Weep Holes in Vacuum Rings

[loc23]

I am using channel rolled with legs in as external stiffeners due to vacuum on a horizontal vessel. Is it permissible under ASME Sect. VIII to drill 1/8" dia. weep holes at the low point for leak detection?

 

[JoeTank]

I see no problem with what you propose. It is not directly addressed an ASME VIII. I would make an additional check on the section properties with the hole.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[jte]

As usual, I agree with Steve. There is no prohibition for drilling the bottom flange of a channel rolled the easy way with the flanges welded to the shell. Just make sure the adjusted moment of inertia with the hole subtracted out is adequate.

Another approach would be to continuously weld the top (keep out any rain) and have intermittent welds on the bottom leg to shell weld. That would give you the same effect as the weep holes.

Presumably there is a good reason to use a channel in its weak axis instead of its strong axis. Normally I'd expect to see the channel rolled the hard way with legs pointing down and one flange welded to the shell kind of like Fig. UG-30(d).

jt