KLINGER Australia : Compression Packings & Gaskets

Correct gasket choice is an important step in the design of a process system as choosing the correct gasket from the beginning can result in significant savings due to longer gasket life, reduced gasket failure and lower leak rates.

This guide is included here to provide practical advice and recommendations on achieving optimum performance from asbestos free gaskets.

This guide is supplied as an initial reference only, and many of the theories behind the recommendations are not discussed in detail.

Maximum Working Pressure - Flanges
The maximum working pressure for ANSI B16.5 carbon steel flanges can be found using the ASME Maximum Allowable Pressures table.

Possible Material Options are

	Class 150	Class 300	Class 400	Class 600	Class 900	Class 1500	Class 2500
Rubber¹
Klingersil C4243
Klingersil C4400
Klingersil C4430²
Klingersil C4500²
Klingersil C8200
Graphite SLS
Graphite PSM-AS
PTFE envelope³
Spiral Wound
maxiprofile
Sealex

	Suitable for use
	Suitable for use depending on temperature, pressure and media
	Not suitable for use
Not exceeding 10 bar pressure and usually for liquids only Recommended Thickness 1.5mm Insert type C4430

Other Considerations
Limitations in steam

Steam duty is perhaps the most common and one of the most arduous gasket applications. It is difficult in part because

Steam is a powerful hydrolyser capable of changing the nature of many polymers and fibres.
An increase in the pressure of saturated steam results in a corresponding increase in temperature. Gaskets under increased stress (ie higher internal pressure) in general require a reduced operation temperature.
Many materials harden in steam leading, in some cases, to embrittlement. This is especially applicable to asbestos free calendered materials.

When discussing temperature limits in steam only approximate guide-lines can be given due to considerations such as

Flange design (ie spigot and recess is far better than raised face)
Gasket thickness (thinner gaskets perform better)
Required service life
Assembly techniques
Maintenance procedures
Degree of acceptable embrittlement
The use of jointing compounds in an assembly

Bearing these factors in mind we suggest that very careful consideration be given to the above parameters, especially where operation is near the borderline of the PT diagrams available on this website. If in doubt contact Klinger (technical_service@klinger.com.au) for technical advice.

Low Temperature Duty

The following conditions need to be met before determining suitability of materials at low temperatures.

The gasket is completely dry when installed
The flange is assembled at ambient temperature
The flange and bolt materials are suitable for low temperature use

If these conditions can be met the following minimum operating temperatures apply

Natural Rubber	-70°C
Neoprene Rubber	-40°C
Nitrile Rubber	-40°C
Viton Rubber	-15°C
PTFE envelope gaskets	-80°C
Klingersil C4500	-196°C
Klingersil C4430	-196°C
Sealex	-196°C
Spiral Wound gaskets	-196°C

Gasket Size
A general rule is that gaskets cut from a sheet (eg Klingersil, Top-chem, etc) can be successfully used at smaller diameters, lower pressures and/or lower temperatures. As diameter, temperature or pressure increase the use of semi-metallic gaskets are more common. This is largely due to the effect of hydrostatic end thrust in reducing stress on the gasket and increasing the chance of a blow-out.

As a general rule, special care should be taken for gaskets above 600mm diameter, or operating above 200°C or 50 bar.

Steps To Effective Gasket Choice
1. Determine the likely gaskets for your application (above)
2. Check Chemical Compatability of the possible Materials
3. Confirm Pressure Temperature Capabilities of Materials

Choosing the Right Gasket