gap in a socket weld carbon steel 2 inch

[visitor633]

I have been welding socking valves for a while never giving a gap. The way I have been reading I should have had problems with cracks. All welds are under 250 psi. No problems yet. Do the cracks show right after or over years. Should I worry about past welds

 

[gtaw]

The need for a gap at the base of the socket is insurance the pipe has sufficient room to move as the weld solidifies and cools to ambient temperature. Provided the material has sufficient ductility the crack may be averted. However, should a crack initiate at the root, it may not propagate to the weld face where it can be detected. The potential for a weld failure exists and as life is, it will most likely fail at the most inopportune time.

Stupid is as stupid does. One can run stop signs and stop lights for many years before the final crash. "But that is the way I've always done it." is little comfort to the people injured or the families of the deceased.

If you are willing to gamble with lives, it is best that you gamble with your own. Take up skydiving without a parachute and leave pipe welding to the professionals.

Best regards - Al

 

[hacksaw]

gap'ing socket weld connections is a geneuine requirement, that is why all work must be inspected by qualified inspectors, usually usually not the welder. In this kind of work, you need to have more than one pair of eyes checking all details.

the greatest risk is in high temperature services, and especially where dissimilar metals are involved.

 

[MJCronin]

The gap requirements for socket welded piping is 1/16 inch and is clearly outlined in both ASME B31.1 and B31.3.

The metaphor regarding "running stop signs" is spot-on.....

Some companies offer devices to ease "fit up time" and ensure that the proper gap is made:

http://www.galgage.com/measuring_gap-a-let.html

This topic has been discussed on this forum many times:

http://www.eng-tips.com/viewthread.cfm?qid=330514

http://www.eng-tips.com/viewthread.cfm?qid=10800

MJCronin
Sr. Process Engineer
Venture Engineering & Construction

http://www.VentureEngr.com