Mill tolerance for A672 Pipes 1

[Pipingclassic]

Hi,
In thickness calculation, generally we are going with mill tolerance of 12.5% for A106 Gr. B and other seamless pipe material, but since A672 made up of A516 plated so mill tolerance shall be different.
Kindly suggest what will be the exact value of mill tolerance we can consider for A672 pipe and some standard reference.

Thanks

 

[metengr]

First, you need to know the nominal thickness of the pipe. Once this is known, ASTM A 672 provides guidance for permissible variations in dimensions, including wall thickness;

11.2 Permissible variations in dimensions at any point
in a length of pipe shall not exceed the following:

11.2.1 Outside Diameter — Based on circumferential
measurement ± 0.5% of the specified outside
diameter.

11.2.2 Out-of-Roundness — Difference between
major and minor outside diameters, 1%.

11.2.3 Alignment — Using a 10-ft (3-m) straightedge
placed so that both ends are in contact with the
pipe, 1⁄8 in. (3.2 mm).

11.2.4 Thickness — The minimum wall thickness
at any point in the pipe shall not be more than 0.01 in.
(0.3 mm) under the specified nominal thickness.

 

[EdStainless]

It does not matter what the starting material is, the finished product must still meet the tolerances in the product specification (presented so nicely by Metengr).

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[TomEun]

You may have good answers from metengr and EdStainless.

Here are some more information.

In general, the thickness control of seamless pipes is more difficult than that of welded pipes (fabricated from plate materials). Therefore seamless pipes require more tolerance.

Here is a general guideline for thickness tolerance of pipes.

Mill under-tolerance of pipe thickness should be complied with the followings unless otherwise specified in the material standards.

- Pipe identified as only “seamless” or pipe indentified as duel grade, such as “seamless or welded”: 12.5%

- Pipe identified as only “welded”: 0.3 mm (0.01 inch)

Hope this helps,

Thomas Eun