The invention provides an automatic
coating process of a
composite coating of a large-size steel
pipe, comprising the following steps of: surface purification treatment, derusting by sandblast, arc aluminum spray, electrostatic
epoxy resin
powder spraying, and the like, wherein the thickness of an
aluminum coating achieves 80-120 micrometers, and the thickness of an
epoxy resin coating achieves 160-220 micrometers. According to the method disclosed by the invention, the
composite coating combined by the
aluminum coating and the
epoxy resin coating is formed on the surface of the large-size steel
pipe by combining the arc aluminum spray with the electrostatic epoxy resin
powder spraying; the
composite coating not only retains the excellent properties of a single
coating, but also combines the characteristics of the sealing action of an arc spraying
coating and the long-term protection of a
cathode, has an anticorrosion coating having high binding power with the surface of the large-size steel
pipe, which averagely reaches 12.0 MPa, service life more than 80 years and intermediate-frequency heating step saving, has the advantages of
water resistance,
impact resistance,
weather resistance, environment friendliness, long-term protection, and the like, can achieve the purpose of long-term anticorrosion, also improves the structural appearance and is mainly used for the large-size steel pipe which has higher requirements for anticorrosion.