ASME B31.3. Welding a weldolet on a reducer?

[Tarkjell]

Can anyone tell me what options I have as a piping stress engineer when it comes to evaluating a pipe designers decision to weld o'lets to fittings such as reducers, tee's and elbows?

I have seen many designs where a weldolet is fitted to an elbow or tee, and I wonder how this is documented.

And now I am challenged to verify a 3" weldolet attached to a 14"x12" eccentric reducer. The o'let will go on the side of the reducer.

Can I treat it as welded to a straight piece of pipe with average reducer diameter and thickness?

Regards
Tarkjell

 

[pennpiper]

A little more information please.
After the Weld-O-Let is this:
a non-continuation branch (a Vent, a drain or PI connection)?
Or
a continuation branch?
What is the Wall schedule?
What is the Pressure and Temperature?

For your information, A reducer is:
1) a short piece of pipe which changes diameter
and
2) a short piece of pipe which has a wall thickness that is thicker than the normal straight pipe

 

[Tarkjell]

Thanks for responding,pennpiper.

The branch is a continuation branch bypassing a valve.
Two 3" o'lets are involved. Upstream the valve the WOL is welded to a straight pipe. Downstream it is to be welded to an ASME B16.9 14"x12" sch 40 carbon steel eccentric reducer. The pressure is 51.1 barg, temperature 121/250 °C/°F

Regards
Tarkjell

 

[C2it]

I've ofter seen a welolet on the bottom of a BF ecc red., usually a drain either side of a control valve or similar,. but on the side ....

You could make an estimate of the strength by using the correct thickness and average diameter of the reducer at the centre line of the weldolet, using ASME B31.3 rules for pressure reinforcement for example .... But you will end up with a horrible weld gap I suspect. SIF's would be questionable too.

Better to move it to an adjacent straight ??

 

[Tarkjell]

Thank you C2it

Surely it would be better to move it. Usually that is what I make the piping designers do. However, ever so often I come across designs where an o'let is connected to fittings.
In the reducer case I'm investigating whether bonney forge will be able to deliver a suitable o'let to avoid the 'horrible weld gap' you mentioned.

I would like to know what B31.3 demands. I suspect I'm required to qualify any B16.9 fitting by paragraph 304.7.2 when it is modified to suit a specific design.

What are your opinions?

 

[C2it]

Tarkjell,

I was really thinking that you should apply B31.3 304.3.2 to your connection. You would need to make some approximations on the geometry to reasonably represent the reinforcement area you have.

Another option ... Have you thought about a small FE model ? FE-Pipe would be ideal for this.

 

[4Pipes]

Not disagreeing with the comments above and in the absence of anything better I would compare it with something that is similiar or clearly more onerous. e.g. A elbolet or a duck foot. I believe the Codes allow judgement. It just means that it is you who will be held responsible. Then again, if I only had 2 locations to locate my chair, I'd rather sit on your weldolet / flat side ecc red than an elbolet.