ASME Boiler Code 1

[emille04]

If I install a new boiler rated for 150 psig, are two isolation valves required by the ASME boiler code or can I install a single check valve and butterfly isolation valve? The boilers do not contain a man hole, instead they have a hand hole only. My understanding of the code is that two forms of isolation are only required if the boiler is above 15 psig and the boiler contains a man hole.

Thanks for the help in answering this question.

 

[Fizza453]

I am presuming that you are talking about the intent of PG-58.3.2 of Section I.
Two stop valves are required when two boilers are connected to a common steam header or when a single boiler is connected to a steam header having another steam source. In this case boiler(s) should have at least one manhole. For two stop valves, Manhole opening is a condition but 15 psig is not a condition.
I am sure two stop valves cannot be replaced by one check valve and one stop valve.
Please see also the following interpretation;


Interpretation: I-82-09
Question: PG-58.3.2 requires, for two or more boilers connected to a common steam header, that the connection from each boiler having a manhole be fitted with two stop valves having an ample free-blow drain between them. Does this requirement apply if neither of the two boilers has a manhole?
Reply: No
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Please see another interpretation

Interpretation: I-92-90
Question: Does the presence of pressure reducing valves in a common steam header waive the requirements of PG-58.3.2 for two stop valves having an ample free blow drain between them?

Reply: No.
.................

Please see another interpreation on subject matter;

Interpretation: I-86-12
Question: When the steam piping of a boiler is to be connected to that of an existing boiler, is this arrangement considered to be multiple boilers on a common header and therefore subject to the provisions of PG-58.3.2?

Reply: Yes.

................

Hope it helps a little.

Nasir
Welding Engineer
DESCON ENGINEERING LIMITED
PAKISTAN

 

[metengr]

If in the USA, please check with the local Jurisdiction or regulatory body for boilers. They have the final word about such installations.

 

[davefitz]

back in the 1990's, the section I code had verbage that allowed "one non-return valve plus one stop valve". The term "non return valve" was mis-interpreted to mean a simple check valve, and severall boilers on header type systems were inadequately protected . A code and civil case ensued, and the result is the current wording that requires 2 stop valves or a dobule block + bleed.

 

[GenB]

No manhole present: the required stop valve on the boiler and the addition of a check valve per boiler will suffice.
No fight your Inspector, he or she may have a different opinion not based on the ASME Code.
now for maintenance purposes if you need to shut down a boiler to replace the only valve on the one boiler...