Spiral steel pipe and steel coil pipe are both welded steel pipes, and the production process of the two is very different. Spiral steel pipe is a spiral seam steel pipe made of strip steel coil as raw material, extruded at regular temperature, and welded by automatic double-wire double-sided submerged arc welding process. The length of the spiral steel pipe is 12 meters, and the delivery is settled by measuring the ruler, and the specification is basically above 219mm. The steel plate coil adopts the T-welding process, which can produce steel pipes with a diameter of more than 400 and a wall thickness of 8-100mm. Usually not cut to length, the delivery is generally weighed. The implementation standards of steel coil products are GBT50205-2001, GBT3092-2001, etc. Coiled pipes are widely used in petroleum, chemical, natural gas transmission, piling and urban water supply, heat supply, gas supply, and other projects.
The price of steel coiled pipes of the same type is higher than that of spiral steel pipes. Steel coiled pipes are mainly used in non-model or thicker industries. There is no limit to the service life of the spiral steel pipe itself, and the service life is mainly related to the operating environment and production process. To prolong the service life of the spiral steel pipe with a poor operating environment, the outer wall and inner diameter of the steel pipe are anti-corrosion. Anti-corrosion spiral steel pipe refers to steel pipes that have been processed by anti-corrosion technology, which can effectively prevent or slow down the corrosion phenomenon caused by chemical or electrochemical reactions during transportation and use. The anti-corrosion spiral steel pipe can effectively prevent or slow down corrosion, prolong the service life of the steel pipe, and reduce the operating cost of the steel pipe.
The anti-corrosion coatings of steel pipelines that are widely used in China include petroleum asphalt, PE jacket and PE foam jacket, epoxy coal tar pitch, coal tar enamel paint, epoxy powder and three-layer composite structure, epoxy coal tar pitch cold wrap tape (PF type), rubber-plastic epoxy coal tar pitch cold-wound tape (RPC type), etc. Currently, the most widely used pipeline anti-corrosion methods are three-layer PE composite structure, single-layer powder epoxy, PF-type cold-wrapped tape, and RPC-type cold-wrapped tape. Tape.
1. Petroleum asphalt has a wide range of raw materials and low prices. But the working conditions are poor, the quality is difficult to guarantee, and the environmental pollution is serious.
2. Epoxy coal tar pitch is easy to operate, but the covering layer takes a long time to cure and is greatly affected by the environment. It is not suitable for fieldwork, and it is difficult to construct at temperatures below 10°C.
3. Epoxy powder anti-corrosion, using electrostatic spraying method, good fusion with the anti-corrosion pipe body of the same material, strong adhesion, but epoxy powder water resistance is poor (high water absorption rate, up to 0.83%), to the cathode Protection design poses certain difficulties. The on-site equipment has high requirements, the operation is difficult, and the quality is not easy to control.
4. 3PE heat-shrinkable material, strong anti-corrosion and sealing of pipelines, high mechanical strength, strong waterproof, stable quality, convenient construction, good applicability, and no pollution to the environment. PE has a low water absorption rate (less than 0.01%), high epoxy strength, low water absorption of PE and good softness of hot melt adhesive, etc., and has high anti-corrosion reliability. The disadvantage is: compared with the cost of other filling materials, costly.
5. The construction of PF-type and RPC-type cold wrapping tape is simple and easy, and the matching three kinds of setting glue make the PF-type epoxy coal tar pitch cold wrapping tape suitable for construction under any environment, any season, and any temperature condition.
6. The characteristics of cold wrapping tape and 3PE heat shrinkable tape are: it is suitable for the main anti-corrosion layer pipes of various materials, while other methods are suitable for the main body anti-corrosion layer pipes of the same or similar materials.
Secondly, with the development, some pipelines also need insulation during anticorrosion. Petroleum is a very complex mixture, and it is easy to corrode pipelines. Anticorrosion is necessary, but product oil pipelines also need insulation under anti-corrosion. Thermal expansion and contraction will freeze and crack pipes, affecting stable supply.