Polyurethane insulation pipe is the abbreviation for insulated pipeline. Insulation pipe is usually used for the transportation of liquids, gases, and other media, and plays a great role in insulation engineering of pipelines in petroleum, chemical, aerospace, central heating, central air conditioning, municipal and other industries.

The technical requirements for polyurethane insulation pipes are as follows:

1. The medium commonly used in heating pipeline systems is hot water, with a hardness of ≤ 0.6mmol/L, pH value of 7-12, dissolved oxygen of ≤ 0.1mg/L, suspended solids of ≤ 5mg/L, oil content of ≤ 2mg/L, and CL ions of ≤ 25ppm

2. Environmental conditions that should be met: The valve is installed in the valve well, with a low temperature of -20 ℃, a high temperature of 65 ℃, a small relative humidity of 30%, and a large relative humidity of 95%.
3. Setting of working parameters: The nominal pressure of the equipment is 2.5Mpa, the working pressure is ≤ 1.6Mpa, and the design temperature is 150 ℃.
4. Performance requirements: The valve is a three eccentric bidirectional metal hard sealed butterfly valve, with manual control as the transmission mode and welded connection as the valve. The valve body can be made of cast iron or forged, and the bearings can withstand the large load transmitted by the valve stem. The valve stem should be equipped with a reliable shaft seal to prevent medium leakage at the valve stem. The design of the valve should have a maintenance free structure that is easy to install and can operate for a long life without frequent operation, maintenance adjustments, or lubrication. Valves can achieve bidirectional sealing capability of the same level, and can effectively seal regardless of pressure from any direction. The bidirectional leakage level should reach ANSIV level, with an indicator device to display the valve's on/off status, and a limit mechanism to ensure that the valve plate is fully open and fully closed.

5. Material requirements: The valve body and material are carbon steel, the valve plate and stem material are stainless steel, the sealing ring material is stainless steel 316L or higher, and the stem material is stainless steel with a minimum of 2Cr13.

Before leaving the factory, the valve must undergo the following tests and provide supporting materials.

Material list (proof of mechanical and chemical properties of the material).

Strength test certificate and test data (conducted in accordance with ISO5208 requirements).
The polyurethane insulation pipe can play a good anti-corrosion role because the polyurethane rigid foam insulation layer is closely bonded to the steel pipe skin, which can isolate the infiltration of air and water. At the same time, its foam pores are all closed, with low water absorption. The high polyethylene shell and fiberglass shell have good anti-corrosion, insulation, and mechanical properties. Therefore, the outer skin of the working steel pipe is difficult to be eroded by external air and water. As long as the water quality inside the pipeline is treated, according to foreign data,. Corrosion resistance, insulation performance, and long service life. Prefabricated polyurethane directly buried thermal insulation pipe can play a good anti-corrosion role because the polyurethane rigid foam thermal insulation layer is closely bonded to the steel pipe skin, which can isolate the infiltration of air and water. At the same time, its foam pores are all closed, and its water absorption is very low. The high-density polyethylene shell and fiberglass shell both have good anti-corrosion, insulation, and mechanical properties. Therefore, the outer skin of the working steel pipe is difficult to be eroded by external air and water. As long as the water quality inside the pipeline is treated, according to foreign data, the service life of prefabricated polyurethane buried insulation pipes can reach more than 50 years, which is 3-4 times longer than traditional trench laying and overhead laying.
7. The outer diameter and wall thickness of the welded butterfly valve interface shall be consistent with the standard for directly buried prefabricated insulation pipelines.