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ASNT Level III- Visual & Optical Testing

My Level III Self Study Notes Reading 4 Section 4B

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6.3.7 Pipeline Coatings<br />

Epoxy powders are specially formulated to enhance corrosion<br />

proof resistance of utility pipe: that is, pipe usually buried<br />

underground, where it is subject to widely varying<br />

pipeline operating conditions. Intimately bonded to the<br />

pipe, the bonded epoxy is unaffected by widely varying soil<br />

compaction, moisture penetration, fungus attack, soil acids<br />

and chemical degradation. To achieve a long lasting bond of epoxy coating to<br />

metal pipe, the pipe must be preheated very carefully to the recommended<br />

preheat of 230 °C (450 °F). A spot on the pipe needs to be touched with the<br />

stick; its melting shows that the correct temperature for coating has been<br />

reached.<br />

Charlie Chong/ Fion Zhang

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