阅读说明：本技术 一种管道聚四氟乙烯内衬等压制备工艺 (Pipeline polytetrafluoroethylene lining isobaric preparation process ) 是由 万德春 杨云旺 于 2020-10-23 设计创作，主要内容包括：本发明属于管道内衬技术领域,公开了一种管道聚四氟乙烯内衬等压制备工艺,在管道内壁和橡胶袋软模之间填充聚四氟乙烯粉并密封后置于高压釜内,将橡胶袋和高压釜中的水压同等加大至特定高压,橡胶袋扩张把聚四氟乙烯压实,从而在钢管内壁形成均匀紧密的内衬。与传统的模压成型法相比,该等压成型工艺所用设备和模具简单,操作方便,且收率高；加工过程中管道内外所受压力相等,不对钢管造成破坏；各处相等的高压致使衬里均匀密实,收缩率低。具体工艺流程包括：A、钢管内表面处理,B、装入橡胶袋软模,C、加聚四氟乙烯粉料,D、密封,E、置于高压釜内注水加压,F、卸压取件,G、脱除橡胶袋软模,H、烧结,I、去内充。(The invention belongs to the technical field of pipeline linings, and discloses an isobaric preparation process of a pipeline polytetrafluoroethylene lining. Compared with the traditional compression molding method, the equal-pressure molding process has the advantages of simple equipment and mold, convenient operation and high yield; the pressure inside and outside the pipeline is equal in the processing process, and the steel pipe is not damaged; equal high pressures throughout result in a uniform and dense liner with low shrinkage. The specific process flow comprises the following steps: A. treating the inner surface of a steel pipe, B, filling the steel pipe into a rubber bag soft mold, C, adding polytetrafluoroethylene powder, D, sealing, E, placing the steel pipe into a high-pressure kettle, injecting water and pressurizing, F, releasing pressure and taking a workpiece, G, removing the rubber bag soft mold, H, sintering, I, and removing internal filling.)

1. An isobaric preparation process for a polytetrafluoroethylene lining of a pipeline is characterized by comprising the following steps: the preparation process comprises the following operation flows:

A. treating the inner surface of the steel pipe: firstly, carrying out oil removal and rust removal treatment on the inner surface of a pipeline (1), and enabling the rust removal grade in the steel pipe to reach Sa 2-Sa 3 grade by adopting a sand blasting treatment mode;

B. filling into a rubber bag soft mold: a rubber bag soft mold (2) is arranged in the pipeline, and a uniform gap of 10-18 mm is reserved between the rubber bag and the pipeline;

C. polytetrafluoroethylene powder addition: adding polytetrafluoroethylene powder into a gap between the rubber bag and the pipeline, and uniformly filling to form a polytetrafluoroethylene layer (3);

D. sealing: a material pressing ring (4) and an end cover (5) are placed in the pipeline, and are fastened by bolts to tightly seal the pipeline;

E. placing in an autoclave, injecting water and pressurizing: placing the sealed pipeline in an autoclave, sealing the autoclave, adding water pressure to 25-30 MPa through a water injection port, and maintaining the pressure for 10-30 seconds;

F. releasing pressure and taking a piece: discharging high-pressure water, and taking the pipeline workpiece out of the high-pressure kettle;

G. removing the soft mold of the rubber bag: removing the nut, taking down the end cover (5) and the material pressing ring (4), and drawing out the rubber bag soft mold (2);

H. and (3) sintering: filling expansion powder into the obtained steel lining polytetrafluoroethylene prefabricated product, sealing, sintering in a sintering furnace at the temperature of 360-375 ℃, preserving heat for 7-10 hours, and cooling;

I. internal filling removal: and cooling to room temperature, taking out the pipeline workpiece, removing the filler, and trimming burrs.

2. The process of claim 1 for the isobaric preparation of a polytetrafluoroethylene lining for pipes, wherein: the polytetrafluoroethylene is dispersed polytetrafluoroethylene powder, and the granularity is 300-800 mu m.

3. The process of claim 1 for the isobaric preparation of a polytetrafluoroethylene lining for pipes, wherein: the pipeline (1) is made of ordinary carbon steel.

4. The process of claim 1 for the isobaric preparation of a polytetrafluoroethylene lining for pipes, wherein: the rubber bag soft mold (2) is made of natural rubber and is 2-3 mm thick.

