WELDING A CUT OUT FLANGE

[chitessy]

All,

Please I will like to know if there is any code or specs on how many times you can cut out a flange and re-weld that same flange.

We have a 24'' X 900#. In modifying a pipe spool, we cut out the flange and we want to re-use it. is there a limit to the number of times we can re-weld a cut out flange.

Professionals, I really need your help.

Regards

Chitessy

 

[LittleInch]

This has been discussed many times and the best advice I can offer is to consider the action as a repair weld (albeit a complete repair weld(!)). This is normally limited to a single repair before you need to start again and completely remove the pipe and its HAZ and ditto that of the flange. I think most prudent engineers would only weld the same thing in the same place a maximum of three times before they start to get nervous. I don't believe it is specified in any code or standard as there are too many variables.

The issue is really one of material changes to the flange due to the heat input from the welding and its impact on the physical properties of the flange, in particular it's hardness, which varies by material, thickness, welding technique etc etc. Unfortunately some tests are destructive, hence a bit difficult to do unless you're trying to prove a point for many other similar fittings

You may be able to utilise the flange more times than twice, but it's really in the hands of the materials / welding engineer and the flange welding face may need to be tested for excessive hardness.

This is a response from the welding institute -

http://www.twi-global.com/technical...s/faq-how-many-times-can-a-weld-be-re-welded/

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[racookpe1978]

At a certain point in time, the COST of two welder/fitters/grinders/labor working to cut/refit/regrind/refit/regrind the flange is ten times the price of a new flange with "good" metal.


You're wasting money and time and schedule trying to salvage a bad job repeated already twice. Field repairs are about 150.00 - 200.00 per hour per man. Your flange can come overnight.

 

[chitessy]

Thanks All for your responds, I sincerely appreciate.

Chitessy