ISO 16276-1:2025

Overview

ISO 16276-1:2025 - "Corrosion protection of steel structures by protective paint systems - Assessment of, and acceptance criteria for, the adhesion/cohesion (fracture strength) of a coating - Part 1: Pull-off testing" specifies procedures for on-site assessment of the fracture strength (adhesion and cohesion) of protective paint coatings on steel substrates (minimum thickness 3 mm). This second edition complements the ISO 12944 series, formalizes pull-off testing practices, and defines inspection areas, sampling plans and acceptance/rejection criteria. It does not prescribe numerical fracture strength values - those must be specified in contract documentation together with the test equipment and manufacturer.

Key topics and requirements

• Scope and applicability: For coatings of any thickness on steel ≥ 3 mm; applicable only when a fracture strength value plus specific test equipment (manufacturer/model) are specified.
• Test principle: Pull-off method - dollies fixed to coating with an adhesive (glue), tensile force applied perpendicular to the substrate until fracture; force is recorded as fracture strength.
• Equipment & accessories: Specified tensile/pull-off apparatus (manufacturer/model as agreed), stainless-steel or aluminium dollies (typically 20 mm diameter; height ≥ ½ diameter recommended), circular cutting device and suitable glues (cyanoacrylate, two‑component epoxide, peroxide polyester, etc.).
• Calibration & performance: Measuring equipment must be calibrated; tensile rate must be uniform and not exceed 1 MPa/s, producing fracture within about 90 s. Non‑uniform or manual loading can give misleading results.
• Preparation & environmental conditions: Recently applied coatings must be cured per manufacturer; if unspecified, dry ≥ 10 days at substrate temperature > 15 °C and RH < 80%. Field conditions (air temp, RH, surface temperature, wet/dry state) must be monitored and reported.
• Sampling, interpretation & reporting: Defines inspection areas, sampling plans, interpretation of results and required test reporting. Pull-off testing is destructive; test panels may be used to prevent damage.

Applications and users

ISO 16276-1:2025 is intended for:

• Coating specifiers and asset owners who require objective acceptance criteria for protective paint systems on steel structures (bridges, offshore, industrial plants).
• Contractors and inspectors performing on-site quality control, corrosion protection verification and contractual acceptance testing.
• Corrosion engineers and QA/QC teams integrating pull-off test results into maintenance decisions, repairs and lifecycle planning.
• Use cases include pre‑acceptance of applied coatings, investigation of coating failures, verification of contractor performance and field validation of laboratory test results.

Related standards

• ISO 4624 - Pull-off test for adhesion (laboratory method referenced)
• ISO 12944 - Corrosion protection by paint systems (complemented by this part)
• ISO 19840 - Measurement and acceptance criteria for dry film thickness on rough surfaces
• ISO 4618 - Paint terminology (adhesion, cohesion definitions)

Keywords: ISO 16276-1:2025, pull-off testing, fracture strength, adhesion/cohesion, protective paint systems, corrosion protection, steel structures, sampling plan, acceptance criteria.