ASME piping to first valve on steam boiler discharge.

[BronYrAur]

I quite regularly see stop valves on the discharge flanges of "high pressure" (15-150 psi) steam boilers. It is my understanding that the piping between the boiler and the first valve must be ASME piping. Many mechanical contractors do not have the ASME stamp, so valves are connected directly to the boiler flanges in order to comply.

How would this be accomplished if the boiler has a threaded connection? I have a situation with the boiler has a 3" threaded coupling for the steam discharge connection. Even if I use a threaded valve, there will be a nipple in between the boiler and valve. How do I comply with ASME?

Thank you.

 

[TBP]

Screwed piping is permitted. Lots of 300# (and above) steam boilers have a number of screwed connections on the the steam drum - including the heads - water column, pressure gauge, vent valves, etc.

 

[BronYrAur]

So a screwed nipple into the boiler and into a threaded flange, immediately followed by a fanged valve, will be OK without any ASME piping required?

 

[TBP]

If it's an ASME compliant boiler - and I can't imagine that it's not - then that's the only way to install it.

 

[TBP]

The screwed piping will still need to be code-compliant, which is entirely doable.