Matters needing attention during the construction of steel – lined ptfe pipe

In daily life we can often see ptfe tube, so, ptfe tube in the process of processing we need to pay attention to what matters?

In the construction process of steel lined PTFE pipe, the following points need to be paid attention to:

1. the seamless steel pipe according to the actual size of the material, the steel pipe and welding ring welding, the ring can use manual argon arc welding, welding splash with a file to clean, and the fillet weld into rounded corner, no sharp edge.

2. Drill a small hole at the end of the steel pipe, mark it clearly, and do not block it. This hole is used to discharge the residual gas between the steel pipe and the tetrafluoroethylene pipe during heating, and is used to observe whether the tetrafluoroethylene pipe is damaged and leaked during pressure test.

3. steel pipe should be pre-assembled before lining. The joint shall be assembled with asbestos gold pad of appropriate thickness, so as to conform to the overall size requirements after lining.

4. after the assembly of seamless steel pipe to sand blasting treatment, to remove the inner wall rust, and then with compressed air to clean the tube cavity. Insert the tetrafluoroethylene tube into the steel tube. If some tetrafluoroethylene pipe is not round and cannot be inserted, hot water, steam or medium frequency heating furnace should be used to heat the tetrafluoroethylene pipe, heating temperature does not exceed 100℃.

5. Consider the length of flanging when cutting the teflon pipe. Generally, 35-40 lengths are set aside above the welding ring surface. An asbestos gold gasket should be placed on the TEflon tube before flanging. Flanging the teflon tube in two steps, first into a bell, this flanging using a tapered cast aluminum piece. When flanging, heat the vivipary with an oxyacetylene flame. The temperature of the fixture is measured with a semiconductor surface thermometer. The temperature should not be too high. The temperature should be controlled between 260℃ and 280℃. When flanging, slowly press down the heated tapered birthgear. When the birthgear reaches the edge of the welding ring, do not press any more. At this time, cool it with water and remove the birthgear when it cools to the ambient temperature. The flanging of the second step further plasticizes the nozzle. This one is flat.

6. after heating, slowly press down and completely press flat, and then cool with water to the ambient temperature, and then remove the plug.

7. the lined pipe with a good blind plate, into the special heating cylinder, connected to the compressed air tube, heating the cylinder with intermediate frequency heating method, so that the overall temperature of the pipeline to about 280℃, and then slowly through 8-LOKGF/cm2 compressed air. Put the tetrafluoron tube in the water tank, immerse the tube in the water, slowly pass into 15kgf/cm2 compressed air, check whether there are bubbles at the hole, if found, it proves that the tetrafluoron tube has been broken. The reason is mainly because of uneven heating or inflation speed too fast. The lined steel pipe shall be sealed at both ends with wood blind plate to prevent damage of the tetrafluoron pipe.

Post time: May-23-2022