After the pipeline installation, the pressure test shall be carried out on the pipeline system according to the design requirements. According to the purpose of the test, it can be divided into strength test to check the mechanical properties of the pipeline, air tightness test to check the connection quality of the pipeline, vacuum test to check the vacuum retention performance of the pipeline system and leakage test based on fire safety considerations. Except for the vacuum pipeline system and the pipeline system with fire protection requirements, most pipelines only do strength test and leak test. In general, the strength test and leak test of pipeline system are carried out through water pressure test, for example, due to design structure or other reasons.

Cross 202 1-02-23 by land.

Fluorine-lined pipelines are lined with fluorine in steel pipelines, including molded steel-lined tetrafluoroethylene pipelines and steel-lined tetrafluoroethylene pipelines.

Molded steel lined PTFE pipeline: PTFE powder is mainly used for molding, die and water pressure forming, and oven drying. Why is the fluorine-lined pipeline called the king of plastics? This kind of pipeline is usually used in the case of large negative pressure and bad medium environment, with remarkable effect, but the relative cost is also high.

Pipe-lined steel-lined PTFE pipe: that is, push pipe (produced by PTFE pipe-making machine, with uniform wall thickness and good compactness) is directly sheathed into steel pipe, and then both ends are turned over. This kind of pipeline is relatively cheap and suitable for a relatively peaceful medium environment.

The manufacturing process of the fluorine-lined pipe with PTFE push (extrusion) pipe tightly lined with straight pipe: firstly, imported PTFE powder is used, pushed (extruded) into a pipe, and then forcibly drawn into a seamless steel pipe (the outer diameter of the lining is slightly larger than the inner diameter of the steel pipe 1.5-2mm) to form a seamless tight lining. In order to reduce the pressure, put it in the furnace and heat it to 180? C carry out constant temperature treatment to make it adapt to 180? When used at the temperature below C, the axial tensile strength of the pushed (squeezed) pipe is obviously better than that of the wound pipe. This kind of pipeline has ideal positive and negative pressure resistance.

The fourth category: PTFE reinforced lined pipe: Fluorine lined pipe is the perfect combination of plastic and metal. At present, the large diameter of push (extrusion) PTFE pipe in China is 200 mm, and the ideal diameter of steel-lined PTFE pipe is only 200 mm. In order to solve the problem of positive and negative pressure resistance of DN25-500mm lined straight pipe and pipe fittings, we adopt the following lining technology: in PTFE loose lining pipe, a metal support ring coated with PTFE is set at regular intervals. 6- 16mm), the inner wall is corrugated, on the one hand, the supporting ring is fixed; On the other hand, the thermal expansion and cold contraction of PTFE lining are well compensated, which makes the pipeline have good positive and negative pressure resistance.