Chemical Resistant Materials for Industrial Use
Here is a failure mode that catches engineers off guard: you select a material using a compatibility chart, it passes the reference check, and six months into service it swells, cracks, or loses its seal. The chart said “resistant.” The process temperature was 60 °C (140 °F), not 23 °C (73 °F). That gap is where specifications fail.
Chemical resistant materials are substances selected to maintain structural integrity under sustained exposure to acids, bases, solvents, or process chemicals. No single material class dominates every chemical environment: temperature, concentration, and exposure duration interact to determine performance. Elastomers such as FKM, EPDM, and polyurethane, alongside engineering plastics and fluoropolymers, each suit distinct industrial chemical conditions. Understanding where each class performs — and where it does not — is the foundation of sound material selection for polyurethane industrial applications and all harsh-environment service.
This article covers the four main material families for chemical-exposure service, where polyurethane fits within the elastomer landscape, how temperature and concentration interact to change the performance equation, and a six-point selection checklist you can apply before finalising any specification. Whether you are evaluating sealing components for harsh environment applications or specifying structural materials for chemical process equipment, the same framework applies.
1. What Chemical Resistance Means in Practice
Chemical resistance is intrinsic to molecular structure — not a surface treatment or a finishing step. A material’s resistance profile is fixed at formulation. No post-process coating makes an incompatible base material suitable for chemical-exposure service.
Resistance is also conditional, not absolute. Three variables always qualify any compatibility rating: the chemical identity (acid, base, solvent, or oil), the concentration (dilute versus concentrated versus vapour), and the exposure temperature. A rating at reference conditions — typically 23 °C (73 °F) and atmospheric pressure — tells you nothing about performance at elevated temperature or high concentration.
Internationally, chemical resistance is measured through standardised immersion testing. ISO 175:2010 specifies the immersion test method for determining the effects of liquid chemicals on plastics and elastomers, providing a harmonised framework for cross-material comparison. ASTM D543-21 defines three evaluation procedures for plastics, covering immersion methods and a mechanical-stress-plus-reagent method; measured parameters include changes in mass, dimensions, appearance, and mechanical properties. For rubber and elastomeric seals, ASTM D471-16a(2021) covers exposure to oils, fuels, and process chemicals under controlled conditions.
Industry compatibility databases such as the Cole-Parmer Chemical Compatibility Guide rate materials per specific chemical at reference conditions. They are a necessary screening tool — and not a sufficient one. Always verify that the database test temperature and concentration match your actual service conditions before specifying.
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2. Material Classes for Chemical-Exposure Service
The four main material families for chemical-exposure applications each carry a distinct performance profile. Selecting on the basis of one property — say, acid resistance — without accounting for mechanical load and operating temperature is how misspecifications happen.
Fluoropolymers and Engineering Plastics
PTFE (polytetrafluoroethylene) is chemically inert from −200 °C to 260 °C (−328 °F to 500 °F) and resists virtually all industrial chemicals. It is the highest-performance option for corrosive static applications. Low mechanical strength is the trade-off: PTFE is best suited to linings, seals, and tubing rather than structural components.
PVDF (polyvinylidene fluoride) offers strong resistance to acids, solvents, and UV exposure alongside structural rigidity. It is widely used in chemical piping systems and pump components where you need chemical inertness without sacrificing stiffness.
PP (polypropylene) and HDPE (high-density polyethylene) are cost-effective for most acids and bases in storage and transfer applications. Both degrade in aromatic hydrocarbons and chlorinated solvents. “Plastic is acceptable” is not a material specification — the chemical class determines which plastic applies.
Elastomers for Dynamic and Sealing Applications
Elastomers serve sealing, gasket, hose, roller, and diaphragm applications — scenarios where shape recovery under compression or cyclic movement is required alongside chemical resistance. The polyurethane vs rubber vs plastic comparison covers the full cross-material overview. Section 3 below goes deeper on elastomer selection specifically.
FKM, EPDM, NBR, and polyurethane each carry distinct resistance profiles suited to different chemical families. No elastomer is universally compatible — the selection depends on which chemicals are present, at what concentration, and at what temperature.
Corrosion-Resistant Metals
Titanium offers exceptional resistance to strong oxidising and reducing acids — nitric, sulphuric, hydrochloric — at elevated temperature. It is the metal of choice for heat exchangers and chemical processing vessels where polymers cannot sustain mechanical load.
Stainless steel 316 resists oxidising acids, mild organic acids, and alkaline environments. It degrades in chloride-rich environments such as seawater and hydrochloric acid; it is not suitable where halide exposure is present.
Nickel and molybdenum alloys — Hastelloy C-276 being a widely used example — handle reducing and highly corrosive chemical environments where stainless steel fails. High cost positions this class as a last-resort specification. These alloys directly answer the common question about which metals are chemical resistant: the answer is that metal selection is as condition-specific as polymer selection, and is absent from almost every published comparison of chemical resistant materials in organic SERP results.
Technical Ceramics and Glass-Lined Equipment
Technical ceramics withstand most strong mineral acids, bases, and organic solvents even at extreme temperatures. They are used in pump components, valve seats, and process equipment where simultaneous chemical resistance and hardness are required.
