Maximum Clearance Between Socket ID and Pipe OD?

[af09]

Do ASME B16.11 or B31.3 (or any other standard)specify the maximum allowable clearance between the socket internal diameter and the pipe outer diameter? All I can find is a minimum gap between the pipe end and the socket shoulder of 1/16 of an inch, but is there any specification for a maximum allowable gap between the ID and OD of the socket and pipe?

The question arises due to a suggested solution of smoothing out (or grinding down) the external threads on a needle valve and having it socket welded to a tee connection. The concern is that the gap created between the two mating pieces would become too big.

 

[LittleInch]

I would guess that the nominal OD of the pipe size of the relevant fitting it ASME B 36.10 is what you should use.

Codes and standards don't really consider people bodging it in this way so don't think of every conceivable option or say don't do this or don't do that. They just say do it this way.

So basically if your ground down once screwed end valve or whatever is now less than the OD of the same size nominal pipe size then you are using a non standard fitting and any failure is now on your head for allowing it. Does that make you feel comfortable?
Yes? - then get on with it,
No? - then tell whoever thought of this penny pinching idea to go and buy the proper sized equipment.

That's what engineering judgement is there for....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[TiCl4]

Engineering judgement indeed. It's hard (impossible?) to do any type of volumetric NDT on the weld itself. You are limited to hydrotesting and dye-pen. Is this application hazardous or non-haz? There is a lot more leeway if non-haz.

Also, grinding down the threads means you may run into minimum required thickness issues based on B31.3 calcs. If the application is high pressure, it may be worth a look to check if tmin of the remaining material is sufficient.

 

[af09]

Thank you guys. I appreciate your insight.

 

[LittleInch]

So what are you going to do?

Keep machining off the threads or doing it properly?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[af09]

The threads will definitely not be machined. The joint will need be done properly. Machining the threads would only increase the instability of the joint by creating too much play and relying on the weld to be the primary support for the joint. Not to mention creating centering issues. None of this makes me feel comfortable.

 

[LittleInch]

Good decision IMHO.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[GD2]

You can still do it, not directly but through a coupling and nipple.

GDD
Canada

 

[af09]

GD2,

Actually, that's an excellent suggestion. Sometimes the simplest of solutions elude us. Thank you my good sir. I tip my hat to you.

 

[LittleInch]

Agreed but then you end up with a screwed joint.

If you're happy with that then just buy a screwed tee...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[af09]

Agreed. However, there are other constraints/variables that limit the situation to only accommodate what GD2 suggested. Thank you guys for your input.

 

[FacEngrPE]

I have seen similar non standard joints, not this particular one. The usual result was a leak we called a wormhole (that was the appearance when the joint was sectioned).