Flow nozzle in B31.1 steam piping
Flow nozzle in B31.1 steam piping
(OP)
Is it necessary that the flow nozzles that are butt welded to steam piping made to ASME B 31.1, need to have code stamp? Basically it is a pipe with a conical contoured nozzle welded inside the bore to control the flow of steam. Both ends of the pipe is butt welded to steam pipes to put it directly on the steam line. Flow nozzles are a bought out item for piping fabricators and the suppliers are normally not ASME stamp holders. The Flow nozzle certification contains the necessary pipe material details that are required by the piping fabricators for welding them to the main steam pipes.





RE: Flow nozzle in B31.1 steam piping
Recent failures with flow nozzles are associated with using a stainless nozzle inside a P91 pipe. Don't do it. For HP main steam pipes, a flow nozzle is not strictly needed- you can use a short radius elbow with an "elbow tap" as indicative of steam flow rate, after it is calibrated.
"Whom the gods would destroy, they first make mad "
RE: Flow nozzle in B31.1 steam piping
Makes an SR ell with an O'let tap sound pretty good, doesn't it?
RE: Flow nozzle in B31.1 steam piping
If you need a HP steam meter purchase one from an established supplier. You have greatly under-estimated what is involved. It comes with welded plates on each end for shipping.
With flow nozzles, you are better off purchasing it with a meter tube to match the piping spec, then all you have to do is install it.
Elbow taps in HP steam? Don't waste your time.
RE: Flow nozzle in B31.1 steam piping
The elbow tap is calibrated during initial commissioning by isolating the HP drum blowdown and comparing the steady state feedwater flow indication ( from a calibrated flow nozzle at the DA or BFP discharge)to the T+P compensated DP across the elbow tap. It is certainly as accurate as the classical use of STG first stage pressure as historically used on 1:1 rankine cycle plants.
"Whom the gods would destroy, they first make mad "
RE: Flow nozzle in B31.1 steam piping
we agree that they are not used for metering where the actual flow is needed.