Piping and Valves Knowledge [Daily Question] 11-4-7

The installation design of PE pipeline systems mainly includes methods such as surface laying, buried laying, indoor building laying, underwater laying, and trenchless construction laying. (1) Main factors considered in floor installation design The floor installation design should take into account all the factors relevant to operational design; in addition, the following factors must also be considered: 1. Temperature 2. Chemical resistance 3. Ultraviolet radiation 4. Possible impact loads. There are two forms of floor installation: a: Placing the pipes directly on the floor; b: Installing them overhead (using supports or suspensions), but protection measures must be applied. (II) Design for buried installation The design for buried installation should address the following issues: ① Requirements for trench excavation and backfilling ； ②Connection methods and laying methods of pipes ； ③Fixing of pipes and design of supports. The buried installation of polyethylene pipes should follow the theory of flexible management. The pipe is a function of the backfill material supporting it, its density, burial depth, surface load, as well as the hoop stiffness of the pipe. The magnitude of the supporting force generated by the landfill layer is proportional to its elastic modulus. The backfill material around the pipe and its quality have a significant impact on the pipe’s deformation and load-bearing capacity. The higher the density of the backfill soil and the greater its elastic modulus, the greater the restraining force on the deformation of the pipes. It can significantly improve the load-bearing capacity of the pipe.

Laying of PE pipes: The laying of polyethylene pipes can generally be divided into two methods: direct burial and serpentine laying. ①For direct burial, since polyethylene pipes have lower strength than metal pipes and are more sensitive to temperature changes, it is essential to pay attention to the burial depth, keep them away from thermal pipelines, and try to avoid laying them in the same trench as other pipes and power lines. In case of special circumstances, it is necessary to maintain certain distances in all directions—up, down, left, and right—in accordance with the relevant standards, and special measures should be taken. ②It can be laid in a serpentine pattern; since the linear expansion coefficient of polyethylene pipes is more than 10 times higher than that of metals, these pipes can be laid flexibly, winding along the terrain, but the bending radius must meet the specified requirements. For 50mm ≤ diameter D ≤ 160mm, the allowable bending radius R should be 50D of the diameter; if there are joints in the pipe section, it should not be less than 125D. ③Installation of valves on polyethylene pipes: Polyethylene valves have the following advantages over steel valves: A. No need for anti-corrosion treatment or regular inspections ； B. No spare parts required, maintenance-free ； C. Can be buried directly without the need for a valve chamber ； D. It has a long service life, reaching over 50 years. ④Construction on special sections refers to work in areas that pass through railways, major roads, rivers, bridges, and similar locations. First, it must obtain the approval of the relevant regulatory authorities ； Secondly, since PE pipes are more susceptible to human-induced damage compared to steel pipes, it is not advisable to use PE pipes in such areas in principle ； Thirdly, if PE pipes must be used, sleeves or other measures should be employed to ensure project quality and the safe operation of gas pipelines.

This post was last edited by security on 2011-4-7 08:02. The installation of polyethylene pipes can generally be divided into two methods: direct burial and serpentine installation. ①For direct burial, since polyethylene pipes have lower strength than metal pipes and are more sensitive to temperature changes, it is essential to pay attention to the burial depth, keep them away from thermal pipelines, and try to avoid laying them in the same trench as other pipes and power lines. In case of special circumstances, it is necessary to maintain certain distances in all directions—up, down, left, and right—in accordance with the relevant standards, and special measures should be taken. ②It can be laid in a serpentine pattern; since the linear expansion coefficient of polyethylene pipes is more than 10 times higher than that of metals, these pipes can be laid flexibly, winding along the terrain, but the bending radius must meet the specified requirements. For 50mm ≤ diameter D ≤ 160mm, the allowable bending radius R should be 50D of the diameter; if there are joints in the pipe section, it should not be less than 125D. ③Installation of valves on polyethylene pipes: Polyethylene valves have the following advantages over steel valves: A. No need for anti-corrosion treatment or regular inspections ； B. No spare parts required, maintenance-free ； C. Can be buried directly without the need for a valve chamber ； D. It has a long service life, reaching over 50 years. ④Construction on special sections refers to work in areas that pass through railways, major roads, rivers, bridges, and similar locations. First, it must obtain the approval of the relevant regulatory authorities ； Secondly, since PE pipes are more susceptible to human-induced damage compared to steel pipes, it is not advisable to use PE pipes in such areas in principle ； Thirdly, if PE pipes must be used, sleeves or other measures should be employed to ensure project quality and the safe operation of gas pipelines. Source: Safety Management Network (www.safehoo.com) Full source: http://www.safehoo.com/Tech/Chemical/201103/172251_2.shtml

