HP Static Seals

Overview

When a standard O-ring isn't enough

High-performance static seals are engineered for applications where there is no relative movement between the surfaces being sealed, and where the consequence of leakage is unacceptable — petrochemical process equipment, energy systems, subsea connections, and critical hydraulic manifolds.

Standard elastomeric O-rings perform reliably in the vast majority of static sealing applications. HP static seals are specified for the conditions that push those limits: sustained pressures above 500 bar, temperatures below –40°C or above 200°C, chemically aggressive media that degrade standard elastomers, or applications subject to repeated pressure cycling that causes fatigue in softer seal materials.

Materials used include PTFE, NBR 90 Shore A, FKM 90 Shore A, urethane, and polyamide — all selected for their ability to maintain geometry and sealing contact under high load and repeated cycling without relaxation.

Product Types

Three HP static seal configurations

1. Head seals — extreme pressure with repeated cycling

Head seals are designed to withstand extreme pressures and repeated load cycles in static face-seal grooves. Their profile combines an active sealing lip that conforms to the mating surface and a rigid axial support element that prevents extrusion under high bolt or hydraulic load.

Parameter	Performance
Operating pressure	Up to and exceeding 500 bar
Temperature range	–40°C to +200°C
Materials	NBR 90A, FKM 90A, urethane, polyamide backup elements
Application	Hydraulic manifold connections, cylinder end caps, high-pressure valve bodies, subsea connections
Groove requirement	Precision-machined grooves — tighter tolerances than standard O-ring grooves. Contact us for dimensional specifications.

2. PTFE and thermoplastic seals — chemically inert, wide temperature range

PTFE and thermoplastic static seals are completely chemically inert against the majority of industrial fluids: acids, solvents, hydrocarbons, and aggressive gases. They maintain their sealing geometry across a temperature range that exceeds any elastomeric material.

Parameter	Performance
Temperature range	–200°C to +260°C (PTFE); thermoplastics vary by grade
Chemical resistance	Virtually universal — specify the fluid for confirmation of PTFE filler compatibility
Limitation	High compression set — PTFE static seals cannot recover from over-compression. Groove tolerances are critical.
Spring-energized option	Spring-energized PTFE lip seals available for low bolt-load face seal applications where PTFE compression set would otherwise cause leakage over time.

3. Encapsulated O-rings — chemical resistance with elastomeric conformability

Encapsulated O-rings combine the chemical resistance of a PTFE outer jacket with the elasticity of an FKM or silicone elastomeric core. The core provides the spring-back that PTFE cannot — the jacket provides the chemical protection that the elastomer cannot.

Parameter	Performance
Temperature range	–60°C to +220°C (FKM core); –100°C to +230°C (silicone core)
Pressure	Moderate static — the PTFE jacket limits the achievable compression ratio vs. solid elastomeric O-rings
Groove dimensions	Same groove as a standard O-ring of equivalent cross-section — drop-in replacement where chemical upgrade is needed
Use case	Chemical process flanges and connectors where the fluid is incompatible with the elastomeric core material but temperature is moderate

Compatibility note: Encapsulated O-rings are not the right choice if temperature alone is the driver — a higher-grade elastomeric O-ring (FFKM, HNBR) will often be a better and more economical solution. Encapsulation is specifically for chemical incompatibility of the elastomer with the process fluid.

Materials

Common HP static seal materials