Repair on the long seam of a pipe

By Niekie3 (***)

Date 05-04-2002 15:00

I assume you are talking about the long seam on seamed pipe? Generally the specification to which these pipes are made specify the repair procedures on the seam, should it be found faulty.

The bottom line is: If you can excavate the defects and repair weld it to a qualified procedure, the repair should be just as good as the original seamed pipe. (If it had no defect!) Typically your procedures and welders would be qualified to ASME IX.

Just a word of caution: You have to establish why the flaws in the seamed pipe managed to get through the required NDT and pressure testing undetected. You may have a bigger problem if you start looking further!

Hope this is what you are looking for. - Are you maybe asking about welding on the pipe while in service?

Regards
Niekie Jooste

By arclyte1 Date 05-06-2002 18:12

Niekie;

Thanks for your response. Our procedures say we cannot weld on the seam of a pipe at all. As you can read in my response to Mike, I have explained my concern. I appreciate your patience and time.

Cathy

By Michael Sherman (***)

Date 05-04-2002 18:55

Is this a rupture or a new pipe that is defective? If I follow your question correctly you are asking the best way to repair this in conjunction with your company procedures of not welding on the seam, correct? The best way is to remove the joint and replace it. I personally would not suggest a clamshell repair for a defective or ruptured seam. As Nieke said, you need to dig a little deeper and determine exactly what is happening here. However, if this is not practical or economical, clamshells can and have been used successfully when installed properly. The space shuttle repair that was just done was a clamshell repair, but I only know what I have read about that one. If this does not help, please send more information.

Mike Sherman
Shermans Welding

By arclyte1 Date 05-06-2002 18:09

Mike;

Thanks for taking the time to answer my question. That is exactly why I was asking because our specs. do not call for welding on the seam of the pipe (out of service). This pipe had been in service for a number of years, and the leak was thought to be on a branch connection at the weld, but it was on the seam of the pipe right up next to the branch connection weld. The crew ended up plugging the tee with a steel pin, cutting both flush with the main, and installed a full encirclement fitting over all and welding it. My only concern was I had heard once a seam starts to split, it can propogate lengthwise and keep splitting unless it is taken out of service. By welding a circumferencial fitting, does that arrest the propogation? Sorry for the terminology, but it is what I am use to. I think you know what I am after.

Cathy

By Michael Sherman (***)

Date 05-06-2002 20:00

Cathy, I believe you are correct. I would equate it to not getting full penetration on a groove weld. You have a crack at the root and it will most likely propagate. It sounds as if the clamshell is covering the split in the seam also, or is it still leaking and this is how you found it was the seam? Regardless, I would suggest the piece be replaced. I hope this helps.

Respectfully,
Mike Sherman
Shermans Welding