1

L
O
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Understanding of piping systems, classifications, sizing and grades , including tubing identification.
Identify the types of valves and their applications and limitations in typical piping system.
Identify the three basic types of steam traps .
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
Define the functions and limitations of various steam traps.
Discuss leading causes for steam trap malfunctions and how to repair defective units.
2

P
S
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Piping is used to connect the various units of machinery and equipment
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Includes:
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Sections of pipe
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Types of fittings to join piping
Valves to control flow
Can also contain other accessories such as: vents, drains, traps, strainers, gages, relief valves, instruments, etc..
Piping Design Considerations


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Type of fluid being transferred
Operating pressures and temperatures
Amount of fluid delivered
Rate of fluid delivered
These conditions determine the type materials, valves, fitting and thickness of pipe or tubing
3

P
S
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Governing factors for piping design
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Federal and private regulatory agencies
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ASME (American Society of Mechanical Engineers)
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Concerns all piping connections to power boilers with superheaters.
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Boiler external piping is required to conform to the standards.
Most other agencies adopt these standards.
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ASTM (American Society of Testing Materials )
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Covers minimum standards for piping systems in power plants, pulp and paper mills, and other industrial plants .
ABS - American Bureau of Shipping-
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A classification or insurance company for ships.
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ABS sets the piping standards for ships, however they used
ASME and ASTM as the source of there rules.
USCG - rules defer to the ABS.
4

P
S
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These codes cover minimum safety requirements for the :
 selection of materials
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Dimensions
Design
Fabrication
Construction
Testing of piping systems
5

P
C
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Threads are NPT (National Pipe Tread) See sizing chart on the next page
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NPT are tapered threads-
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¾˝ per foot

Before threads are engaged, the male threads are covered with a liquid, paste, or tape (Teflon) to :

Lubricate the threads
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Help seal the joint
6

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“ male” and “female” threads allow the joint to be engaged by hand a distance shown as F in the drawing below.
When tightened with a wrench the male threads should extend into the female close to the distance E or the effective thread length.
The last few threads will be imperfect .
USCG prohibits the use of threaded joints in systems which the fluid temperatures are over 925 o F.
7

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Male threads:
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
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Measure the outside diameter of the large portion of the thread at " A ";
Find figure nearest this dimension in column 1 or 2 of chart.
The dimension in column 3 will be your nominal pipe thread size.
Female Threads:



Measure top diameter of thread at " B ";
Find figure nearest this dimension in column 1 or 2 of chart.
The dimension in column 3 will be your nominal pipe thread size.
8

OD Fraction
Inch (for quick reference only)
Actual (decimal)
Inch.
Pipe Thread Size
Normal engagement for tight joint
(dimension " C ")
Threads per Inch
5/16 0.3125
1/16 0.2611
27
13/32 0.405
1/8 0.2639
27
35/64
43/64
0.540
0.675
1/4
3/8
0.4018
0.4078
18
18
27/32
1-3/64
1-5/16
0.840
1.050
1.315
1/2
3/4
1
0.5337
0.5457
0.6828
14
14
11-1/2
11-1/2 1-21/32
1-29/32
2-3/8
1.660
1.900
2.375
1-1/4
1-1/2
2
0.7068
0.7235
0.7565
11-1/2

PIPING CONNECTIONS -
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Butt joint
Socket -welding joint
10

PIPING CONNECTIONS -
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A flange allows two pipes to be mechanically connected together
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Or a pipe to be mechanically connected to a valve, tee, or other piece of equipment.
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The principle of a flange is to use a mechanical force to pre-load the gasket sufficiently so that when internal pressure is applied, there is enough contact stress between the flanges and gasket to maintain a seal.
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The flange itself needs to be connected to the pipe .
This is usually achieved by welding , though threaded and other weldless connections also exist.
11


Types of flanges include
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WELDNECK
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SLIP-ON
SOCKET
WELD
THREADED
 are common types.
12

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The joints between flanges have to have gaskets between the faces of the flanges.
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Gasket material will depend on the fluid in the system
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Most are cut from sheet gasket material , which comes in different thicknesses, 1/32˝, 1/16 ˝, 1/8 ˝ are common thicknesses
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Another type of gasket that can be used is the crush type
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Also known as Flexitallic gaskets for the compa ny that developed them
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Have steel outer ring reinforcing ring and a center portion that is designed to be crushed.
13