Glass-lined reactors and vessels are standard in pharmaceutical and chemical processing where metal ion contamination is unacceptable. Glass lining is brittle: controlled thermal cycling and inspection regimes are mandatory, and this class is not appropriate for impact or dynamic loading.
3. Elastomers for Chemical Exposure — Where Polyurethane Fits
Standard elastomer reference guides cover nine rubber families: EPDM, FKM, silicone, NBR, neoprene, PVC, TPE, butyl, and natural rubber. Polyurethane is absent from every major published comparison — despite being a widely used industrial elastomer class for seals, rollers, abrasion pads, and chemical-contact components. That gap is worth addressing.
EPDM offers strong resistance to acids, alkalis, and oxygenated solvents. It degrades rapidly in petroleum oils and aromatic hydrocarbons. If your process involves hydrocarbon exposure, EPDM is not a candidate regardless of its acid compatibility.
FKM (Viton) provides broad resistance across oils, fuels, and many concentrated acids. It fails against ammonia and concentrated caustics. FKM is the performance leader for mixed-chemical harsh environments, but it is not universal — ammonia-based cleaning agents or concentrated sodium hydroxide exposure eliminates it from consideration.
NBR (nitrile) excels in oil and fuel resistance and degrades in acids, alkalis, and ketones. Formulation-level variation within NBR grades is significant: grade-specific compatibility data is required before final selection, not a generic “nitrile is oil-resistant” assumption.
Polyurethane and TPU compete for oil-resistant seals, abrasion-critical components, and low-temperature chemical environments. Pepson’s E680A special polyester TPU is rated for oil resistance and flex resistance with a temperature floor of −50 °C (−58 °F) — the lowest floor in the Pepson TPU range, making it a candidate where chemical exposure coincides with cold-temperature process conditions. Polyether TPU grades offer better resistance to hydrolysis and polar solvents than polyester grades, with a temperature floor of −40 °C (−40 °F — the only temperature where the Celsius and Fahrenheit scales coincide). General polyester grades floor at −30 °C (−22 °F).
The important positioning point: PU is a multi-property candidate. Where chemical resistance, abrasion resistance, and low-temperature flexibility must all be satisfied simultaneously, PU grades offer combinations that single-property elastomers do not. For polyurethane chemical resistance profiles broken down by chemical class, see the dedicated material science reference. For seal and gasket applications, see polyurethane gaskets and seals.
No single elastomer dominates across all chemical types. Hansson (2017), Lund University confirmed this by testing FKM, EPDM, and silicone gaskets against nitric acid, caustic base, and peroxide at elevated temperature: FKM maintained sealability across all environments; EPDM failed fastest in caustic base. No single elastomer class dominated across all chemical–temperature combinations. Selection requires chemical identity, concentration, and temperature together — not a generic compatibility rating.
4. How Temperature and Concentration Change the Equation
The Hansson (2017) study makes the temperature interaction visible in numbers. FKM and EPDM gaskets tested in caustic base at elevated temperature diverged sharply: FKM carried a projected service life of approximately 200 days; EPDM failed at approximately 50 days. That is a 4× difference. The cause was not the chemical alone — it was temperature amplifying the degradation mechanism, not simply accelerating an otherwise linear process.
Temperature does not only speed up chemical attack. It can change which degradation mechanism dominates. A material rated compatible at 23 °C (73 °F) may swell, crack, or lose tensile strength at 60 °C (140 °F) under the same chemical at the same concentration — because a different failure mode is now active.
Concentration is an independent variable. ASTM D471-16a(2021) requires test conditions to specify chemical type, concentration, and temperature because the same elastomer behaves differently across combinations. A material that passes dilute acid at room temperature may fail concentrated acid at 50 °C (122 °F) — these are not the same test.
Low-temperature environments add a third constraint. At sub-zero process temperatures, grade selection must satisfy both the chemical resistance requirement and the low-temperature flexibility floor simultaneously. Pepson TPU polyether grades are rated to −40 °C (−40 °F — the only temperature where the two scales coincide); special polyester E680A to −50 °C (−58 °F); general polyester to −30 °C (−22 °F). The grade with the best chemical profile may not be the grade with the right temperature floor. You need to verify both.
For guidance on temperature-range selection and how polyurethane grades perform across the thermal spectrum, see polyurethane temperature resistance.
The practical implication: never specify from a room-temperature compatibility chart for a process running at elevated temperature or elevated concentration. Require supplier test data at service conditions, or specify testing per ASTM D543-21 at those conditions.
5. A Six-Point Selection Checklist
Six inputs are required before material selection for chemical-exposure service can be finalised. Specifying chemical resistant materials without all six is the most common cause of premature component failure in industrial chemical resistance applications.
1. Chemical identity and class. Acid, base, solvent, oil, or a mixed-chemical environment? The material class that resists acids may not resist oils, and vice versa. Mixed environments require checking each chemical in the process stream independently.
2. Concentration. Dilute versus concentrated versus vapour. The same chemical at different concentrations can produce different failure modes. Vapour-phase exposure can penetrate materials that resist liquid-phase contact.
