ASNT Level III- Visual & Optical Testing
My Level III Self Study Notes Reading 4 Section 4B
My Level III Self Study Notes Reading 4 Section 4B
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7.2.2 Removing Rust and Scale<br />
Rust and mill scale are normally removed by mechanical<br />
methods such as wire brushing or grinding. If appropriate<br />
for a particular test, the use of a severe etchant requires only<br />
the removal of loose rust and mill scale. Rust may also be<br />
removed chemically. Commercially available rust removers<br />
are generally inhibited mineral acid solutions and are not<br />
often used for test object preparation.<br />
Most surface tests require complete removal of rust and<br />
mill scale but a coarsely ground surface is often adequate<br />
preparation before etching.<br />
Grinding may be done manually or by belt, disk or surface<br />
grinding tools. Surface grinders are usually found only in<br />
machine shops. Hand grinding requires a hard flat surface<br />
to support the abrasive sheet. Coolant is needed during<br />
grinding and water is the preferred coolant but kerosene may<br />
be used if the test material is not compatible with water.<br />
Charlie Chong/ Fion Zhang
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