Preferred Weld Detail

[Paulettaa]

Dear All,

Which one of the following weld details is preferred for nozzles with and without reinforcement.

I want to know about fabrication and mechanical design aspects of choosing between one of these.

Warm Regards

 

[kiad]

the groove angle depends upon you, in fact you have to make sure the groove design and your welding will result in full penetration for the groove.

 

[SnTMan]

From a design standpoint (i.e. UG-37 or other rules as applicable) there likely would be no difference between the details. All are full penetration details. Single sided welds might be preferred as less work by the fabricator. Double welding (C) is generally preferred as it is more likely to result in sound weld metal thru the joint. Some client specs require double welded joints if at all possible.

As to groove angles, not uncommon for these to vary with material thickness.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[racookpe1978]

Double-sides groove welding does require adequate access to both side of the pressure vessel to do the welding. This also requires interior access (confined space rules, confined space limits, many, many more hours of extra people (confined space watch, fire watch, access team in some locations, extra briefs, confined space gas free testing, retrieval equipment, etc.)

Double-sided weld preps also allow/force back-grinding and a purge for some metals or you get extreme sugaring (stress risers on the back of the weld) if not ground out. So sometimes they are better than a backing strip or a consumeable insert.

If you can get enough strength with a one-sided groove prep welded from the outside, do it. ALL of your prep's require an inside weld - the most difficult and expensive.

 

[Paulettaa]

Thank you all for your replies.

Is there any concern regarding the weld details where it comes to contact with process fluid? I mean does it happen that in some environments it would be better to minimize the weld which contacts the process fluid by making the bevels from outside and putting only the root of the weld in contact with interior part of the equipment?

 

[r6155]

None of them for your example.

As a general recommendation, all set-in branches should be welded on the inside of the shell if they are accessible for the purpose, otherwise preference should be given to set-on branch connections (see PD 5500)

Avoid reinforcing pad. PWHT for nozzle with full penetration weld and reinforcing pad requires more holding time at temperature . See ASME VIII -1 UW-40 and UCS-56

Regards
r6155