Storage, Installation, Testing,
Operation and Maintenance Guidelines
for Diaphragm Valves
Storage and handling
Because metal housings and plastic liners can become brittle at low
temperatures, use care when handling valves at temperatures below
Also, do not remove wooden end protectors provided with each valve
until you're ready to install the valve. After you remove them, inspect
the valve and liner for possible physical damage.
Test the installed valve to the pressure not exceeding the
working pressures. CAUTION: Do not
use steam to pressurize the valve for testing. Reason: The temperature
of steam is difficult to control and can easily exceed the temperature
limits of the liner.
After the first system thermal cycle and subsequent shutdown, check and
retorque the flange bolts to the valves
After the system is put into service at the expected operating temperature,
check each valve for leaks. If a valve is leaking from the bonnet/body
connection, tighten the bolting 1/6 turn in a
criss-cross pattern. Repeat
as necessary until the leak stops. Make sure that improper alignment or
support is not the cause of the leak.
During nominal operation, a visual inspection for leaks should be made on
a regular basis by the operator.
Preventive maintenance -
- Gaskets are not required between flanges of lined diaphragm valves
and lined pipe because the plastic faces of each provide the sealing.
- Retorque bonnet bolts immediately before installation. Torquing
should only be done on the system in the ambient, cooled state, never
while the process is at elevated temperature. Otherwise, excessive force
could be applied to the plastic faces.
Bonnet hex nut torque valves (ft-lbs)
- Follow flange Bolt Torquing guidelines.
- Do not overtighten. This could damage the sealing faces.
- For connecting valves to unlined flanged faces, see
pipe connect details.
Corrective maintenance -
How to Replace Diaphragms
If the valve has to be replaced, follow these steps:
- To maximize the life of the diaphragm, do not tighten the handwheel
beyond one-half turn after initial shut-off.
- Grease the handwheel spindle every four months with a quality,
high-temperature grease. Be careful not to over-grease.
- The travel stop is factory set, but can be adjusted as follows
- Loosen the set screw
- Close valve at operating pressure until it seals and then turn the
handwheel clockwise an additional one-quarter turn.
- Position the travel stop against the valve handle and tighten the
- Do not steam-clean polypropylene, or PVDF-lined valves. You can use
steam to clean PFA-lined valves, but be sure to keep the steam temperature
below the maximum temperature limit of the plastic and the diaphragm.
- Make certain the line is isolated, pressure relieved, drained, and
appropriate safety equipment (chemical goggles, face shield, protective
clothing, etc.) is worn before attempting to remove the valve.
- Remove the valve from the line. If the valve has been used in hazardous
chemical service, make sure it is thoroughly cleaned and/or neutralized
before repairing or disposing of it.
- Install the new valve according to procedures explained in the
"Installation" section of this page.
"This page is a machine translation of the source page, which is written in
English. This translation is intended to provide a general idea of the
page's content, and is not guaranteed for accuracy."