6
PI-178
July 2020
18. If equipment malfunctions or a system malfunction is suspected,
immediately stop cleaning activity and relieve the pressure in the system
before attempting any repairs. Always follow the manufacturer’s repair
instructions.
19. Only trained persons should be authorized to perform any mainte-
nance or repair.
20. Following any repairs, the system should be operated at low pressure
for test. Bring equipment up to operating pressure slowly.
21. For shutdown in freezing conditions, even for brief periods, drain
water from all components. Prior to starting operations in freezing
conditions, the operation of all equipment components must be checked
carefully to make sure components are not frozen and can be operated.
22. Store components properly by protecting them from damage when
not in use. Be sure all safety warning tags and markers remain intact.
PRESSURE RELIEF DEVICES
1.
Read General Safety
section prior to installing Relief Valve and/or
Pressure Relief Devices.
2. A waterblast system should include both primary and secondary
pressure relief protection:
A. For primary protection a primary rupture disc assembly or spring-
loaded relief set at 1.2 times, maximum operating pressure is
recommended (i.e. relief valve is set at 12,000 psi if maximum
operating pressure is 10,000 psi)
B. For secondary protection a rupture disc assembly containing a
manufacturer’s approved disc having a burst rating of 1.4 times
maximum operating pressure is recommended.
Only use a rupture disc holder which will NOT permit the
use of coins or other objects in place of discs.
3. Relief devices should never be mounted so the discharge could strike
personnel.
4. Never install a shut-off valve between the pump and relief device.
5. “Set pressure” must be prominently displayed on all relief devices.
Never install or use a relief device unless its “set pressure” is known.
6. Do not attempt to correct a leaking relief valve by increasing spring
tension as this will increase its set pressure.
