4
3 installation
rigging
Safety valves must be handled carefully and
never subjected to sharp impact loads. While
in the shipment case or when uncrated they
should not be bumped or dropped. rough
handling may alter the pressure setting, deform
valve parts and affect seat tightness adversely.
When it is necessary to use a hoist, a sling
should be placed around the valve body and
bonnet in a manner that will ensure that
the valve is in a vertical position to facilitate
installation.
flange protectors should remain in place until
the valve is ready to be installed on the system.
inspection
Safety valves should be inspected visually
before they are installed to ensure that no
damage has occurred during shipment or while
in 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 seals protecting the
spring setting and ring adjustments should be
intact. if seals are not intact, the valve should
be inspected, tested and new seals installed
before use.
inlet piping
Safety valves should be mounted in a vertical
position, directly on the pressure vessel; the
nozzle should have a well-rounded approach
that provides smooth, unobstructed flow
between the vessel and the valve. a safety valve
should never be installed on a fitting having
an inside diameter smaller than the inlet
connection of the valve as restricted flow can
cause faulty valve operation.
inlet piping (nozzles) must be designed to
withstand the total resultant forces due to the
valve discharging at the maximum accumulated
pressure and the expected piping loads.
Crosby
SerieS HSJ Safety valveS
InstallatIon, operatIon and maIntenance InstructIons
outlet piping
Discharge piping should be simple and direct.
Where possible, a short vertical pipe connected
through a long radius elbow discharging
directly into the atmosphere is recommended.
Discharge piping should be designed so as not
to impose any loading on the valve. excessive
discharge piping may cause seat leakage or
faulty valve operation. the inside diameter of
the discharge pipe must never be less than that
of the valve outlet.
valve effluent must discharge to a safe disposal
area.
valve bodies are provided with pipe thread
openings for drains. these should be connected
to prevent any accumulation of fluid in the
valve body. in addition, it is recommended that
discharge piping also be drained to prevent any
accumulation of fluid. Care must be observed
to ensure that the drains are directed or piped
to a safe disposal area.
the precise nature of the loading and
the resulting stresses will depend on the
configuration of the valve and the discharge
piping. this must be taken into consideration
by those responsible for the installation of the
safety valve and associated vessel or piping.
Determination of outlet reaction forces is the
responsibility of the designer of the vessel and/
or piping.
Many valves are damaged when first placed
into service because of failure to clean the
connections properly when installed. it is
essential that the valve inlet, the vessel and the
line on which the valve is mounted be cleaned
thoroughly of all foreign material. the inlet
connection bolts or studs should be tightened
uniformly to avoid straining or distorting the
valve body.