Spiral Wound Gasket-Advancements and Applications

A spiral wound gasket (SWG) is the semi-metallic seal that keeps flanged joints tight through heat, pressure and thermal cycling: a stainless V-winding wraps a graphite or PTFE filler, and rings hold it steady under bolt load. Standard builds follow ASME B16.20 and API 601, and they seat with our flange gaskets.

What the Spiral Wound Gasket Is

The construction is simple and proven: a preformed metal strip wound on edge with a soft filler between the wraps. The V-profile acts like a spring, so the gasket recovers as the joint heats and cools. Inner and outer rings — carbon or stainless — centre the gasket and stop it from buckling under torque.

• Stainless winding — 304, 316L or alloy grades for strength and spring-back.
• Graphite or PTFE filler — sealing and chemical resistance to match the media.
• Inner ring — keeps the gasket from blowing inward into the bore.
• Outer ring — centres the gasket and limits bolt-load over-compression.

Advances in Materials and Emissions Control

Modern SWGs use flexible graphite filler for higher temperature and lower creep, and controlled-density windings that hold torque through thermal cycles. Inner rings calm flow at the bore; outer rings cut wind-up during installation. For refineries and chemical plants, low-emission grades tested to API 601 and 607 targets keep fugitive emissions in check.

Key Benefits

• Spring-back handles thermal cycling better than flat sheet gaskets.
• Wide temperature and pressure range within one gasket family.
• Filler choice covers steam, hydrocarbons, chemicals and cryogenics.
• Standard dimensions — interchangeable across ASME B16.20 flanged joints.

Where They Are Used

Spiral wound gaskets seal flanges on valves, pumps, boilers, heat exchangers, reactors, tanks and pipelines — anywhere a joint sees temperature swings or hazardous media. They cover utility steam in power plants, hydrocarbon service in refineries, and hygienic duty where compliant fillers are specified.

In the Joint

The gasket sits between the flange faces and the bolts squeeze the winding until the filler flows into the face serrations; the pipe flanges carry the pipe and the bolt load. Torque evenly in a cross pattern, and never reuse a spiral wound gasket once the joint has been opened.

Installation and Care

Check the flange face for damage, place the gasket centred in the bolt circle, and bring the bolts up in stages and cross-pattern to the specified torque. Avoid over-compression — the outer ring is a stop, not a target. At turnaround, inspect for wind-up, filler loss and corrosion, and replace rather than re-torque a gasket that has taken a set.

Frequently Asked Questions

Graphite or PTFE filler — which one?

Graphite handles high temperature, steam and hydrocarbons and recovers well under cycling. PTFE suits strong chemicals and clean service but creeps more at heat. Match the filler to the media and temperature.

When is an inner ring required?

Use an inner ring where flow velocity, turbulence or vacuum could pull the gasket inward, and on larger sizes where it helps spread bolt load across the winding.

Can a spiral wound gasket be reused?

No. Once a joint is opened the winding has taken a set and the filler has thinned; fit a new gasket to keep the seal predictable.