Weldolet Vs Sweepolet 1

[Turbonorman]

Hello everyone,

I hope someone can help me. I have been given a design for a Pig Trap and for flushing purposes there is a weldolet off the main pipe.

I have a couple of questions regarding the use of a weldolet:
1. Are there any advantages of using a weldolet compared to a sweepolet?
2. Are there any situations when one (weldolet or sweepolet) would be preferential?
3. Any fabrication/operating issues with either?
4. Any other methods of introducing a flushing branch on to the main pipe?


I really appreciate any help and look forward to responses.

Many Thanks

TurboNorman

 

[XL83NL]

Not knowing the line size makes it difficult to give an exact answer, as the line size will have influence on whats preferential.
Anyway, here's my POV.

Weldolets (aka WOL) are cheaper in terms of purchasing cost than sweepolets (aka SOL).
WOLs may, in some situations (large dia, thin wall) warp the pipe, i.e. unstraight and oval, due to excessive heat input arising form the relative thick required weld metal layer.
Since for WOLs the weld metal thickness is always greater than for SOLs (where one only welds the base metal wall thickness), welding may require some extra time to allow cooling off on the heat input to prevent banana-warping the pipe.
SOLs are less standard, I think most of the time custom made. Without having specific experience with SOLs, preparing and beveling the pipe for it may be more difficult/time-costuming compared to WOLs. For WOLs, you can weld them on, and then bore through the hole. This gives a smooth weld profile on the inside. This may give the best option for a flushing branch, as there is not weld metal 'sticking into the run' (provided the pipe doesnt become oval, as this will cause the pig trap to become stuck perhaps).
Since the saddle form is quite specific (but then again, the SOL may be laid down on the pipe, and the contour can be drawn), and a lot bigger than WOLs, more material has to be removed.
If you use a SOL and the run pipe is large enough in dia, you may counter grind the root weld to become flush.
WOLs can be RT-ed, SOLs can.
WOLs are likely to give more peak stress than SOLs, since the latter has a much more continuous profile into the branch.

Hope this helps,
regards

 

[LittleInch]

I agree with XL83NL.
In answer to your questions
1) WOL are cheaper and more commonplace to fabricate and now the patent has expired, can be purchased from a number of different suppliers in many materials
2) If you have high loads, vibrations or other forces on the branch or a thin wall pipe and your fitting size is > 50% of the run pipe, sweepolets may help. AFAIK, sweepolets are a custom fitting supplied by Bonney Forge and as they form part of the pipe need to be specifically manufactured to the same OD, wt and material grade as the pipe, hence are not available "off the shelf".
3) Fabrication is realtively straight forward for both, operation identical
4) There is also a "weldoflange" made by Promat, up to 2" branch size which combines a standard flange with a weldolet as a single forged item avoiding one or two small welds. You could also use a reducing tee, but I think this is quite unlikely for a pig trap.

You say you've been "given a design" - Are oyu doing some changes or just curious?

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[Turbonorman]

Hello XL83NL and LittleInch,

Many thanks for the replies, great help!
More information on the main runner pipe, it is 168.3mm OD (6"), wall thickness is 12.7mm.
Flushing pipe is 2".

It is more curiosity than anything, for my own benefit. First time I have come across using WOLS and SOLS in a design.

Thanks

 

[XL83NL]

The "weldoflange" LittleInch refers is another option.
However, from my experience I know these are very expensive. On a recent Shell job we purchased 1" or 1.1/2" of these weldoflanges. I called them flangolets (BonneyForge's trademark name).
They costed around 700 euros a piece, which is by far more than one would buy a flange+pipe+WOL and weld those together.
Nipolets could be another solution to reduce one weld (the weld connection the WOL to the adjacent pipe/fitting).