Price budget for polyurethane prefabricated pipes

Price budget for polyurethane prefabricated pipes

Causing deformation and structural damage to the so-called economical HDPE outer protective pipe, dynamic and static loads compress, bend or exceed the rated pressure on the pipe diameter, resulting in excessive deformation of the outer protective pipe and buckling failure. Moreover, poor quality of raw materials or low level of processing technology can lead to widespread circumferential stress cracking and damage. Multiple serious accidents have occurred, causing significant losses.

Price budget for polyurethane prefabricated pipes
As the polyurethane rigid foam insulation layer is closely bonded to the outer skin of the steel pipe, it can isolate the infiltration of air and water and play a good anti-corrosion role. 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 well, according to foreign data, the service life can reach more than 50 years, which is 3-4 times longer than the service life of traditional trench laying and overhead laying.

It is widely used in insulation and cooling projects in urban centralized heating, cold storage, warm rooms, coal mines, petroleum, ports, chemical and other industries. However, high-density polyethylene has poorer weather resistance and lower heat resistance than fiberglass. High density polyethylene has a heat resistance of 60 ℃ -70 ℃, while fiberglass has a heat resistance of 100 ℃ -120 ℃, so it should be taken seriously in application! This product is divided into three layers from inside to outside: the working steel pipe layer. According to the design and customer requirements, seamless pipes (GB8163-87), spiral steel pipes (GB9711-88; SY/T5037-92), and straight seam steel pipes (GB3091-93) are generally selected. After the surface of the steel pipe is treated with shot blasting and rust removal technology, the rust removal grade of the steel pipe can reach Sa2 level in GB8923-1998 standard, and the surface roughness can reach R=12.5 microns in GB6060.5-88 standard. The second layer: polyurethane insulation layer, which is made by injecting the rigid polyurethane foam solution into the cavity formed between the steel pipe and the outer protective layer with a high-pressure foaming machine. It is commonly known as the "pipe in pipe foaming process". Its functions include insulation, waterproofing, and supporting the self weight of the heating network. When the temperature of the conveying medium is -50 ℃ -120 ℃, rigid polyurethane foam is selected as the insulation layer; when the temperature of the conveying medium is -50 ℃ -150 ℃, rigid polyurethane foam is selected as the insulation layer. Third layer: High density polyethylene insulation layer, prefabricated into black (yellow) plastic pipes with a certain wall thickness, which are used for backup after being treated with corona technology. Its functions are twofold: firstly, to protect the polyurethane insulation layer from mechanical damage caused by hard objects; secondly, to prevent corrosion and waterproofing of the polyurethane insulation pipe

2. The application of fiberglass reinforced plastic (FRP) outer protective pipes in the process and products of directly buried prefabricated high-temperature steam insulation pipes fully taps into the potential of FRP: light weight, high strength, good corrosion resistance, strong electrical insulation, excellent processability, and certain temperature resistance (higher than HDPE), which have been developed. But its elastic modulus is low, 10 times smaller than steel (E=2.1 × 106), and decreases more with increasing temperature. The strength and stiffness of the product are insufficient, and it is prone to deformation; Long lasting poor temperature resistance, creep, low wet strength (50% decrease in strength when working in a wet environment for a long time) [13], as well as low aging performance and interlaminar shear strength, are important reasons for the damage of outer protective pipes of fiberglass materials in recent years. Different resins have different acid and alkali resistance.
Improper design, unreasonable structure, excessively small wall thickness, and rough manufacturing cannot guarantee the integrity of the insulation structure, especially in harsh weather conditions where on-site construction and joint patching are more affected by moisture; Improper or misuse of materials, use of alkali glass fiber cloth or soil fiber cloth, and exposure to ultraviolet light, corrosion by soil chemical media, and rough mechanical damage during rough construction are all direct causes of accidents that cannot be guaranteed in terms of quality.