Minimum allowable distance between a pipe weld and geometry change (transition piece) in ASME IIII 1

[Mellco]

Hi,

I have a two pipes that are joined by dissimilar welding and one of the pipes has a bore size change to allow the homogenous ened of the two metals to be joined (different pipe schedules). Can anyone tell me if there is a rule in ASME III that gives minimum allowable distance from a weld to a geometry change, i.e. bore change?

Thanks in advance of any responses.

 

[pennpiper]

The answer to your question is: No, the ASME B31 Piping Codes do not address this.

prognosis: Lead or Lag

 

[racookpe1978]

The usual minimum length between adjacent butt welds is 1 inch (25 mm), and some companies offer a standard elbow with just that tangent extension on each end of the elbow to avoid just this kind of multiple pup-piece welding.

You're thinking of using a transition part (reducer or adapter? ) instead of a pipe stub, but the principle is similar.

 

[pennpiper]

racookpe1978,
I do not think the original post was about the distance two welds.

I think it was about a possible distance requirement between the end of a taper bore bevel(on a thicker wall pipe) and a single weld joining that modified pipe to a thinner wall pipe.

Mellco, would you please clarify this for us?

prognosis: Lead or Lag

 

[Duwe6]

It's very poor practice, but the counter-bored taper can end at the toe of the root. MUCH better detail is to have the counterbore REALLY deep, with the thin end about 1-wallthickness [or more] from the end of the pipe. With the bore that far back, it should not cause problems during x-ray or UT. Counterbore lines under the weld cap cause a LOT of [wrong] x-ray rejects.