Level Spud Reinforcement Calcs 1

[loc23]

When a level transmitter spud (its thickness greater than the head or shell into which it is welded) is welded into an ASME pressure vessel, would this spud need reinforcement calculations per UG-36(c)? I question this because the spud will always be plugged or have transmitter installed, thereby becoming one unit.

 

[jte]

loc23-

Probably not. As long as the cutout in the head or shell is less than 2 3/8" you'll be exempt from reinforcement calc's per UG-36(c)(3)(a), and it would be an unusual level transmitter which would require a larger connection. The thickness of the attached nozzle doesn't enter into the reinforcement reuqirement exemption.

My definition of a spud (see, for example

http://www.wfi-intl.com/

and go to "products" and look at "flanged pipet")may vary from yours; we only use them on piping. I'd use a long weld neck nozzle for level instrument connections in vessels.

jt

 

[loc23]

This spud is similar to a "Rosemount" sanitary spud for a differential pressure transmitter. It is 5.98" od and has an o-ring seal at the inner face (vessel side). So the hole in the head is much larger than 2.375".

 

[JStephen]

It will require reinforcement calculations. It may or may not require any additional reinforcement. Suggest you contact your vessel designer or fabricator.

The fact that the hole is always filled is immaterial; the stress is not carried by the plug part but by the outer frame. The thickness of the item wouldn't exempt it from reinforcement calculations, but may make the fitting self-reinforcing, where no additional reinforcing plate is required.

You may need to radiograph, hydrotest, etc., after welding it in, as well.