Safety relief valves equipment testing

Safety relief valves are normally tested in the shop, or even on the equipment at atmospheric temperature. The set tolerances on the valves as manufactured are established by die Code as discussed earlier. In order to recognize the difference between the test temperature and the actual operating temperature at actual relief, the corrections shown in Table 7-lA and 7-lB are applied. An increase in temperature above design causes a reduction in valve set pressure due to the effects of temperature on the spring and body. 

Selection of Safety Relief Valve Testing Equipment... 

Occasionally, there may be business pressures or maintenance scheduling problems that would encourage the delay of prooftesting of safety critical alarms and shutdown systems. Such situations can also delay of vessel inspections and safety relief valve testing. Some type of variance procedure or review policy should be defined to handle this occasional need. Such a policy ought to require the review of all of the inspection and test records on the specific equipment involved as well as an approval of the superintendent of the area. 

Selection of safety relief valve testing equipment... 

Vital periodic testing and maintenance of safety valves, pressure relief valves, stop valves, and other items is usually carried out on a 12-month cycle. Boiler plant equipment fitted with such appurtenances (and thus requiring regular checks), include boilers, heaters, deaerators, evaporators, and economizers. 

Pressure relief valves are a critical safety item in almost all process facilities. Pressure relief valves simply must work. This means that they must never be blocked in from the equipment item(s) that they are protecting. Yet their very criticality means that relief valves will have to be routinely isolated and/or removed from the system that they are protecting so that they can be maintained and tested— both for the pressure at which they open and, more rarely, for their flow capacity. 

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