Welding of slip-on flanges 1

[ansh93]

Should you weld slip-on flanges from inside and outside?

 

[LUDPEKA1]

Yes

 

[pennpiper]

Yes!

 

[LUDPEKA1]

To expand on my yes answer from earlier. Our inspection procedures call for a dye check on the root & final pass of both of the weld locations. On top of this a 1/8 inch hole is drilled and tapped into what will be the space between welds, prior to installation, so that when all welding is finished the space is pressurized with air at 80 psig and the welds soap tested.

 

[ansh93]

Thank you LUDPEKAI, pennpiper.
I just strted to write at this forum. Please let me know if I miss any formality.

ansh93

 

[rumandcola]

This is not simply good practice, it is actually mandatory in all pressure piping or vessel codes to weld on both sides of a slip on flange.

 

[grandnobi]

I am neither questioning that double-welding of slip-on flanges is a good and recommended practice, nor is it my intention to encourage anybody to single-weld slip-on flanges. However, mbc2009 is wrong in stating that double-welding was a general mandatory requirement by all piping codes.

e.g. ASME B31.3 (2008) defines specific criteria for double-welding of slip-on flanges in Par. 308.2.1 and expressly permits single welding as per Par. 328.5.2:

308.2.1 Slip-On Flanges
(a) A slip-on flange shall be double-welded as shown in Fig. 328.5.2B when the service is
(1) ...
(2) ...
(3) ...
(4) ...

328.5.2 Fillet and Socket Welds.
(b) If slip-on flanges are single welded, the weld shall be at the hub.

 

[LUDPEKA1]

@ ansh93; First welcome to Eng-tips forums, it’s a great place to get information and learn. My advice when asking a question is to added as much detail as possible. To use your original question for example, if you have a specific situation that you need to install a slip-on flange include as much information about the job that you can. Such as applicable codes, type of service, design pressure, temperature ……. If you don’t have a specific application and are just asking for general information include that in your question. The more information that you can include the better your responses will be.

Lud

 

[MJCronin]

Yes, Yes, Yes....