Ten safety valve tips to protect employees, facility, profits

Follow these safety valve tips and make sure you are protected.

07/30/2013


When things go wrong, safety valves have only one function—to protect your people, plant and profits. When safety is at stake it’s vital not only to have the best equipment but make sure it is specific and fitted correctly. There is no room for mistakes:

  1. Transport valves upright and never lift them by the easing lever.
  2. Safety valves should always be installed with the bonnet vertically upward.
  3. Always set at least a 5 psig margin between relief pressure and system operating pressure to ensure tight shut off.
  4. Always seal the valve against tampering. Sealing wire and a lead seal are most commonly used.
  5. On steam systems always ensure that no condensate can collect on the upstream side of the valve disc.
  6. Before first lifting an installed valve, always flush the system first. Dirt in the system can damage the valve seat
  7. For steam and gases the discharge pipework should rise, and for liquids it should fall. Rising discharge pipework must be drained.
  8. Repairing, refurbishing and resetting valves must be done only by authorized personnel.
  9. To cut discharge noise use a large diameter discharge pipe or insulate it, but never insulate the safety valve itself.
  10. Regularly use the lifting lever to ensure the valve opens and minimize the risk of corrosion of mating surfaces.

Content provided by Spirax Sarco, originally published in Steam News Magazine.



Ryan , TX, United States, 08/26/13 09:35 AM:

About point 3: 5 psig is not a valid rule of thumb and I believe "relief" pressure should say "set" pressure. Safety valves (with the exception of remote sensing pilot operated devices) need to have at least a 10% margin between set pressure and maximum system operating pressure to avoid chattering. The springs have a 10% tolerance which is why relief pressure for most scenarios is treated as set pressure + 10% overpressure (full lift). On the other end of that, you may have the valve begining to unseat and reseat within 10% of set pressure, which may cause chatter if you are operating within that 10% margin. Remote sensing pilot operated valves can have set pressures much closer to operating pressure, depending on the valve. The tolerance range is typically less than 10%.
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