5. The process of claim 1 for the isobaric preparation of a polytetrafluoroethylene lining for pipes, wherein: and in the step E, in the process of water injection and pressurization, the rubber bag and the autoclave are synchronously pressurized, so that the pressure of the inner wall and the outer wall of the pipeline is equal, and the stress is offset.

Technical Field

The invention relates to the technical field of pipeline linings, in particular to an isobaric preparation process of a polytetrafluoroethylene lining of a pipeline.

Background

The steel pipeline is widely used in related industries such as chemical industry, petroleum industry, medicine industry and the like, and in practical application, as the pipeline transports corrosive substances, especially strong acid and strong alkali, the steel pipe can be seriously corroded, and the service life of the steel pipe is greatly shortened. The polytetrafluoroethylene has high chemical inertia, does not react with strong corrosive media such as hydrofluoric acid, concentrated hydrochloric acid, nitric acid, concentrated sulfuric acid, boiling sodium hydroxide solution and the like, can work for a long time at the temperature of minus 60-260 ℃, and is widely used as a corrosion-resistant lining material for chemical equipment and accessories. The lining polytetrafluoroethylene steel pipe plays an important role in transporting strong corrosive media, and has great application value in the field of chemical industry.

The traditional forming technology of the polytetrafluoroethylene lining of the pipeline mainly comprises a winding method, a mould pressing method and the like. The winding method has the defects that the operating parameters are difficult to control, the product has the defects of pipe detachment, bubbling, stress cracking and the like, and in actual use, the product is not resistant to negative pressure and is easy to crack between layers to cause leakage. In the traditional tetrafluoro molding process, because lining products with different sizes need pressing machines with different tonnages and complex dies, the investment cost is high, and the operation is difficult. Because the polytetrafluoroethylene powder pressure transmission is difficult, the die pressing product wall thickness should not undersize, to the bigger pipeline product of major diameter, often can be because the pressurized inhomogeneous elasticity phenomenon that appears, lead to the goods to scrap. In addition, the pressure-bearing strength of the carbon steel shell is low, and the molding water pressure is controlled to be 8-15 MPa, so that the lining is not pressed tightly enough, the shrinkage rate is high, and the problems of pipe removal, bubbling and the like are easy to occur.

Disclosure of Invention

The invention aims to provide an isobaric preparation process for a polytetrafluoroethylene lining of a pipeline, which realizes the processing of high-quality lining products and makes up the defects of the forming methods such as a winding method, a mould pressing method and the like commonly used in China in the prior art for manufacturing the polytetrafluoroethylene lining of the pipeline, thereby improving the technical level of the polytetrafluoroethylene products in China and saving the production cost.

In order to achieve the purpose, the invention is realized by the following technical scheme: an isobaric preparation process for a polytetrafluoroethylene lining of a pipeline comprises the following operation flows:

A. treating the inner surface of the steel pipe: the method comprises the steps of firstly, carrying out oil removal and rust removal treatment on the inner surface of a pipeline, and enabling the rust removal grade in the steel pipe to reach Sa 2-Sa 3 grade by adopting a sand blasting treatment mode.

B. Filling into a rubber bag soft mold: a rubber bag soft mold is arranged in the pipeline, and a uniform gap of 10-18 mm is reserved between the rubber bag and the pipeline.

C. Polytetrafluoroethylene powder addition: adding polytetrafluoroethylene powder into the gap between the rubber bag and the pipeline, and uniformly filling to form a polytetrafluoroethylene layer.

D. Sealing: and (4) placing a material pressing ring and an end cover, fastening by using bolts, and tightly sealing the pipeline.

E. Placing in an autoclave, injecting water and pressurizing: and (3) placing the sealed pipeline in an autoclave, sealing the autoclave, adding water pressure to 25-30 MPa through a water injection port, and maintaining the pressure for 10-30 seconds.

F. Releasing pressure and taking a piece: and discharging high-pressure water, and taking the pipeline workpiece out of the autoclave.

G. Removing the soft mold of the rubber bag: and (4) dismounting the nut, taking down the end cover and the material pressing ring, and drawing out the rubber bag soft mold.

