QTC and TC - API 6A

[Felisha007]

Good day all,

Can some one please explain the difference between the TC and QTC.

I know that TC is required for PSL 1 materials and PSL 2- 4, it required QTC for each heat # or batch.

Is the difference size, or heat treatment or thickness???

Regards

 

[SPDL310]

In API 6A TC = Test Coupon. QTC = Qualification Test Coupon. It would be helpful if you referenced the applicable sections and the standard which you have questions about.

 

[Felisha007]

"For material heat-treated in a continuous furnace, the QTC shall consist of a sacrificial production part or a
prolongation removed from a production part. The sacrificial production part or prolongation QTC shall qualify only
production parts having an identical size and shape. The QTC shall qualify only material and parts produced from
the same heat and heat-treat lot." API - 6A (Qualification test coupons)

"For material heat treated in a continuous furnace, the TC shall consist of a sacrificial production part or a
prolongation removed from a production part. The sacrificial production part or prolongation TC shall qualify only
production parts having identical size and shape. The TC shall qualify only material and parts produced from the
same heat and heat-treat lot." API 6A (Test Coupons)

These are both extraction from the API 6A code.

Please help me understand.

 

[SPDL310]

The difference between a TC and a QTC is the purpose that they are used for. A QTC is used to qualify a welding, heat treat etc. procedure. A TC is used to test production parts.

 

[Felisha007]

SPDL310 - Thank you for the information. It was quite helpful but my colleague told me otherwise.

Clarity -

TC is used to test the initial part prior to any welding and heat treatment ( before mass production) and QTC is used to test after the heat treatment, welding has been applied to the part - after mass production.( as I was told by a colleague)- or is it that QTC is used to qualify a procedure i.e welding, heat treatment - as my understanding of your statement above.

Thanks in advance

 

[SPDL310]

If you read the requirements in 6A for TC and QTC they are identical with respect to welding.

5.6.3.2 welding on the TC is not allowed, except for attachment-type welds.

5.7.3.2 Welding on the QTC is not allowed, except for attachment-type welds.

My understanding is that the testing and size requirements are the same for TC and QTC. A QTC would be taken to qualify a weld procedure or welder and included in a PQR or WPQ. Regardless of the terminology used the same testing can be preformed on a TC or QTC. I believe that API make the distinction so that coupons used for routine testing and procedure qualification are taken in the same manner. That being said I am not a quality or documentation expert. If the colleague that you have asked is they may very well be right. I just find it hard to believe that API would call something a qualification coupon if it was not taken in order to qualify a procedure, but to instead test post weld, when both TC and QTC forbid welding other than for attachments.

 

[Felisha007]

Thank much

 

[texag]

I should refer you both to a previous thread on this topic. There is quite a bit of misinformation and misunderstanding in this current thread.

API 6A TC vs. QTC
thread330-299646

~texag

 

[SPDL310]

I stand corrected, and would like to apologize for the incorrect information. To all future readers please disregard all my previous posts, and see the above referenced thread for an accurate discussion on the topic.

Thank you for the correction texag.