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Atmospheric relief valve type 1100
Installation and maintenance instructions
5. Storage and first handling
Safety relief valves are often on the job site months before they are installed. Unless they are
properly stored and protected, their performance may be seriously affected. Rough handling may
damage flanges or cause misalignment of the parts. It is best to leave the safety valves in their
shipment cases and store them in a dry place under cover until they are to be installed. Flange
protectors, sealing plugs and valve gag should remain installed until just prior to installation.
Unpacked valve should be moved or hoisted with a chain or sling using the two lifting eyes on the
top of the body in such manner as will insure that the valve is in vertical position during lift.
When safety relief valves are unpacked and the flange protectors removed, immediately prior to
installation, meticulous care should be exercised to prevent dirt from entering the inlet and outlet
ports while bolting in place.
While hoisting to the installation, care should be exercised to prevent bumping the valve against
steel structures and other objects.
6. Installation
General Requirements
For optimum performance, safety valves must be serviced regularly and otherwise maintained.
So that servicing can be properly performed, valves should be located in a manner that allows for
easy access. Sufficient working space should be provided around and above the valve to permit
access to the water ring connections and the visual gauge indicator. If two or more valves are
located close together, the outlets should be parallel so as to offer as much protection as possible
to personnel repairing, or working close to the safety valve.
Excessive line vibrations are known to produce shifts in safety valve set pressures. Vibrations may
possibly introduce chatter, causing damage to the valve and reduce its capacity. This vibration also
contributes to increased incidents of seat leakage. Considerations should be given to eliminating
this problem prior to installing the valve on the unit.
Regarding flanges connections, it is utmost importance that the gaskets used are dimensionally
correct for the specific flange and that they fully clear the valve inlet and outlet openings. Gaskets,
flange facings and bolting should meet the service requirements for the pressure and temperature
involved.
Inspection
Each atmospheric relief valve should be visually inspected before installation to ensure that no
damage has occurred during shipment or storage. All protective material, sealing plugs and any
extraneous material inside the valve body or nozzle must be removed.
The valve nameplate and other identifying tags should be checked to ensure that the particular
valve is being installed at the location for which it was intended.
The valve seal protecting the spring setting should be intact. If not, the valve should be inspected,
tested and seal properly installed before use.
Inlet Piping
Many safety valves are damaged when first placed in service because of failure to clean the
connections properly before installation. Because foreign material passing into, and through, a
safety valve is damaging, the system on which the valve is tested and finally installed must be
inspected and cleaned. New systems are prone to contain welding beads, pipe scale, and other
foreign materials which are inadvertently trapped during constructions, and destroy the valve
seating surfaces the first few times the valve opens. Therefore, the system should be thoroughly
purged before the safety valve is installed.
Valve should be mounted in a vertical position, directly on the pressure vessel. Nominal tolerance
on vertical installation is plus or minus 1 degree.
The ASME Boiler and Pressure Vessel Code limits the distance between the safety valve inlet and
the boiler to the length of a standard tee fitting. The nozzle should have a well-rounded approach
that provides smooth, unobstructed flow between the vessel and the safety valve. Header nozzle
corners must be rounded to a radius of no less than 1/4 of the opening diameter. A safety valve
should never be installed on a fitting having an inside diameter smaller than the inlet connection of
the valve. Such restriction of flow can cause faulty valve operation.
Steam flowing vertically out a discharge elbow produces a downward reaction on the elbow.
Bending stress in the valve is determined by the production of this reactive force and the moment
arm between the point of steam exhaust and the section being analyzed for bending stress. The
effects of reaction force, vibration and seismic loads will depend on the configuration of the safety
valve and the discharge piping. Determination of outlet reaction forces is the responsibility of the
designer of the vessel and/or piping.
Pentair reserves the right to change the contents without notice
ETS-07002-EN
Caution
Never lift the full weight of the valve by
the lifting lever or the valve gag.
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