Over the decades, welding techniques have expanded and branched to cover a greater number of scenarios. The result of this proliferation is that there are today dozens of different welding techniques and methods. Even the types of welds have expanded and become more intricate.
Today, there are five popular welding joints:
A socket weld and a butt weld are inherently different types of joints that are used for different applications. Let’s begin with socket welds.
A socket weld is almost exclusively used for pipe fitting and welding, joining pipes of different size. A socket weld is created by inserting the smaller pipe into a recessed area of the larger pipe (fitting). Socket welds are on the simpler side of joints and can be made rather easily. On top of this, socket welds do not require much preparation such as beveled ends and can be done after simply cleaning the fitting and the weld area.
While socket welds have many benefits, strength is not one of them. Due to its design, socket welds cannot sustain a lot of weight or pressure (relative to butt welds) and are thus much better suited for smaller pipe fitting projects.
As mentioned earlier, butt welds join two objects by welding from one end to the other. Butt welds come in various types, usually depending on the type of bevel created. One of the similarities that butt welds share with socket welds is that both can be used to join pipes, albeit differently. However, unlike socket welds, butt welds can only be used on pipes with the same diameter and with the same thickness.
The ends of pipes with different diameters or thickness will not be congruent and thus a perfect, clean butt weld is not possible. Furthermore, the pipe ends that are joined are beveled and thus require more preparation.
To help you navigate through the differences between socket welds and butt welds, we’ve laid out the differences between these two popular welding joints on the basis of important welding criteria:
Socket welds have the upper hand in this aspect as they can be used to connect pipes of different sizes and thicknesses. However, this does not mean that socket welds can be used to join pipes of any size. Due to inherent design limitations, socket welds are usually limited to small pipelines (small bore piping) with diameters less than NPS2 or DN50.
On the other hand, butt welding offers welders more freedom as even pipes with larger diameters can be welded together as long as they are similarly sized.
Socket welds are fairly strong and reliable. They are often used for pipes that transport everything from toxic materials to expensive liquids that cannot be leaked. They are also used for steam under 600 PSI. Socket weld pipe fittings also come in different pressure ratings, commonly 3000, 6000, and 9000.
However, if it’s pure strength that you’re looking for then butt welds win. In terms of pure strength, durability, and corrosion and temperature resistance, butt welds are better than socket welds. In most cases, butt welded joints will be almost twice as strong as socket welds.
Butt welds require significantly more preparation and welder skill. Most butt welds will also require a beveled end at an angle between 30 or 37.5 degrees for the welding bead to be filled. Socket welds, on the other hand, require minimal preparation, usually limited to cleaning the workpiece, and basic welding skills.
Testing and inspection is another important aspect that needs to be considered when choosing between socket welds and butt welds as both of these types of joints are different when it comes to testing and inspection.
For non-destructive testing, socket welding offers magnetic particle testing and penetrant testing as two options. There is only one non-destructive testing option available for butt welds which is X-ray inspection.
Butt welds are more expensive to create, install, test and maintain. Since socket welds are relatively much simpler in both design and maintenance, they will almost always be the cheaper alternative.
In a nutshell, butt welds are a more versatile type of joint that offers greater strength and reliability. However, there is a direct cost associated with these benefits and they require a higher skill level and budget to produce. Whereas socket welds are more affordable but are very limited in their applications, often only used for small bore pipe fitting.