Low Stress Spiral Wound Gaskets (SW600 LS / LSI)

At Kriloha Ltd., we recognize that not every flange is built for brute force. In many specialized chemical and pharmaceutical processes, the piping and vessels are constructed from fragile materials like glass-lined steel, fiberglass, or thin-gauge alloys. Using a standard spiral wound gasket in these systems often leads to disaster—the high bolt load required to seat the gasket can warp or crack the flanges themselves. The Kriloha SW600 LS (Low Stress) and LSI (Low Stress with Inner Ring) series were developed to bridge the gap between high-performance metallic sealing and delicate hardware requirements.

As a top supplier of rubber seals and gaskets, Kriloha Gaskets has re-engineered the classic spiral wound architecture for this “soft-touch” application. The secret lies in our Soft-Set™ Engineering. We utilize a modified V-shape metallic winding that is tensioned during the manufacturing process to be more “yielding” than a standard gasket. This allows the gasket to compress and conform to the flange surface at roughly 50% of the seating stress required by a conventional ASME B16.20 gasket.

Furthermore, the filler material (graphite or PTFE) is designed with a specific protrusion height. This ensures that the soft sealing element creates a primary barrier immediately upon contact, while the metallic winding provides the secondary spring-back to handle pressure surges. The LSI version is particularly popular because the inner ring provides a definitive compression stop. This prevents the maintenance team from accidentally over-tightening the bolts and “bottoming out” the gasket, which is the most common cause of flange damage in fragile systems.

By choosing Kriloha Low Stress gaskets, you are investing in a product that respects the mechanical limits of your equipment while providing the blowout resistance and fire-safety of a metallic seal. These gaskets are often used as “problem solvers” in facilities where Class 150 flanges consistently leak or warp. Kriloha’s commitment to precision engineering means you no longer have to choose between a leaky soft gasket and a flange-damaging hard gasket. Our SW600 LS series offers the best of both worlds: extreme sealing integrity and gentle mechanical interaction.

Primary Use Cases

Glass-Lined Steel Flanges: Ideal for fragile piping systems where high bolt torque would crack the glass lining.
FRP (Fiberglass Reinforced Plastic) Piping: Providing a metallic-grade seal for non-metallic piping systems.
Thin-Wall Aluminum or Plastic Vessels: Used in food processing and specialty chemical storage where flange thickness is minimal.
Misaligned or Older Flanges: Excellent for applications where bolts cannot be tightened to standard specifications due to age or hardware limits.
Large Diameter Thin Flanges: Sealing large manways on atmospheric tanks that lack the rigidity for high-tension bolting.

FAQs

How much less torque do I need for a Low Stress gasket?

Typically, Kriloha Low Stress gaskets are designed to seal at a seating stress as low as 5,000 psi, whereas standard gaskets often require 10,000 to 25,000 psi to fully seat the metal windings.

Can I use a Low Stress gasket on a standard Class 150 steel flange?

Yes. They are actually an excellent solution for Class 150 flanges that have a history of leaking due to bolt relaxation or slight flange misalignment.

Is the “LSI” version always better than the “LS”?

For most applications, yes. The “I” stands for the Inner Ring, which provides critical protection against inward buckling and acts as a safety stop to prevent over-compression.

Are these gaskets fire-safe?

Yes. Because they are constructed from metallic strips and inorganic fillers like graphite, they retain the inherent fire-safety ratings of traditional spiral wound gaskets.

Can Kriloha manufacture these for glass-lined equipment (like Pfaudler or De Dietrich)?

Absolutely. We specialize in custom-sized Low Stress gaskets specifically designed to match the dimensions and torque limits of major glass-lined reactor and piping brands.