Tell tale holes --- Piping support

[1THN1]

Is it stated in code (ASME B31.3) that you will need "tell tale holes" when you peripheral weld a piping support (rolled plate) to a pipe?


Anybody with more info on this subject?


Regards,
Torgeir

 

[MisterDonut]

I believe this refers to leaving a small gap in the weld that would allow any fluid to drain out, thus "telling" if a leak is present.

 

[eliebl]

Be cautious using the term telltale hole. It is used in two places (I believe) in Section VIII-1 describing the weep hole in a pad but also to describe a hole drilled partway through the shell to serve as a corrosion indicator. I do not know of anywhere that they actually use the corrosion indicator variety.

EJL

 

[JohnBreen]

Hello Torgeirhn

B31.3, in paragraph 328.5.4(g), states in part that ".....A vent hole shall be provided at the side (not at the crotch) of any pad or saddle to reveal leakage in the weld between the branch and run and to allow venting during welding and heat treatment..."

I am not completely clear on what you mean by a "peripheral weld at a piping support (rolled plate) to a pipe". However, if you are welding a reinforcement pad (aka "doubler plate") to the OD of a pipe at a trunnion type support (welded appurtenance), for example to accommodate "punching shear" or to distribute the load over a greater area, it would seem to be unnecessary (albeit harmless) to provide a vent hole in the reinforcement plate as neither the attaching welds, the plate nor the trunnion will be pressure retaining boundaries (pressure leakage will not be possible). If you are welding a trunnion made from a pipe section to the reinforcing pad it would be good practice to provide a vent hole in the trunnion to allow venting during welding (the ASME B31 Codes for Pressure Piping are not intended to be design manuals and they do not document all "good practices").

Regards, John.