Weld preparation best practice
Weld preparation best practice
(OP)
Hi, I was wondering if there is any good source for weld preparation best practice. Things like prep angle, gap, root face, back gouging, backing runs, specialized first run, etc. I normally reference the pressure vessel codes and think I have a reasonable understanding of how it should be done but I am getting conflicting information from a fabrication shops 'welding engineer'.
As an example, what would be a recommended preparation angle for welding a set in nozzle into a pressure vessel? It is double welded double bevel with a cover fillet all the way around the nozzle. The material is about 60-65mm thick. Also for this thickness what would be the best root face. Should a large one be used to avoid having to back gouge or should it be small and back gouge always. Also they use a very small gap so i would recommend increasing the angle to ensure full penetration.. but I am not an expert on the subject.
Cheers for the help.
As an example, what would be a recommended preparation angle for welding a set in nozzle into a pressure vessel? It is double welded double bevel with a cover fillet all the way around the nozzle. The material is about 60-65mm thick. Also for this thickness what would be the best root face. Should a large one be used to avoid having to back gouge or should it be small and back gouge always. Also they use a very small gap so i would recommend increasing the angle to ensure full penetration.. but I am not an expert on the subject.
Cheers for the help.





RE: Weld preparation best practice
RE: Weld preparation best practice
Then again this is being manufactured over seas and this weld preparation would never be used here, so I may not be that far off the mark?..
Either way I would still like some information just so I can design my own work correctly, not to stipulate how experience fabrication shops should weld.
RE: Weld preparation best practice
Remember, smaller angle -> less weld material and less prep time and less waste material and much less welding time. More profit for them.
So if all the cost advantages are pushing them to scrimp on the angle, and the only penalty is to you for a bad weld, can you be sure they are actually welding correctly down inside the metal?
65 mm is deep - not unheard of, but very deep. (Make a full side of two pieces of wood with "their" angle and with the AWS/ASME limited angle, then try to wedge a rod down into the tip of their joint. Sobering results)
If "they" are getting all these apparent savings, are you really sure they are actually doing the back gouging (have you (your independent inspector) actually seen them? Have you measured the back-gouged depths and partitioned a test strip. Make them justify their "best profits" (er, "best practices") to you.
They might be right. Most weld shops (here) are good. Some are not.
RE: Weld preparation best practice
Hg
Eng-Tips policies: FAQ731-376: Eng-Tips.com Forum Policies
RE: Weld preparation best practice
Hg
Eng-Tips policies: FAQ731-376: Eng-Tips.com Forum Policies
RE: Weld preparation best practice