Drill and Tap Valve for Sealant Injection - Nullifies "Fire Safe" Valve Design? 1

[Zylinderkopf]

Greetings:

Please know that I had performed a “search” of this Forum as it pertains to the subject matter prior to starting this “thread”, and could not find the information that I am seeking.

I have recently made a move from downstream refining to working at a chemical plant. The refining sites where I have been previously employed utilised the subject maintenance activity on valves located in many services, including hydrocarbon service.

The company site where I am now has a prohibition against Drill and Tap Valve for Sealant Injection at valves installed in any hydrocarbon service. When I had enquired about this matter, the response was that the “drilling and tapping procedure removes the ‘fire safe’ quality of the valve being worked”.

I have tried, in-earnest, to find either some Code-related or valve-design related information that pertains to whether-or-not Drill and Tap Valve for Sealant Injection procedure does (in fact) invalidate a “fire safe” valve design quality.

I then contacted the Contractor at my site that would perform such work (TEAM) and their representative only commented to me that they “have never been allowed to drill and tap / pump sealant into any valves at this site” (sic).

I know that I must be “missing something”, but I’m struggling to find the answer(s).

If you Valve experts have any (kind) words of advice for me then I will be grateful.

 

[gerhardl]

Could the answer be as simple as following reasoning:

A certified fire-safe valve has been firesafe tested in a real fire under given, controlled, conditions. (Usually as a type, which sometimes also qualifies equal valves in near dimensions and pressure classes). Any change or intrusion of/in a certified product (valve) of mechanical art will juridically make the certification invalid. This juridical viewpoint is valid, even if the intrusion seemingly, by 'normal' mecanical reasoning, will have no or little consequences. The reason is simply that this is not incorporated in the test, and as such not proven.

My sidecomment is that you will here have two mechanical changes: the actual drill and tap, and secondly the sealant injection which could have different behavior according to different fluids by chemical reaction. Secondly the necessity of sealant will indicate already incurring smaller mechanical changes from a 100% fully performing valve, as originally tested, and may also 'camuflage' increasing differencies over time.

 

[gerhardl]

A PS to my post above: I see you describe 'firesafe design', which may indicate that the valves could be constructed equal to already tested firesafe valves, but has no actual valid certification itself. Even if this is the case, the reasoning is the same.

 

[Zylinderkopf]

Greetings, gerhardl:

Thank you very much for the time that you had taken to style your excellent response. Since the time that I had submitted the originating Post, I have found (and attached) and NRC document that provides their position as it pertains to the subject matter.