Immersion Testing
What Is Immersion Testing?
Immersion testing is a broad category of material testing in which specimens — materials, components, coatings, or assembled products — are fully or partially submerged in a defined liquid medium for a specified time, temperature, and concentration to evaluate their resistance to chemical attack, absorption, swelling, property degradation, and structural integrity in liquid service environments.
Virtually every material that encounters liquids in service — whether a polymer seal in hydraulic fluid, a metal component in seawater, a coating on a submerged pipeline, or a medical device in body fluids — must be qualified through immersion testing to confirm its performance and safety in the intended application.
Why Immersion Testing Is Critical
Liquids interact with materials in multiple ways that cannot be predicted from dry-state property data alone. Polymer absorption and swelling, metal corrosion and pitting, coating delamination and blistering, adhesive disbonding, and composite matrix degradation are all phenomena that only manifest under liquid exposure. Immersion testing provides direct, accelerated evidence of these interactions — validating material selection, predicting service life, and identifying failure modes before products reach the field.
Major Immersion Testing Methods
ASTM D543 — Resistance of Plastics to Chemical Reagents
One of the most widely used immersion standards for polymers. Specimens are immersed in defined chemical reagents (acids, alkalis, solvents, fuels, oils, etc.) at specified concentrations and temperatures for defined exposure periods (typically 7, 30, and 180 days). Changes in mass, dimensions, appearance, and mechanical properties are measured before and after immersion.
ASTM D543 categorizes reagents into groups ranging from Group 1 (milder reagents, including water and dilute salt solutions) to Group 5 (aggressive reagents, including concentrated acids and strong oxidizers) — enabling systematic evaluation of chemical compatibility.
ASTM D471 — Rubber Properties in Fluid
Evaluates the resistance of vulcanized rubbers to swelling, shrinkage, and property change after immersion in oils, fuels, hydraulic fluids, and other service liquids. Changes in volume, hardness, tensile strength, and elongation after defined immersion periods characterize elastomer-fluid compatibility.
ASTM D570 — Water Absorption of Plastics
Measures water absorbed by a plastic specimen after immersion in distilled water at 23°C (or elevated temperatures) for 24 hours or until equilibrium absorption is reached. Water absorption data quantifies moisture sensitivity and supports predictions of dimensional change and mechanical property loss in humid service environments.
ASTM G31 — Immersion Corrosion Testing of Metals
Metals are immersed in corrosive solutions (acids, salt solutions, industrial process fluids) under defined conditions to measure corrosion rate (mass loss per unit area per unit time, in mils per year or g/m²/day) and identify attack morphology (uniform, pitting, crevice, intergranular).
ASTM B117 / G85 — Salt Spray and Modified Salt Spray
While technically a spray/fog exposure rather than full immersion, salt spray testing is functionally similar to immersion testing for evaluating coating and metal corrosion resistance in marine and industrial environments.
ASTM C868 — Chemical Resistance of Protective Linings
Evaluates polymeric linings applied to metal substrates — immersed in chemical reagents to assess blistering, softening, loss of adhesion, and penetration through the lining. Critical for chemical storage tank and pipeline lining qualification.
Parameters Measured in Immersion Testing
- Mass change (% weight gain or loss): Indicates absorption or leaching
- Dimensional change: Swelling or shrinkage from fluid absorption
- Visual changes: Blistering, color change, surface attack, cracking, delamination
- Mechanical property retention: Tensile strength, elongation, hardness, and modulus after vs. before immersion
- Corrosion rate and attack morphology (metals)
- Seal integrity (for coatings and linings)
Industry Applications
Seals and Gaskets: Elastomeric seals for hydraulic systems, automotive fuel systems, and chemical process equipment must be qualified for compatibility with specific service fluids through ASTM D471 immersion testing.
Polymeric Pipes and Fittings: PVC, CPVC, HDPE, and PP piping for chemical process, water treatment, and industrial applications is immersion-tested per ASTM D543 to confirm chemical resistance in service environments.
Marine and Offshore: Metal alloys and coatings for submerged structures, ship hulls, and offshore platforms are evaluated through seawater immersion testing (ASTM G31 and G46)to assess corrosion behavior and coating performance.
Medical Devices: Implants, catheters, and surgical instruments are immersion-tested in simulated body fluids (saline, Ringer’s solution) to evaluate biocompatibility and long-term corrosion or degradation behavior.
Electronics: PCBs, potting compounds, and connector assemblies are immersion-tested to evaluate moisture resistance, ionic contamination sensitivity, and electrolytic corrosion under high-humidity or condensation conditions
Conclusion
Immersion testing — spanning chemical reagent resistance, rubber fluid compatibility, water absorption, metal corrosion rate, and coating lining integrity per ASTM standardized protocols — provides the liquid exposure performance data essential for qualifying polymers, elastomers, metals, coatings, and assembled products across seals, piping, marine, medical, and electronics applications. Selecting the right immersion medium, temperature, duration, and post-exposure property measurements for the specific material system and service environment is what determines whether immersion test results accurately predict real-world chemical resistance, dimensional stability, and structural integrity — making liquid compatibility qualification as fundamental to material selection as any dry-state mechanical characterization.
Why Choose Infinita Lab for Immersion Testing?
Infinita Lab is a trusted USA-based testing laboratory offering comprehensive immersion testing services — for polymers, metals, elastomers, coatings, and assembled products — across an extensive network of accredited facilities. Our advanced equipment and expert professionals deliver highly accurate and prompt results to ASTM, ISO, and customer-specific standards.
Looking for a trusted partner to achieve your research goals? Schedule a meeting with us, send us a request, or call us at (888) 878-3090 to learn more about our services and how we can support you. Request a Quote.
Frequently Asked Questions
What is the most important immersion test for plastic chemical resistance? ASTM D543 (Resistance of Plastics to Chemical Reagents) is the primary standard — evaluating mass, dimensional, and property changes after immersion in a broad range of defined chemical reagents. It is the starting point for assessing plastic material suitability in chemical service environments.
How does immersion testing differ from accelerated weathering? Immersion testing evaluates material behavior in specific liquid environments (chemical solutions, fuels, oils, water). Accelerated weathering simulates outdoor environmental degradation (UV radiation, heat, moisture cycling) — a complementary but distinct type of environmental testing.
How long do immersion tests typically run? ASTM D543 specifies 7-day and 30-day standard immersion periods for many reagents, with 180-day extended tests for long-term compatibility evaluation. Metal corrosion immersion tests (ASTM G31) typically run 24 hours to 3 months depending on corrosion rate and required data quality.
Can immersion testing predict long-term service life in chemical environments? Immersion testing at elevated temperatures can be used with Arrhenius modeling to project long-term ambient-temperature service life — similar to thermal aging predictions. However, validation against long-term field experience is always recommended for life-critical applications.
What ASTM standards govern immersion corrosion testing for metals? ASTM G31 governs laboratory immersion corrosion testing of metals. ASTM G46 covers examination and evaluation of pitting corrosion. ASTM G48 covers pitting and crevice corrosion resistance of stainless steels in ferric chloride solution.
