Weld penetration details

[mariolucas75]

Dear All,

Attached herewith the nozzle to shell weld detail (set through)...
Could you please have a look and advise that the shape of bevel i draw next to the drawing is correct way i understand it...
Also what is the "arc"-like marking on the drawing ?

Thank you so much

 

[r6155]

See:
AWS A2.4:2020 – Standard Symbols For Welding, Brazing, And Nondestructive Examination

 

[Trestala]

It is the groove of the back-chipping/back-gouging

 

[mariolucas75]

r6155 / Trestala​

Tank you very much for your reply.

So can we say following: a fillet weld was welded (45 degree triangle), afterwards the back-side (opposite side) was gouged and the weld was deposited on opposite side ?

 

[Trestala]

From the inside, the nozzle-to-shell weld (45°, bevel/groove weld) will be welded first. Then from the outside, the root of the first weld is then gouged. Welding to be done afterwards from the outside (30°) for the nozzle neck-to-pad bevel/groove weld including the 10mm fillet.

 

[r6155]

Additional comments.
1) BC (back gouging) can cause problems. There are welding procedures that do not require BC.
2) NDE and testing is required for this example. Be careful

Regards

 

[mariolucas75]

Additional comments.
1) BC (back gouging) can cause problems. There are welding procedures that do not require BC.
2) NDE and testing is required for this example. Be careful

Regards

Why it can cause problems ?
NDE after back-gouging ? MPI (carbon steel)

 

[r6155]

1) BC is very difficult on a nozzle neck weld. Visual examination. Test with a mock-up to qualify the procedure. Try to avoid reinforcing pad.
2) Visual examination and air leak test of the completed connection.

 

[Trestala]

Please ignore r6155 comments. This weld configuration is very typical and most of certified manufacturers are capable of doing this configuration. Reinforcing pads are well utilized in the industry for certain and non-special services, no need to try to avoid it. Pad leak testing per Code to be done accordingly.

 

[jt1234]

95% of vessels come with reinforcing pads on nozzles. Back gouging is very common before putting the first pass from the other side for all kinds of reasons.
Ignore r6155 comments.

 

[r6155]

@ jt1234

The people on this forum have enough sense to think for themselves, they don't need you to show them the way.

 

[r6155]

Additional comments
Following examples to demostrate that BC (back gouging) is impossible to do. Hence there are WPS that do not require BC

Example 1)
Shell NPS 10, nozzle NPS 4 whit reinforcing pad. Access impossible to do BC.

Example 2)
Piping NPS 4, access impossible to do BC for circumferential weld.

​

 

[Krausen]

So can we say following: a fillet weld was welded (45 degree triangle), afterwards the back-side (opposite side) was gouged and the weld was deposited on opposite side ?

The shell-to-nozzle weld is not a fillet weld. It's a full-pen groove weld. The reason for back-gouging this weld is to ensure you have a clean full-pen weld all the way through. This is standard practice in industry. r6155, as usual, should be ignored.

 

[gtaw]

Double sided groove welds made without back gouging are considered to be partial joint penetration groove welds unless the WPS was qualified without back gouging.



From the sketch, it appears the bevel groove on the bottom side is welded first and then back gouged from the top side. Then the top side is welded to produce a complete joint penetration groove weld.

Without knowing the applicable welding standard, I could only suggest that a welding symbol consisting of multiple reference lines be used to indicate the sequence of welding. Having said that, a cross section of the joint is also acceptable by a number of welding standards, however, it maybe more difficult to specify the welding sequence with only a sketch.

 

[r6155]

@ gtaw
The groove weld of the reinforcing pad is made without BC (it is impossible to do) and full penetration cannot be verified.
Therefor do you consider that is not a full penetration weld?.

 

[gtaw]

I'm not saying this is a good detail for the application. The question was asked what the sketch meant. If the nozzle and vessel is large enough to have access to both sides of the joint, it isn't impossible. We don't have all the information to make that call.

 

[r6155]

Be simple.
See
ANSI/AWS B2.1-1-201-96(R2007) Standard Welding Procedure Specification (SWPS

SMAW electrodes E6010 (no backing is required) + E7018

If no backing is required, then no need to do BC

 

[Trestala]

Incorrect r6155. Please ignore such comments from r6155 as he does not understand full penetration weld requirements.

 

[Trestala]

@r6155, it seems reading comprehension is not your strong suit about that topic you've referred. Your comments all over this forum are often misleading and does not benefit others who genuinely try to help and share knowledge.

 

[Morcuse]

It is very unfortunate that this thread, like others, has been hijacked by individuals more interested in debating egos than contributing constructively.