On 7 October 2026, the International Organization for Standardization formally published ISO/TS 25393:2026 — a technical specification titled Fasteners — Coating system assessment — Complementary and additional aspects to CQI-11. It is a slim document, just eighteen pages, but it fills a gap that has irritated fastener buyers and quality managers for years.
What the Standard Actually Does
CQI-11, the Automotive Industry Action Group's electroplating process evaluation guideline, has been the default reference for auditing plating shops since its third edition in 2019. The problem is that CQI-11 was written for general automotive parts. It does not address the peculiarities of fasteners — small parts, high throughput, tight thread tolerances, and the ever-present risk of hydrogen embrittlement.
ISO/TS 25393:2026 steps in as a companion document. It clarifies how CQI-11 should be applied specifically to fastener electroplating processes, and it calls out additional requirements that fastener coating systems must meet but that CQI-11 alone does not cover.
The specification references three core ISO documents as its technical foundation:
- ISO 4042:2022 — the standard for electroplated coating systems on fasteners
- ISO/TR 20491:2019 — the technical report on hydrogen embrittlement fundamentals in steel fasteners
- ISO 16047:2005 — the torque/clamp force test method for threaded fasteners
It also notes consistency with ASTM F1941/F1941M, the U.S. standard for electroplated coatings on threaded fasteners, so North American buyers are not looking at a conflicting framework.
Why the Hydrogen Embrittlement Section Matters Most
The most consequential part of the new specification is its treatment of hydrogen embrittlement prevention. CQI-11 mentions hydrogen management in broad terms. ISO/TS 25393:2026 drills down to fastener-specific controls: bake-out times and temperatures after acid pickling and electroplating, testing protocols, and the link between process parameters and the risk of delayed fracture in high-strength steel fasteners.
For buyers sourcing Grade 10.9 and 12.9 bolts — the grades used in wind turbines, high-pressure vessels, and heavy structural connections — this is not a footnote. A bolt that looks perfect on the outside can fail catastrophically months after installation if hydrogen was trapped in the steel during plating and not baked out properly. The new standard gives buyers a clearer checklist for auditing whether their suppliers' plating lines are actually managing this risk.
What the Standard Covers Beyond Hydrogen
The eighteen-page document also addresses practical coating properties that buyers test for but rarely see specified in a unified way. Annex A covers coating chemistry and thickness consistency. Annex B covers thread gageability and assembly fit — the question of whether a plated bolt still accepts a standard nut without binding or excessive torque. Annex C covers torque-tension testing, and Annex D covers corrosion testing alignment with salt spray requirements.
These annexes are informative, not normative, but they give suppliers and buyers a common language. A purchasing manager in Germany, a quality engineer in Texas, and a plating shop in Asia can all point to the same table when a batch of zinc-plated bolts arrives with borderline thread fit or inconsistent coating weight.
What This Means for Fastener Buyers
The specification is voluntary, not a regulatory mandate. No customs officer will ask for an ISO/TS 25393 compliance certificate at the border. But the buyers who will feel its impact first are the automotive and industrial OEMs whose supplier quality manuals already require CQI-11 plating audits. Those manuals are now being updated to reference ISO/TS 25393:2026 for fastener-specific plating lines. Tier-one suppliers, in turn, are pushing the requirement downstream.
For buyers who do not operate under IATF 16949 or automotive supply chains, the standard is still worth reading. It offers a ready-made assessment checklist for electroplated fastener suppliers, covering hydrogen embrittlement, thread fit, coating thickness, and corrosion performance. Even if you never quote the standard number in a purchase order, you can use its structure to ask sharper questions during supplier audits.
How FLRS Aligns with the New Requirements
At Shaanxi Flourish Industrial Co., Ltd., our surface treatment capabilities already map to the core requirements referenced in ISO/TS 25393:2026. We offer zinc plating, hot-dip galvanizing, PTFE coating, and Dacromet (zinc flake) coating across our bolt, nut, and washer product lines. Our quality system includes salt spray testing per ASTM B117 and coating thickness measurement. For high-strength grades 10.9 and 12.9, our process controls include post-plating hydrogen relief baking, and our laboratory performs hardness, tensile, and yield strength testing on representative samples from each production lot.
We also provide EN 10204 3.1 and 3.2 material certificates, dimensional inspection reports, and salt spray test results with every shipment. Third-party inspection through SGS, Bureau Veritas, or TÜV can be arranged on request. As buyer quality expectations tighten and standards like ISO/TS 25393:2026 gain traction in supply chain audits, having documented coating process controls and traceable test data is no longer a premium offering. It is baseline table stakes.
Sources
- ISO/TS 25393:2026, Fasteners — Coating system assessment — Complementary and additional aspects to CQI-11, published 7 October 2026. Official publication details available at ISO.org (reference number 90125, ICS 21.060.01).
- ISO/TC 2/SC 14 — Surface coatings committee catalogue, ISO.org.
