Fitting Rating 1

[kkddkk]

Hello,
Why socket weld fitting is rated in pound (i.e.3000#, 6000# and 9000#) and butt welded fitting are rated with wall thickness?
Thanks alot.

 

[hella]

With a socket weld fitting, the highest stress will be in the fillet weld between the fitting and the tube, so the tube wall thickness does not come into play in the pressure rating of the fitting.
Here is a great explanation of weld stress for various geometries -

http://www.gowelding.com/calcs/index.htm