According to the American Welding Society (AWS), welding can be stated as, “The manner in which materials fit together.”
Welders must have an in-depth understanding of the various techniques and practices used in the industry to do their job successfully. And this includes welding joint types.
Among numerous pipes, joint types, fittings, flanges, valves, the socket weld fittings, and the butt weld fittings are the two popular and common types. They both are quite essential for various home improvement projects, but the applications may vary from task to task.
So, which one would be best for your construction projects between Butt Weld Vs Socket Weld?
This decision depends on your requirements. The butt weld has high strength with complete fusion. In contrast, the socket weld is easy to install and it is not necessary to bevel the pipe for preparing the socket weld.
What Is Butt Welding?
Butt welding is to attach two pieces of metal such as pipe, framework in factories, and flanges by heating up or applying pressure, or doing both.
The welding can either be automated or done by hand on steel pieces or can also be done with brazing for copper pieces. In factories, it is economical for companies to use when building things out of metal.
It is essential to maintain the penetration while welding, and with thin pieces of metal, this is possible. In butt welding, there are two specific types.
Butt welding is done with the Arc, TIG, or MIG welder held at a slight angle to increase the weld’s strength.
The metal’s surface area that is melted during the welding process is called the faying surface. This surface can be shaped before welding to enhance the strength, which is called edge preparation. This preparation may be alike or on both members, or you can shape each side differently of the butt joint.
What Is Socket Weld?
Socket weld(SW) is a pipeline insertion welding method, where a pipe is attached and fitted to the recessed part of a flange, fitting or sometimes a valve too. It is entirely in the periphery of the large pipe, and it is a fillet weld.
Socket welding elements have socket weld flanges and socket weld pipe fittings. Based on applications, different types of fittings contain 45/90 degree elbows, tees, caps, cross, coupling, union, socket.
These fittings are defined in ASME B16.11 standard. These are high-pressure pipe fittings and available in three pressure ratings – class 3000, class 6000, and class 9000. These fittings can be specially manufactured to suit users’ requirements in various stainless and special alloys. The flanges can be manufactured according to various standards such as ANSI/ASME B16.5, JIS B2220.
The standard encompasses the ratings for temperatures, tolerances, and pressures and gives huge information for material requirements for fittings with alloy steel and forged carbon.
Differences Between Socket Weld Fittings And Butt Weld Fittings:
Before going any further, take a glance at the butt weld vs socket weld chart to find out which one is right for you.
| Features | Socket weld | Butt weld |
| Diameters | Suitable for pipes with small diameters[less than DN50] | Suitable for both big and small diameters |
| Bevel in the ends | There should be a beveled end from 30 to37.5⁰ | There is no need of any angle at the end |
| non-destructive testing method | magnetic particle testing (MT) and penetrant testing (PT) | Ray inspection |
| Design | Doesn’t require that much effort | Requires more effort for designing |
| Easy-to-install | Yes | No |
| Strength | Less | More |
| Extra cost for welders or installation | Not that much | More than socket welding |
Different Diameters:
Socket weld is generally for welding pipes with small diameters – smaller than DN50, and the maximum diameter is DN100(or 4″). In contrast, Butt weld is widely used for both big and small diameters.
Welding Groove And Welding Seam:
Usually, for butt welding, there should be a beveled end from 30 to 37.5° to fill the welding bead. There will be a compound beveled end for super thick walls.
On the other hand, socket welding doesn’t need an angle, and it can directly weld the part. The seams are fillet welds.
Various Non-Destructive Testing:
There are two non-destructive testing methods for socket welding – magnetic particle testing (MT) and penetrant testing (PT). The magnetic particle testing is for carbon steel parts, and the penetrant testing for stainless steel parts.
In contrast, the butt welding shall be 100% tested to ensure no leakage, and it is necessary to do the radiographic inspection.
Actually, butt welding requirements are higher than socket welding requirements as well as the testing requirements.
Cost:
Usually, the socket weld fittings price is more than butt weld fittings. That being said, butt welding fitting will need extra cost as it is more difficult to weld and fit-up properly and would require more time and the expertise of skilled welders.
Socket Weld Vs Butt Weld – Which One To Choose?
The choice depends on one’s requirements, preferences, and budget.
According to the weld’s strength and the force condition, butt welding is better than socket welding.
Socket weld is easy to install, but it requires approx. 1/16″of gap at the bottom of the pipe to allow thermal expansion. However, there might be cracks in the fitting. And socket weld is troublesome in corrosive fluid service due to crevice corrosion.
Butt weld is praiseworthy in terms of strength, corrosion resistance, fatigue, and temperature compliance. However, it is tough to fit-up and weld properly, which needs skilled welders and much time.
If we compare butt weld vs socket weld – both the pressure level and the cost of the socket welding are higher than that of butt welding.
The issue of a socket weld system is the expansion gap and the space between the OD of the pipe and the fitting ID. By corrosive products, and mainly in stainless steel pipe systems, the crack between pipe and flange, fitting, or valve can encounter corrosion problems.
For service applications, where complete weld penetration to the inside of the piping is required, socket welds are not acceptable, and generally, butt welds can be done.
Why You Should Choose Butt Welding:
Butt welds provide several advantages, such as –
- High strength with complete fusion
- The welded metal cannot go through the pipe bore. So, leakage risk is much lesser than the threaded fittings.
- Distortion control
- Easy to inspect
Why You Should Not Go For Butt Welding:
There are some drawbacks as well:
- Welding geometry can limit applications
- Sensitive to faying surface conditions
- Fixturing or backing may be required
Why You Should Go For The Socket Welding:
- It is not necessary to bevel the pipe for preparing the socket weld.
- The cost for constructing them is lower since the exact requirements or skilled welders are not needed.
- Fatigue resistance may be lower than that in butt-welded construction for the fillet welds and abrupt fitting geometry. However, it is still better than that of most mechanical joining methods.
- Tack welding is no needed for alignment as the fitting ensures proper alignment.
Why you should not go for Socket weld Fittings:
- There is a space in the internal crevices and, they are not preferred for radioactive and corrosive purposes since this buildup of material can cause problems in its operation.
- Socket welding is not recommended for Ultrahigh Hydrostatic Pressure (UHP) in Food Industry application as they do not permit full penetration and leave overlaps and crevices that are challenging to clean, creating virtual leaks.
FAQs
Why should there be a distance between two welds in a pipe?
The gap is there to prevent the overlap of heat-affected zones.
What is the minimum distance to be maintained between two welds in a pipe?
The thumb rule to the minimum distance between adjacent butt welds is 1D. If not, it is never closer than 1-1/2″. If your pipe is 3″ NPS the distance should be 4″. If this is not possible, it should not be less than 1½”.
The lowest spacing of circumferential welds between centerlines should not be less than four times the pipe’s wall thickness of 25 mm, whichever is greater.
Final Words
Which is the winner of this welding battle of butt weld vs socket weld, according to you? Keep in mind the caveats and always check if there is any leakage in your pipes. Let me know in the comment section about your favorite welding type!
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