Leakage Question
Leakage Question
(OP)
Hi all,
Situation : Installed fully welded ball valves up to 24", with soft seal, are found to be leaking. These valves are used for gas pipelines and have been in service for about 5 years.
Question :
While they are obviously leaking, are there "acceptable" leakage rates, based on industrial standards, practices, recommendations?
Are such occurrences common?
Thanks!
Situation : Installed fully welded ball valves up to 24", with soft seal, are found to be leaking. These valves are used for gas pipelines and have been in service for about 5 years.
Question :
While they are obviously leaking, are there "acceptable" leakage rates, based on industrial standards, practices, recommendations?
Are such occurrences common?
Thanks!
RE: Leakage Question
Would you work on a line which is supposed to be isolated, and is leaking through a defective valve?
Steven van Els
SAvanEls@cq-link.sr
RE: Leakage Question
I agree with Steve van Els. Valves for gas service should be "bubble tight". More likely the valve seat is scored or the valve is assembled or installed incorrectly. An inspection of the valve is wise.
RE: Leakage Question
RE: Leakage Question
I agree with pkelly54 in that all valves leak to some extent. Bubble tight is a matter of definition (how many bubbles per minute and at what pressure). You need to determine the acceptable leak rate for your application and then determine why your valves are leaking at an unacceptable rate. Disassembly and inspection are most definitely required. Also mentioned was that the valves in question are equipped with soft seats. There may be some trace compounds in the gas stream that have degraded the elastomer seals. Analysis of the gas may be in order to understand all components of the stream.
RE: Leakage Question
Hope this help
Process
RE: Leakage Question
Most Ball valves are supplied with emergency sealant injection systems that can be used to assist seal integrity. Depending on the extent of seat damage - valve sealants can restore seal integrity.
To my knowledge, most of the larger valves are cycled infrequently, so sealant use would be minimal.
The main reasons for seat failure would be incorrect elastomer selection (kstaylor)either on the part of the buyer or seller. The belief that "Viton is Viton is Viton" is incorrect. Correct elastomer selection plays a vital role in valve reliability. The least admitted reason is poor installation practice (shipping, storage, commisioning etc..) Any place where dirt and grit can get between the ball and seat.
Although I can't give you an "operational" leakage figure, I hope this helps.
RE: Leakage Question
RE: Leakage Question
Mike
RE: Leakage Question