Carbon steel pipe foaming technology is a mixture of polyurethane black and white materials in proportion, which undergoes chemical expansion and is filled between the steel pipe and the outer protective tube of polyurethane foam insulation pipe. The one-step foaming process is currently widely used. The one-step foaming process involves adding polyether or polyester polyols (white material) and polyisocyanates (black material), water, catalysts, surface active agents, foam adhesives, other additives, and other raw materials together. After mixing at high speed, foaming is carried out.

Technical standards: 1. Regulations for 20 # carbon steel pipes: 20 # carbon steel pipes should comply with standard regulations, such as GB/T9711.1, GB/T9711.2, GB/T8163, etc. Before foaming, the surface of the 20 # carbon steel pipe should be cleaned to remove pollutants such as rust, grease, and moisture. 2. Insulation layer: It should comply with the requirements of GB/T29047 for 20 # carbon steel pipes, and the thickness of the insulation layer should not be less than 60kg/m3. The outer protective pipe of 20 # carbon steel pipes should ensure normal operation in an environment of -50 ℃ to+50 ℃. When polyurethane foam insulation pipes are injected into foam forming, the reaction liquid stays in the mixing room for a short time, usually only a few seconds or tens of seconds. During and after the construction period, various parameters of soil corrosiveness and cathodic protection will be measured to confirm cathodic protection