Lean tube, also known as composite pipe, or flexible pipe, is a welded steel pipe with PE coating after surface treatment of a high-quality steel pipe. The outer surface is made of a plastic layer of PE and inner surface is coated with rust resistance. The diameter of standard lean tube is 28mm. The plastic thickness is 1.2mm. The pipe racking system is the modular system for lean tube and lean pipe connector, which can transfer the thought into actual structure with individuality. The manufacture is simple and fast with low cost.