Full Penetration Welds

By macddonagh Date 03-05-2003 07:51

Does somebody know if you can do a full penetration (as opposed to a partial penetration) weld on a 323 mm CHS with a wall thickness of approx. 32 mm and still grind the weld surface back flush so the CHS appears seamless. Presumably to achieve full strength you would have to use a backing ring? Generally, what effect does grinding the surface of the weld have on the strength of the weld?

By Niekie3 (***)

Date 03-07-2003 19:11

Hi

I am not quite sure if I understand your question. Are you concerned with code requirements, or merely the technical feasability of performing the job?

Assuming it is merely the technical feasibility, then yes, almost anything is possible in welding. Certainly, welding something around 30mm thick is not that unusual.

Grinding the weld surface flush should not create a weakness, as long as it is indeed flush and not ground under size. Regarding the backing, you will need to either use backing or double sided welding if this is possible.

Regards
Niekie Jooste

By dasimonds (**)

Date 03-08-2003 18:26

CHS?

"wall thickness" implies pipe to me, as does the use of a backing ring. Is there anything that says you can't do an open root using GTAW to avoid the backing ring? I don't think a backing ring is required to achieve full strength.

I can't remember the last time I did a pipe joint with a backing ring.

As Niekie stated, as long as the weld isn't ground below flush, grinding shouldn't pose any problems concerning strength.

Dale Simonds

By jwright650 (*****)

Date 03-08-2003 18:54

If he is talking about structural codes, he might be welding pipe or tubing, both require a backing ring to be considered full pen, welding from one side. Tig is not considered prequalified and would require testing, to prove your welding procedure, and welder's ability, for the use of Tig from one side with an open root.
John Wright

By dasimonds (**)

Date 03-09-2003 12:13

I wasn't aware of that. Thanks for the clarification.

Do you know what "CHS" stands for?

Dale Simonds