Quick Summary:
- Multiple major valve standards are undergoing revision or have been recently published in new editions — including API 6D (2021 edition with updated DBB/DIB definitions), ISO 15848-1 (enhanced fugitive emission classes), and the ongoing revision of IEC 60534 control valve sizing standards — and engineers specifying valves today must ensure they reference the current edition, not previous versions embedded in older project specifications.
- The emerging body of hydrogen valve standards — including ISO 14687 for hydrogen fuel quality, ASME B31.12 for hydrogen piping and tentative guidance from API and CGA for high-pressure hydrogen valves — is still fragmented and evolving, creating genuine uncertainty for engineers specifying valves for hydrogen energy projects where no single authoritative standard yet covers all service conditions.
- Global regulatory convergence on fugitive emissions — with the EU Methane Regulation, US EPA tightening of LDAR requirements, and equivalents in Canada and Australia all moving towards enhanced monitoring, lower leak thresholds and stricter repair timelines — means that engineers specifying valves for new projects should treat ISO 15848 Class A as the baseline minimum, not an enhanced option.
API 6D 2021 Edition: Key Changes
The 2021 edition of API 6D (Specification for Pipeline and Piping Valves) brought several significant updates from the 2014 edition. The most technically significant are the revised definitions and testing requirements for Double Block and Bleed (DBB) and Double Isolation and Bleed (DIB) configurations. The 2021 edition more precisely defines DBB as a single valve providing two seating surfaces, both of which seal simultaneously against pressure from the same direction — each seat providing independent sealing from the same pressure source. DIB-1 and DIB-2 designations clarify configurations where each seat seals independently from fluid pressure on either side.
This clarification resolves longstanding ambiguity in project specifications that referenced “DBB” without specifying which configuration was intended. Projects that reference API 6D for double block and bleed requirements should confirm they’re using the 2021 edition definitions and that the valve supplier’s DBB/DIB designation is consistent with the project intent. A valve supplied as “DBB” to the 2014 edition definition may or may not meet the 2021 edition requirement — confirmation is needed.
The 2021 edition also updated requirements for seat closure force testing at elevated temperature — confirming that thermal effects on seat materials are addressed in the qualification testing. This is particularly relevant for ball valves with composite PTFE seats that may change dimensions at elevated temperature. Vendors supplying API 6D valves for elevated temperature service should confirm their test data covers the complete design temperature range, not just ambient temperature seat tests.
ISO 15848-1: Fugitive Emissions Standard Updates
ISO 15848-1 (Testing of Valves — Measurement, Test and Qualification Procedures for Fugitive Emissions) continues to evolve as the primary international standard for low-emission valve qualification. The standard’s Class A, B, C classification system (with Class A being the most stringent at ≤1×10⁻⁴ mg/s per mm of stem diameter) is increasingly referenced as the baseline requirement in new project specifications rather than as an enhanced option.
Industry observers note a trend towards projects specifying “ISO 15848-1 Class A for all valves in VOC service” as standard language, rather than the previous practice of specifying Class A only for valves in high-consequence services. This reflects both tighter regulatory expectations and the reduced cost premium for Class A qualified valves as manufacturers have standardised their low-emission packing designs. Engineers reviewing existing project specifications that reference “enhanced fugitive emissions” without specifying a specific ISO 15848 class should update these references to specify the class explicitly — “enhanced” is not a defined term in the standard and creates procurement ambiguity.
IEC 60534 Control Valve Sizing: Ongoing Revisions
The IEC 60534 series covering control valve sizing, noise prediction and flow capacity testing is undergoing a revision cycle that addresses several known limitations of the existing editions. The sizing equations for two-phase and wet steam service (currently addressed only approximately in the existing standard) are being strengthened. The noise prediction methodology in IEC 60534-8 is being updated to better address valve trim configurations that weren’t common when the current edition was written — particularly multi-stage and low-noise cage designs whose noise generation mechanisms differ from single-stage trims.
Engineers should be aware that the sizing methodology in the current IEC 60534 editions has known limitations at extreme conditions — very high pressure ratios in gas service, two-phase flows with high vapour fractions, and certain novel trim geometries. The published equations should be used with awareness of these limitations, and for complex or marginal cases, direct consultation with the valve manufacturer’s specialist application engineering team provides a more reliable sizing result than the standard equation alone.
