For Small Pipe Diameter Up To And Including Dn40 Stainless Steel 321 Socket Weld Fittings

The difference between socket weld and counterpart weld is as follows:

1. The fillet weld is formed by socket weld, while the butt weld is formed by butt weld. From the strength and stress of the weld, the butt joint is better than the socket joint. Therefore, the butt joint should be used in high pressure level and bad service condition.

2. Socket weld is generally used for small diameter pipe less than or equal to DN40, which is more economical. Butt weld is generally used for DN40 or above. Socket weld is mainly used for weld small caliber valves and pipes, fittings and pipes. Small-caliber pipelines are generally thin-walled, prone to edge misalignment and ablation, and difficult to butt weld, which is more suitable for socket weld. In addition, socket welded sockets have a reinforcing effect, so they are often used under high pressure. However, socket weld also has its shortcomings. One is that the stress condition after weld is not good, and it is easy to occur that the weld is not penetrated, and there are gaps in the pipe system. Therefore, socket weld is not suitable for the pipeline system used for the sensitive medium of crevice corrosion and the pipeline system with high requirements for cleanliness. Furthermore, the wall thickness of ultra-high pressure pipeline is very large even if it is small diameter, so butt weld can be used to avoid socket weld as far as possible.

3. The diameter of the former must be large or small before it can be inserted into weld. The diameter of the latter can be the same or different.

4. weld groove forms are different.

5. weld process is different. The strength after weld is different.

6. The lower pressure level and smaller caliber are mostly socket weld, while the higher pressure level is usually butt weld. The butt weld needs 100% flaw detection test to ensure no leakage.

7. As the name implies, socket weld is to insert the pipe into the weld, butt weld is directly opposite to the pipe mouth weld. Generally, the requirement of butt weld is higher than that of socket weld, and the quality after weld is also good, but the detection method is relatively strict. Radiographic inspection is needed for butt weld, magnetic powder or penetration inspection for socket weld (such as carbon steel for magnetic powder and stainless steel for penetration). If the requirement of fluid in pipeline for weld is not high, socket weld is suggested to be used to detect the advantages of convenient socket weld: no grooving problem; no misalignment problem; the weld position can be adjusted to flat weld.

Socket and socket fittings are mainly formed by round steel or ingot die forging blank, and then processed by lathe forming a high-pressure pipe connection fittings.

Socket weld

Socket weld is to extend the pipe into the valve body for welding. After forming, the shape of socket weld is similar to that of the internal thread connection. Generally speaking, under 2 "carbon steel pipe and stainless steel pipe, socket weld is used more; under 2" stainless steel pipe also has butt weld, such as flange flange of sliding sleeve; titanium pipe, dual-phase steel, nickel-based alloy and so on are basically butt weld.

Commonly used raw materials for socket weld are carbon steel, stainless steel, alloy steel, etc.

Common grades of carbon steel: Q235, 20, A105, etc.

Common grades of stainless steel: 304, 304L, 316, 316L, 321, 00Cr17Ni14Mo2, etc.

Common grades of alloy materials: 15CrMo, 1Cr5Mo, 16Mn, 12Cr1MoV, F11, F22, 10CrMo910, etc.

Other Material: Copper Alloy, Nickel Alloy, etc.