What are the general principles for selecting pipes and pipe fittings?
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Pressure, medium, and operating environment are required to determine the material, wall thickness, and specifications of fittings and pipes. For pipes, first consider the standards and material – whether it is carbon steel or stainless steel. Pipes that conform to standard GB8162 are cheaper than those that conform to standard GB8163. Pipes made according to standard 5310 or 9948 are generally much more expensive per ton than those made under standard 8163; therefore, it is essential to pay close attention to the standards when purchasing pipes. There are many other standards, which will not be listed one by one. Fittings, as well as standards and materials. There are also pipe fittings, especially those with larger diameters, which tend to have variations in wall thickness; as long as they meet the standards, that’s sufficient.
Seamless steel pipes are pipes without welds, manufactured using hot processing methods such as piercing and hot rolling. If necessary, the heat-treated tubes can be further cold-worked to achieve the desired shape, size, and properties. Currently, seamless steel pipes (with specifications ranging from DN15 to DN600) are the most widely used pipes in petrochemical production facilities, and their manufacturing process is also quite mature. However, for pipes with large diameters (DN≥250) and thick walls (greater than SCH100), domestic production capacity is still lacking; therefore, such pipes still need to be imported at present. 1. Carbon steel seamless pipes: In petrochemical production facilities, the commonly used standards for carbon steel seamless pipes include GB8163, GB9948, GB6479, GB3087, and GB5310. The GB8163 standard for \"Seamless steel pipes for fluid transport\" is the most widely used standard in pipe manufacturing. The manufacturing methods include hot rolling, cold drawing, and hot expansion. The size range spans from DN6 to DN600, with wall thicknesses available in 66 different specifications ranging from 0.25 mm to 75.0 mm. There are 4 material grades available: 10, 20, 09MnV, and 16Mn. These pipes are suitable for transporting various fluids. GB9948 \"Seamless Steel Tubes for Petroleum Cracking\" is a manufacturing standard for steel tubes made from various materials such as carbon steel, chromium-molybdenum steel, and stainless steel; the manufacturing methods include hot rolling and cold drawing. Its size range is DN6 to DN250, with wall thicknesses comprising 16 specifications ranging from 1.0 mm to 20.0 mm. The carbon steel material grades it uses are 10 and 20, a total of 2 types. Under normal circumstances, it is often used in situations where GB8163 steel pipes are not suitable.
Chemical composition of SA 106Gr.B: C ≤0.25, Mn=0.27–0.93, P≤0.035, S≤0.035, Si ≤0.1, Cr≤0.4, Cu≤0.4. Mechanical properties: ób≥415/MPa, ós≥240/MPa. The chemical composition of this material does not correspond to any domestic materials; its mechanical properties are similar to those of domestic 20# steel per GB/T699 standards. ASTM is a set of American standards for steel pipes – ASTM pipe A106A corresponds to Chinese standard GB8163 with material grade 10#, while A106B corresponds to Chinese standard GB8163 with material grade 20#.
Nominal diameter (DN) is defined according to GB/T 1047; it consists of the letters DN and a dimensionless integer, and represents the specifications of pipe components. 3.4 Pipe, tube: a sealed, hollow, continuous structure used for transporting liquids or transmitting liquid pressure. 3.5 Piping components are mechanical elements used to connect or assemble pressure-sealed piping systems; they include pipes, pipe fittings, flanges, gaskets, fasteners, valves, safety devices, as well as items such as expansion joints, flexible connectors, pressure-resistant hoses, filters, instruments in the pipelines (such as orifice plates), and separators. 3.6 Pipe-supporting elements are components that transfer the loads on pipes – including the weight of the pipes themselves, the load resulting from operating pressures and temperature differences, as well as loads caused by wind, earthquakes, snow loads, impacts, and displacement strains – to the pipe rack structure. It is divided into two categories: fixtures and structural attachments. Fixing elements include suspension-type fixing elements such as rods, spring hangers, tie rods, hammers, tension bolts, support rods, chains, guide rails, and brackets, as well as load-bearing fixing elements such as saddles, rollers, supports, and sliding bearings. Structural attachments refer to components attached to pipes using welding, bolted connections, or clamping methods, such as lugs, pipe hangers, clamps, pipe grips, U-clips, and splints. 3.7 Fittings: A category of pipe components that typically includes elbows, tees, reducers, pipe caps, flanged stubs, and union joints. 3.8 Pipe supports are structures that support pipes; through these supports, the loads and thrusts are transferred to the pipe rack. The pipe rack is composed of columns, beams, or frames made of steel structures or reinforced concrete structures; it can be fixed on independent foundations, as well as on equipment or walls. Classified by type, they include single-column, double-column, and cantilever types, etc.
Thank you for sharing. Are there any materials regarding which standards should or must be used under different operating conditions? What is the basis upon which design institutes determine which standards to adopt?