Hi All, Can someone tell me as t
Hi All, Can someone tell me as t
(OP)
Hi All,
Can someone tell me as to what type of block valve (ball / gate) should be used upstream and downstream of relief valves in process piping?
Thanks in advance.
Can someone tell me as to what type of block valve (ball / gate) should be used upstream and downstream of relief valves in process piping?
Thanks in advance.





RE: Hi All, Can someone tell me as t
You should look at the P&ID and only install block valves if and when the P&ID says they are to be installed.
Then, as to the type of valve, you should only install the type of valve that is designated as the primary block valve for use in the piping line class (Piping Specification) for the applicable (pressure, temperature, commodity) system.
Go talk to a Piper.
RE: Hi All, Can someone tell me as t
http://virtualpipeline.spaces.msn.com
RE: Hi All, Can someone tell me as t
RE: Hi All, Can someone tell me as t
I totally agree with pennpiper's response that:
The primary reason for isolating a relief valve by providing block valves before and after the relief valve is so that a faulty relief valve can be repaired or replaced while the plant system is still in operation. When that situation occurs, there must be another installed and available relief valve to protect the plant system.
That applies whether the plant system has a short runtime or a long runtime.
Milton Beychok
(Visit me at www.air-dispersion.com)
.
RE: Hi All, Can someone tell me as t
http://virtualpipeline.spaces.msn.com
RE: Hi All, Can someone tell me as t
I dont givbe that much for CSO and would prefer LO. But operators hate the keys i know.
Best regards
Morten
RE: Hi All, Can someone tell me as t
RE: Hi All, Can someone tell me as t
Since compressors are taken down for simple repairs like hot valves, oil changes on the engines, we inspect relief valves then. On pumps with 100% spares, no block valves too. On storage tanks, block valves under the relief valve, we are not going to empty a tank to inspect a relief valve.
RE: Hi All, Can someone tell me as t
Within California, block valves to isolate PRV's are allowed in refineries in accordance with the Petroleum Safety Orders http://www.dir.ca.gov/title8/6858.html: (3) Stop valves may be installed between a pressure relief device and the operating vessel for the purposes of inspection, repair and/or replacement of the pressure relief device. Where stop valves are installed, the employer shall develop, implement, and maintain a written plan containing all of the following:
So they are clearly allowed by ASME VIII-1, and may be allowed depending on the jurisdiction.
Now, to answer starrproe's question, I've usually seen gate valves in this service, with the stems in the horizontal position so that a dropped gate will not unintentionally block the path. This is in line with various company standards, and also with the California Petroleum Safety Orders: Valves as permitted above shall not be gate valves installed with the stems pointing above the horizontal plane of the valve body or globe valves installed so that the disk will open against pressure. This limitation need not apply to stop valves closing the vessel from its source of pressure. Other provisions acceptable to the Division may be used to assure that the valve is in the open position.
I don't see an advantage to ball valves, except perhaps for small pipe sizes.
jt
RE: Hi All, Can someone tell me as t
The selection will probably be based on price, if there is a difference, and site preference, if there is a preference.
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RE: Hi All, Can someone tell me as t
See section 322.6.1 of ASME B31.3 for more info on adding block valves in pressure relief piping.
Tim
RE: Hi All, Can someone tell me as t
A car seal is more documenation and tracking. A physical lock is a physical lock.
One can do both.
"Do not worry about your problems with mathematics, I assure you mine are far greater."
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RE: Hi All, Can someone tell me as t
At remote B31.8 sites, we just put a little wire on our 3/4" valves connected to our overpressure protection transmitters and SCADA. The regulators only got excited when the saw no chain and lock on our mainline valves. We locked the clutch handle so the handwheel would turn but not the valve, that really got them scratching their heads.