H. And (3) sintering: and filling the obtained steel lining polytetrafluoroethylene prefabricated product with expansion powder, sealing, sintering in a sintering furnace at the temperature of 360-375 ℃, preserving heat for 7-10 hours, and cooling.

I. Internal filling removal: and cooling to room temperature, taking out the pipeline workpiece, removing the filler, and trimming burrs.

Preferably, the polytetrafluoroethylene is dispersed polytetrafluoroethylene powder, and the granularity is 300-800 μm.

Preferably, the pipeline is made of common carbon steel.

Preferably, the soft mold of the rubber bag is made of natural rubber, and the thickness of the soft mold is 2-3 mm.

Preferably, in the step E, during the water injection and pressurization process, the rubber bag and the autoclave are synchronously pressurized, so that the pressure on the inner wall and the outer wall of the pipeline is equal and the stress is offset.

By adopting the technical scheme, the invention has the beneficial effects that:

1. the pipeline polytetrafluoroethylene lining isobaric preparation process adopts an isobaric forming method to manufacture the pipeline polytetrafluoroethylene lining, the required equipment and the required mould are simple, and the pipeline polytetrafluoroethylene lining can be manufactured only by a high-pressure water pump, a high-pressure kettle and a rubber bag soft mould. Compared with the traditional winding method and mould pressing method, the method has the advantages of simple operation, production block and raw material saving.

2. According to the isobaric preparation process for the polytetrafluoroethylene lining of the pipeline, as the polytetrafluoroethylene product is prepared by adopting an isobaric forming method, polytetrafluoroethylene resin powder between the rubber bag and the inner wall of the pipeline can be uniformly and regularly pressed, and the obtained product is uniform and smooth in surface, so that the problems of defects or bubbling are not easy to occur.

3. According to the isobaric preparation process for the polytetrafluoroethylene lining of the pipeline, the polytetrafluoroethylene is pressed by adopting a mode of equal pressurization inside and outside the pipeline, and the inner wall and the outer wall of the steel pipe in the kettle are subjected to equal high pressure, so that the stress of the steel pipe is balanced, the bearing force is not large, and the steel pipe is not damaged. In the common mould pressing method, the pressure-bearing strength of the carbon steel shell is low, and the forming pressure is controlled to be 8-15 MPa, so that the lining is not pressed tightly enough, the shrinkage rate is high, and the problems of pipe detachment, bubbling and the like are easy to occur. In contrast, the pressure of the isostatic pressing method is controlled to be 25-30 MPa, the polytetrafluoroethylene powder is pressed to be more compact under high pressure, the strength is high, the shrinkage rate in the sintering process is small, the permeation resistance is stronger, and the service performance in a high-pressure or negative-pressure environment is good.

Drawings

FIG. 1 is a structural diagram of an isobaric production of a polytetrafluoroethylene lining for a pipeline according to the invention.

In the figure: 1 steel pipe, 2 rubber bag soft moulds, 3 polytetrafluoroethylene powder layers, 4 pressure rings, 5 end covers and 6 water injection ports.

Detailed Description

The process flow of the present invention is specifically described below by way of examples.

Example 1: referring to the attached drawings, the preparation process of the polytetrafluoroethylene lining of the pipeline comprises the following specific operation flows:

A. treating the inner surface of the steel pipe: firstly, carrying out oil removal and rust removal treatment on the inner surface of the pipeline 1, and enabling the rust removal level in the steel pipe to reach Sa2 level by adopting a sand blasting treatment mode;

B. filling into a rubber bag soft mold: a rubber bag soft mold 2 is arranged in the pipeline, the thickness of the rubber bag is 3 mm, and a uniform gap of 16 mm is reserved between the rubber bag and the pipeline;

C. polytetrafluoroethylene powder addition: adding polytetrafluoroethylene powder with the granularity of 700 mu m into a gap between the rubber bag and the pipeline, and uniformly filling to form a polytetrafluoroethylene layer 3;

D. sealing: a material pressing ring 4 and an end cover 5 are placed in the pipeline, and are fastened by bolts, so that the pipeline is tightly sealed;

E. placing in an autoclave, injecting water and pressurizing: placing the sealed pipeline in an autoclave, sealing the autoclave, adding water pressure to 30 MPa through a water injection port, and maintaining the pressure for 10 seconds;

F. releasing pressure and taking a piece: discharging high-pressure water, and taking the pipeline workpiece out of the high-pressure kettle;

G. removing the soft mold of the rubber bag: removing the nut, taking down the end cover 5 and the material pressing ring 4, and drawing out the rubber bag soft mold 2;

H. and (3) sintering: filling expansion powder into the obtained steel lining polytetrafluoroethylene prefabricated product, sealing, sintering in a sintering furnace at 365 ℃, preserving heat for 10 hours, and naturally cooling;

I. internal filling removal: and cooling to room temperature, taking out the pipeline workpiece, removing the filler, and trimming burrs.

