Car seals
Car seals
(OP)
As we know, car-sealing is a common term for allowing maintenance for relief valves. Now, I have a client using terms like safety car-seal open and safety car seal closed.
I was wondering if anyone knows any legal definition devining the difference between a car sealed open valve and a safety car sealed open valve?
I was wondering if anyone knows any legal definition devining the difference between a car sealed open valve and a safety car sealed open valve?





RE: Car seals
RE: Car seals
To find out the difference (if there actually is any) you must ask the Client who is using this terminology.
RE: Car seals
RE: Car seals
Good luck,
Latexman
RE: Car seals
RE: Car seals
Given that the seal is used for safety reasons, the name has evolved further to 'safety car seal'.
Although car seals can be an effective means to prevent tampering (either inadvertent or deliberate), once the seal is removed, in the case of relief systems, the system can be vulnerable to incorrect sequence of operation.
Various API and ASME codes recognise this hazard and recommend the use of valve interlocks to eliminate this possibility. API RP 520 (Pressure Relieving Systems for Refinery Services - Part II Section 4- Isolation Valve Requirements) and API RP 14E (Design and Installation of Offshore Production Platform Piping Systems - Para 5.8b [2] - Relief Device Piping) specifically recommend interlocks in this situation to ensure that (over)pressure protection of the vessel is not compromised. These recommendations are also in accordance with the requirements of ASME - Section VIII - Appendix M.
RE: Car seals
There is, however, a legal difference between "locked open / closed" versus "car sealed open / closed" (e.g. putting a "seal" versus a "padlock" on a plug valve or ball valve. One (car sealing) requires a procedure that is more difficult to "get around" for anyone wanting to "swing the valve for a few minutes and nobody need be the wiser". A padlock can be re-used...a seal with a serial number can't.
Maybe that's the difference that someone was trying to draw attention to in their terminology.
Regards,
SNORGY.