Pipes and tubes are connected with butt weld fittings (BWF). They are also known as pipe fittings, pipe clamps, and pipe junctions. Tube clamps, tube connectors, and elbow joints are all the butt types of weld fittings. Pipe and tube systems of different diameters can be joined using pipe butt welding fittings. The number of butt joints required depends on the system size. The joints are fused or butt welded at the ends to prevent leakage. 

Butt weld fittings are rectangular or round objects (called bodies). There are a variety of materials that can be used for pipe fittings, including copper, brass, aluminum, and stainless steel. Depending on the joint and region, they are made from different materials. Fittings are available in universal sizes to fit any pipe or butt weld tube fittings size. 

The tubing is soldered to the fitting and then inserted into a pipe where it can be connected to other sections of the pipe. Assembling the fittings correctly may take several minutes and require some skill. In time, hopefully, everyone gains efficiency with practice.

What is a Butt Weld Fittings

Welding is used to connecting the ends of pipes or fittings. Weldable steel pipe fittings can be used to branch off, change the direction of flow, attach auxiliary equipment, or reduce pipe size.

Forged steel butt weld fittings are manufactured according to ANSI/ASME B16.9.

Check the differences between socket weld fittings.

Also known as welded pipe fittings

Welded pipe fittings are also known as butt weld fittings. Compared to socket welds and threaded fittings, these would offer certain advantages when used in stainless steel and carbon steel. 

Unlike socket weld fittings, butt weld fittings come in sizes starting at 1/2 inch up to 72 inches.

There are several types of Butt weld pipe fittings, like the general category of pipe fittings:

Elbows with 45-degree or 90-degree buttwelds

Tees and Reducing Tees, Reducers, Caps, and Crosses for buttwelding

Butt weld Elbow

The butt weld elbow is used to change fluid direction in pipeline systems. It has long radius (LR) and short radius (SR) types and has different degrees covering 45 degrees, 90 degrees, and 180 degrees. As a result, there are:

LR 45-degree butt weld elbow:

45-degree elbow with a long radius (1.5 x diameter) and a 45-degree change in fluid direction.

LR 90-degree elbow:

Long radius 90-degree steel pipe elbow (1.5 x Diameter).

SR 45-degree elbow: Short radius (1 x diameter) elbow in 45 degrees, changing direction.

SR 90-degree elbow: elbow with a short radius (1 x Dia).

180-degree steel pipe tee

More than a 90-degree elbow we will call it a steel bend. Like LR/SR 180-degree bend.

In accordance with ANSI, butt weld elbow pipe fitting dimensions may be specified as diameter (in NPS) and thickness, samples as LR 90 degree elbow 4 inches and schedule 40 or schedule 80 thickness.

Butt weld Te

With its 90-degree branch along with a straight pipe, the Butt weld tee provides a connection for installing additional equipment to a pipeline. By using the tee structure, the same sides of the ends could be butt welded fittings to the pipe, and 90 branches were left open for welding another pipe.

Butt weld Equal Tee

Butt weld Reducing Tee

Similar to an equal tee, the 90-degree branch has a smaller diameter than the straight pipe. It is used to install equipment or pipes that are smaller in size.


Common material types of butt weld fittings

Like socket weld fittings, butt weld fittings are now available as elbows, tees, outlets, reducers, and caps. These are some of the most common types of butt weld fittings and would be specified according to the schedule of pipe and nominal pipe fittings.

Body material

Butt weld fittings come in alloy, stainless, and carbon steel materials. Therefore, it usually starts with welded or seamless pipes. Multiple processes can be used to forge tees and elbows, among other shapes, by forging.

Stainless steel butt weld fittings are usually in thin thickness

As with normal pipes, butt weld fittings are available from Schedule 10 to Schedule 160. Butt weld fittings are more common in stainless steel. The reason for this would be its cost advantage. In stainless steel fittings, schedule 10 fittings would also be more common.

Carbon steel butt weld fittings

A234 WPB (most common) and WPC, MSS-SP-75 WPHY, and a schedule 40 steel pipe fitting, STD, or 80, with pressure classes ranging from 1500 psi, 2500 psi, 3000 psi, 6000 psi, and 9000 psi.

Alloy steel butt weld fittings

Material for alloy steel butt welds is usually ASTM A234 WP1, WP5, WP9, WP11, WP22, WP91, etc.

Classified by pipe fittings dimensions

Dimensions of but weld fittings pipe are based on ANSI B36.10 and B36.19 standards.

Diameter range: 1”, 2”, 3”, 4”, 6”, 8”, and up to 36”.

Thickness range: Schedule 10, schedule 40, schedule 80, XS, XXS, and SCH 160

Butt weld fitting dimensions consist of diameter in NPS and thickness in the schedule.

Concentric reducers, eccentric reducers, long radius elbows, and tees. These fittings can be used in construction projects for a variety of reasons, including branching off, changing the direction of flow, or mechanically connecting equipment to the system. Butt weld fittings would be sold according to a pipe schedule.

Key steps in the manufacturing process are as follows:

  • Planning: based on fitting specifics and client requirements; includes creating part identification in the manufacturing system.

  • Selection of raw material: metal; plate or pipe.

  • Cutting

  • Heating.

  • Forming.

  • Welding: for fittings that are not simple elbows, returns, bends, reducers or caps.

  • Inspection and tests: according to standards and client requirements.


How a butt weld fitting is made

Hot forming would be used to make this type of pipe fitting. This would involve bending and forming the pipe. This fitting would be made from a pipe that would first be cut to length. Using dies, this would then be heated and molded into specific shapes. To achieve the desired mechanical properties and remove residual stresses, heat treatment would also be performed.

Benefits of butt weld fittings

  • The welded connection would help to get a more robust connection
  • Continuous structure of metal would add to the strength of the piping system
  • When butt weld fittings are matched with the appropriate pipe schedules, they provide seamless pipe flow
  • Various turn radii are available by using Long Radius, Short Radius, or 3R elbows
  • Found to be cost-effective compared to the socket weld or threaded counterparts
  • These fittings would be available in Schedule 10, thus allowing for a thinner wall option
  • Schedule 10 and Schedule 40 configurations are more common for these fittings.

Butt Weld Fittings Have Beveled Ends Treatment

As per ASME B16.25 standards, all butt weld fittings will have beveled ends. By doing this, it would be possible to create a full penetration without having to make any additional preparations.

Stainless steel, carbon steel, alloy steel, aluminum, nickel, and high-yield materials are the most commonly used materials for these types of fittings.

Functions Of Butt Weld steel Pipe Fittings

For stainless steel and carbon steel, butt weld pipe fittings would be the joining components. By doing so, pipes, valves, and equipment could be assembled onto the piping system. Besides complementing pipe flanges in any piping system, butt weld fittings also allow:

  • Change the direction of flow in a piping system
  • Join or connect equipment and pipes
  • Provide access, branches, and takeoffs for auxiliary equipment.

A common example would be to use buttweld pipe fittings on a pipe that is being reduced by a concentric reducer. In order to connect this to equipment, it would be welded fittings to a weld neck flange.

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