Hi all, I am looking for how others pressure test reactors and other chemical vessels whilst in service: Do you do this every batch? What pressure do you test to? (100% of operating pressure or more or less?) How long do you hold the test for? What is your acceptable leak rate? We are having some discussion within the company I work for as to whether it should be 80%, 100% or 110% of normal operating pressure. The level of acceptable leak rate is another discussion ongoing. Your help, as ever will be much appreciated both from within and outside the chemical industry. If you could tell me which industry you work in I can collate answers accordingly. Thanks, Coy Tanger.

How are you intending to pressure test with gas/air? Large energy potential here if it goes wrong! Much better to pressure test hydrauically, if possible. Are you working to engineering pressure codes e.g. ASME, if so what class of vessel do you have, PD5500 is another pressure vessel design standard. Are you familiar with PSSR and PED? I would say you need to speak to a competent engineer and/or refer to your WSE, if the vessel falls under PSSR. What does testing to 80% of the normal operating pressure prove? If in normal use it will be operated at a higher pressure. Might be ok for a leak check, but thats about it. It would be normal to pressure test to more than the normal operating pressure - maybe 1.5 x. Depends on the type of vessel and the code the vessel was manufactured to Also if the vessel is still in service, you will need to make sure it is physically isolated from other vessels in case you get a leak across to other vessels - other vessels may have lower pressure ratings and be damaged by the pressure test. Does the vessel get subject to lots of cyclic pressure applications? Are you happy the fatigue life is ok? If you over pressurise the vessel you can seriously reduce the fatigue life of the vessel.

Jane Very true what you say, but as we don't know the full details of this pv, we can only answer in generalities. But we are not dealing with an aircraft skin - this might be a double skinned reaction vessel, it might be single skinned - I assume this pressure vessel won't have square windows and stress raisers in the corners of the window!! No thought not... Are you the Jane Blunt from OU T357, last year?

It appears that you do not have a wrriten scheme of examination which should also specify type of testing etc. There is comprehensive HSE guidance at:- HSE have a Guidance Note GS4 on Safety in Pressure Testing--surprisingly, this is not available for free download! http://books.hse.gov.uk/...alogueCode=9780717616299 Pressure test safety. CRR168/1998--this underpins the above guidance--although it is published as an HSE Contract Reasearch Report, it is very detailed and comprehensive. http://www.hse.gov.uk/re...rr_pdf/1998/crr98168.pdf My advice would be to involve a "competent person" as the consequences of getting something wrong is pressure testing can be disastrous

A little O/T didn't do T357 did its predecessor T353, & T401. I finished my OU MEng in 2005. All I can say at the moment is echo the comments to date. This is a complex area and really should also have input from the vessel design team & manufacturers as to the requirements. We can all imagine various scenarios at this stage, and without the requisite information we are all clutching at straws! However, the testing regime, is not something to be considered lightly, along with leakage. Leakage could for example be benign release of small ammounts of pure water, from a component which has a very small risk of catastrophic failure, however, it could be from a crack in a pipe flange stub, which could be the early warning for a sudden catastrophic failure resulting in the uncontrolled release of harmful substances. Coy, it looks like you have a few of us hooked with this please come back with a little more information. p.s. IIRC under the PSSR you need CEng to sign off the testing regime for systems above a certain specification, below this it is IEng IIRC. HTH Paul

Sorry O/T Need to get my CEng application resurrected, but being self employed finding the time is a pain! My last application took too long as my old boss sat on it for too long and then lost it! Paul