Socket Weld Fittings and Their Uses

The four different types of connectors for pipe fittings are known as slip-on flanges, threaded flanges, socket welds (counterbore), and butt weld necks.

Slip-on flanges are the most common type. Buttweld fittings and socket weld fittings are two kinds of steel pipe fittings that are often used for pipeline construction projects.

Since each of them seems to have its own unique mix of advantages and disadvantages, you may not be able to decide which one is best for achieving the specific goal you have in mind.

Definition Of The Terms Used in Socket Weld Fittings

A pipe connection feature known as a socket weld is created by putting a pipe into a depression that is already present in a fitting, a valve, or a flange. In contrast to buttweld fittings, socket weld fittings are often used for piping with a nominal diameter of NPS 2 or less, which is referred to as “small bore pipes.” Socket-weld fittings are typically employed for pipes with smaller diameters.

The term “socket weld fitting” refers to an attachment detail for pipes that has a socket as well as a counterbore. In this scenario, the pipe may be positioned such that it fits into a fitting that has a depression in it.

In order to join valves or pipes to other components of the pipe, fillet welds should be welded together and then sealed. When it comes to a lot of different applications, socket weld fittings are a fantastic option.

When planning your pipeline construction project, it is important to think about the many benefits that come with high structural strength and low leakage.

Pipe may be joined to other lengths of pipe, as well as valves and fittings, using a particular sort of seal weld called a fillet weld.

When the advantages of superior leakage integrity and structural strength are relevant to design considerations, socket-welded connections are a suitable option. This may be the case if structural concerns are vital.

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Using Socket Weld Fittings in Applications

  • Socket-weld fittings are adaptable to a broad variety of industrial uses and are designed to withstand low to medium pressure in confined spaces. They may be used in a wide range of situations.
  • This strategy is used when it is determined that the pipe will be in place permanently. They also have excellent flow properties because of the design process that went into their creation.
  • When used with a separate ASME pipe, which can be bought separately, the pipe’s diameter can be changed.
  • Reducers, tees, elbows, and other socket-welded pipe fittings may be used in pipelines to carry expensive, flammable, or hazardous items where there is no danger of leaking. These types of products can be transported in pipelines since there is no chance of them spilling.

There Are Several Different Types of Socket-Welded Pipe Fittings

Like butt weld fittings, socket weld fittings come in a variety of materials, such as carbon steel flanges, alloy steel flanges, and stainless steel pipe fittings.

Socket-weld fittings may also be used in conjunction with butt-weld fittings.

Depending on the specifics of the application, it may include items like flanges, couplings, reducers, reducing tees, socket weld inserts, and socket weld elbows.

Advantages and Disadvantages

The socket weld has a number of advantages and disadvantages, which are as follows:

  • For the pipe end to be ready for an insert weld, it doesn’t have to be thoroughly polished every time.
  • While doing temporary tack welding, alignment is often not necessary. This is due to the fact that adhering to the fitting principle will help to ensure that the alignment is precise.
  • Because of its shape, the socket weld inserts won’t be able to fit through the pipe bore.
  • It is possible that construction costs could be lower than those for connections that are butt-welded. Because it doesn’t have the right tools, it doesn’t meet the requirements for a perfect fit-up bevel.


  • It is the responsibility of the welder to guarantee that the expansion gap between the pipe and the socket shoulder is a predetermined distance, which is often somewhere in the range of 1.6 millimeters.
  • Corrosion might be encouraged by some media because of the expansion gap and internal fractures that are present in the socket weld system.
  • Because of this, it has been determined that they are not appropriate for use in environments that are corrosive or radioactive.
  • In the food industry, these kinds of fittings can’t be used with very high water pressure.
  • There are a few possible explanations for this, one of which is that the addition blocks total penetration. In addition to that, it would create gaps and fractures, making it more difficult to clean.

Application of Socket Weld Fittings

But weld fittings have a higher strength resistance than socket weld fittings, which have a lower strength resistance.

When they are available, SW fittings are often put to use for very small pipelines that have NPS 3 or below pipe widths.

When it comes to SW fittings, the installation process is rather simple. As a result of the fact that it typically takes around 1/6 inch of the gap at the bottom of the gap to enable socket access, it makes thermal expansion easier.

On the other side, the gap may result in overstressing concerns, which might lead to the fitting’s fillet weld being cracked.

In addition, it has been shown that socket welding is problematic in the service of corrosive fluids because crevice corrosion may occur. It is necessary to do an evaluation of the application’s medium.

The Differences Between Buttweld and Socket Weld Fittings

ASME B16.11 is the reference standard for socket weld fittings. A pipe may be placed into the hidden part of the fitting.

The pipe and fitting may both be square-cut without the requirement for a beveled end or any further preparation other than cleaning the outside. It will make welding and installation activities easier.

When it comes to buttweld fittings, the ends that are welded onto the pipe ends must have the same thickness as the pipes, according to ASME B16.9. In this case, the fittings’ ends might be polished to match the purpose.

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