Pipe Wall Thickness 1

[dash81]

Hi everybody,

I have read about pipe wall thickness calculation using B31.3 and I have seen that the final wall thickness considers manufacturer's tolerance (For Example, 12.5% for A106).

My question is ¿do I also have to consider this manufacturer's tolerance when I'm calculating under other B31 codes (B31.4, B31.8, etc)?

Thanks a lot.

 

[BigInch]

The wall thickness (Barlow) equation used in B31.4 and B31.8 do not include a manufacturering tolerance term.

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[Sid7]

cmanjarres

The 31.8 considers the underthickness tolerances in the wall thickness calculation by means of Basic Design Factor.

So you DO NOT need to consider it separately in wall thickness calculation.
(refer section 841.11 ASME B31.8)
regards

Siddharth
These are my personal views/opinions and not of my employer's.

 

[CountOlaf]

In B31.1 (Power Piping, 2007) para 104.1.2, it states that...

"If pipe is ordered by its nominal wall thickness, the manufacturing tolerance on wall thickness must be taken into account. After the minimum wall thickness is calculated, this minimum thickness shall be increased by an amount sufficient to provide the manufacturing tolerance allowed in the applicable pipe specification or required by the process."

It's similar to the "c" adder (mechanical allowances) in B31.3 (Process Piping, 2006), para 304.1.1, although it doesn't describe it as explicitly in this code.

 

[dash81]

Thanks a lot for your valuable comments...

 

[jte]

As for B31.4, 402.3.1 states that ...In setting design factor, due consideration has been given to and allowance has been made for the underthickness tolerance... provided for in the specifications approved by the Code."

jt

 

[greg211]

Hi everyone,i am having problem calculating for the wall thickness of a stainless steel pipe of a thick wall pipe (d/t<20) for a subsea application, a subsea manifold to be precise. Please can anyone furnish me with procedure to calculate it?

 

[JohnBreen]

greg211

Please start a new thread for your question

JB