welding on old welds

Date 09-03-2013 01:07

If a part has been cut off and you are reusing it there is very little 'old' weld there if it has been properly cleaned and prepped before the new work. At least, if done PROPERLY.

This is really a call of the project engineer though.

No, I do not recall an article doing rewelds over welds.

Have a Great Day, Brent

By MKNIK

Date 09-03-2013 06:58

good day to all ...

well well I have a similar situation and recalling the article by Professor Giovanni S. Crisi February 2012, my case is, multiple repairs in a welded joint in pipes A106 Gr B, although interpreting the manufacturer's quality certificate according to their carbon percentage ranging from 0.16% -0.19% by weight, this is considered as low-carbon steels. although the A106 Gr B fit your specifications or medium carbon.
the question is what is recommended to submit multiple repair the weld?

is for a gas service line fuel 8 "Ø ced 60, under the guidelines of ASME B31.3.

greetings rusbeli r.

By welderbrent (*****)

Date 09-03-2013 13:20

I do remember something, now that you mention it, by the Professor. And, it may have been submitted in an article 1-2 years ago. I know the discussion got rather involved here on the forum. You should be able to use the 'Search' function and find it. If it is the same article, it was not intended to be code interpretation or deep research, just a topic of personal experimenting meant to show an everyday approach to the subject to be considered by many users that would not be affected by code or contract restrictions.

Have a Great Day, Brent

By welderbrent (*****)

Date 09-03-2013 13:31

Check out this link:

https://www.aws.org/cgi-bin/mwf/topic_show.pl?tid=29958

It was started by the Professor as an encouragement for conversation about his, and others, article to help them analyze further and to encourage others who may have deeper resources and abilities to go further with the tests.

The thread is covering the same topic as the article. You will notice some pretty tense posts concerning how it was conducted and the applications made.

Still, it is very interesting and has some merit under some circumstances. Care must be taken though in how it is applied for any usage.

Don't try to use it as supporting evidence in and of itself to tell a customer there is no problem removing a poor weld 12 times because the welder just can't get it right. As the article and thread point out there are many things to be taken into consideration.

Have a Great Day, Brent

By MKNIK

Date 09-04-2013 07:10

good day ...

if in fact I read the article and speaks for 6 repairs, is a good job.

greetings. rusbeli r

By 803056

Date 09-04-2013 13:24 Edited 09-04-2013 21:56

In general terms I would expect the base metal to respond to a repair or a weld located adjacent to an existing weld to be no different than a multiple pass groove weld or a multiple pass fillet weld.

If there is a concern about heat input and maximum interpass temperature due to the need to meet minimum notch toughness values, then the weld repair must meet the same conditions and restrictions as the original weld. One must be cognizant of any preheat requirements as well.

If the base metal is time at temperature sensitive, such as may be the case with heat treatable aluminum, then the repair weld will cause the same accumulative damage as a multiple pass production weld. As is the case with the initial production weld, the interpass temperature and heat input should be monitored closely while making the repair.

In the case on a repair of a nickel based alloy, consideration must given to the maximum interpass temperature just as was the case with the initial production weld.

When repairing austenitic stainless steel the repair procedure must consider the possibility of sensitization due to the additional time at temperature in the HAZ from the added weld beads. The more weld beads deposited, the greater the time spent in the sensitizing temperature range and the greater the risk of sensitization. If the application is a dry environment, who cares about sensitization?

The bottom line is the engineer must consider the nature of the base metal being repaired, how it responds to thermal cycling, and the environment the weldment will be operating in. If there are concerns, the engineer can qualify a repair procedure that simulates or replicates the actual conditions to be encountered.

Best regards - Al

By G.S.Crisi (****)

Date 09-04-2013 21:35

I feel indeed rewarded by the fact that the article of which I was one of the authors is still the subject of discussion in this Forum, after one year and a half it was published on the February, 2012 issue of Wedling Journal.
As Brent has mentioned above, the article was intended to be "just a topic of personal experimenting meant to show an everyday approach to the subject to be considered by many users that would not be affected by code or contract restrictions". Brent is also right at saying that "Care must be taken though in how it is applied for any usage". Also, "Don't try to use it as supporting evidence in and of itself to tell a customer there is no problem removing a poor weld 12 times because the welder just can't get it right", but yes inded, you can use it as a starting point for a friendly discussion with your client.
As always, Al's post looks like a chapter of an encyclopedia.
I have the whole article in electronic format and I can send it to eck by e-mail if he wants.

Giovanni S. Crisi
São Paulo - Brazil

By 803056

Date 09-04-2013 21:58

Your research and your article were good starting points for anyone involved with or concerned with the consequences of making repairs to a weld.

Best regards - Al

By welderbrent (*****)

Date 09-05-2013 14:54

I second that. It was great in it's intended purpose.

I just hope that someone will expand upon it at some point.

Have a Great Day, Brent