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The flange faces must be aligned properly
The bolts must be tightened in the proper sequence
The proper bolt diameter is 1/8 bolt hole dia.
˝ smaller than the flange
The proper bolt length is with 2-3 threads of the bolt extending through the nut
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Compression Fittings- Seamless alloy tubing like for hydraulic lines and lube oil lines
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Flared fittings- Tubing, copper, Air lines
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Soldered- low pressure, copper and brass water lines, refrigerant
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Cemented- PVC, low pressure, drain lines
14

P
M
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To accurately describe pipe, you need the following information:
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OD - Outside Diameter
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ID - Inside Diameter
OD-ID= Wall Thickness or Schedule
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Schedule is identified by
 standard schedule 40
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Extra Strong Schedule 80
Double Extra Strong Schedule 160
Other schedules Schedule 20, Schedule 120
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The higher the number, the thicker the pipe
15

P
M
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Pipe is measured by nominal dimension
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Called iron pipe size (IPS ) and wall thickness
Nominal means close to but may not indicate actual dimension
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Sizing from 1/8˝ to 12 ˝ are known by their nominal inside diameter.
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The nominal outside diameter is standard regardless of schedule or wall thickness.
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An increase in the schedule results in a decrease of the inside diameter.
12 ˝ and over is designated by the actual OD, the wall thickness, and the weight per foot.
Pipe can also be described by its class of use:
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Class 1 pipegood on systems of 150 psi and above, and
150 o F and above
Class 2 pipegood on systems below 150 psi and 150 o F.
16

P
M
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Tubing is measured by OD and wall thickness .
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For example:
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Copper tubing wall thickness designated by letters
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Type K
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Type L
Type M
Type K copper tubing is the thickest, L is medium, and M is the thinnest.
17

P
F
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Fittings are used in piping systems to:
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Redirect the flow of fluid- 45 o Elbows, 90 o Elbows,
Extend a straight line of flowCouplings
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Split flowTees, Y connectors
Allow for easy access to parts of the systemUnions
Fittings may be installed by threading, welding, brazing, or the fittings may be flanged .
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It really depends on the types of fluid, the system pressure, and the system temperature as to what connection method will be used.
Unions by design can be installed two ways; however there is only one correct way (cover in class).
18

19

P
S
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All piping systems need to have support .
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The can be from the top, sides or underneath piping system.
The will be installed is such a way as to allow for support of the piping in the system, plus the weight of the fluid contained within.
Must allow for expansion of the system piping
Types of supports:
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Spring
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Solid clamp
Roller 20

V
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Maintenance
Operation
Casualty Control
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Open fully then back off ¼ turn.
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Valve won’t jam
The next person won’t try to open it further
21

V
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Disk attached to stem.
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Disk seats against a seating surface in the body
Seat-
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The seat and disc of valves used for high temperature service are often surfaced with a hardened material
Valve Body-
Bonnet
Stuffing Box
Packing gland or packing nut
Valve wheel (Hand wheel) 22

T
- G
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Disc attached to stem
Disc seats against a seating surface
May be fully open & closed, or partially open
Good for throttling .
Large pressure drops across globe valves, especially when throttling.
Should be installed so that the flow comes from under the seat.
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
System pressure will assist in opening the valve
If the packing needs attention, there will be no system pressure in the bonnet of the valve.
23

G
V
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interposed perpendicular to axis of flow.
Allows for straight through flow with
.
applications (the disc will vibration & chatter)
Operate
.
Come in a wide variety of sizes and types
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Rising Stem
Non Rising Stem 24

N
P
V
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For fine adjustment of flow .
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Tapered point at the inside end of the valve stem.
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Used for throttling , especially when small quantities of gas or liquid are to be flowing.
25

B
V
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Lightweight, less space required than a gate or globe.
Quick acting (requires only ¼ turn.)
Can be used to throttle .
Low pressure application
Smaller place.
26

C
V
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Some are automatically operated with no hand wheels or stems and some have the capability of being shut off.
Used to prevent return or back flow
Several Types
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Lift Check
Swing Check
Ball
Stop Check Valves (can be positively shut off)
27

B
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Quick opening (1/4 Turn)
Excellent for full flow applications
Can also be used for throttling
The fluid flow acting on the partially exposed ball can cause erosion .
High pressure plug valve
28

S
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Prevents the passage of grit, scale, marine life, and other foreign matter that could obstruct pump suction valves, throttle valves etc
Baskets can be removed for easy cleaning.

