for thermal insulation Temp. range 60 to 550 °C For Pipes, Ductwork and
Equipment. NOT applicable for Embedded/Buried lines, buildings and structures.
2.
For operating temperatures above 550°C, decide material and thickness on case to case basis.
Doc. No. OTV –00043, Page 14 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
Table - 3
Insulation Thickness for Cold Insulation
Nom
Dia. (in)
0.5
0.75
1
1.5
2
3
4
6
8
10
12
14
16
18
20
Flat
Surface
Upto
+5
+4 to
-7
-8 to
-18
-19 to
-32
35
40
40
45
45
50
55
60
60
65
65
65
65
70
70
70
50
50
55
60
65
70
75
80
85
90
90
90
95
95
95
95
60
65
70
75
80
90
95
100
110
115
115
120
120
125
125
125
80
80
85
95
100
110
115
130
135
140
145
150
155
155
160
160
Operating Temperatures in ° C
-33 to -46 to -61 to -76 to -91 to
-45
–60
-75
-90
-100
90
95
105
115
120
130
140
150
160
170
175
180
185
185
190
190
110
120
125
135
145
160
170
185
195
205
215
220
225
230
230
230
125
135
140
155
165
180
190
210
225
235
240
245
255
260
265
265
145
155
160
175
185
205
220
240
255
265
275
280
290
295
300
300
155
165
170
190
200
220
230
255
270
280
290
300
305
315
320
320
-101
to
-120
165
175
185
200
215
235
250
275
290
305
315
315
320
330
340
345
-121
to
-130
170
180
190
210
220
240
255
280
300
310
325
330
340
350
355
355
-131
to
-145
180
185
195
215
225
250
265
290
305
320
335
340
350
360
365
365
-146
to
-155
180
190
200
220
230
255
270
295
310
325
340
345
355
365
370
370
Types of Insulation Materials

Rigid Polyeurethene Foam
Tracing
In case of tracing, steam or electrical tracing shall be used.
Doc. No. OTV –00043, Page 15 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
8.0
Process Block Valves Philosophy
8.1
Single Block Valves
Single block valves shall be installed for the following conditions:










8.2
In piping at all vessels and tanks nozzles, where the nozzle is below liquid level of the vessels and
tanks.
In exchanger inlet and outlet, only if exchanger requires frequent inspection or cleaning.
In suction and discharge piping of pumps, turbines and compressors.
At equipment in auxiliary piping for gland oil, flushing oil, cooling water and for removal of
equipment.
At equipment in steam piping for steam driven equipment.
At fuel oil and fuel gas piping to furnaces or fired heaters. Valve shall be located 15m from the
equipment and accessible for rapid operation in emergency.
For drains to closed drain header. Install a check valve, one pair of flanges and a bleed valve
upstream of block valve. (Note: Flanges and bleed to be provided between check and block
valves.)
In product lines to slop header. Install a check valve and block valves.
For gas stream <100 barg pressure or liquid system of <60 barg pressure. If the operations will be
more frequent than twice per annum, or the system contains gases or liquids, which are potentially
toxic, then a double block and the bleed system will be used.
In lines to flare header
Double Block Valves
Double block valves shall be installed for the following conditions:






9.0
For cases where cross contamination cannot be tolerated.
For vents and drains in ANSI Class 600 rating and over.
For drains containing C5 (plus lighter hydrocarbons) or lighter hydrocarbons. In this case the double
block valves must be minimum of 100cm straight pipe apart. A check valve will be installed
upstream of the first block valve. A pair of flanges shall be provided between the check and first
block valve.
Where high pressure (above ANSI CI 300 rating) is likely to be removed on the run; e.g. spared
machinery or equipment.
For gas stream >100 barg or liquid systems > 60barg or gas/liquids which are potentially toxic.
For the equipment which may be opened for maintenance “ on the run” (e.g. filters).
Utility Station Location Philosophy
Utility steam, air and service water outlets shall be furnished with hose connection of minimum size 1”
nominal. As a general rule provide first block valve (ideally at header) followed by a ¾” bleeder, check
valve and block valve adjacent to equipment or piping. All utilities are to terminate with a hose connection
(Assuming a maximum hose length of 25m, utility stations for LP steam, service water and plant air shall
be provided at following locations:
Doc. No. OTV –00043, Page 16 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
In Process Units




