Joint coating method

The invention discloses a joint coating method. The method comprises the steps that: firstly, surface treatment is carried out; secondly, preheating is carried out on a steel pipe; thirdly, the surface is coated with a joint coating piece; fourthly, the joint coating piece is coated with a metal interior lining panel; fifthly, coating and tightly locking are carried out on a steel hoop and an electric heating device; sixthly, warming is carried out by a program; seventhly, equipment is disassembled. The metal interior lining panel is high in rust-proof capacity, and is tightly connected with the joint coating piece as a whole in an adhesive mode, so that the barrier property to visible light, ultraviolet light, water, oxygen, and vapour of a joint coating layer is greatly improved, the mechanical damage resistance to a pointed object is enhanced, and the service life of the joint coating layer is greatly prolonged. By means of the steel hoop to carry out tightly locking and pressuring, enormous pressure is exerted on the joint coating piece during the softening and bonding process, the bonding strength on the steel pipe is greatly improved, the peeling strength under 23 DEG C can reach above 250 N / cm, the peeling strength under 50 DEG C can reach above 100 N / cm, and the peeling strength under 23 DEG C and the peeling strength under 50 DEG C are twice and five times stronger than the heat shrinking sleeve (belt) joint coating respectively.