The Advantages and Disadvantages of Using Weld Neck Flanges
Weld neck flanges are flanges that are designed to be integrated into piping systems by what industry welders describe as butt welds. The production of these flanges is more expensive because of the long necks that are present. Weld neck flanges are preferred for use in high-stress applications. By welding pipe to the neck of the flange stress is transferred to the pipe. The inside diameter of the flange is machined to match the inside diameter of the tube reducing friction and obstruction of flow. The flanges are also available in some different types of material such as copper, stainless, cast iron, galvanized steel, as well as aluminum. There some advantages when we use this kind of flange along with just a few disadvantages.
Weld Neck Flange Advantages
Suitable for high pressure and high heat applications:
Some of the flange materials such as stainless steel are highly resistant to heat. The extreme pressure that is developed in piping applications throughout the industry calls for high-pressure resistance. A welded flange is stronger that a bolt-on flange. The bolt-on flange sometimes calls for a gasket that could cause leaks.
Reduced friction and interference:
The welded connection will not interfere with the flow of the fluid. With the reduced friction, the fluid will not develop turbulence allowing for less vibration and a smoother flow. Less turbulence will also allow for a quieter operation.
Easier Alignment:
The neck of the flange will allow for a more accurate easier alignment to the pipe saving time. The alignment is also much more precise with less tolerance.
Testing of the pipe and joints are easier:
Radiography test can be much easier to perform because of the easy access the flanges allow.
Durable connection:
Stress on the inside is transferred to the neck of the flange taking the pressure off the pipe allowing for a more permanent connection.
Leakage prevention:
In most applications using the weld neck flanges, the weld is made inside and outside of the flange. This will provide a connection that is more leak proof.
Ease of installation:
When using the butt flanges it is easier to determine pipe length applications because the calculations do not have to account for the space taken up by threads on bolt-on applications. Slip-on flanges also require calculation using the insertion amount.
Weld Neck Flange Disadvantages
Welding skill:
The installation of these flanges do require the skills if a more advanced welder. The inside of the connection needs to be smooth to reduce friction in the flow of material. The outside weld also needs to pass a certain criteria that is determined by certain codes. Installation of the butt flanges need to be left to the more skilled and trained welder.
Leak occurrence:
Despite the installation techniques that well trained welders use each connection has to pass a radiography test. When the tests are complete and the weld is sufficient there could still be air bubbles in the weld that the test did not detect. Over time these bubbles will develop leaks. Regardless of the welder’s skill set these bubbles occur and leaks will develop over time. These leaks can be repaired without replacing the entire flange.
The installation techniques of weld neck flanges have been greatly improved over the older techniques. The welding industry has made big steps in training welders to perform using better equipment and methods that make these type of installations safer and with less test failures. There will always be a need for this type of flange installation for many years to come. I am sure that in the years to come there will still be better techniques develop for the installation of weld neck flanges that will keep the industry on top.
Weld Neck Flange Advantages
Suitable for high pressure and high heat applications:
Some of the flange materials such as stainless steel are highly resistant to heat. The extreme pressure that is developed in piping applications throughout the industry calls for high-pressure resistance. A welded flange is stronger that a bolt-on flange. The bolt-on flange sometimes calls for a gasket that could cause leaks.
Reduced friction and interference:
The welded connection will not interfere with the flow of the fluid. With the reduced friction, the fluid will not develop turbulence allowing for less vibration and a smoother flow. Less turbulence will also allow for a quieter operation.
Easier Alignment:
The neck of the flange will allow for a more accurate easier alignment to the pipe saving time. The alignment is also much more precise with less tolerance.
Testing of the pipe and joints are easier:
Radiography test can be much easier to perform because of the easy access the flanges allow.
Durable connection:
Stress on the inside is transferred to the neck of the flange taking the pressure off the pipe allowing for a more permanent connection.
Leakage prevention:
In most applications using the weld neck flanges, the weld is made inside and outside of the flange. This will provide a connection that is more leak proof.
Ease of installation:
When using the butt flanges it is easier to determine pipe length applications because the calculations do not have to account for the space taken up by threads on bolt-on applications. Slip-on flanges also require calculation using the insertion amount.
Weld Neck Flange Disadvantages
Welding skill:
The installation of these flanges do require the skills if a more advanced welder. The inside of the connection needs to be smooth to reduce friction in the flow of material. The outside weld also needs to pass a certain criteria that is determined by certain codes. Installation of the butt flanges need to be left to the more skilled and trained welder.
Leak occurrence:
Despite the installation techniques that well trained welders use each connection has to pass a radiography test. When the tests are complete and the weld is sufficient there could still be air bubbles in the weld that the test did not detect. Over time these bubbles will develop leaks. Regardless of the welder’s skill set these bubbles occur and leaks will develop over time. These leaks can be repaired without replacing the entire flange.
The installation techniques of weld neck flanges have been greatly improved over the older techniques. The welding industry has made big steps in training welders to perform using better equipment and methods that make these type of installations safer and with less test failures. There will always be a need for this type of flange installation for many years to come. I am sure that in the years to come there will still be better techniques develop for the installation of weld neck flanges that will keep the industry on top.