Example 2: referring to the attached drawings, the preparation process of the polytetrafluoroethylene lining of the pipeline comprises the following specific operation flows:

A. treating the inner surface of the steel pipe: firstly, carrying out oil removal and rust removal treatment on the inner surface of a pipeline 1, and enabling the rust removal level in a steel pipe to reach Sa2.5 level by adopting a sand blasting treatment mode;

B. filling into a rubber bag soft mold: a rubber bag soft mold 2 is arranged in the pipeline, the thickness of the rubber bag is 2 mm, and a uniform gap of 14 mm is reserved between the rubber bag and the pipeline;

C. polytetrafluoroethylene powder addition: adding polytetrafluoroethylene powder with the granularity of 500 mu m into a gap between the rubber bag and the pipeline, and uniformly filling to form a polytetrafluoroethylene layer 3;

D. sealing: a material pressing ring 4 and an end cover 5 are placed in the pipeline, and are fastened by bolts, so that the pipeline is tightly sealed;

E. placing in an autoclave, injecting water and pressurizing: placing the sealed pipeline in an autoclave, sealing the autoclave, adding water pressure to 28 MPa through a water injection port, and maintaining the pressure for 20 seconds;

F. releasing pressure and taking a piece: discharging high-pressure water, and taking the pipeline workpiece out of the high-pressure kettle;

G. removing the soft mold of the rubber bag: removing the nut, taking down the end cover 5 and the material pressing ring 4, and drawing out the rubber bag soft mold 2;

H. and (3) sintering: filling expansion powder into the obtained steel lining polytetrafluoroethylene prefabricated product, sealing, sintering in a sintering furnace at the temperature of 370 ℃, preserving heat for 9 hours, and naturally cooling;

I. internal filling removal: and cooling to room temperature, taking out the pipeline workpiece, removing the filler, and trimming burrs.

Example 3: referring to the attached drawings, the preparation process of the polytetrafluoroethylene lining of the pipeline comprises the following specific operation flows:

A. treating the inner surface of the steel pipe: firstly, carrying out oil removal and rust removal treatment on the inner surface of the pipeline 1, and enabling the rust removal level in the steel pipe to reach Sa3 level by adopting a sand blasting treatment mode;

B. filling into a rubber bag soft mold: a rubber bag soft mold 2 is arranged in the pipeline, the thickness of the rubber bag is 2 mm, and a uniform gap of 12 mm is reserved between the rubber bag and the pipeline;

C. polytetrafluoroethylene powder addition: adding polytetrafluoroethylene powder with the granularity of 300 mu m into a gap between the rubber bag and the pipeline, and uniformly filling to form a polytetrafluoroethylene layer 3;

D. sealing: a material pressing ring 4 and an end cover 5 are placed in the pipeline, and are fastened by bolts, so that the pipeline is tightly sealed;

E. placing in an autoclave, injecting water and pressurizing: placing the sealed pipeline in an autoclave, sealing the autoclave, adding water pressure to 26 MPa through a water injection port, and maintaining the pressure for 30 seconds;

F. releasing pressure and taking a piece: discharging high-pressure water, and taking the pipeline workpiece out of the high-pressure kettle;

G. removing the soft mold of the rubber bag: removing the nut, taking down the end cover 5 and the material pressing ring 4, and drawing out the rubber bag soft mold 2;

H. and (3) sintering: filling expansion powder into the obtained steel lining polytetrafluoroethylene prefabricated product, sealing, sintering in a sintering furnace at the temperature of 375 ℃, preserving heat for 8 hours, and naturally cooling;

I. internal filling removal: and cooling to room temperature, taking out the pipeline workpiece, removing the filler, and trimming burrs.