API 5L Grade X52 to ASTM 105 Flange compatibility

[Manisch]

Dear experts,

A situation regarding the subject matter has emerged within a project, I am working on.

As proposed by the contractor, an API 5L Grade X52 pipe( 18", Sch 40) needs to be reviewed regarding it's compatibility with the ASTM 105 Flange (instead of ASTM A694 F60 Flange.

The discussion was open sometimes back in a thread, that's closed now.
Link

Having gone through the discussion I understand, it can be accepted and there's no issue with the compatibility.
At the same time I will appreciate, if experts can help with a code reference to the formula;
'S1 x t1 = S2 x t2, where, S1, t1 is the SMYS and the minimum thickness at the welding hub of the flange and S2 and t2 are the SMYS and nominal wall thickness of the pipe end, provided that S2/S1 ratio do not exceed 4."

Best regards,

Manisch Kumar
Piping Engineer.

 

[LittleInch]

The thickness is simply that calculated according to whichever design code you are using using the SMYS of the flange material - A105 looks to be about 36Kpsi.

The ratio I've never seen before and wonder if its been misquoted. The maximum angle of the weld taper is often quoted as 1:4. Again you need to look at the design coed this is being built to.

Why can't you just get an F60 flange?

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

 

[Manisch]

your response is appreciated, LittleInch.

F60 can't be procured as its not easily available in market, this being a shutdown activity, the lead time for F60 is also very high.
Given the situation, I find it difficult to convince the Client. Here I am looking for some solid technical justification with reference to code, design code is ASME B 31.8.

Thanks

 

[1503-44]

The issue is not the Flange thickness. The issue is the wall thickness of the neck. A105 Is 36 ksi material, so it will need 52/36 x the wall thickness of the X52 material. When the Flange neck is bored out, you will remove most of that material and the flange will become overstressed in the bored region, 52/36 ratio, = 44% over stress allowable. A105 can be welded to X52, but becomes more difficult at X60-X70 levels.

I suggest you install a thick walled X52 pup, wall thickness equal to Flange neck, then bore one end of that pup to match the main pipe's wall.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[weldstan]

These disimilar thickness welds are performed quite often for the reasons given by the OP. I have specified the method proposed by 1503-44 above to make things easier for client and fabricator to accept in the past.

 

[LittleInch]

The min thickness of the flange where it welds to the is the same as any piece of pipe using the SMYS of the flange material - see section 841.1

Figure I-5 as below is the code reference for how to weld different thicknesses. For flanges the ID of the flange should be the ID of the pipe.

This might be where the 4:1 ratio appears?
Also note the 0.5t max difference. X52 to A105 is about the max difference in stress you're going to find acceptable.

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

 

[1503-44]

That's the only place I've ever seen the 1to 4 ratio, not that ever needed to search for any other reference.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[Manisch]

all above clarifications & suggestions are very helpful, I am now compiling my writeup to present it to the client.

Having gone through the MSS-SP-44 Cl. 5.3 Hub Design & 5.4 Welding End, its clear to have same pipe & the flange IDs.
Here in case, Figure 2'Bevel Detail for Wall Thickness(T),22mm (0.88in.)or Less' is the fit-up guidance we are going to adopt.

Thanks

Manisch

 

[Krausen]

Why not just order a F52 SCH40 bore flange?

 

[1503-44]

Long lead item.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[Krausen]

In my experience, F-52 flanges under MSS-SP44 are readily available & typically dual cert F42/F52. Due to this flange size being 18" though, that may not be the case, as this is not a very common size. Typically you jump from 16" to 20". Things have gotten a little crazy lately in the supply chain around world lately, but I haven't experienced that much disruption in the carbon steel flange market.

 

[1503-44]

OP stated that is the issue.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[saplanti]

OP mentioned F60 flange supply not F52 flanges. Assuming supply is problem for both, I would suggest a F52 transition piece between A105 flange and X52 pipe which satisfies the wall thickness requirement on both sides if this is required for one connection only. Please note that this application will reduce the inner diameter on the transition piece and A105 flange. In case the flange connection is on bend or rise it will be a weaker point.

If many flanges are required I would ask F52 flanges as minimum.

 

[1503-44]

You mean like this? "24 Oct 22 14:33
I suggest you install a thick walled X52 pup, wall thickness equal to Flange neck, then bore one end of that pup to match the main pipe's wall."


Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[saplanti]

Yes, I see that. But I had to warn OP with consequences.

 

[Krausen]

F-52s are typically not long lead time items. Check the code you're under for allowable wall thickness differences at buttwelds. A transition pup may not even be necessary.

 

[KevinNZ]

I think we have missed the point where you can calculate the require thickness of the A105 material and if this less that the thickness of the pipe then you can weld the A105 flange in.

eg if the X52 pipe is XS (12.7mm), The required wall thickness, at design pressure, of the A105 flange end 11.5mm then you can weld XS pipe to XS flange.

One condition, the stress analysis will need to redone with the lower strength material at the pipe to flange weld.

If the A105 flange end needs to be thicker than the pipe then an inside tapper does not work, you need a thick A52 pup, as above.

 

[LittleInch]

So long as the thickness of the flange is not more than 50% thicker than the pipe thickness then you can make up the difference in the weld on the outside.

See the diagram I posted above.

It's much better to maintain a constant ID, especially in pipelines.



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