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Inside and outside inspection method of plastic coated steel pipe

Now, the use of various environmental protection products has brought great help to our life. The use of environmental protection products is very beneficial to environmental protection, in line with the concept of national sustainable development. Plastic coated steel pipe is also very popular in engineering construction as environmental protection pipe products. It has various applications in our life. Plastic coated steel pipe can be used in various forms of circulating water system and fire water system. The plastic coated steel pipe has superior functions, convenient connection, strong corrosion resistance, can greatly improve the power of circulating water, and is very beneficial to production and life. Plastic coated steel pipe can also be widely used in the drainage and transportation of buildings, providing great convenience for the use of building circulating water. Plastic coated steel pipe is also used in the chemical industry, including the transportation of various chemical liquids, but also for mine ventilation pipes. Plastic coated steel pipe is based on steel pipe, coated with high adhesion, impact resistance, anti-corrosion and weather resistant thermosetting flame-retardant powder coating, and applied with sand blasting pretreatment, preheating, internal coating, external coating, curing, post-treatment and other technologies to extinguish the fire. It is an upgraded high cost performance product of traditional steel pipe and galvanized steel pipe. Through coating and anti-corrosion of steel pipe or galvanized pipe, the corrosion and scaling problems of ordinary steel pipe in the process of buried and water transportation are solved. The phenomenon of pipe blockage and spray blockage is eliminated, and the service life of the pipeline is increased, and the service life is more than 50 years. The epoxy resin powder was modified by adding flame retardant to the powder coating of inner and outer coating steel pipe. The coating has good high temperature resistance and will not burn or soften in long-term use. In the traditional manufacturing method of inside and outside plastic coated steel pipe, the first step is to sand blast the steel pipe, which has a lot of pollution and complex technology. The indoor temperature inner and outer coating (elastomer) pipes adopt advanced metal anti-corrosion technology, and the bottom adopts anti rust and anti-corrosion coating. Antirust coating needs to meet special performance requirements: antirust and anticorrosion, strong adhesion, non-toxic, spraying, good anticorrosion performance, etc. In addition, the traditional internal and external plastic coated steel pipes are fired at high temperature and sprayed with electrostatic powder to achieve good adhesion between the coating and the inner wall of the steel pipes. Thickness measurement of plastic coated steel pipe Take two sections of different length from both ends of the coated steel pipe, and use electromagnetic thickness gauge to measure the coating thickness of any four straight points on the circumference of each section. The test results shall meet the requirements of 5.4. Pinhole test of plastic coated steel pipe The length of pipe section test piece is about 1000mm. Check the coating of steel pipe with electric spark leak detector under the specified test voltage. The coating thickness shall not be greater than 0.4mm, the test voltage shall be 1500V, the coating thickness shall be greater than 0.4mm, and the test voltage shall be 2000V. Check whether there is electric spark. The test results shall meet the requirements of 5.5. Adhesion test of plastic coated steel pipe According to 7.4.2 of CJ / T 120-2008, the test results shall meet the requirements of 5.6. The coated steel pipe with DN ≤ 50mm shall be subject to bending test. The length of pipe section test piece is (1200 ± 100) mm. At the temperature of (20 ± 5) ℃, the bending angle is 30o, and the radius of curvature is 8 times of the nominal diameter of steel pipe. During bending test, there is no filler in the pipe, and the weld is located on one side of the main bending surface. After the test, cut the test piece from the middle of the arc and check the inner coating. The test results shall meet the requirements of 5.7. Flattening test of plastic coated steel pipe DN >; 50mm coated steel pipe flattening test. The length of pipe section test piece is (50 ± 10) mm. At a temperature of (20 ± 5) ℃, place the test piece between two plates and gradually compress it to four fifths of the outer diameter of the test piece on the pressure tester. When the coated steel pipe is flattened, the weld seam is perpendicular to the direction of force application. After the test, check the inner coating, and the test results shall meet the requirements of 5.8.