Slip on flange and butt weld fitting 7

[nabeel3]

Dear experts
Please see the attached photo. Is it allowed to weld a butt welded reducer fitting (8x12) directly into slip on flange.

 

[XL83NL]

What design code?

Im assuming B31.3 here. Allowed; yes. Good practice? Thoughts on that differ. There are various topics (this 1 for example) on the same subject, do a site or Google search next time.

Huub
- You never get what you expect, you only get what you inspect.

 

[HTURKAK]

The use of butt welded reducer fitting (8x12) directly welding into slip on flange is not acceptable. The slip on flanges are used together with straight pipe pieces..

Typical spool with reducer with slip on flanges shall have short pipes at both sides of the reducer. What is the reason for this set up? Apparently, the inside of reducer plain grinded to get a straight portion. What is the situation for 12 in side?


Either use two short pipes with dias 8 in and 12 in both sides of the reducer or choose Welding neck flange...

 

[LittleInch]

hturkak,

I agree with XL83NL - it may not be a good practice or recommended, but I suspect the OP is asking is it permitted under the piping code (assumed to be B 31.3). "Not acceptable" without a reference to a code or whether this is your opinion doesn't really add anything.

I would note that the reducer has a bevel end which isn't good for a fillet weld really.

We need to have a good cross section sketch through the joint really to see what the outside of the SO flange is being welded to.

And why is this being done? Did someone screw up the flange ordering or the dimensions so you don't have space??

Pressure and service would be good to know as well.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[HTURKAK]

Dear LittleInch , will you please show us any reference , ( any code, piping handbook , design guide, recommended practice , moreover any ISO dwg..etc..) that , butt weld reducer is welded directly to SO flanges?

I do not know your past practice , however,i do not remember , i did not see such a set-up.

 

[LittleInch]

It's a very strange arrangement for sure, but the point I'm making is that the code doesn't say it can't happen, therefore the default is that so long as its welded properly, then it is permitted.

Just because the OP wants to do something that no one ever thought of doesn't make it "not acceptable", only your personal view.

I happen to agree with you that this looks very odd and I wouldn't allow it to happen if I had any responsibility for it, but that doesn't mean it can't happen.

Please elaborate on why you believe it to be "not acceptable" and we might make some head way.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[KevinNZ]

Butt weld fittings are for butt welding. Any other weld would not meet the intent of the fitting code and require special design.

 

[nabeel3]

Dear all

Thanks for the response. The project is a sewer treatment plant. Material is Stainless steel. We are following ASME B31. 3 as a piping code. This is a compressed air line. I am working in client side. Please see attached photo.

 

[HTURKAK]

I happen to agree with you that this looks very odd and I wouldn't allow it to happen if I had any responsibility for it, but that doesn't mean it can't happen.[/b]

Please elaborate on why you believe it to be "not acceptable" and we might make some head way.]

You wouldn't allow it to happen if you had any responsibility for it, but still acceptable ?..
The picture that OP posted shows 8X12 in. reducer is concentric . The concentric reducers do not have any flat portion which may be adopted for SO flanges. Now imagine the exterior welding of reducer to SO flange at 12 in side.. The annular space between flange and reducer will be around 1/2 in. What kind of weld will suit properly for this fully offset position ?

The SO flanges are welded to pipe with fillet welds ..

 

[goutam_freelance]

If possible from layout point of view a pipe spool of 1.5D-2D length can be welded to existing pipe bend and slip on flange can be welded to pipe extension using standard welding. This way you can use the already procured elbow. But only if ------.

Engineers, think what we have done to the environment !

https://www.linkedin.com/in/goutam-das-59743b30/

 

[LittleInch]

You wouldn't allow it to happen if you had any responsibility for it, but still acceptable ?..

Correct because that would be my personal Opinion as opposed to a technical argument relating to codes and standards.

I think KevinNZ as usual has an excellent comment which is the fitting code, presumably ASME B16.9, is quite specifically in its title "...Buttwelding fittings"

Now I can't find in there any specific requirement in B16.9 that the fittings need to be buttwelded, but maybe the authors didn't think that was required when it is implicit in the title of the code.... and in it's scope (my emphasis)

"This Standard covers overall dimensions, tolerances,
ratings, testing, and markings for factory-made wrought
buttwelding fittings

Therefore the use of a slip on flange would, IMHO, mean that the fitting is now an unlisted component to B 31.3.

If however the manufacturer of the reducer were to certify that it could be attached using SO flanges, then that may be sufficient to move forward.

HOWEVER, ASME B 31.3, fig 328.2.5B clearly shows that for a slip on flange, the hub needs to be fully over the pipe end, with the end of the pipe or fitting within "the lessor of T or 6mm." This looks a LOT more than 6mm - closer to 12 or more

Nabeel3 - Why on earth is this arrangement being considered?? It is at best sub optimal and at worse would put whoever approves this in difficulty if it failed in service. Are you trying to justify this or trying to say it is not acceptable?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[hacksaw]

Nabeel3,
are the flange and reducer the same material class?

 

[nabeel3]

They are of same material class

 

[LittleInch]

But WHY are you doing this strange arrangement??

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[hacksaw]

mabelel3,

A bit puzzled as to why your flange is painted. Are you sure it is Stainless?

 

[saplanti]

In the hydraulic power industry and penstock applications we provided butt welding for the large flat flanges, however we used a weld prep on both sides to be able to ease NDT.

Ask your manufacturer how they are going to provide NDT for the connections. If they cannot, forget it. You mention that this is compressed air piping, you think about the disaster it will cause.

As said above but weld fitting needs to be welded to another but weld fitting or pipe.

 

[DekDee]

Interpretation 26-27
Subject: B31.3-2014, Interpretation of Paras. 328.5.2 Weld Fitting to SO/SW Flange
Date Issued: September 27, 2017
File: 17-2236
Question: In accordance with ASME B31.3-2014, does the Code prohibit welding a
buttwelding fitting to a slip-on or socket weld component?
Reply: No. The Code is not a design handbook. Many decisions that must be made to
produce a sound piping installation are not specified in detail within this Code.
The Code does not serve as a substitute for sound engineering judgments by the
owner and the designer.

 

[LittleInch]

Well that answers that question!

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.