Welding on Existing Pipe 2

[MZ Leom]

Hi all weld specialist. This is my first post. Most of the time, the reason for weld defect given by welders is due to welding of new pipe to old pipe. Is this reason acceptable? Any ideas to prevent or eliminate the weld defect?

 

[weldstan]

Poorer cleanliness of the old pipe both metallurgically and externally and lack of knowledge of the grade chemistry of the old pipe would be factors generating more welding flaws/defects.

 

[kingnero]

Make them weld a similar joint on new materials and see how that works out...

 

[Tmoose]

Much more info is required to evaluate the "reason" being "acceptable" and especially how to prevent "weld defects."

What are the actual weld defects? Porosity, undercut, cracks, internal defects identified with UT or RT, and much much more.

 

Unless there is a dimensional mismatch, that is a weak excuse.

'Dirty' steel means high in sulphur and in sulphide inclusions, but if S and P are within ASTM limits the pipe should still be quite weldable. How does the welder even know the pipe composition to make such a claim?


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[r6155]

It depends on the materials, I assume that the welding is in situ and:
1) is the welder qualified for that welding position?
2) Is the welding procedure approved?
3) What code?
4) What conditions during welding?: Wind, cold ambient temperature, dry electrodes, preheat ... etc.

Regards

 

[LittleInch]

"Most of the time", welders will give anyone who they think doesn't have a good idea about welding any old bull shit they think will stick.

There is nothing wrong with "old pipe" that a good weld prep can't get over. Of course the old pipe and new pipe need to be compatible types and free from contamination to be able to weld them together and should conform to a certain welding procedure, but if the welders don't do it properly then you will get defects.

To be a bit brutal, I think they can see you coming....

If you want more info then you need to provide a lot more info on the pipes, the welding procedure being used and type of "defect" found.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mfgenggear]

MZ Leom
Hi all weld specialist. This is my first post. Most of the time, the reason for weld defect given by welders is due to welding of new pipe to old pipe. Is this reason acceptable? Any ideas to prevent or eliminate the weld defect?

answer yes if not weld prep. correctly.
weld preparation and removing moisture and contamination.

heat the pipe to remove moisture. pipe needs to be ground down with a rotary file. and cleaned with acetone.
and as kingnero stated do a weld test procedure with two new pipe connections. then NDT for weld defects.
this will tell you every thing.

 

[mfgenggear]

if it appear this badly corroded all bets off

https://www.corrosionpedia.com/21-types-of-pipe-corrosion-failure/2/1484