At grade to serve equipment within a maximum 25m radius.
At top platforms of drums located at the grade.
At first level platforms of structures and towers.
At second level platforms of structures and towers.
In Off-Sites

10.0
Utility stations will be provided near pump stations and chemical injection systems. (Direct
connections from utility header to process vessels must be avoided to stop process fluid entering
into utility system.
Isolation Blinds / Spading Philosophy
Isolation blinds will be provided as follows:




On all spared pumps, turbines and compressors on the equipment side of the block valve, where
applicable.
At unit limits either between double blocks or on unit side. (refer Section 2.0).
At equipment, which can be physically entered, provision for temporary blinds.
For vents and drains- provision for temporary blinds.
Nominal Line Size (Inches)
12” and under
Over 12” inches
11.0
Blind Type
Spectacle Blind
Circular with spacer
Tank Fittings and Accessories Philosophy
The following guidelines will be used (as a minimum) during detail engineering to specify fittings and
accessories for all types of atmospheric tanks.
11.1
Manholes – Number and Sizes
Shell
Nominal
Tank Dia.
(Meters)
3 to 6
> 6 to 12
>12 to 18
>18 to 45
>45
All Tanks Types
Roof
Roof
Fixed Roof Tanks
Floating
Tank
Internal Floating Roof
Roof
Fixed Roof
Number
Size
(inch)
Number
Size
(inch)
Number
Size
(inch)
Number
Size
(inch)
1
2
2
2
3
24
24
24
24
24
1
2
2
2
2
24
24
24
24
24
1
1
1
2
2
24
24
24
24
24
1
2
2
2
3
24
24
24
24
24
Internal Floating
Roof
Size
Number
(inch
)
1
24
1
24
1
24
2
24
2
24
Doc. No. OTV –00043, Page 17 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
11.2
Filling and Suction Nozzles – Minimum Sizes
Nominal Tank Diameter (meters)
<14.9
15.2 to 30.1
30.4 to 60.5
>61
11.3
Roof Drains
Nominal Tank Diameter (meters)
<6
6 to 18
> 18
11.4
Nozzle Diameter
(Inch)
3
4
6
8
Drain Diameter
(Inch)
3
4
6
Sample / Gauge Hatch
Provide one 8” gauge hatch for level measurement per tank.
11.5
Water Draw-off/Drain – Number and Sizes
All draw-off connection shall be furnished complete with the following:
4” nozzle, 1200mm diameter by 610mm deep-water draw-off sump, internal pipe terminating 100mm
above bottom of sump and drain valve.
Nominal Tank Diameter (meters)
<12
12.1 to 45
46 to 61
>61
Number Required
1
2
3
4
Water draw-off nozzles shall be located near shell manholes to facilitate cleaning of sumps.
12.0
Equipment Design Philosophy
12.1
Pressure Vessels Design
Design Pressure
The design pressure for pressure vessels shall be as per the following criteria:
a. For operating pressures upto 70 kg/cm2g, the highest of the following to be considered :
Doc. No. OTV –00043, Page 18 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
•
•
•
Maximum Operating Pressure + 2.0 kg/cm2
Maximum Operating Pressure x 1.1
3.5 kg/cm2 (g)
b. For operating pressures above 70 kg/cm2g :
•
•
For operating pressures between 70 and 140 kg/cm2g : Operating Pressure + 7.0 kg/cm2
For operating pressures greater than 140 kg/cm2g
: Operating Pressure x 1.05
c. For vessels operating under vacuum, design pressure to be 1.0 kg/cm2g and full vacuum.
Notes:
1.
For equipment connected to flare (e.g, flare knockout drum), design pressure of equipment to be
same as flare design pressure.
2.
Equipment in circuits that can be evacuated by an ejector and suction drum on reciprocating
compressor will be designed for full vacuum conditions in addition to operating conditions. Strippers
using steam will be designed to full vacuum conditions.
3.
Mal-operation during the steam out of vessels is not to be considered.
4.
The vessels open to atmosphere shall be designed for full of water condition.
5.
Design pressure mentioned above does not include the liquid head.
Design Temperature
The equipment design temperature shall be as follows:



For temperature below 0o C
For temperature above 0oC
Boiling water service
: Lowest possible operating temperature
: Operating Temperature + 30oC
: Saturation temperature at design pressure.
Note: For exchangers, pumps, compressors, filters, etc., use as above pressure vessel design
temperature
12.2
Pump Shut Off
Equipment in a pump discharge circuit with a down stream block valve shall have a design pressure
which should be the higher of the two :
- suction vessel operating pressure + normal liquid static head
pressure
-
+ pump differential shut-off
suction vessel design pressure + maximum liquid static head + pump differential pressure (at normal
flow)
For estimates of pump shut off head on motor driven centrifugal pumps at normal operating suction
pressure, use the suction pressure plus 1.25 times the rated differential pressure of pump. The suction
pressure shall be the vessel normal operating pressure plus the normal liquid static head.
For constant speed turbine driven pumps, use the suction pressure 1.35 times rated differential pump
pressure. For variable speed turbine pumps, uses the suction pressure plus 1.5 times rated differential
pump pressure.
Doc. No. OTV –00043, Page 19 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
For a full liquid system at the discharge of a positive displacement pump, the mechanical design pressure
shall be higher of these two:
•
•
P (rated) discharge + 2 kg.cm2
P (rated) discharge * 1.1
The shut off pressure will be confirmed based on equipment purchased.
12.3
Tank Design
The minimum design pressure and design temperature requirements of tanks shall be as below:
Design Pressure
Cone Roof Tank
Dome Roof Tank
:
:
+20 mbarg / -6 mbarg
0.04 to 1.04 barg
Tank design pressure does not include liquid head. Design pressure is for the top of the tank. Maloperation during steam out is not to be considered. A vacuum breaker shall be provided.
Blanketed storage tanks shall have a blanketing pressure of 150 mmwc unless specified by client.
Design Temperature
The tanks design temperature shall be as follows:



For temperature below 0o C
For temperature above 0oC
Boiling water service
: Lowest possible operating temperature
: Operating Temperature + 30oC
: Saturation temperature at design
pressure.
The minimum design temperature shall be the lowest temperature expected in service.
12.4
Tower Overhead System
For equipment in a tower overhead system with a relief valve, the design pressure shall be arrived as
follows:
a)
b)
12.5
In front of a train of equipment, design pressure to be compatible with the relief valve set pressure
plus liquid static head.
In rear of a train of equipment, design pressure to reflect relief valve set pressure, liquid static
together with line and equipment pressure losses, including fouled equipment.
Compressor Systems
For centrifugal or axial compressor, the design pressure of upstream equipment should be set at a safe
margin above the settle-out pressure. The safe margin is normally at least 10%.
Downstream equipment will be set at blocked in conditions.
For reciprocating compressors, each stage is fitted with safety valve at a margin above the normal
discharge pressure by the vendor. The piping and equipment downstream will be set at blocked-in
Doc. No. OTV –00043, Page 20 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
condition. The upstream equipment will be set at in the usual way, above the normal operating pressure
or the settle out pressure and protected by relief valve.
12.6
Piping Systems
Design pressure for the piping will normally be at least equal to theoretical maximum expected operating
pressure and similar to the connected equipment.
Design temperature for the piping will take into consideration flowing conditions, shut conditions and solar
radiation and will be similar to the connected equipment.
For relief valve inlet pipe, design temperature and pressure will be same that of the connecting
equipment. For discharge pipe, design temperature must be determined separately.
12.7
2/3rd Rule for Heat Exchangers
For shell and tube heat exchangers the low-pressure side shall be specified for a mechanical design
pressure at least equal to 2/3rd of high-pressure side mechanical design pressure. If this is not possible, a
relief valve of adequate size must protect the low-pressure side. 2/3rd rule shall necessarily be adhered to
when:
•
LP fluid is on tube side
•
Relief discharge cannot be connected to flare header owing to nature of fluid
•
Relief discharge is two phase and cannot be connected conveniently to a low-pressure destination
with free-draining piping.
•
Liquid relief cannot be connected to CBD system
•
When the 2/3rd criteria calls for an increase by less than a factor of 1.5 of the mechanical design
pressure of the LP side as would be calculated from normal estimation procedures.
13.0
Minimum Liquid Surge Requirement
The “liquid surge volume” within a vessel is determined by the following factors:

The control range

The manual intervention range

The required residence time for separation, degassing, etc.

The possibility of liquid slugs in the feedline.
The surge time shall not be confused with residence time as surge time is hold up time between two level,
usually HLL and LLL, while residence time is hold up time from NLL to empty vessel.
The guidelines for Surge time is given below:
Service
Feed to unit
Product to storage
Feed to tower
Feed to furnace
Compressor suction
Manual control and manual intervention
Surge time (minutes )
LLL to HLL
15 – 20
2
5–7
4 – 10
5
20
Level transmitters and level gauges shall cover the cut-off point (low-low / high-high) also
Doc. No. OTV –00043, Page 21 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
14.0
Utility Conditions
The plant utility conditions are project specific. However, The Typical utility conditions for the plant is
given below for guidelines only:
S. No.
Parameter
1
High Pressure Steam (HP) *
Pressure, kg/cm2
38
40
Temperature, oC
380
390
Medium Pressure Steam (MP) *
Pressure, kg/cm2
12
14
Temperature, oC
210
290
Low Pressure Steam (LP) *
Pressure, kg/cm2
3
4
Temperature, oC
143
175
Condensate Return (Suspect / Pure) *
Pressure, kg/cm2
8.5 / 6
Temperature, oC
40 / 90
Service Water
Pressure, kg/cm2
3
5
Temperature, oC
Ambient
Cooling Water*
Supply
Pressure, 4
4.5
kg/cm2
Return
Pressure, 2.2
2.5
kg/cm2
Supply
Temperature, 28
33
o
C
Return Temperature, oC
45
Demineralised Water *
Pressure, kg/cm2
4
7.5
Temperature, oC
30
40
Boiler Feed Water (HP / MP) *
Pressure, kg/cm2
47/25
50/28
Temperature, oC
100
Plant Air (Oil and water free) *
Pressure, kg/cm2
4
5
Temperature, oC
40
Instrument Air *
Pressure, kg/cm2
5
6
Temperature, oC
Dew Point
Fuel Gas
Pressure, kg/cm2
2
3
Temperature, oC
35
45
Fuel Oil (@ BL / @ burner) *
Supply
Pressure, 8 /6.4
10/8.4
kg/cm2
Return
Pressure, -/2.5
-/3.5
kg/cm2
2
3
4
5
6
7
8
9
10
11
12
Minimum
Normal
Maximum
Mechanical
Design
42
400
46
420
15
305
18
350
4
190
7
240
100 / 100
150
6
10
65
5
7
2.8
7
65
45
65
8
45
12
65
-/35
100-110
- /40
150
8
50
10
65
7
= (-) 40
10
65
4.5
55
6.5
65
12/10.4
18
-/3.5
18
Doc. No. OTV –00043, Page 22 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
13
Temperature, oC
Nitrogen *
Pressure, kg/cm2
Temperature, oC
140
210
240
260
4
6
40
7
10.5
Dew Point = (-) 100
atmospheric pressure
o
C at
* The operating and design conditions are typical and tentative and shall not be used for design purposes.
For actual utility conditions please refer project design basis of the specified project.
15.0
Noise Control
Sound Level Limits for Personnel
All process units should conform to a work area limit of 90 dBA. The maximum eight-hour exposure level
for personnel exposure shall not exceed a continuous sound pressure level of 87dBA. This limit does
neither apply to locations where excessive noise exposure is infrequent, or to non-recurring operating
conditions such as venting.
At no time shall personnel be exposed to sound- levels in excess of 115 dBA. Hearing protection does not
alter this requirement.
Area Sound Level Limits
The following limits shall apply to all plant areas and buildings.
Executive office, conference rooms
Semi-private offices, small conference rooms
General offices, laboratories
Control rooms
Workshop offices
Personnel shelters
Workshops, machine rooms
Operating areas within 15m of permanent operator's station
