INSTALLATION, OPERATION & MAINTENANCE MANUAL (IOM) IOM-123-BASIC
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MODEL 123 — BASIC
BACK PRESSURE / RELIEF REGULATOR
SECTION I
I. DESCRIPTION AND SCOPE
The Model 123 is a back pressure relief regulator used to control upstream (inlet or P1) pressure. Sizes are 1/2", 3/4", 1", 1-1/2" and 2" (DN15, 20, 25, 40 and 50). With proper trim utilization, the unit is suitable for liquid, gaseous, or steam service. Refer to Technical Bulletin 123-TB for design conditions and selection recommendations.
CAUTION A
This is not a safety device and must not be substituted for a code approved pressure safety relief valve or rupture disc.
SECTION II
II. INSTALLATION
CAUTION B
For welded installations, all internal trim parts, seals and diaphragm(s) must be removed from regulator body prior to welding into pipeline. The heat of fusion welding will damage non-metallic parts if not removed. NOTE: This does not apply to units equipped with extended pipe nipples.
1.An inlet block valve should always be installed.
2.If service application is continuous such that shutdown is not readily accomplished, it is recommended that an inlet block valve, outlet block valve, and a manual bypass valve be installed.
3.Pipe unions should be installed to allow removal from piping.
4.An inlet pressure gauge should be located approximately ten pipe diameters upstream and within sight. An outlet pressure gauge is optional.
5.All installations should include an upstream relief device if the inlet pressure could exceed the pressure rating of any equipment or the maximum inlet pressure rating of the unit.
CAUTION C
Installation of adequate overpressure protection is recommended to protect the regulator and all downstream equipment from damage in the event of regulator failure.
Supply @ P1
System
Demand
P1 SRV
Model 123-33 |
Bypass |
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BP/Relief |
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Regulator |
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P2 |
Discharge
Recommended Piping Schematic for
Back Pressure/Relief Station
6.Clean the piping of all foreign material including chips, welding scale, oil, grease and dirt before installing the valve. Strainers are recommended.
7.In placing thread sealant on pipe ends prior to engagement, ensure that excess material is removed and not allowed to enter the regulator upon startup.
8.Flow Direction: Install so the flow direction matches the arrow cast on the body. The body has an angle configuration with a side inlet and bottom outlet.
9.Regulator may be installed in a vertical or horizontal pipe. If it is a steam system, ensure the piping is properly trapped and oriented.
10.A. Basic Regulator- (See Figure 1): Regulator may be rotated around the pipe axis 360°. Recommended positions are with spring chamber vertical upwards, or horizontal. Orient such that the spring chamber vent hole does not collect rainwater or debris.
10.B. Cryogenic Regulator -
Option-5 or -36 (See Figure 2):
a.Recommended installation is with spring chamber hanging vertical downward below the body. This method allows water to drain; i.e. rain water.
b.Recommend inert purge gas to spring chamber through vent hole and out drain hole.
WARNING 1
The maximum inlet pressure is equal to 1.5 times the larger number of the stated range spring on the nameplate, and is the recommended “upper operative limit” for the sensing diaphragm. Higher pressures could damage the diaphragm. (Field hydrostatic tests frequently destroy diaphragms. DO NOT HYDROSTATIC TEST THROUGH AN INSTALLED UNIT; ISOLATE FROM TEST.)
11.Regulators are not to be direct buried underground.
12.For insulated piping systems, recommendation is to not insulate regulator.
SECTION III
III.PRINCIPLE OF OPERATION
1.Movement occurs as pressure variations register on the diaphragm. The registering pressure is the inlet,
P1 or upstream pressure. The range spring opposes diaphragm movement. As inlet pressure drops, the
range spring pushes the diaphragm down, closing the port; as inlet pressure increases, the diaphragm pushes up and the port opens.
2.A complete diaphragm failure may cause the regulator to fail closed.
SECTION IV
IV. STARTUP
1.Start with the block valves closed. A bypass valve may be used to maintain inlet pressure in the upstream system without changing the following steps.
2.Relax the range spring by turning the adjusting screw counterclockwise (CCW) a minimum of three
(3) full revolutions. This reduces the inlet (upstream) pressure setpoint.
3.If it is a “hot” piping system, and equipped with a bypass valve, slowly open the bypass valve to preheat the system piping and to allow slow expansion of the piping. Ensure proper steam trap operation if installed. Closely monitor inlet (upstream) pressure, via gauge, to assure not over-pressurizing.
NOTE: If no bypass valve is installed, extra caution should be used in starting up a cold system; i.e. do everything slowly.
4.Crack open the inlet (upstream) block valve.
5.Slowly open the outlet (downstream) block valve observing the inlet (upstream) pressure gauge. Determine if the regulator is flowing. If not, slowly rotate the regulator adjusting screw counterclockwise (CCW) until flow begins.
