Nick-Break Test

Date 05-29-2003 04:34

API STANDARD 1104 NINETEENTH EDITION, SEPTEMBER 1999 paragraph 5.6.3.1 establishes: "...Nick-break specimens prepared in this manner from welds made with certain automatic and semiautomatic processes may fail through the pipe instead of the weld..."

Some nick-break specimens tested (prepared from welds made with a manual process -SMAW-) broken in the fusion zone or in the weld/fusion zone, should the specimens be considered as proper tested specimens? API STD 1104 does not clarify if the fail shall be located through of the welds, along the notches of the specimens.

The exposed surface of the specimens meet the requirements of the standard. May above tests be considered as a success testing?

I will be grateful for any opinion.

H. Garcia.

By chall

Date 05-29-2003 12:54

Mr Garcia,

Pipeline owner/operators are very particular about how API 1104 is interpreted. Any perceived deviation from the requirements will cause them to quickly lose confidence in your performance.

This is how I would approach your situation:

1) Assuming the tensile testing produced acceptable results, I would attempt to cut more straps from the remaining test material. I would notch them slightly deeper and redo the nicks. I mentioned tensile testing because perhaps you are dealing with material that does not meet the minimum strength requirements (and that is where the true problem is).

2) I think 1104 is clear in that they are expecting the weld to be inspected for impurities. A break outside the weld area does not fulfill that expectation. The only option is to perform another test.

Charles Hall

By iesca

Date 05-29-2003 19:48

Mr. Hall,

The tensile testing produced acceptable results; were tested 4 specimens. I am going to redo the nicks.

Thank you very much.

H. Garcia.

By JTMcC

Date 05-29-2003 20:23

Mr. Hall really nailed this one, the whole point of a nick test is to visually check the weld metal, that's why you cut the nicks. If you can't look, you haven't done a proper nick test. Every time I have seen this happen, the inspector required more straps be cut.

JTMcC.

By iesca

Date 05-30-2003 21:30

Thank you JTMcC,

Your comment clarify me the subject. More straps were cut and the nick break tests were done again; the testing results were O. K.

H. Garcia.