1. When PE pipes pass through railways or highways, reinforced concrete sleeves should be installed; the minimum diameter of such sleeves shall be the diameter of the PE pipe plus 200 mm. Strict waterproofing measures must be taken when the pipes pass through the exterior walls of basements or underground structures. 2 u8 s1 C! ^! O8 ~: R5 q 2. At the connections between PE pipes and metal valves or fire hydrants, steel-plastic conversion devices should be used, and a valve chamber is required. For connections using polyethylene valves, a valve chamber is not necessary, but a valve protection sleeve is required. 3. When laying PE pipes, metal tracer wires should be buried along the direction of the pipes. A warning tape should be installed at a distance of not less than 300 mm above the pipe top, with prominent warning signs on it. 4. When pipeline installation and laying work is interrupted, the pipe ends should be sealed with plugs or similar items to prevent debris from entering. . r- v1

The installation of polyethylene pipes can generally be divided into two methods: direct burial and serpentine laying. ①For direct burial, since polyethylene pipes have lower strength than metal pipes and are more sensitive to temperature changes, it is essential to pay attention to the burial depth, keep them away from thermal pipelines, and try to avoid laying them in the same trench as other pipes and power lines. In case of special circumstances, it is necessary to maintain certain distances in all directions—up, down, left, and right—in accordance with the relevant standards, and special measures should be taken. ②It can be laid in a serpentine pattern; since the linear expansion coefficient of polyethylene pipes is more than 10 times higher than that of metals, these pipes can be laid flexibly, winding along the terrain, but the bending radius must meet the specified requirements. For 50mm ≤ diameter D ≤ 160mm, the allowable bending radius R should be 50D of the diameter; if there are joints in the pipe section, it should not be less than 125D. ③Installation of valves on polyethylene pipes: Polyethylene valves have the following advantages over steel valves: A. No need for anti-corrosion treatment or regular inspections ； B. No spare parts required, maintenance-free ； C. Can be buried directly without the need for a valve chamber ； D. It has a long service life, reaching over 50 years. ④Construction on special sections refers to work in areas that pass through railways, major roads, rivers, bridges, and similar locations. First, it must obtain the approval of the relevant regulatory authorities ； Secondly, since PE pipes are more susceptible to human-induced damage compared to steel pipes, it is not advisable to use PE pipes in such areas in principle ； Thirdly, if PE pipes must be used, sleeves or other measures should be employed to ensure project quality and the safe operation of gas pipelines.

Reply to 1# Xiao Luotou: 1. The pipes must maintain a specified slope of 0.002–0.003. 2. To prevent the formation of air pockets, there should be no local upward protrusions on the horizontal main pipes; if the elevation changes, an exhaust valve should be installed at the highest point before the horizontal main pipe drops.

The installation of polyethylene pipes can generally be divided into two methods: direct burial and serpentine laying. ①For direct burial, since polyethylene pipes have lower strength than metal pipes and are more sensitive to temperature changes, it is essential to pay attention to the burial depth, keep them away from thermal pipelines, and try to avoid laying them in the same trench as other pipes and power lines. In case of special circumstances, it is necessary to maintain certain distances in all directions—up, down, left, and right—in accordance with the relevant standards, and special measures should be taken. ②It can be laid in a serpentine pattern; since the linear expansion coefficient of polyethylene pipes is more than 10 times higher than that of metals, these pipes can be laid flexibly, winding along the terrain, but the bending radius must meet the specified requirements. For 50mm ≤ diameter D ≤ 160mm, the allowable bending radius R should be 50D of the diameter; if there are joints in the pipe section, it should not be less than 125D