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A Socket Weld Fitting is a pipe attachment detail in which a pipe is inserted into a recessed area of a valve, fitting or flange.
In contrast to buttweld fittings, socket weld fittings are mainly used for small pipe diameters (Small Bore Piping); generally for piping whose nominal diameter is NPS 4 or smaller.
To join pipe to valves and fittings or to other sections of pipe, fillet-type seal welds be used. Socket-welded Joints construction is a good choice wherever the benefits of high leakage integrity and great structural strength are important design considerations.
Fatigue resistance is lower than that in butt-welded construction due to the use of fillet welds and abrupt fitting geometry, but it is still better than that of most mechanical joining methods
SW Fittings are family of high pressure fittings are used in various industrial processes.
Description | Class Designation | ||
3000 Lbs | 6000 Lbs | 9000 Lbs | |
Elbows 45 degree, Elbow 90 degree, Tees, Crosses, Couplings, Half-Couplings, End or Pipe Caps |
½ - 4 | ½ - 2 | ½ - 2 |
½ - 4 | ½ - 2 | ½ - 2 | |
½ - 4 | ½ - 2 | ½ - 2 | |
Pipe Size by Wall Thickness |
SCH 80 & XS | SCH 160 | XXS |
Plugs and Bushings are not identified. They may be used up through Class 6000 NPS
• ADVANTAGES AND DISADVANTAGES OF SOCKET WELD FITTINGS
--Advantages
1. The pipe need not be beveled for weld preparation.
2. Temporary tack welding is no needed for alignment, because in principle the fitting ensures proper alignment.
3. The weld metal can not penetrate into the bore of the pipe.
4. They can be used in place of threaded fittings, so the risk of leakage is much smaller.
5. Radiography is not practical on the fillet weld; therefore correct fitting and welding is crucial. The fillet weld may be inspected by surface examination, magnetic particle (MP), or liquid penetrant (PT) examination methods.
6. Construction costs are lower than with butt-welded joints due to the lack of exacting fit-up requirements and elimination of special machining for butt weld end preparation.
--Disadvantages
1. The welder should ensure for a expansion gap of 1/16 inch (1.6 mm) between de pipe and the shoulder of the socket.
ASME B31.1 para. 127.3 Preparation for Welding (E) Socket Weld Assembly says:
In assembly of the joint before welding, the pipe or tube shall be inserted into the socket to the maximum depth and then withdrawn approximately 1/16" (1.6 mm) away from contact between the end of the pipe and the shoulder of the socket.
2. The expansion gap and internal crevices left in socket-welded systems promotes corrosion and make them less suitable for corrosive or radioactive applications where solids buildup at the joints may cause operating or maintenance problems. Generally require butt welds in all pipe sizes with complete weld penetration to the inside of the piping.
3. Socket weld is unacceptable for UltraHigh Hydrostatic Pressure (UHP) in Food Industry application since they do not permit full penetration and leave overlaps and crevices that are very difficult to clean, creating virtual leaks.
The purpose for the bottoming clearance in a socket weld is usually to reduce the residual stress at the root of the weld that could occur during solidification of the weld metal, and to allow for differential expansion of the mating elements.
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Yaang Pipe Industry Co., Ltd. is an international supplier of piping solutions for flange, butt welding fittings, socket welding fittings and threaded fittings. Our products are widely used in different industrial fields, including oil and gas, chemical industry, petrochemical industry, power plant, pulp and paper industry, environmental and water conservancy engineering, engineering projects, etc.