To my knowledge only API 1104 recognizes the nick break test. One must remember it is only used for cross country transmission lines, so the acceptance criteria is pretty loosey goosey.

OK, OK, now that I have your attention, the nick break test is a quick means of assessing the soundness of the welded test coupon. Excellent for training welders so they can get immediate feed back on how they are progressing. The coupon is cut into strips with a torch, about 1 1/2 inches wide from the 2:00, 4:00, 8:00, and 10:00 O'clock positions. There is no need to grind the reinfrocement from either the face or the root. Simply cut notches about 1/16 inch deep at opposite ends of the weld (which is transverse to the length of the piece just removed from the welded nipples). Then break the sample using the notches as the initiation points for the weld failure. The objective of the test is to fracture the weld so you can examine the fractured surfaces so you can look for slag inclusions, incomplete fusion, porosity, etc.

I don't apologize for poking a little fun at the API tests, they are after all the most liberal I've ever had to work with. Consider for a moment that bend specimens for AWS, ASME, or NAVSEA TP248 is 3/8 inch thick and are is bent around a 1 1/2 inch diameter mandrel. The samples must experience at least 20% elongation without exceeding the allowable acceptance limits (no individual open defect more than 1/8 inch in length). The API criteria only requires the guided bend sample to elongate by less than 10% without exceeding the acceptance criteria of API to pass.  AWS, ASME, and NAVSEA TP248 require smaller bending diameters for thinner materials to ensure the proper elongation requirements are met. API uses the same diameter, 3 1/2 inch, for all thicknesses and strengths (of material).

As liberal as API 1104 is, it gets the job done and it is good enough for the work it is intended for. However, the engineer has to do his homework and compare the requirements of API to those of the applicable construction before accepting API certification for welding that has to meet ASME, AWS, or a military welding standards.

Best regards - Al