standard for blowdown

[gill78]

Is there a standard which describes a certain amount of mass in a line where automatic blowdown is no longer required and manual blowdown will suffice. I have been asked to look into this and told it will be in a standard somewhere and I am looking in API and NORSOK, but with very little luck.

Does anyone have a clue as to where I can start this search.

Regards,

Gillian