or maintenance station
35 dBA
45 dBA
50 dBA
55 dBA
65 dBA
70 dBA
75 dBA
85 dBA
Noise reduction
The following methods will be considered for noise reduction.
Heaters
:
Intake / outlet silencers, Acoustic lining / lagging
Motors
:
Low noise motors or enclosures
Air Cooled Heat Exchangers
:
Decrease tip speed, Hub seals, Acoustic
shrouds on gear or belt drives, Low noise
motors
Compressors
:
In line silencers Lagging Acoustic Enclosures
Valves
:
Low noises trim Acoustic lagging Silencers
Vents
:
Silencers
Flares
:
Acoustically baffled multi-port nozzles
Plant Fence Line Noise Levels
Doc. No. OTV –00043, Page 23 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
Plant fence line noise levels shall not exceed the following:
Leq
LIO
72dBA
75dBA
Where Leq is the equivalent continuous equal energy level. LIO is the 10% excess sound level.
During the detailed engineering phase of the project noise shall be further controlled by placing limitations
on the suppliers of new equipment and for the refurbishment of existing equipment where applicable.
Meteorological Conditions
The pertinent data shall be referred from Project Design Basis, to be provided by the client.
16.0
Aromatics Handling
Special precaution shall be given when handling the process streams containing Aromatics (Carcinogen)
with following specifications:
•
Benzene content greater than 1% by weight
•
C6 through C9 aromatics greater than 25% weight
•
Butadine content greater than 5% by weight
In handling these streams following precautions shall be taken:
•
•
17.0
Pumps shall be dual mechanical seals
The followings shall be connected to closed blowdown system
1.
Vessel drains
2.
Pump drains
3.
Control valve, level gauge and level instrument drains.
Corrosion Allowance
The minimum corrosion allowance shall be as per the following table:
Sl. No.
1
2
3
4
5
6
7
18.0
Service
Carbon Steel Pressure Vessels
Carbon steel atmospheric vessels
Alloy steel vessels
Stainless steel vessel
Clad / lined vessels
Carbon steel / LAS exchangers
SS / HAS / Non ferrous exchangers
Corrosion Allowance (mm)
3
3
1.5
Nil
3 mm clad thk
3
Nil
IBR Requirements
Doc. No. OTV –00043, Page 24 of 25
Process Design Manual
Process Engineering Design Basis (Rev 0, October 2000)
The IBR requirements are as below:

Vessels:
Any closed vessel exceeding 22.75 litres in
capacity which is used
exclusively for generating steam under pressure and include any mounting or
other fittings attached to such vessels, which is wholly or partially under pressure
when steam is shut-off comes under IBR.

Piping


:
Any pipe through which steam passes and if :
Steam system mechanical design pressure exceeds 3.5 kg.cm2g
or
Pipe size exceeds 254 mm internal diameter.
Then the pipe is under IBR.

The following Items are not under IBR

Steam tracing

Heating Coils

Tubes of Tanks

Steam Jackets

All steam users (Heat Exchangers, vessels, condensate pots etc.) where condensate is flashed to
atmospheric pressure i.e. downstream is not connected to IBR system are not under IBR and IBR
specification is done at last isolation valve upstream of equipment.
All steam users where downstream piping is connected to IBR i.e. condensate is flashed to
generate IBR steam are covered under IBR.
Deaerator, BFW pumps are not under IBR and IBR starts from BFW pump discharge.


Doc. No. OTV –00043, Page 25 of 25