Meaning of "Intersection Weld" in B16.9

[jfklein]

Hello,

I have a question for the forum:

What is the meaning of the term "intersection weld" in section 1.3 of ASME B16.9, Factory-Made Wrought Buttwelding Fittings (the term is also used in 14.1.1 of MSS SP-75)?

To be more specific, in the fabrication of a pipe-to-pipe tee (ie: a tee fabricated by welding a branch pipe to another length of pipe), is the weld that attaches the branch pipe to the other pipe considered an "intersection weld"?

In case you don't have B16.9 handy, here is the text quoted from section 1.3:

"1.3 Fabricated Fittings
Fabricated laterals and other fittings employing circumferential or intersection welds are considered pipe fabrication and are not within the scope of this Standard."

Any help with this would be greatly appreciated.

Jonathan Klein

 

[rneill]

Branch connections fabricated by directly attaching the branch pipe to the run pipe (a stub-in) without the use of an extruded tee or a weldolet is covered by B31.3. The design of such a branch connection is discussed in Clause 304.3 and typical welding details are discussed in Clause 328.5.4 of B31.3.

I believe these are the type of branch connections that are being excluded from B16.9 (since they are directly addressed in B31.3 and a "fitting" is unnecessary - pipe is directly attached to pipe).

Having said this, while such connections were common in the past, in my experience they are not commonly used anymore although you may still see them for large bore piping. The exception would be "Y-laterals" for pipelines that are made this way but the branch is attached at a 45 degree angle.

 

[jfklein]

Thanks for the response.

So, are you saying that an "intersection weld" is the weld used on a stub-in connection (ie: branch pipe to run pipe connection)?

 

[rneill]

I is my interpretation of what they are saying -that any of the details shown in Fig 328.5.4 of ASME B31.3 would be outside the scope of B16.9.