SPECTROSCOPY (Field Chemical Analysis)

This nondestructive testing method identifies metal alloys in-situ. A portable optical emission spectrometer (also known as a field chemical analyzer or spark tester) accurately determines the elemental composition of the material. In addition to the elements identified with an X-Ray Fluorescence analyzer, spark-testing units can identify carbon, sulphur, and phosphorus.

Traditional chemical digestion tests are accurate, but require the removal and shipping of samples to a laboratory and receiving results within 3-5 days. In contrast, spark-testing units are portable and provide results instantaneously without removing samples. The examinations can be performed on carbon steels, stainless steels, and nickel-based alloys.

Limitations include:

• The surface of the component is tested, if there are any metallurgical features such as decarburization, the test will be inaccurate.



• A model of the material to be tested must be available; currently only iron base and nickel base alloys can be tested.

Spectroscopy is commonly performed on welds and weld overlays, welding qualification coupons, castings and forgings, valves and their components, pipe and fittings, machined parts, plate material, and structural steel. The surface of the part to be tested must be accessible and clean. Spectroscopy can be performed on components requiring certification to NACE MR0175/ISO 15156. Most spectrometers test parts with surface temperatures ranging between -5°F and 125°F. However, some spectrometers can test parts at temperatures as high as 800°F.

Test results are summarized in an inspection report. For NACE MR0175/ISO 15156 inspections the subject of the examination is die stamped with an IRISNDT identification number.