Spring-Energized PTFE Seal RFQs: Gland Dimensions, Spring Type and Cold Service

A spring-energized PTFE seal is specified as an assembly: the sealing jacket, energizer and installation geometry work together. Matching an outside diameter and calling the material PTFE leaves important questions unanswered. A useful RFQ identifies the gland, pressure direction, movement, medium and temperature history before asking the supplier to recommend the complete seal.

Identify the sealing arrangement

State whether the application is a rod seal, piston seal or face seal. Mark the pressure side and identify which surface moves, if any. Keep static, reciprocating and rotary duties distinct. For an existing part, provide an authorized product reference or section specification that identifies the functional features.

Use a drawing revision and a consistent dimensional reference. A measurement taken from a removed part should be labeled as such, rather than silently becoming the manufacturing dimension. If the original specification is unavailable, separate measured observations from requirements that still need confirmation.

Describe the gland, not just the seal envelope

Provide the mating diameters, groove width and depth, their tolerances and the relevant clearance. Identify the mating materials and any available surface specification. Include information about eccentricity, alignment or movement that the equipment designer considers relevant. These inputs let the supplier assess fit and working contact together.

Installation access belongs in the RFQ too. State whether the housing opens, which edges the seal must pass and what assembly constraints exist. Ask for the selected manufacturer’s installation instructions. Do not assume that an existing gland or an informal stretching method is suitable for a different seal construction.

The spring designation has a functional meaning

The Parker PTFE Seals Design Guide distinguishes helical, cantilever and canted-coil energizers by their load-deflection behavior. It explains that spring load affects sealing contact, friction and wear, while available deflection affects compensation for dimensional variation and wear. Its guidance also addresses polymer shrinkage in cryogenic designs. These are selection considerations, not a universal recommendation for one spring type.

Ask the supplier to identify the proposed spring geometry, load option and material. If a specification names only a V-shaped spring, request the actual design reference rather than assuming that all similarly described energizers are interchangeable. Keep an approved energizer configuration linked to the seal drawing and jacket specification.

Review every material that sees the medium

List the process medium and any relevant cleaning substances, mixtures or changes in concentration. Identify whether the spring is exposed to the medium in the proposed construction. Ask for compatibility review of the selected jacket compound and energizer material under the actual conditions.

PTFE is a material family, not a complete compound specification. Record whether the proposal uses unfilled, filled or modified material and request its manufacturer designation. Where special purity or regulatory requirements apply, state the required evidence explicitly. Do not infer a finished-seal approval from the base polymer’s name.

Make cold service an operating history

A minimum temperature alone does not describe the whole duty. Tell the supplier whether the seal starts cold, cools while pressurized, cycles between temperatures or must move during cold operation. State the low-pressure and vacuum conditions separately where they are relevant, together with any pressure reversal.

Ask the manufacturer how its recommended configuration addresses these transitions and the required sealing result. A broad material temperature statement does not prove that the assembled seal meets a specific cold-start leakage or friction requirement. Define the acceptance basis and identify what evidence is needed for the actual application.

Keep the quotation reviewable

• Gland and mating-part references, including tolerances and revision.
• Pressure direction, operating range and any reversal or vacuum duty.
• Static or moving service, with the relevant motion description.
• Medium, cleaning exposure and complete temperature history.
• Proposed jacket compound, spring configuration and spring material.
• Required leakage, friction or endurance acceptance criteria and unresolved items.

Common questions

Can a stronger spring be specified as an automatic improvement?

Ask the supplier to assess the sealing requirement together with friction, wear and available deflection. More spring load is not a stand-alone approval criterion.

Does a cold-temperature material rating approve a cryogenic assembly?

No. The finished configuration and its operating transitions need application-specific assessment.

See IKSONIC’s spring-energised seal information and custom spring-energized PTFE seal listing. Contact IKSONIC with authorized gland and operating information, requesting a recommendation for the complete jacket-and-spring assembly and its stated application limits.