Spiral Wound Gaskets

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SHASON Spiral Wound Gaskets are semi metallic products designed for high pressure and temperature applications. A variety of forms of the gasket are available and these can be manufactured in various materials or sizes to suit your requirement.

With over thousands of satisfied customers who have procured SHASON spiral wound gaskets, we are confident that we can meet all your service requirements.

Please specify the following when ordering Spiral Wound Gaskets.

• Type of Spiral Wound Gasket required
• Standard of the gasket (flange standard)
• Nominal size and pressure class
• Gasket Thickness
• Quantity
• Material
• - Inner Ring
  - Metal winding
  - Filler
  - Outer Ring

The sealing element of the spiral wound gasket consists of a V-shaped metal strip spirally wound in combination with a soft sealing material filler. The metal strip provides outstanding resilience, while the flexible sealing filler guarantees excellent sealing.

Due to this combination of materials, the spiral wound gasket is suitable for sealing under severely fluctuating temperature and pressure conditions. Depending on the application the spiral wound gasket can be specified with outer and/or inner rings

• Spiral Wound Gaskets are suitable for use across a wide range gasket stress range
• Spiral Wound Gaskets can be used to seal fluid pressures up to 400 bar and from cryogenic temperatures up to 1000oC
• Spiral Wound Gaskets are robust and simple to install
• The outer guide ring simplifies assembly and prevents blow-out of gasket
• By combining different winding materials and metals, the gasket can be tailored to suit a wide variety of operating conditions

Benefits of Center Ring:

The spiral wound gasket outer centering ring provides the following benefits:

• Optimum location between the bolts
• Protection of the spiral wound element
• Additional security against gasket blow-out
• Acts as compression limiter preventing overloading and over compression of the spiral wound element
• Prevents radial-flow of soft fillers, 1such as PTFE.

For these reasons it is preferable to use spiral wound gaskets with outer centering rings. The outer ring is marked with nominal size, pressure class, standard and materials.

Benefits of the Inner Ring:

The spiral gasket inner ring provides the following benefits:

• Prevents radial-flow of soft fillers, such as PTFE + Graphite
• Reduces turbulence-minimising flow resistance
• Acts as a heat shield when the spiral wound gasket is subjected to high temperatures.

Inner and outer rings are particularly recommended for use on spiral wound gaskets exceeding class 600lbs, but specifically recommended for high temperatures and pressures to optimise the operational reliability of the spiral wound sealing element. Inner rings are mandatory for PTFE filled spirals.

The material selected for the inner ring and winding metal is usually the same as the flange metal. This prevents corrosion and differential expansion problems. The outer centering ring is generally manufactured from carbon steel with an anti- corrosion treatment. However, the ring may also be manufactured in the same metal as the flange to prevent corrosion problems.

The table below may be used to select the correct filler. It should be pointed out that graphite will be the optimum filler in most cases. Only where graphite could cause media contamination, or is not chemically resistant, should the use of another type of filler material be recommended. In such cases, an alternative solution might be to select a gasket.

Graphite is universally chosen because of its good chemical resistance, resistance to ageing, good gas tightness and ability to operate at high temperatures.

PTFE is a high quality synthetic material with the following characteristics: excellent chemical resistance, resistance to 260O C, resistant to ageing, excellent gas tightness.

When installing a Spiral Wound Gasket, check the dimensions of the Gaskets for use between pipe and pressure vessel flanges. The procedure is as follows:-

Measure ID of flange contact face.

Measure Gasket ID. If Gasket ID is not 1/8" larger than flange ID, do not use it unless it can be installed perfectly centered.

A Spiral Wound Gasket does not have the same feel as other Metallic or Non-Metallic Gaskets during the bolting-up. It's different-because it gives a little bit under each bolt as it is tightened. It is therefore important to tighten the bolts in small steps in proper sequence as shown hereunder. Final tightening must be uniform with each bolt pulling same load. This will guarantee a trouble free joint. If not uniform, the joint may leak-particularly after it has been in hot service. Tighten the bolts after 24 hours and again a week later.