If a removed seal does not recover its earlier shape, document its condition and service history before assigning a cause. Compare the used part with the drawing, material identification and an unused sample where available. A compression-set test can support the material review, but it does not replace an investigation of the assembled seal.
Keep the question specific: are you reviewing a supplier's laboratory result, investigating leakage after service, or choosing an acceptance test for a new part? Each task needs a different set of records.
Read the test conditions with the result
ASTM D395 addresses rubber under compressive stress and includes different test arrangements. Its public guidance identifies compression-set tests as mainly relevant to static stressing conditions. Ask for the applicable method and edition rather than requesting an unqualified percentage.
| Report information | Question for the review |
|---|---|
| Compound and specimen identity | Does the sample represent the specified material and relevant production state? |
| Method and specimen dimensions | What arrangement and measurements produced the reported result? |
| Compression and exposure | What loading condition, temperature, duration and medium were used? |
| Recovery and final measurement | When and under what conditions was the specimen measured after release? |
| Acceptance requirement | Which customer specification and limit apply to this result? |
Compare candidate results on a common basis. If methods or conditions differ, identify the difference before ranking materials. A value without specimen and exposure details is an incomplete basis for a procurement decision.
Preserve the evidence from the actual seal
Photograph the seal in its installed orientation if possible and record how it was removed. Identify the material lot, drawing revision, installation date and operating interval. Include normal and peak temperatures, fluid composition, pressure events and cleaning exposures.
Measure the used and reference parts using an agreed approach and record the time since removal. Retain observations of cracks, cuts, swelling or displaced material separately from the recovery measurement. A description of the visible condition is more useful than labeling every flattened seal a material failure.
Review the assembly as well as the material
Request the mating-part geometry, closed gap, tolerances and installation method. Identify changes in the component, lubricant or operating conditions since approval. If leakage occurred, record the test or service conditions and the location observed before disassembly.
Keep dimensional recovery, retained force and leakage performance as distinct evaluation questions. If force retention is part of the application requirement, specify the relevant test discussion. If assembly function is the acceptance criterion, define the assembly test rather than inferring its result from a material value.
Agree what a revised sample must demonstrate
State the proposed material or geometry change and the comparison needed. Identify the exposure conditions, sample quantities, measurements and approval responsibility. Keep trial results connected to the compound and part revisions so a successful evaluation can become a clear repeat-order specification.
Ask how the comparison represents the intended duty. A static laboratory test does not establish performance for every movement, pressure cycle or service duration. Use the application's requirements to decide what additional component evaluation is needed.
Start with the part and service records
Send RubberQ the seal specification, available reports, photographs and operating history. Review seal and O-ring requirements, prepare the failure-investigation information, and discuss the material and component evaluation plan.