Table of Contents
Advertisement
CROSBY STYLE JQ 4 IN. PRESSURE RELIEF VALVE
INSTALLATION AND MAINTENANCE INSTRUCTIONS
6.2 Breaking Pin Assembly
Refer to Table 6.1.B for the breaking pin
assembly. This assembly includes a Plunger
Assembly (32) which backs up a Lower
Diaphragm (37). The Plunger Assembly is held in
position by a Breaking Pin (31) which is placed in
tension when pressure in the tank acts against
the lead diaphragm.
6.2.1 Yoke (30), Plunger with Columns (32) and
Breaking Pin Housing (35)
These items are factory assembled parts. All
parts are interchangeable between the 300 lbs
and the 375 lbs valves.
6.2.2 Breaking Pin (31)
Breaking Pins (31) are manufactured with a
⅜ in. diameter. An unpainted breaking pin is
used on the 300 psig valve. A yellow breaking
pin is used on the 375 psig valve. The Breaking
Pin has an accurately machined neck which
at a temperature of 70°F (21.2°C) is designed
to break at 300 psig ± 15 psig or at 375 psig ±
15 psig. The manufacture of breaking pins is a
specialized and carefully controlled procedure.
They are factory-tested by breaking one pin
in each lot of fifteen to verify the accuracy of
the manufacture.
6.2.3 Lubrication
Only halogenated Fluorocarbon (FKM) lubricants
identified as being completely inert in liquid and
gaseous chlorine may be used.
6.3 Installation Parts
(Customer Supplied Parts)
6.3.1 Studs
Studs must be in accordance with Drawing 102
(13.1.3).
6.3.2 Gaskets
For information on gaskets used when mounting
the valve to the vessel, refer to Pamphlet 95
(13.1.2) Gaskets for Chlorine Service, Edition
6, January 2021 can be purchased at following
web address: https://www.chlorineinstitute.org/
products/pamphlet-95
TABLE 6.2 PARTS AND TOOLS - TEST EQUIPMENT
Item
Description
40
Adapter flange
43
Filler
44
Gasket (drawing 102, item 8)
46
Test diaphragm
47
Test bonnet
48
Lower diaphragm spanner
49
Lower diaphragm holding fixture
53
Angle valve wrench
/ ₁₆ in. box)
54
Housing wrench (6 -
5
55
Adjusting bolt and nozzle spanner
56
Strap wrench (18 in. long, strap 2 - 14 in. wide)
60
Wrench bar 1 in. diameter x 36 in.
6.4 Tools and Test Equipment
All of the special tools or parts needed to test the
Style JQ 4 in. valves are listed in Table 6.2.
6.5 Test Equipment
6.5.1 Test Pressure Gauge
Pressure gauges must be recalibrated at least
once every six months and have 600 psig range,
5 psig graduations and ± 1/2% or better accuracy.
Other instruments with comparable readability and
accuracy to the above may be used.
6.5.2 Gas Pressure Control
WARNING
Failure to follow these instructions can cause
damage to the valve and potentially personal injury
from an over pressure event.
To test the Breaking Pin (31), it is necessary
to raise the pressure very slowly. A pressure
regulator suitable for the cylinder pressures
involved and equipped with a cylinder pressure
gauge (usually 0 to 3000 psig) should be used.
The regulator output should not be capable
of supplying pressure in excess of 500 psig.
The use of a small needle valve following the
pressure reducing valve will improve the control
of the test pressure.
6.5.3 Gas Supply
A convenient supply of dry air or nitrogen in a
cylinder can be used for testing the safety valve
proper. Helium should be used to leak test the
breaking pin assembly.
7. PREPARATION FOR TEST
7.1 Frequency
CAUTION
USCG regulations require that safety valves on
chlorine barges be retested every three years.
For barges, the safety valve should be visually
examined prior to each time chlorine is loaded.
If the Upper Diaphragm (2) is ruptured, bulged
or wrinkled, the valve should be removed and
disassembled per this section and rebuilt per
Section 8 or Sections 9 and 10.
Material
Part No.
Steel
101047
Steel
101048
(See Drawing)
- - - -
Steel
101050
Steel
SA-58511
Steel
101051
Steel
101052
(See Drawing)
100864
Steel
101053
Steel
101054
Steel
101055
Steel
101057
7.2 Safety Precautions
CAUTION
Failure to follow these instructions can cause
damage to the valve and potentially personal injury.
Always wear proper PPE.
The following safety precautions are to supplement
existing facility procedures and any specific
precautions in this manual. These precautions
must be understood and applied during
disassembly, repair and testing of the safety valve.
• The working area must be properly vented
• Chlorine vapor may be trapped within the
• Chlorinated residues could be present.
7.3 Removal of Valve from Tank
WARNING
Tank pressure must be released before removing
the valve from the container. Failure to do so could
result in personal injury.
Take proper precautions when removing the
valve from the tank. Remove the valve gasket
from the manway cover, being careful not
to score the groove. Inspect the groove and
arrange for any necessary maintenance. Protect
the safety valve housing within the breaking
pin assembly when removed from the tank and
during transportation to the maintenance area.
7.4 Visual Inspection
A visual inspection of the safety valve should
be made after the valve is removed from the
tank and prior to disassembly. Note the general
appearance of the valve:
• Note any indication of corrosion.
• Inspect the Lower Diaphragm (37)
• Inspect the Upper Diaphragm (2)
• Check the gasket surface where the
• Check the valve identification tag.
• Consider tagging the valve indicating
Drawing Ref. 13.1
127
127
102
127
127
128
128
128
128
128
- - - -
- - - -
when disassembling and cleaning
the valve.
safety valve between the valve seats and
the upper and lower diaphragms.
Appropriate handling procedures should
be developed.
for failure.
for bulging.
Breaking Pin Housing (35) bolts to the
manway cover. Corrosion/erosion or
physical damage should be noted.
unusual appearance or conditions (e.g.
need for decontamination).
6
Advertisement
Table of Contents
