Isolation requirement for piping and pipeline 1

I don't know of any ASME standard that covers double block and bleed valve requirements. SAES-L-310 covers service to process line tie-in requirments.

ncnpiping ...

Did you bother to read the Scope section in the beginning of ASME B31.1/B31.3 ? ..... There is something there that should help you

As I recall, there is a figure there that defines each piping code liitations and shows double block and bleed at boiler drains..

MJCronin
Sr. Process Engineer

It will be an Aramco standard or philosophy which lays out the company requirement for isolation which usually varies by product classification and hazard potential and pressure or ASME B 16.5 pressure class ( Class 150,300,600 etc). ASME B 31.1 has some specific clauses about boiler drains and gas feed isolation, but otherwise is not prescriptive.

Be very careful how you call different isolations. Many people use Double block and bleed when they really mean Double ISOLATION and Bleed.

A DBB valve officially designation in API 6A is one valve which seals from both sides with the ability to vent or drain in between those two seats/seals . A double block and bleed valve SYSTEM is two valves with vent/ drain in between.

The UK HSE publish a very useful freely available document which guides you through the process of deciding what is required / to be determined for each case. Attached.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.