GB/T 37589-2019Technical specification for anticorrosion of steel pipe and fitting lining with fluoroplastics (English PDF)

3.1 Matrix

Steel pipe and fitting before lining.

3.2 Lining thickness

Lining layer thickness of steel-plastic composite pipe.

3.3 Drawing molding

Lining process that allows a seamless gap between the lining layer and the matrix through a certain mechanical method.

3.4 Wrapping

Lining process that uses thermal expansion to make the fluoroplastic film tightly merged.

3.5 Roto-lining

Composite tight lining process that the plastic powder is the main raw material, and the multi-directional rotary hot-melt technology has a certain peel strength after multiple feedings and one-time molding.

3.6 Transfer molding

Process that melts and extrudes plastic pellets into molds and then cools and demolds. serious break in the matrix, and the specifications meet the requirements of the production record table.

5.2.1.4 Conduct annealing and stress-relieving for the matrix with conforming

The temperature is 150°C~250°C.

5.2.1.5 Heat the composite straight tube after stress relief to 150°C~300°C

(according to different materials) after flanging. Cool and mold.

5.2.2 Iso-static lining of fittings

5.2.2.1 Assemble conforming matrix and elastic mold

5.2.2.2 Inject plastic powder into the module gap. Plastic powder shall be clean and free of impurities. Then blindly put it into the pressure tank and slowly pressurize it to 15MPa~35MPa. Slowly relieve the pressure after holding pressure for 10min~30min.

5.2.2.3 Check the inner wall for cracks, impurities and other bad phenomena. If there are, it shall return to work.

5.2.2.4 Sinter the conforming matrix after molding according to the parameters in Table 5 or the sintering parameters provided by the raw material manufacturer.

5.2.2.5 Check the inner wall after sinter cooling. There shall be no cracks on the surface of the fluoroplastic, and the thickness shall meet the technical specifications or contract requirements.

5.2.3 Sheet lining of pipes and fittings

5.2.3.1 Apply conforming adhesive to the inner surface of the conforming matrix.

The thickness of the adhesive shall be tested after ventilating and drying.

Continue working only after it meets the requirements of the enterprise standard.

There must be no bad phenomena such as impurities and cracks.

5.2.6 Roto-lining of pipes and fittings

5.2.6.1 Install conforming matrix on roto-molding machine. After heating to the sintering temperature, it rotates and revolves simultaneously.

5.2.6.2 Put the screened powder into the matrix. At the same time continue to use the sintering temperature to rotate and revolute.

5.2.6.3 When the raw material is naturally and evenly attached to the matrix lining surface, then remove the heat source. Slowly cool down while rotating.

5.2.6.4 After cooling, inspect the rotomolded lining surface for cracks and impurities, and the wall thickness is uniform.

5.2.6.5 If the inspection is conforming, the sealing surface shall be conducted for plane processing to ensure the tightness.

5.2.6.6 The minimum thickness of the lining after molding shall meet the requirements of 5.4. The minimum outer diameter of the sealing surface shall meet the requirements of 5.5. The scratches and depressions of the flanging surface shall not exceed 20% of the wall thickness.

5.2.7 Coating lining of pipes and fittings

5.2.7.1 The matrix shall be preheated to evaporate water before powder coating. Preheating temperature is 150°C~300°C.

5.2.7.2 Before liquid spraying, mix the prepared compound fluoroplastic coating 30min~60min in advance evenly.

5.2.7.3 Spray to the surface of conforming matrix to reach the thickness of single mode and sinter. The thickness of powder single mode is generally 50µm~150µm. The thickness of liquid single mode is 15µm~40µm. The sintering temperature is set according to the parameters in Table 5 or according to the sintering parameters provided by the raw material manufacturer.

5.2.7.4 After the single film is sintered, check the surface for cracks and sand holes and then continue working.

5.2.7.5 Repeat 5.2.7.3 and 5.2.7.4. In the meantime, use the thickness gauge to test the thickness in multiple areas and points until the required thickness is […]