Compatibility Standards

ISO 23936:2011 for Aging

ISO 23936 Annex A defines procedures for predicting the progressive degradation of elastomeric materials exposed to H₂S at elevated temperatures over extended periods, supporting accurate material selection and service life prediction in oil and gas environments.

Under ISO 23936, optional bespoke chemical aging tests are performed by immersing test samples in media such as brines, acids, bases, hydrocarbons, and gas mixtures under elevated temperature and pressure to simulate service conditions. This exposure accelerates chemical reactions between the fluid and elastomer, allowing systematic tracking of property changes like tensile strength, elongation, hardness, and volume as they approach predefined acceptance criteria. The material is considered to have reached the end of its useful life when these limits are attained, allowing clear data-driven service life estimation.

Acceptance criteria under ISO 23936 include:

• Hardness: +10 / -20 units (+5 / -20 units when initial nominal hardness is 90, Shore A or IRHD)
• Volume change: +25% / -5%
• Tensile properties (modulus at 50% or 100% elongation, tensile strength, elongation at break): ±50%

The preferred test piece geometry is the tensile dumbbell, tested in an unconstrained, free-standing mode to ensure uniform exposure. Post-exposure analysis includes tensile, hardness, compression, and visual inspections to evaluate degradation.

NORSOK M710 Edition 3 for Aging

NORSOK M-710 is a standard set by the Norwegian petroleum industry to certify sealing materials for use in demanding environments where H₂S is present. Bespoke testing based on the standard but containing brines, acids, bases, and hydrocarbon testing media can also be performed. While it primarily defines testing for thermoplastics, NORSOK M-710 references ISO 23936-2 for elastomers, aligning test methodologies and data interpretation practices across non-metallic materials to ensure consistency in material qualification for harsh service conditions.

The standard provides a structured framework for predicting the progressive degradation of thermoplastics under elevated pressures and temperatures, supporting reliable material comparison and service life prediction in critical oil and gas applications.

Under the NORSOK M-710 procedure, sample materials are submerged in testing media, such as brine, acid, base, hydrocarbons, or bespoke test fluids, at specified temperatures and pressures for a defined period. This controlled exposure is designed to accelerate chemical reactions between the fluid and the thermoplastic while systematically shifting material properties toward predefined acceptance limits. Aging can also be performed without a testing media, using only temperature and pressure conditions for thermal aging evaluations.

After exposure, the samples undergo detailed testing, including tensile, hardness, compression, and visual inspections, to assess material changes systematically. Testing is performed on finished-state components in an unconstrained, free-standing mode to ensure uniform exposure across all surfaces.

Accelerated testing typically involves using three elevated temperatures above service conditions, generating different times to reach acceptance limits. By plotting the log of failure times against the reciprocal of the test temperature, a linear trend can be established, enabling accurate service life predictions at operational temperatures using the Arrhenius relationship.

Acceptance criteria under NORSOK M-710 include:

• Volume change: +5% / -1%
• Tensile properties (modulus, strength, strain at break): ±50%
• Visual inspection: No dissolution, cracking, blistering, or physical deformation permitted

Alpine Polytech applies these standards to support confident material selection, performance envelope development, and long-term service suitability for thermoplastics operating in harsh environments.

NACE TM0187 and TM0296

NACE aging standards focus on evaluating elastomer and nonmetallic material resistance to sour and sweet service environments commonly encountered in oil and gas operations, providing systematic frameworks for compatibility assessment under H₂S, CO₂, hydrocarbon, brine, and acid/base exposure conditions.

NACE TM0187 defines procedures for immersing elastomer specimens in sour liquid hydrocarbons (H₂S environments) under elevated temperatures and pressures to measure changes in mass, hardness, tensile properties, and volume. This standard helps determine whether elastomer materials maintain integrity and mechanical properties in sour liquid environments, ensuring service reliability.

NACE TM0296 specifies test methods for aging elastomers in sour gas environments, including H₂S, CO₂, and hydrocarbons, under high pressures and temperatures. The standard details pre-conditioning, exposure procedures, controlled depressurization, and systematic post-test evaluations to assess volume change, hardness, tensile properties, and overall material compatibility in sour gas service.

These NACE standards collectively support predictive aging evaluations for elastomers in sour and aqueous environments, helping determine suitability and service life under harsh conditions. Testing is typically performed using elevated temperatures and pressures to simulate worst-case scenarios, followed by mechanical testing and visual inspections to verify integrity post-exposure.

API Standards for Aging

API standards often reference NACE or incorporate similar aging procedures but within the broader framework of elastomer and sealing system validation for oilfield applications:

API 6A (Annex F) includes aging requirements for nonmetallic seals in sour and sweet service, specifying temperature, pressure, and fluid compositions for compatibility validation for Specification for Wellhead and Christmas Tree Equipment.

API 6DSS References environmental testing under pressure and temperature with relevant test fluids for evaluating seals and nonmetallic components in Subsea Pipeline Valves.

API 17D requires elastomer qualification under temperature and pressure aging in relevant service fluids, including sweet and sour hydrocarbons and brines in Subsea Wellheads and Tree Equipment.

API 16A and 16C address compatibility aging for elastomers in blowout preventer and choke/kill systems, often referencing NACE conditions for sour environments and specifying exposure durations and evaluation metrics.