Isobaric preparation process for polytetrafluoroethylene lining of pipeline

Abstract

The invention belongs to the technical field of pipeline linings, and discloses an isobaric preparation process for a polytetrafluoroethylene lining of a pipeline. The process comprises the followingsteps of filling polytetrafluoroethylene powder between the inner wall of the pipeline and a rubber bag soft mold, sealing, putting into an autoclave, equally increasing the water pressure in a rubberbag and the autoclave to a specific high pressure, and expanding the rubber bag to compact polytetrafluoroethylene, so that forming the uniform and compact lining on the inner wall of a steel pipe. Compared with a traditional compression molding method, the isobaric molding process has the advantages that equipment and molds used are simple, operation is convenient, and the yield is high; the pressures inside and outside the pipeline are equal in the machining process, and the steel pipe is not damaged; and the lining is uniform and compact and low in shrinkage rate due to everywhere equal high pressure. The specific technological process comprises the steps of A, steel pipe inner surface treatment, B, rubber bag soft mold loading, C, polytetrafluoroethylene powder adding, D, sealing, E,water injection and pressurization in the autoclave, F, pressure relief and part taking, G, rubber bag soft mold removal, H, sintering and I, inner filler removal.

Description

technical field [0001] The invention relates to the technical field of pipeline linings, in particular to an isobaric preparation process of pipeline polytetrafluoroethylene linings. Background technique [0002] Steel pipelines are widely used in chemical, petroleum, pharmaceutical and other related industries. In practical applications, because the pipelines transport corrosive substances, especially strong acid and strong alkali, steel pipes will be severely corroded and extremely Greatly shorten its service life. PTFE has high chemical inertness, does not react with strong corrosive media such as hydrofluoric acid, concentrated hydrochloric acid, nitric acid, concentrated sulfuric acid and boiling sodium hydroxide solution, and can work for a long time at a temperature of -60 to 260 °C , Widely used as corrosion-resistant lining material for chemical equipment and accessories. The PTFE-lined steel pipe plays an important role in the transportation of strong corrosive m...

AI Technical Summary

Problems solved by technology

The operating parameters of the winding method are difficult to control, and the products often have defects such as detachment, bubbling, and stress cracking. In actual use, the products are not resistant to negative pressure, and the interlayers are easy to crack and cause leakage.

However, in the traditional PTFE molding process, because different sizes of lining products require presses of different tonnages and complex molds, the investment cost is high and the operation is difficult.

Due to the difficulty in pressure transmission of PTFE powder, the wall thickness of molded products should not be too small. For pipe products with relatively large length and diameter, there will often be uneven tightness due to uneven pressure, resulting in product scrapping

In addition, due to the low pressure bearing strength of the carbon steel shell, the forming water pressure is controlled at 8 to 15 MPa, resulting in insufficient compression of the lining, large shrinkage, and prone to problems such as detachment and bubbling.

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