Socket weld or back weld threaded connection
Socket weld or back weld threaded connection
(OP)
Hello Gentle men,
for produced water service (in O&G production), corrosion is always a thing of concern. we have pipes 2" or less that needs to be buried (maybe some higher than 2")
1. If is a fair statement to state that corrosion is more of a worry in a socket weld than a threaded connection (I understand that crevice corrosion may be an issue only with socket weld, right?
2. with number 1 (corrosion) in mind, is it right to say that threading will be better if the pipe schedule is high enough or does it make any difference if it's socket welded or threaded?
3. If threaded is better, is it a bad practice to backweld the threaded connection as long as the exposted thread is covered by weldment to avoid stress rizers on the exposed threads?
DOES IT MAKE ANY DIFFERENCE IF
1. it's a natural gas serviec
2. or Oil piping
SUMMARY: is it better to have a good wall thickness, thread it and backweld (if need be) than to socket weld and stand the chance of suffering from corrosion in produced water, oil, and gas service piping?
THANK YOU VERY MUCH
for produced water service (in O&G production), corrosion is always a thing of concern. we have pipes 2" or less that needs to be buried (maybe some higher than 2")
1. If is a fair statement to state that corrosion is more of a worry in a socket weld than a threaded connection (I understand that crevice corrosion may be an issue only with socket weld, right?
2. with number 1 (corrosion) in mind, is it right to say that threading will be better if the pipe schedule is high enough or does it make any difference if it's socket welded or threaded?
3. If threaded is better, is it a bad practice to backweld the threaded connection as long as the exposted thread is covered by weldment to avoid stress rizers on the exposed threads?
DOES IT MAKE ANY DIFFERENCE IF
1. it's a natural gas serviec
2. or Oil piping
SUMMARY: is it better to have a good wall thickness, thread it and backweld (if need be) than to socket weld and stand the chance of suffering from corrosion in produced water, oil, and gas service piping?
THANK YOU VERY MUCH
As much as possible, do it right the first time...





RE: Socket weld or back weld threaded connection
Socket welded connections are typically used in applications of high pressure and pipe loads.
RE: Socket weld or back weld threaded connection
Mike Halloran
Pembroke Pines, FL, USA
RE: Socket weld or back weld threaded connection
A socket weld's single inherent "crevice" is inside the pipe. The outside of a proper socket weld is a smooth solid surface that will be exposed to the dirt and soil. (Are you sure you're not going to protect the pipe in any way? Doesn't sound like any oil & gas or other petrochemical installation I've heard of ....)
A threaded joint is exposing the "crevices" (threads) both inside and outside: Outside to the soil on every male-threaded piece and fitting, and inside to the pipe fluid on every female threaded fitting.
RE: Socket weld or back weld threaded connection
And we're considering going with socket welding in the near future. But I also found a paragraph in the B31.3 code which requires that if threaded connections must be seal welded, then the weld have to cover all threads.
As much as possible, do it right the first time...
RE: Socket weld or back weld threaded connection
And, since continuous extra welding is very, very expensive for almost all pipes greater than 1 or 2 inches, they are economically forcing you to do what is really wanted; Don't weld threaded joints. 8<)