Welding: Destortion free zone

[metootoo]

I'm designing a receptacle using A106 B 24" sch 60 pipe. The ID will be machined for a very close fit to what goes inside (.01" gap). This pipe the be welded to a large plate. I'm trying to figure out the minimum length to make the pipe such that the welding will not effect the shape/size of the machined area on the other end of the pipe. Is there a rule or formula to determine this?

FWIW: 24" sch 60 = 24" OD x .969 wall

 

[Goahead]

Assuming that your design is correct and that the thickness ratio between tube and plate is not larger than 1 to 3, and that you plan only a fillet weld around the pipe, if you could possibly arrange a provisional water tank around some length of the pipe (if it stands vertical while welding)
with running cooling water, you should be able to reduce the distance to an acceptable length.

http://www.welding-advisers.com/

 

[metootoo]

Until I can find some way to know for suer, gut-feeling-calcs suggest that it should be ok if nearest machined feature is 18 inches away.

I guess what needs to be known is, at what temperature will the pipe shape be compromised and will it reach that temperature 18 inches from the weld on a 24" pipe sch 60 pipe without the use of additional heat dissipation methods?

 

[Tmoose]

I'm afraid of the residual stress induced by shrinking weld metal, not so much the temperature achieved. Lincoln has a batch of material on distortion control. Preheat, back step welding, symetrical weld procedures (2 welders 180 apart on pipe). The stresses are still in there, just balanced.

 

[desertfox]

Hi metootoo

Is it possible you could weld the parts together first and then machine the bore.

Regards

desertfox

 

[metootoo]

Desertfox....that would be a no-can-do. It's being welded to a 16' diameter plate.