manufacturing defects in 316L stainless steel pipe

[eamonn2020]

Hi,
has anyone come across this inside New 316L stainless steel pipe?

 

[MJCronin]

Could we get a little more information ?

Are we looking at seamless or ERW welded pipe ?... What is the outside diameter/wall thickness ? .... What is the pipe design specification ?

Do you have multiple pipe lengths (or fittings) with the same defect in the same lot, or is this a single defect ?

Where in China is the manufacturing plant located ?

Are we looking at the end of a fitting or is this picture of a long straight section of pipe ?

How far do the defects extend ? Is the wall thickness thinner in the area of the defect ?

Can you supply some dimensions or place a scale against the defective pipe and take additional picture ?

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My guess: .... This is mill fabrication error - a weld mismatch in ERW HF "seamed" piping .... Possibly sold to you as "seamless" ???

More information = better answers

MJCronin
Sr. Process Engineer

 

[eamonn2020]

4" schedule 40S ASME SA312 ASME SA376 114.3x6.02mm
Seamless pipe. Straight section. Your looking at open end of straight section. Defects are uniform and 500mm in length.
It's a manufacturing defect if sorts not related to welding of any kind.

 

[EdStainless]

This looks to be cold finished pipe, or is it hot finished?
If the wall in those places is still over 5.27mm then there is nothing wrong with this pipe.
It is only pipe.

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P.E. Metallurgy, consulting work welcomed

 

[weldstan]

As Ed says, if it meets the min wall at the ID surface flaws, it is acceptable. It's obviously a forming flaw but not necessariy a defect.

 

[eamonn2020]

Wall thickness is 3.7mm at worst area.we know its outside spec. Was looking for info as to possible causes?

 

[EdStainless]

Do you know who made it?
Do you know how it was made? (extruded or pierced)
Was it cold finished? If so then how? (drawn or pilger)
You need to know what processes were involved in order to start chasing causes.

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P.E. Metallurgy, consulting work welcomed

 

[mk3223]

May contact the pipe vendor to confirm as these marks might be resulted from the manufacturing defect in the shop because of the damaged tool.
Just wondered if your process service may require the pipe internal with a smooth surface.

 

[weldstan]

Since it does't meet the spec requirents, send it back to the supplier for replacement.

 

[LittleInch]

Never seen anything like that before.

Not quite sure how it got through any form of QA / QC though.....

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

 

[MJCronin]

Piping Specification ASTM A376 contains specific and clearly defined requirements for "Workmanship, Finish and Appearance" in Section 10 of the standard.

The deep internal gouges clearly disqualify your section of dog excrement from meeting the requirements of Section 10.

ASTM A376 also enables the purchaser to impose additional quality requirements on piping AS PART OF THE STANDARD ....

Clearly, there are no QA/QC requirements in your organization ...

A few modest questions (that you will probably ignore)

1) What is the country of origin of this pipe segment ?

2) Who manufactured this pipe ?

3) What markings are on the exterior of the piping ? .... Was the pipe clearly marked ASTM A376 or some other standard ?

Can you supply any additional pictures and have you found pipe fittings with the same serious defect ?

MJCronin
Sr. Process Engineer

 

[moltenmetal]

I've seen some very ugly bore on seamless pipe especially of heavy wall thickness. But I've never seen a defect which put the wall thickness under tolerance. Not yet at least. And in that time I've seen one (1) through-wall defect in welded seam pipe as well. I've seen lots of weld defect "indications" on radiographs of heavy wall welded seam pipe though.