6.Continue to slowly open the outlet (downstream) block valve until fully open.
7.Observing the inlet (upstream) pressure gauge, rotate the adjusting screw clockwise (CW) slowly until the inlet pressure begins to rise. Rotate CW until the desired setpoint is reached.
8.Continue to slowly open the inlet (upstream) block valve. If the inlet (upstream) pressure exceeds the desired setpoint pressure, rotate the adjusting screw CCW until the pressure decreases.
9.When flow is established steady enough that both the outlet and inlet block valves are fully open, begin to slowly close the bypass valve if installed.
10.Develop system flow to a level near its expected normal rate, and reset the regulator setpoint by turning the adjusting screw CW to increase inlet pressure, or CCW to reduce inlet pressure.
11.Reduce system flow to a minimum level and observe setpoint. Inlet pressure will rise from the setpoint of Step 9. (Ensure that this rise does not exceed the stated upper limit of the range spring by greater than 50%, i.e. 30 - 80 psig (2.1 - 5.5 Barg) range spring, at maximum flow the inlet pressure should not exceed 1.5 x 80 psig (5.6 Barg), or 120 psig (8.3 Barg). If it does, consult factory.)
12.Increase flow to maximum level if possible. Inlet
(upstream or P1) pressure should fall off. Readjust setpoint as necessary at the normal flow rate.
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IOM-123-BASIC |
SECTION V
V. SHUTDOWN
1.On systems with a bypass valve, and where system pressure is to be maintained as the regulator is shut down, slowly open the bypass valve while closing the inlet (upstream) block valve. Fully close the inlet (upstream) block valve. (When on bypass, the system pressure must be constantly observed and manually regulated. Close the outlet (downstream) block valve.
CAUTION D
Do not walk away and leave a bypassed regulator unattended.
2.If the regulator and system are both to be shutdown, slowly close the inlet (upstream) block valve. Close the outlet (downstream) valve only if regulator removal is required.
SECTION VI
VI. MAINTENANCE
WARNING 2
SYSTEM UNDER PRESSURE. Prior to performing any maintenance, isolate the regulator from the system and relieve all pressure. Failure to do so could result in personal injury.
A.General:
1.Maintenance procedures hereinafter are based upon removal of the regulator unit from the pipeline where installed.
2.Owner should refer to owner's procedures for removal, handling, cleaning and disposal of nonreuseable parts, i.e. gaskets, etc.
3.Refer to Figure 1 for basic regulator, Figure 2 for cryogenic regulator, and Figure 3 for blow-up of the composition seat trim.
B.Diaphragm Replacement:
WARNING 3
SPRING UNDER COMPRESSION. Prior to removing spring chamber, relieve spring compression by removing the adjusting screw. Failure to do so may result in flying parts that could cause personal injury.
1.Securely install the body (1) in a vise with the spring chamber (2) directed upwards.
2.Rotate the adjusting screw (17) CCW until removed from the spring chamber (2).
3.Draw or embed a match mark on the body (1) and spring chamber (2) flanges.
4.Remove diaphragm flange nuts (8) and bolts
5.Remove spring chamber (2), range spring
(18)and spring button (19).
IOM-123-BASIC
6.Remove diaphragm sub-assembly consisting of the diaphragm(s) (3), pressure plate (2), lock washer (13), piston (14), piston nut (6) and pusher plate gasket (5). NOTE: Refer to the quantity of diaphragms (12) incorporated per the bill of materials listing. Depending on inlet pressure level, multiple metal diaphragms may be “stacked”.
7.Loosen the piston nut (6) and separate all parts (3, 5, 13, 14 & 20) of the diaphragm sub-assembly. Clean the pusher plate gasket
(5) surface if the piston (14) is to be reused.
8.Inspect pressure plate (20) for deformation due to over-pressurization. If deformed, replace.
9.Remove diaphragm gasket (4) for metal diaphragm. NOTE: No diaphragm gasket (4) for composition diaphragm.
10.Clean body (1) and diaphragm flange. NOTE:
On regulators originally supplied as “special cleaned”, Option-5, -36 or -55, maintenance must include a level of cleanliness equal to Cashco’s cleaning standard #S-1134. Contact factory for details.
11.For metal diaphragms (3), place the diaphragm gasket (4) on the body (1) flange. A light coat of gasket sealant is recommended.
12.Reassemble diaphragm sub-assembly by placing piston (14) in a vise, post upwards, grasping on the hexagonal surface. Place the pusher plate gasket (5), diaphragm(s) (3), pressure plate (20) and lock washer (13) over the threaded post. Ensure that the pressure plate (20) is placed with curved outer rim down next to the diaphragm (3) surface. Place a thread sealant compound on the threads of the piston (14) post prior to tightening the piston nut (6) to the following torque values:
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