What is Pipe Joint?
Pipe joints in water supply are major components of plumbing system provided to connect multiple pipes. There are several types of pipe joints, but their selection depends on pipe sizes, material and flow pressure etc..
Pipe joints are connections at pipe ends that ensure that two pipe sections can be joined to each other to install a pipeline of any length.
Joints give strength to the pipeline because longer pipeline sections tend to bend. Joints should be joined together properly to ensure that a tight seal is established to prevent leakage.
Pipe joints are integral to any piping system because it is not possible to have a continuous length of pipe for a pipe network. These joints can make or break a pipeline system depending on the resulting durability of the technique used to form the joint.
There are different materials of pipes used in the pipeline industry depending on the need and the type of product that will be conveyed through the pipe.
Types of Pipe Joints
Believe it or not, there are several different types of pipe joints. All of them hold a different purpose. Depending on the situation and system that is going to be installed, things like pipe size, material, and flow pressure play a part in what kind of pipe joints will be used.
Let’s go review the different types and determine what sets them apart from each other.
- Threaded joint
- Brazed joint
- Soldered joint
- Welded joint (butt welded, socket welded)
- Flanged joint
- Compression joint
- Grooved joint
#1. Threaded joint in Pipe
Threaded pipe Joint is one of the common types of Pipe joint, in this type of joint, pipe are connected by screwing with the help of threads which are provided for end of each pipe.
The only difference in the thread is One pipe having internal threads and the other one having threads externally. This method provides a secure and leak-resistant connection.
Threaded pipe joints are commonly used for connecting Cast iron pipes, copper pipes, PVC, steel, or other metal pipes in various plumbing, industrial, and commercial applications.
Threaded joints are available from 6mm diameter to 300mm diameter pipes. They are preferable for low temperature areas and low pressure flows.
In the areas of high temperature, the joints may expands and leaked due to thermal expansion. Installation of threaded joint is easy but good maintenance required.
This makes sense because we commonly see threaded joints used for water supply for our shower, toilet, sinks, etc.
They are used in applications where easy assembly and disassembly are necessary, or where welding is not preferred.
#2. Brazed joint in Pipe
Brazing is the process of jointing pipes using molten filler material at above 840oC. Brazing is generally used for joining copper pipes or copper alloy pipes.
The filler material majorly consist tin which has great affinity towards copper. But because of its weak property tin is added to other materials like nickel, bismuth, silver and copper.
The melting point of parent metal should be higher than filler metal. Mechanical strength of brazed joint is low compared to other joints. This type of joint is suitable in moderate range of temperature areas.
Unlike welding where the base metals melt, in brazing, the base metals remain solid. Brazing is commonly used for joining materials like copper, brass, steel, aluminum, and other metals and alloys.
Brazed joints find applications in various industries, including automotive, aerospace, electronics, HVAC (heating, ventilation, and air conditioning), plumbing, and manufacturing.
Common applications include joining refrigeration components, electrical contacts, plumbing fittings, and assembly of intricate components in manufacturing.
#3. Soldered joint in Pipe
A soldered joint is a common type of pipe joint used in plumbing, particularly with copper pipes. Soldering is also similar to brazing but the only difference is in case of soldering the filler metal melts at below 840oC. Soldering also used to joint copper and copper alloy pipes.
Before proceeding to soldering flux called paste is applied to pipes and fittings to prevent them from oxidation from flame. Here also we require skilled workers for installation.
Soldered joints are suitable for low temperature areas. These are having low mechanical strength as brazed joints.
Soldering is widely used for copper pipes in water supply systems due to its effectiveness, strength, and reliability.
Soldered joints are primarily used for joining copper pipes in water supply systems, heating systems, and other plumbing applications.
#4. Butt Welded Joint in pipe
In plumbing Butt welding is used to join the Pipe together when the pipes are the same diameter. In other words, both end are connected together right at the end with no overlap.
It is the most common type of welding. Skilled workers are required to install the joint. These joints are generally used for large commercials and industrial piping systems.
Butt weld provides good strength for the joint and it can resist high pressure because of smooth and continuous surface inside the joint.
Butt weld joints are expensive, to make it economical sometimes internal weld backing rings are used, which joins the pipe with less amount of filler material. But these rings may fail under heavy stress and cracks are developed.
The joints are fixed and do not opened for maintenance purposes. External smoothing of welded portion will give good appearance to the piping system.
Butt weld joints are widely used in various industries, including oil and gas, chemical processing, power generation, and shipbuilding.
#5. Socket Welded Joint in Pipe
Socket welded joints are used wherever there is a high chance of leakage in joints. This joint is the opposite of a butt welded joint because this type is suitable for pipes with different diameters. For this, you put one pipe into the other, so there is overlap.
If pipes having similar diameter, then required fittings are used. Welding cost is generally lower than butt welding. Fatigue resistance is lower for socket welded joints when compared to butt weld joints. However, socket welded joint give good results when compared with other mechanical joints.
Socket weld joints are commonly used in smaller pipe sizes for applications such as petrochemical plants, food processing, and instrumentation systems.
#6. Flanged Joint in Pipe
Flanged joints are specifically used for pipes in large diameter as well as high pressure flows. In general they are used for plain end pipes or threaded pipes. A flanged joint in a pipe is two flange components that are connected together using bolts at the joint to prevent leaking.
Generally these are made of cast iron, steel etc. these are having good strength and do not fail against high pressure.
Against high temperatures the bolts may fail under creep lost their grip so, fixing of bolts should be done properly while installing. They are also useful for repairing pipelines and maintenance purposes.
Flanged joints are popular in a wide range of industries due to their strength, versatility, and ease of assembly and disassembly.
#7. Compression Joint in Pipe
When the pipes have plain ends they are joined by installing some fittings at their ends then that type of joint is called compression joint. The pipe ends will be fitted with a threaded fittings or couplings hence they are connected.
So, in this case we can connect pipes of different materials and different sizes. But the joints should be properly fitted to resist flow pressure otherwise they may fail and leakage occurs.
Compression fittings are available in different materials and selection of fittings may depend upon our requirement.
#8. Grooved Joint in Pipe
In case of grooved joint, the pipe ends consist grooved edges which are connected by elastomer seal and then ductile iron made grooved couplings are used as lock for elastomer seal. This grooved couplings are connected by bolts. These joints are easy to install and economical.
Grooved joints will give good resistance against pressure and allows moderate axial movement due to thermal expansion. But, in high temperature Areas elastomer seal may lost its strength and torsional failure occurs. So, these are permitted to moderate temperature areas.