The invention relates to a
polyethylene coated steel
pipe and on-line method and apparatus for preparing same. Steel
pipe is employed as base material for
polyethylene coated steel
pipe, and the outer surface of the steel pipe is coated with jointless annular
polyethylene gummed tape. Production facilities of the pipe includes steel pipe shot-blast
rust cleaning
machine comprised of a rotating cylinder bracket, a rotating cylinder, a feeding wheel, a support wheel, a feeding worm wheel speed
reducer, a feeding
direct current dynamo, a high-frequency
induction heating coil, a driving worm wheel speed
reducer, a driving
AC motor and a
electrical control cabinet, and a steel pipe outer anticorrosion
coating machine comprised of a
induction heating transformer, a walking frame, a swing frame, a rotating frame, a winding device, a supporting frame, a low-
voltage electrical casing and a controller. In pipeline installation locale, the steel pipes are welded into pipelines after derusted by the steel pipe shot-blast
rust cleaning
machine, the steel pipe outer anticorrosion
coating machine is nested on the pipeline and carries out
helical motion, after high-frequency
induction heating on the steel pipe, the spray head injects the
epoxy powder on outer surface of the steel pipe, after high-frequency induction heating of the belt-winding cylinder,
adhesive tape and polyethylene gummed tape pulled out from the winding device become hot tapes, by
helical motion of the steel pipe outer anticorrosion
coating machine along pipeline centre-line, the
adhesive tape and polyethylene gummed tape are coated on the outer surface of the steel pipes.