A method for forming unevenness on an outer surface of a synthetic resin-coated steel pipe and an apparatus therefor.

摘要

In order to improve the bonding strength between a synthetic resin-coated steel pipe and concrete applied arround said synthetic resin-coated steel pipe for weight protection, unevenness formed of groove portions and ridge portions arranged alternately is formed on the outer surface of the synthetic resincoated steel pipe (11) by pressing the synthetic resin coating layer (11 A) with a working tool (18) having an uneven inner surface (20) under a condition where at least one member of said working tool (18) and said synthetic resin coating layer (1.1 A) is kept at a temperature at which the synthetic resin is melted.