3. Operating temperature range — upper and lower bounds. Elevated temperature amplifies degradation; sub-zero temperatures impose flexibility requirements. Both ends of the operating range must be verified, not just the typical service temperature.
4. Exposure duration and cycle. Continuous versus intermittent exposure. Cyclic wetting and drying can accelerate degradation through mechanisms — swelling stress, surface attack — that continuous immersion does not activate in the same way.
5. Mechanical load and application type. Static component, dynamic seal, structural element. A material that passes chemical compatibility but fails under mechanical load in service is not a viable specification. Multi-property test data at service conditions is the only reliable basis for a final decision.
6. Regulatory and compliance requirements. FDA or USDA approval for food and pharmaceutical contact; ATEX certification for explosive atmospheres; NSF standards for potable water applications. Compliance requirements can immediately eliminate candidates that pass all performance checks.
Compatibility chart ratings are a necessary first screen. They are reference-condition ratings at a single temperature and concentration — not service-condition guarantees. When two candidate materials both pass the compatibility screen, differentiate on temperature range, mechanical performance (hardness, tensile strength, elongation at break), and total cost of ownership across service life including replacement frequency.
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FAQ
What material is chemical resistant?
No single material is universally chemical resistant. The material that suits a given application depends on the specific chemical, its concentration, and the operating temperature. Among commonly specified chemical resistant materials, fluoropolymers such as PTFE offer the broadest chemical inertness but low mechanical strength. FKM elastomers resist oils, fuels, and many acids. Engineering plastics such as PVDF handle acids and solvents with structural rigidity. Polyurethane grades suit oil-resistant, abrasion-critical, and low-temperature harsh environment applications.
What are the five types of resistant materials?
Rather than a fixed five-type taxonomy, the practical grouping for industrial specifiers follows use-case scenarios. For acid storage and transfer, fluoropolymers (PTFE, PVDF) and corrosion-resistant metals (titanium, Hastelloy) are the candidates. For oil-resistant dynamic seals, FKM, NBR, and polyurethane compete depending on temperature and mechanical load. For alkali exposure, EPDM and glass-lined equipment are frequently specified. For high-temperature and structural chemical service, technical ceramics and nickel alloys handle what polymers cannot. The selection by scenario is more useful than a numbered list because chemical environments rarely fit neat categories.
What does “chemical resistant” mean?
A material is chemical resistant when it maintains its dimensional stability, mechanical properties, and surface integrity under sustained exposure to a specific chemical at defined conditions of concentration and temperature. The formal definition follows test standards such as ISO 175:2010 and ASTM D543-21, which classify resistance based on measured changes in mass, dimensions, appearance, and mechanical properties after controlled immersion. Resistance is always condition-specific — the same material may be resistant to dilute acid at room temperature and incompatible with concentrated acid at 60 °C (140 °F).
What metals are chemical resistant?
Titanium resists strong oxidising and reducing acids (nitric, sulphuric, hydrochloric) at elevated temperature and is used in heat exchangers and chemical processing vessels. Stainless steel 316 handles oxidising acids, mild organic acids, and alkaline environments but degrades in chloride-rich conditions. Nickel and molybdenum alloys such as Hastelloy C-276 are specified for reducing and highly corrosive environments where stainless steel fails. All metal selections are condition-specific — concentration, temperature, and chloride content all determine which grade is appropriate.
What are examples of chemical resistant materials?
Common examples of chemical resistant materials across material classes include: PTFE for broad chemical inertness in static linings and seals; PVDF for acid and solvent piping; EPDM for alkali, acid, and steam sealing applications; FKM (Viton) for oil, fuel, and mixed-acid harsh environment applications; polyurethane and TPU for oil-contact seals and abrasion-critical components requiring low-temperature flexibility; titanium for strong-acid process equipment; and glass-lined vessels for pharmaceutical reactors requiring metal-free contact surfaces. The right choice for your application depends on which chemical class, concentration, and temperature are present in service.
Conclusion
Chemical resistance is always condition-specific. A material that performs under dilute acid at room temperature may fail under concentrated acid at 60 °C (140 °F). Chemical identity, concentration, temperature, and mechanical load must all be specified before any material can be confirmed as suitable for a given service environment.
The main material families — fluoropolymers, elastomers, corrosion-resistant metals, and technical ceramics — each suit distinct combinations of chemical class and operating condition. Within the elastomer class, polyurethane and TPU fill a gap in the standard comparison landscape: they offer combinations of chemical resistance, abrasion resistance, and low-temperature flexibility that single-property elastomers do not.
Pepson polyurethane and TPU grades are available in polyether, general polyester, and special polyester formulations, covering Shore 80A to 70D with temperature floors from −30 °C to −50 °C (−22 °F to −58 °F). If you are specifying elastomeric components for chemical-exposure environments and need grade-level guidance, our engineering team can advise on formulation selection based on your service conditions.
Pepson has manufactured high-performance polyurethane elastomers since 1998, serving industries worldwide from our Dongguan, China facility. Our material science expertise and quality manufacturing deliver solutions optimized for demanding applications.
