Does anyone know aclear definition of a pressure vessel vs pressure piping and how to classify if a section of pipework (eg a header) is a pressure vessel or pipe component.
For set-in, fabrication and NDT are easier. If roundness of the vessel body is critical (like headers, manifolds ...), set-on creates less weld shrinkage and out-of-roundness.
You can machine the face to the extent that the flange minimum thickness is maintaned. Please note that the raised face dimension is not critical.
To avoid welding and if the defecs are deep, you may machine the face just to make those defects whithin the acceptable range rather than completely...
1- Pipe location to be confirmed.
2- Machine diggig to start from somewhere close to the pipeline and not over it.
3- Durring digging, pipeline locator should be used to confirm the location and distance to the pipe.
4- When close to the pipe (approx 300mm, use hand dig to expose the pipeline...
If you working under API code, it tells you the tollerances inc ovality, buckles and etc.
That is why you use gauge plate after hydro test. I think difference in diameter up to 5% of inside pipeline dia is acceptable so your is 0.5% that looks ok.
