Gaskets
Gasket:
A gasket is a sealing device and it is in the form of ring or sheet.
It is widely used in the chemical industries in almost every equipment between flange joints, between pipe and pump outlet, main holes of the vessel and tanks,
in the heads of STHE etc.
So the selection of the gasket and its installation is of immense importance.
A leakage from a flange can result a loss of product it can result in the released of toxic and hazardous chemical which can impact the human and environment.
The gasket can help to achieve a reliable seal to prevent the leak from the flange joint.
It is the most important of choose the right material of the gasket for the application it is tube used.
The gasket manufacture needs the following information to manufacture the gasket as per you requirement.
1. Flange type/size.
2. Pressure.
3. Operating temperature.
4. Fluid flowing inside the pipe.
Types of gaskets:
There are number of type of gaskets, but we will discuss about the major types used in industries.
1. Non-Metallic: ASME B16.21
These gaskets can be fabricated from CNAF (compressed non-asbestoes fibre) PTFE, TEFLON, rubber or graphite. Therefore, these gaskets can easily be compressed with low tension boiling.
These type of gaskets are generally used in low temperature and low pressure applications, except graphite gasket as they can be used up to temp. 4600C.
Rubber and elastomer gaskets shall not be used in pipelines carrying hydrocarbons.
2. Metallic Gaskets: ASME B16.20
These gaskets are fabricated from one or a combination of metals to the required size and shape.
Frequently used Gaskets are RTJ (RING-TYPE-JOINT GASKETS):
RTJ are designed to seal by ‘INTIAL LINE CONTACT ‘or wedging action between the malign flange and the gasket. By applying pressure on the seal interface through bolt force,
the softer metal of the gasket flows to the micro fine structure of the harder flange material and creating a very tight and efficient seal.
Installation of Gaskets:
1. Clean the mating surface e.g. should be free of dirt, oil, moisture, etc. this helps in good seal quality.
2. Place the gasket properly between the two flanges.
3. Bolts should be tightened even diagonal way for uniformity.
4. Finally check for any leakage through pressure or hydrotest.
You also need to check your gaskets routinely for sign of aging if you see that your gaskets. Have begun to leak or crack, replace them immediately.