What Is a Flexible Pipe Fitting?
Flexible pipe fittings are flexible pipe fittings that can be bent freely.
They are used as pipe fittings for various equipment, including water supply and drainage pipes and gas pipes. Due to their flexibility, they are used to connect pipes that are prone to expansion and contraction due to thermal expansion and pipes with equipment that is prone to vibration.
They can also absorb induced vibrations in the event of earthquakes. Stainless steel such as SUS 304 is used as the material, but non-metallic materials such as rubber are also used in some cases. The connection method of flexible pipe fittings is the same as for general pipe fittings such as threaded or flanged fittings, and the length can also be selected to a certain extent freely.
Uses of Flexible Pipe Fittings
Flexible pipe fittings can transport a wide range of fluids, from liquids such as water and oil to gases such as air, steam and gas, due to their excellent earthquake and heat resistance. They are highly versatile and there is a wide variation of fittings. Typical applications for flexible pipe fittings are.
1. Applications Exposed to Vibration
Due to their ability to absorb vibration, flexible pipe fittings are used as pipework for pumps, tanks and rotating machinery in factories. If the pipework for vibrating machinery is not flexible, the vibrations can be transmitted to the building, causing the building itself to shake.
They are also used for piping connecting buildings and for vibration isolation equipment. As Japan is a country where earthquakes occur frequently, this can prevent damage to pipework in the event of ground vibration or settlement caused by earthquakes.
2. Applications Exposed to Thermal Changes
In applications subjected to severe thermal changes, such as steam pipework, the repeated expansion and contraction may cause deterioration and damage. Flexible pipe fittings are used to relieve the stresses caused by these thermal changes.
3. Other Applications
When new pipework is required in addition to existing equipment and pipework in factories, etc., the new pipework may inevitably interfere with the existing equipment and pipework. One solution is to combine various types of piping, but if a flexible pipe fitting is used, existing equipment and piping can be bypassed with a single flexible pipe fitting, and the work can be carried out easily.
Features of Flexible Pipe Fittings
Most flexible pipe fittings are made of stainless steel such as SUS 304. Some are made of non-metallic materials such as rubber. Stainless steel is not flexible, but can be made flexible by using a bellows or tube construction.
Bellows construction is the so-called bellows shape. There are two types of bellows: single bellows and double bellows, where a single bellows can accommodate displacements mainly in the axial direction and angle, as well as perpendicular to the axial direction. Tubular construction, on the other hand, refers to a corrugated spring-like shape.
In the case of rigid PVC pipe fittings, which have been used for a long time, it is not possible to make a connection if the pipe is misaligned. With flexible pipe fittings, installation is possible even if there is a misalignment, and the construction work is relatively less time-consuming.
Types of Flexible Pipe Fittings
There are various types of flexible pipe fittings, depending on the connection method. The typical type is the flange type, which can be used for a wide range of applications from small to large diameters.
Threaded types are also often used and are used to connect pipes with a diameter of 65 mm or less. Unions and nipples are the most common connection methods.
Other Information on Flexible Pipe Fittings
Points to Note About Flexible Pipe Fittings
Flexible pipe fittings are a convenient component, but there are some precautions to be taken when using them. First of all, there is a minimum bending radius depending on the bore size. The majority of flexible pipe fittings are made of stainless steel and can be damaged if they are installed with a smaller than the specified minimum bend radius.
Secondly, there are also restrictions on length. If the joints are installed longer than the prescribed length, they will not exhibit the seismic and thermal expansion resistance that they should. Lastly, they are very vulnerable to torsion. Flexible pipe fittings can be easily damaged when subjected to torsion.