Pipeline Transition Piece requirement for large grade difference 1

[Hayms]

Hello,

This is more general question.

I know ASME B31.4/31.8 and CSA Z662 clearly define the requirements for a transition piece based on the WT Change between the existing pipe and the new pipe.

Is there a Canadian or US Code/Specification for Oil/Liquid system that defines the requirement for a transition piece if there is minimal WT difference, but a large grade/SMYS difference between the two pipes, Eg: Grade X56 to Grade B is a 21 KSI difference, but the WT difference is less than 1.6mm. Would a Transition piece be required here?

Thank you.

 

[LittleInch]

If the lower smys pipe is still OK at the thinner wall thickness then you don't need one.

If it isn't then you do.

But look at the code for an acceptable inner misalignment. You might be in luck.

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

 

[1503-44]

Welding is somewhat easier if there is no more than a 10ksi difference.
However it is left to qualifying your welding procedure.

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

 

[Hayms]

Hello LittleInch,

The low SMYS/Low WT pipe is passing.

Thank you for the suggestion on the inner misalignment, I will check it out.

 

[LittleInch]

Then not sure why your higher grade pipe is a thick as it is.....

I'll dig out the code section on Monday.

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

 

[r6155]

The difference less than 1.6mm is not a problem. The transition is in the weld.

Regards

 

[1503-44]

Sounds like a bad use of material. Your 56ksi pipe is too thick and you are nowhere at full pressure allowable, or your Grade B pipe blows up. Or pressure is very very low and your 56 pipe is very very much overdesigned.
What diameters and walls are you trying to join?
Pressure and design factor are?

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

 

[LittleInch]

The code example below is B31.4, but think 31.8 is the same. So an internal mismatch of <2.5mm is OK - see a) below.

But I echo Mr 44 - The advantage of higher SMYS is a thinner pipe for the same pressure and temp, but you don't have this for some reason??

Can you explain or was that just a made up example?

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