Specifying a Welding Procedure

[Foxtrap]

Howdy all,

I am about to write my first welding procedure. How do I start? It is for an Oil Prodution pressure body. Is there any tips about what is my responsibility as the designer and the responsibility of the fabricator. Where can I find help on welding joint design, number of passes, any special instructions?

How much detail is involved? I am also sending this to be done overseas. Is it common to write the standards of materials and inspection codes that they should adhere to in this country or is that the responibility of the manufacturer to translate if it is made there then sent back here to be used?

Foxtrap

 

[henri2]

IMO, the fabricator's welding engineer or welding expert should develop the WPS and present it to you for review. That's the AWS approach and I am sure ASME and API adopt a similar approach.

As the designer, your responsibility entails designing the joint, specifying materials (base metal, weld strength etc).

The WPS is essentially a "recipe" for fabricating the weldment.

In the event the joint is not prequalified, testing is required to develop the WPS.

BTW, what welding code are you using on this project?

 

[21121956]

Hi Foxtrap:

If you search

http://www.lincolnelectric.ca/knowledge/articles/list.asp,

you will really find valuable information for your purposes. That place was recommended by the forum fellow engineer metenger.

Good luck ¡

 

[metengr]

Foxtrap;
With the limited information that you provided, here is my advice;

The responsibility of the designer is to assure proper selection of materials, perform the necessary engineering calcs, and list detailed process steps for fabrication (drawings, etc) so that the part can perform as intended in service.

The fabricator is responsible for following the process steps identified by the designer.

For repairs you have two possibilities; either repair of a component which has been fabricated, placed in service and resulted in a problem OR during the stage of fabrication, a problem developed and needs to be corrected. In your post, you did not mention why you needed weld repair.

The actual weld repair should be a collaborative effort between you (the designer with the engineering basis regarding performance of the part in service), and the welding expertise of the fabricator.

If you are in over your head regarding welding (which is the case based on your post) and the fabricator you are dealing with does not have any expertise in welding or weld repair, you need technical help from an outside source.

I would recommend you find a metallurgical laboratory that is local to you and hire the services of a metallurgist that has welding experience or background. Development of a detailed repair guideline that includes a Welding Procedure Specification and Qualification of this procedure is a rather complicated process if one does not have a materials/welding engineering background.