HCMP produced by continuous helically winding of corrosion-protected steel sheets from 300 to 3,600 mm dia.
A lock-seam formed on the pipe circumference during shaping both contributes to stiffness and acts as an integrating coupler.
WProtect type coating for extra protection
Polymer coating of galvanized steel, also called «Wprotect», is a technology discovered, patented, and employed the US since 1974 and in Europe since the late 1990s.
Application of 300 um HDPE film onto the preheated galvanized steel surface creates a uniform coating across the sheet surface.
The coating is applied onto both sheet faces. Such a coating is the best barrier against natural zinc and steel corrosion, mechanical impacts and chemical attacks.
If design engineering foresees such a protection, 100-year service life is guaranteed virtually in any environment.
Due to its insulating properties, the polymer coating provides 86.6 kV/mm electrical endurance. For bilateral 300 um coating it means 21.6 kV electrical endurance.
This value exceeds earth currents observed in electric railway embankments by far.
The polymer coating ensures total protection of corrugated helically steel pipes from corrosive effects of earth currents.
Additional polymeric coating WProtect 800 train (HDPE) withstands almost all corrosive substances such as acids, alkalis and salts commonly found today in storm sewers and underground culverts.
The coating is able to withstand sand clay and gravel impact without detriment of adhesion to metal, and provides abrasion resistance equal to over 50 ml bitumen layer.
WProtect 800 train (HDPE) bonds with a galvanized pipe both chemically and physically providing an excellent long-term resistance to mechanical and electrical corrosion and abrasion.
Specimens of corrugated steel sheets coated with WProtect 800 train (HDPE film) have been put through microscopic and IR-microspectrometrical lab testing after 22 years of service.
The specimens have been studied for cracks with an optical microscope.
All specimens have shown good physical condition. No evidence of chemical degradation or cracking has been found.
Service life of HCMP with extra polymer coating is expected to be long. Such coated pipes will serve at least 100 years.