Lean pipe, also known as composite pipe or flexible pipe, is a welded steel pipe with a plastic resin coating after surface treatment. It consists of a thermally bonded plastic layer on the outer surface and an anti-corrosion layer on the inner surface. Adhesive is used between the coating and the steel pipe to prevent separation.

Finished products feature an attractive appearance, wear resistance, bright color and rust prevention, making them an ideal alternative to stainless steel products. The standard diameter of lean pipe is 28mm. The plastic layer is made of PE or PVC, with standard steel wall thicknesses of 0.8mm, 1.0mm and 1.2mm. Customized lean pipes with thicknesses of 1.5mm and 2mm are also available.

Common colors include beige, white, black and red. Custom finishes can be provided to meet different requirements.