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Simplex — only one basket, flow must be stopped to clean
Duplex — two baskets — flow may be diverted to allow cleaning of offline strainer
Y-Strainers
29

S
T
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Steam traps are used is systems to
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Drain condensate from heat exchangers
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They hold steam in heat exchangers until it has completely collapsed to condensate.
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Allows latent heat available in steam to be exchanged
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They are used in low points of steam piping systems help avoid water hammer
Three main functions of steam traps are
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Allow condensate which was steam to collect and flow back to the condensate system.
Vent air and other gases
Prevent the escape of steamloss of available latent heat.
30

S
T
P
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A steam trap is an automatic valve
 it senses the difference between steam and condensate.
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The trap discharges the condensate
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 with little or no loss of steam, which contributes to high operating efficiency.
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Steam traps are divided into three main groups :
 thermostatic
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 mechanical thermodynamic
31

T
T
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It measure temperature
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The balanced-pressure thermostatic trap has a liquid-filled bellows that expands and contracts.
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When steam is in contact with the bellows

 causes the bellows to expand closes the valve
If condensate or air is in contact with the bellows,
 bellows contracts and condensate is discharged
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Steam pressure does not affect the operation of this trap,
32

T
T
33

T
T
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The bimetallic trap also works according to the thermostatic principle.
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Two strips of suitably different metal bonded together
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The top strip expands more than the bottom one when heated allowing cool air and condensate to pass through

As steam enters the traps and heats up the bimetallic strip, the strip bends and closes off the valve.
34

T
T
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The liquid expansion thermostatic trap is operated by the expansion and contraction of a liquid-filled thermostat
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When the steam is turned on, air and condensate pass through the open trap.
As the condensate temperature increases , the oil in the thermostatic element expands and closes off the valve.
An adjusting nut positions the valve relative to its seat, which allows the trap to be set at a given temperature, usually 212 ℉ , or lower.
Some liquid expansion traps are used for freeze protection. When the temperature drops to 40 ℉ , the trap opens, creating enough flow to prevent freeze-up.
35

M
T
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Mechanical traps distinguish between steam and condensate by their different densities .
Various floats are used to operate the discharge valve.

 a ball floats on the surface of the condensate as the condensate level drops,

 ball covers the discharge passage prevents the loss of steam
Air must be removed for the trap
 can be vented automatically form the float trap
36

M
T
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Figure shows a float-and-thermostatic trap

Float rises when condensate enters , opening the valve
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

The valve closes if there is no condensate in the trap
If there is a temperature drop caused by air, the valve opens .
Element expands and closes when steam enters the trap.
37

M
T
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The inverted bucket trap
When system condensate enters
 bucket is at the bottom and valve open


Air vented through a small hole on top of the inverted bucket water level rises on both the inside and outside of the bucket
As steam fills the inverted bucket and makes it float , close valve .

Steam slowly escapes out of the bucket through the vent hole.
If the escaping steam is replaced by condensate,

 bucket sinks opens the valve
38

39

T
T

Or disk traps,
 identify steam and condensate by the difference in their kinetic energy or velocity as they flow through the trap

Low pressure flash steam
 pushing down on the large surface on top of the disk
 overcomes the force of the live steam pushing up in the smaller, exposed disk area .
40

THERMODYNAMIC TRAPS
41

T
T
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After startup, cool condensate lift the disk off its seat
As the temperature of the condensate increases,


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Some of it flashes into steam
The mixture of steam and condensate flows outward across the underside of the disk.
Because flash steam has a larger volume

 the flow increases as more flash steam is formed high velocity causes a low-pressure area
 to be formed under the disk and the expanding flash steam exerts pressure on top of the disk,
 forcing the disk downward and stopping all flow
42

T
T



 although the flash steam pressure is much lower but the large exposed area
As the flash steam above loses heat, some of it condenses, reducing the pressure above the disk.
The disk is again lifted off its seat, and the cycle repeats itself .
43

44