Codes and Standards for leak testing valves 12

[pipewelder1999]

What industry codes and standards are used for leak testing of valves?

Any information is helpful along with any links to informative sites.

Thanks

 

[NGiLuzzu]

Dear All,
what do You mean, precisely, with "ZERO LEAKAGE"?
Please define...

(I've got my own idea, of course, but I'd like to hear the other ones before explaining mine) ;-)

Thanks and Regards, 'NGL

 

[jsummerfield]

API STD 598 Applies to Valve Inspection and Testing. Table 5 is the Maximum Allowable Leakage Rates for Closure Tests. For all resilient seated valves and metal seated valves two-inch and smaller the note follows: “ bThere shall be no leakage for the minimum specified test duration (see Table 4). For liquid test, 0 drops means no visible leakage per minimum specified test duration. For gas test, 0 bubbles means less than 1 bubble per minimum specified test duration.

Now you have to see table 4. For closure valves two-inch and smaller the duration is 15 seconds, 2.5-inch through 6-inch is one minute. Larger than 6-inch is two minutes.

This is often regarded as bubble tight. However, this is the new valve requirement. Do not bet your life that any block valve even nearly approaches these figures in an operating plant. I estimate that 80% would not meet this requirement after testing and initial operation based upon my last non-scientific example with several hundred API-598 compliant API-6D ball valves.


John

 

[cliff6361]

Any leak rate must include volume vs time. General industry standards such as API 598 and MSS SP 61 give acceptance leakage as a rate.

Bubble tight valve seats should only be expected with new valves and on valves as they are tested under good control. Bubble tight or zero leakage should only be counted over the specified test times. Several years ago no one beleived valve manufactures tested their valves prior to shipment. Of course this was not the truth but endusers and contracters set their own testing many in not so ideal conditions and proceeded to wear the valve seat out testing anf testing to prove their point.

After valves have been installed one should not be surprised the torture construction, loop tests and blow downs has on good valve seats. It happen all to often.