Pipeline corrosion protection measures

At present, domestic and international long- distance pipelines for corrosion-resistant coatings are mainly coal tar enamel, two layer structure of PE, three-layer structure of PE, FBE (FBE), double-layer fusion bonded epoxy powder ( FBE layer ) covering layer.

Coal tar enamel with good insulation properties, low water absorption, corrosion-resistant bacteria and plant roots penetrate the material adequacy and long service life and low price. The main disadvantage is lower mechanical strength, suitable temperature range is narrow, low and easy brittle, production and construction process may escape of toxic gases, requires strict smog measures. Used abroad for more than 70 years of history, in recent years due to environmental restrictions gradually replaced by other coatings. 2 layer PE structure has good insulation properties, low water absorption, high mechanical strength, tough wear-resistant, acid salts and bacteria, corrosion resistance, temperature changes, sufficient material advantages, the price is lower. Drawback is poor resistance to ultraviolet radiation, exposure to sunlight for too long and easy to aging, poor adhesion with steel surface, anti- cathodic stripping poor performance. PE layer electrostatic shielding effect is not conducive impressed current cathodic protection. 3-layer PE anti-corrosion layer structure combines a high-density polyethylene coating, FBE advantages. It is an epoxy powder and firmly with the pipe surface, the use of high density polyethylene resistant to mechanical damage, a special layer between the two layers so that the three molecules bond to form a composite structure, to achieve corrosion properties, good combination of mechanical properties, is currently the leading pipeline engineering preferred coating. FBE (FBE) has a steel surface with a solid, good insulation properties, high mechanical strength, resistance to temperature changes, resistance to chemical corrosion, etc., suitable for a variety of harsh natural environment. The main disadvantage is poor resistance to ultraviolet radiation, since the covering layer is thin, scratch and bump performance is poor. Abroad from the 1960s began to be used pipeline corrosion, has developed rapidly and is currently used on the international pipeline corrosion largest amount of overburden. FBE layer ( layer FBE) and 3-layer PE structure is similar, with good overall performance, high mechanical properties. FJC also with double FBE, good compatibility, cladding surface smooth. In addition, the cathode shielding problems can be avoided with the cathodic protection system matching better than the three-layer structure of PE. It is internationally developed a new kind of coating, the most suitable for use across the mountain section and the stonework.