Where to get high quality socket welding flanges?
Socket Weld Flanges (SW Flanges) are similar to slip-on flanges in outline, but the bore is counter-bored to accept pipe. The diameter of the remaining bore is the same as the inside diameter of the pipe. The positive of this is that is creates a smooth bore with the proper welding and grinding. The negative of this type of flange is that it can be more expensive than a slip-on due to more intricate machining, and they can be less readily available than slip-ons due to the fact that the bottom half of the inside diameter must be made to the same schedule as the pipe that is being used. (you must specify the schedule needed) These socket weld flanges were initially developed for use on smaller sizes of pipe at higher pressure ratings.
Socket Weld flanges are typically provided with a raised face, flat face, or RTJ facing. When a raised face is necessary for socket weld pipe flanges, the standard height is 1/16 inch for socket weld pipe flanges less than 400#. For socket weld pipe flanges of 400# and up, the standard socket weld pipe flange raised face height is 1/4 inch.
The socket welding flange is similar to a slip-on flange except it has a bore and a counterbore dimension. The counterbore is slightly larger than the O.D. of the matching pipe, allowing the pipe to be inserted into the flange similar to a slip-on flange. The diamter of the smaller bore is the same as the I.D. of the matchine pipe A restriction is built into the bottom of the bore which sets as a shoulder for the pipe to rest on. This is eliminates any restriction in flow when using a socket welding flange.
Socket Weld flanges were initially developed for use on small-size high pressure piping. Their static strength is equal to Slip On flanges, but their fatigue strength 50% greater than double-welded Slip On flanges.
The connection with the pipe is done with 1 fillet weld, at the outside of the flange. But before welding, a space must be created between flange or fitting and pipe.
ASME B31.1 1998 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assembly of the joint before welding, the pipe or tube shall be inserted into the socket to the maximum depth and then withdrawn approximately 1/16″ (1.6 mm) away from contact between the end of the pipe and the shoulder of the socket.
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. The image shows you the X measure for the expansion gap.
The disadvantage of this flange is right the gap, that must be made. By corrosive products, and mainly in stainless steel pipe systems, the crack between pipe and flange can give corrosion problems. In some processes this flange is also not allowed. I am not an expert in this matter, but on the internet, you will find a lot of information about forms of corrosion.
Also for this flange counts, that principle always firstly a pipe must be welded and then just a fitting.
DETAILS OF SOCKET WELD FLANGE
1. Socket Weld flange 2. Filled weld 3. Pipe
X = Expansion gap
Dimensional Tolerances of Weld Neck Flanges ASME B16.5
Socket Welding Flanges, SW Flange
The counterbore is slightly larger than the O.D. of the matching pipe, allowing the pipe to be inserted into the flange similar to a slip-on flange.
The socket welding flange is similar to a slip-on flange except it has a bore and a counterbore dimension.
The diamter of the smaller bore is the same as the I.D. of the matchine pipe A restriction is built into the bottom of the bore which sets as a shoulder for the pipe to rest on.
This is eliminates any restriction in flow when using a socket welding flange.
Standards, Dimensions & Weight
The Socket Welding Flange is attached to the pipe by a fillet weld around the hub of the flange. An optional internal weld may be applied in high stress applications.
- ASME/ANSI B16.5 Class 150 SW
- ASME/ANSI B16.5 Class 300 SW
- ASME/ANSI B16.5 Class 600 SW
- ASME/ANSI B16.5 Class 1500 SW
Specifications of Socket Welding Flanges:
This flange type will be welded to a pipe or pipe fitting with a single full penetration, V weld (Buttweld).
1. Weld Neck flange 2. Butt Weld3. Pipe or Fitting
Size: 1/2” to 60”, DN 12mm to DN 1500mm
Pressure class: Class 150 to Class 2,500, PN 2.5 to PN 250
Facing: RF / RTJ
Material of Socket Welding Flanges:
Cabon steel: A105, A350 LF2
Stainless steel: A182 F304/F304L/F316/F316L/F321
Alloy steel: F11, F12
Packing: plywood case and plywood pallet
Advantages and disadvantages of Socket Weld fittings
The pipe need not be beveled for weld preparation. Temporary tack welding is no needed for alignment, because in principle the fitting ensures proper alignment.
The weld metal can not penetrate into the bore of the pipe.
They can be used in place of threaded fittings, so the risk of leakage is much smaller. 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.
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.
- The recess on the inside diameter of the socket weld flange allows for a good fit of the pipe allowing for a smooth flow of liquid.
- Socket welding flanges work well for smaller sizes and higher pressure temperature conditions.
- They are similar to slip-on flanges, but must specify the schedule of the pipe where they will be used for with socket welds.
Uses of socket weld flanges:
- They are ideal for small diameter applications.
- They are used for high pressure applications.
- Socket weld flanges have an internal recess on the inside diameter which allow for a smoot flow of the process fluid.
- They create a smooth bore with the proper welding and grinding.
The differences between socket welding and butt welding
Socket welding can be used for pipes with small diameters, and it is generally applied to pipes or pipe fittings whose diameters are less than DN50.
Butt welding is widely used for pipes with big and small diameters, and threaded welding or socket welding is used for pipes with small diameters.
Usually, there should be a beveled end from 30 to 37.5° for butt welding in order to fill the welding bead. Of course, there will be a compound beveled end for super thick walls.
Socket welding doesn’t require a bevel, and it can directly weld the part.
3. Welding seams
Socket welding seams are fillet welding seams.
Butt welding seams are butt welding seams, and the requirement for butt welding is high.
4. Non-destructive testing
The non-destructive testing methods for socket welding are magnetic particle testing and penetrant testing. Penetrant testing is used for stainless steel parts and magnetic particle testing is used for carbon steel parts. The testing method of butt welding is 100% ray inspection.
Source: China Socket Welding Flanges Manufacturer – Yaang Pipe Industry Co., Limited (www.metallicsteel.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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