A gasket is basically specially made material that has a role of sealing the connection between two flanges in order to prevent any leakage during the work. Generally, when you connect two pipes of two flanges, the fluid will leak in any case due to irregularities of both face-ends and therefore the gasket comes as a “seal” to prevent the leakage. Specialist Sealing Products are made of few materials and each of them is used in certain conditions and for a unique purpose.
Why the gaskets are so important?
You might ask, but why don’t we weld two ends and solve the problem? Of course, this is achievable in some cases, but more often this is impossible due to the irregularity of ends, material and simply because the welding is not an option due to dangerous gases and possible explosion that can occur due to the flame and temperature.
The gaskets are used simply because they easily prevent the leakage that can be catastrophic. This is not so dangerous in case of water, but when you are working with the hazardous liquids and materials, the seal must be correct and fit well.
What type of gasket do I need?
This depends on several factors and you need to consider all these in order to get the best one and ensure the tight connection. Not all sealing is applicable to all materials and conditions, so make sure you check the following factors. Temperature can deform the gasket material due to the high temperature and cause leaking. The pressure is the second factor that influences the option, as different fluids create different pressures. Corrosion can damage the sealing so you need to take into consideration this fact also.
This leads to another factor and that is the type of fluid that you will be working with. Once you decide what types of fluids will be there, make sure you take into consideration the movement of these as these can damage the sealing under the temperature and pressure. Last, but not least is the price, and you MUST avoid the cheap ones, since these are made of low-quality materials.
The types of gaskets
There are generally three types: metallic, non-metallic and composite. The non-metallic, also known as a soft one, are usually made of graphite, rubber, Teflon and compressed non-asbestos fiber. These are usually used for low-pressure flanges and usually available in full face and inside bolt circle forms.
The metal ones are made of soft iron, low carbon steel, Inconel and stainless steel. Used mostly in high-temperature and high-pressure cases, where the high level of tension is predicted. They are not cheap and they are pretty robust.
The composite ones are made of the combination of metal and non-metal materials and can be used in a variety of temperature/pressure ranges, due to the tight structure. These are used on raised face and female-male flanges. The spiral wound gasket is the most known form of this type and it consists of three parts: filler material, rings (inner and outer) and the winding material.