V-Basic Ring vs W-Basic Ring for Spiral Wound Gaskets

A spiral wound gasket seals by spring load, and the winding profile decides how that load survives temperature and pressure swings. Choosing between a V-basic ring and a W-basic ring is therefore a service question before it is a budget question. This guide compares both profiles for refinery, petrochemical and power duties and shows where standard flange gaskets already meet the requirement.

How the Winding Profile Works

A spiral wound gasket is not a solid metal part. It is a multilayer composite built from a preformed metal strip and a non-metallic filler, wound together and fixed into a defined cross-section. The winding profile is the geometry of that cross-section, and it controls resilience, contact stress and stress relaxation.

Two optional rings frame the windings: an inner ring and an outer ring in carbon steel or stainless steel, which keep the gasket from buckling and hold it centred in the joint. The gasket must also match the facing of the mating pipe flanges, such as raised face (RF) or male-and-female (MFM) joints.

• Metal winding strip — 304 or 316 stainless steel, titanium or Inconel, giving mechanical strength and temperature tolerance.
• Filler — graphite, PTFE or ceramic fibre, giving elasticity and conformability to the sealing faces.
• Precision winding — strip and filler wound alternately into the required cross-section.
• Inner and outer rings — optional, for positioning and blow-out resistance.

That layered metal-filler-metal build is what makes the gasket springy: the strip carries the load and the filler closes the microscopic roughness of the flange face. Everything else — V or W — is a question of how the peaks and valleys are arranged.

V-Basic Ring: The Standard Choice

The V-basic ring is the classic preformed profile. The strip is wound at a fixed angle, so the cross-section shows a continuous run of peaks and valleys, and the design has been in service for about a century.

• Resilience — the V geometry stores elastic energy under compression and keeps the sealing force steady through temperature and pressure changes.
• Compression adaptability — it seats easily and fills microscopic irregularities on the flange face.
• Stress distribution — the V angle spreads the load path and limits local stress concentration.
• Track record — a century of application history makes its behaviour predictable.

Typical duty is medium to high pressure, roughly PN25 to PN100 (Class 150-600), across a wide temperature band from -200 °C to +800 °C depending on the filler. It handles steam, hydrocarbons and chemical media on raised face and male-and-female flanges. For about 80% of the sealing points in a conventional refinery or chemical plant, the V-basic ring is the safe and economical answer.

W-Basic Ring: For Severe Duty

The W-basic ring folds two V profiles into one, so the cross-section shows a double-V, or W, shape with a denser packing of peaks and valleys. More peaks per inch means more contact points per unit area.

• Higher sealing specific pressure — more contact peaks give a stronger initial seal, 40-70 MPa against 25-40 MPa for the V profile.
• Anti-relaxation — the repeated spring structure resists creep and stress relaxation better.
• Thermal cycling — the seal stays steadier through severe temperature swings and pressure fluctuations.
• Service life — the redundant geometry lengthens maintenance intervals.

This profile is aimed at critical service above PN160 (Class 900-2500), at units with frequent start-ups and shutdowns, at toxic or flammable media that cannot tolerate leakage, and at key equipment such as reactors, high-temperature exchangers and main steam lines. It also costs more to make.

Side-by-Side Comparison and Selection

Typical values for a standard graphite-filled spiral wound gasket; exact ratings depend on size, materials and the specification ordered.

The W profile wins on performance under extreme conditions but costs about 20-40% more. The V profile gives the best cost-to-performance ratio in standard service. The choice is not about which design is better, it is about which one suits the duty.

• Choose the V-basic ring when service stays below PN100 (Class 600), temperature and pressure are stable, and the budget is tight.
• Choose the W-basic ring above PN160 (Class 900), under severe thermal cycling, or with hazardous media.
• Choose the W-basic ring when a shutdown costs far more than all the gaskets in the joint.

Never select on price alone: a single leak event can cost more than every gasket fitted over the whole life of the equipment.

Frequently Asked Questions

Which profile fits a Class 150 raised-face joint?

The V-basic ring. Its 25-35% compression rate seats easily on a raised face, and the PN25-PN100 range covers Class 150 service with margin.

How do I read the recovery and compression figures?

Compression is the deformation needed to seat the gasket: 25-35% for the V profile and 20-30% for the W profile. Recovery is the spring-back kept after unloading: 15-25% for V against 10-20% for W, and it governs how the joint behaves when the temperature falls.

Why does the W profile show a lower recovery rate?

Its denser cross-section trades spring-back for contact density: 8-12 peaks per inch instead of 5-7. The gain is in sealing specific pressure and anti-relaxation, not in recovery.

What temperature range can these gaskets cover?

The construction is rated from -200 °C to +800 °C, but the upper limit depends on the filler. Graphite, PTFE and ceramic fibre each have their own ceiling, so confirm the filler before you set the temperature limit.

Which filler suits steam and hydrocarbon service?

Graphite is the usual choice for steam and hydrocarbons across a wide temperature band; PTFE suits chemical media where graphite is not acceptable. Match the filler to the medium and the temperature together.