Gaskets for leak Proof Flanged joints

A gasket is a soft sealing material closed between two flanges in order to make a leak-free sealing application. For proper functioning and cost-effectiveness of flanged joints:-

• Flanges must be enormous stiff and massive.
• Flange faces should be super smooth.
• Flanges should be closed without tension on the pipes
• Flanges should be 100% parallel.

But the above is economically not feasible.

Functions of a Gasket

Hence the solution is to use relatively light and cheap flanges in combination with the correct finish in combination with compressible soft GASKET. So the main functions of a GASKET are:

• The gasket material has to fill the uneven surface of the flange in order to prevent leakage between the gasket and the flange surface.
• The gasket material has to overcome the misalignment of the flanges in order to prevent leakage between the gasket and the flange surface.
• Leakage through the gasket has to be reduced to the minimum against internal pressure-Emission

Characteristics of a Gasket

• The gasket material has to be soft in order to compress this in the irregularities of flanges.
• The gasket should be Gas-Liquid tight so that it does not leak or cause emission.
• The gaskets should not creep under influence from stress and temperature. This could result in lower bolt stresses and possible leakage.
• The resilience of the gasket should take static and dynamic effects due to stress, temperature, and pressure.
• The gasket has to withstand internal pressure without being blown out.
• The gasket should be capable to achieve sealing at elevated temperatures.
• It has to be resistant to the chemical attack of the medium without polluting the media.
• It should possess anti-stick properties such that when opening the flange, the gasket has to loose easily from the flange.
• It has to be stiff enough to make installation as easy as possible.

Gasket Selection

• Flange Construction- The thickness of the flange has an effect on the bolt load and therefore seating stress. Thin and deformed flanges need softer gaskets.
• Standardization-
• Quality Studbolts-
• Emission Parameters- Each selected gasket has different emission parameters.
• Flange Misalignment- Maximum misalignment of flanges will be 0.4 mm.

Why do Gaskets Leak?

• Damage during assembly
• Poor Gasket selection
• Excessive flange rotation
• Gasket damage or relaxation due to flange rotation
• Gasket damage due to differential thermal expansion
• Incorrect assembly bolt load
• Load loss due to thermal fluctuation
• Gasket load loss due to pressure and or piping loads
• excessive gasket relaxation
• Excessive gasket load

What costs are involved with a Gasket failure?

• Low profit due to leakage
• Cost of online sealing with clamps
• Cost of re-matching
• Cost of replacement equipment
• Cost of Engineering and maintenance hours spent addressing leakage
• Report of incidents and additional paperwork
• Pollution of environment
• Cleaning costs
• Possible personal injuries
• Cost of disassembly, repair and machining

What could engineering do to prevent leakage through Gaskets?

• Proper selection of the correct assembly bolt stress
• Correct location, constraint and width of the sealing
• Consideration of bending loads, misalignment.
• Quantify effects of gasket creep/relaxation
• Quantify effects of temperature and pressure
• Maximum permissible assembly load
• Correct gasket selection
• Root cause analysis

Basic calculations for Gasket Selection

Gasket Materials

• Rubber gasket
• Fibre Sheet Gaskets (Asbestos, Aramide, Acrylic, Carbon, Ceramic, Rockwool, Glass fibers, Carbon fibers, Graphite)
• PTFE Gaskets
• Graphite Gaskets
• Spiral Wound Gaskets
• Cam profile Gaskets
• Flat Metal Reinforced Gaskets
• Ring Type Joints
• Insulating Kits
• Metallic Gaskets