Hydrogen Valve Standards: The Current Landscape
The hydrogen energy industry is developing faster than the standards framework can keep pace. Engineers specifying valves for high-pressure hydrogen service — electrolysis plants, hydrogen refuelling stations, hydrogen pipeline distribution, and hydrogen storage — currently navigate a fragmented landscape of standards and guidance documents, none of which comprehensively covers all aspects of hydrogen valve engineering.
ASME B31.12 (Hydrogen Piping and Pipelines) provides the primary piping design standard for hydrogen service and references ASME B16.34 for valve pressure-temperature ratings. API 6D and API 600 cover pipeline and industrial valves respectively but don’t specifically address hydrogen embrittlement qualification requirements. The Compressed Gas Association (CGA) and various national standards bodies have published guidance on hydrogen compatibility for materials and seals, but consensus standards specifically for hydrogen valve qualification are still emerging.
The practical consequence is that engineers specifying valves for hydrogen service currently need to assemble a specification from multiple sources — ASME for pressure ratings, ASME B31.12 for piping design requirements, ASME Special Working Group guidance on hydrogen-compatible materials, CGA guidance on elastomers for high-pressure hydrogen service, and vendor-specific hydrogen service qualification data. This is not the same as specifying for an established service like sour gas (where NACE MR0175 provides a single comprehensive reference) — it requires more engineering judgment and more explicit specification writing to fill the gaps.
EU Methane Regulation and Valve Implications
The European Union Methane Regulation (EU 2024/1787), which entered into force in 2024 and applies to the oil, gas and coal sectors, establishes binding requirements for methane leak detection and repair (LDAR) at upstream production, midstream transmission and storage, and import infrastructure. The regulation requires: survey-based LDAR at defined frequencies; component-level measurement using OGI (optical gas imaging) and quantification; and repair timelines that are significantly shorter than previous voluntary or national requirements.
For valve engineers, the EU Methane Regulation means that any valve on a pipeline or facility serving the European market — whether operated by an EU company or an importer — must meet the LDAR survey and repair requirements. This effectively mandates a fugitive emissions management programme, including regular inspection of valve stem seals, flanged connections and other emission sources, and repair within defined timelines when leaks above threshold are detected. Valves specified with ISO 15848 Class A low-emission packing from new are significantly less likely to trigger repair requirements in these surveys — the upfront specification cost is directly offset by reduced LDAR programme costs.
NORSOK Updates for Norwegian Continental Shelf
NORSOK standards — the Norwegian offshore industry standards developed collaboratively by the NCS industry and the Norwegian Petroleum Directorate — continue to be updated and remain highly influential for North Sea projects beyond Norway’s exclusive economic zone. NORSOK M-001 (Materials Selection) and NORSOK M-630 (Material Data Sheets) are key references for offshore valve material specification in addition to API and ISO standards. Projects in the UK and Norwegian North Sea typically reference both API and NORSOK standards, with NORSOK taking precedence on the Norwegian continental shelf where NPD/PSA requirements apply.
Engineers on international projects should confirm the applicable regulatory framework for the installation territory and identify which standards hierarchy applies — API for North American and most export-oriented projects, EN/ISO for European regulatory compliance, NORSOK for NCS-specific requirements. Where conflicts or gaps between standards families exist, the project’s engineering basis document should specify which takes precedence, rather than leaving this ambiguous for individual engineers to resolve case-by-case.
What This Means for Practising Engineers
The practical implication of a continuously evolving standards landscape is that valve specifications cannot be static. A project specification written in 2018 referencing specific standard editions may reference superseded editions that no longer reflect current industry requirements. The standard practice of updating project specifications at each project phase to reflect current standard editions is essential — not bureaucratic overhead but genuine quality assurance.
For engineers maintaining existing plant specifications, a periodic review against current standard editions (every 3–5 years for mature plants, at each major modification for active projects) identifies where the specification has fallen behind current requirements. The areas most likely to have evolved are: fugitive emissions requirements (consistently tightening), hydrogen service qualification (rapidly evolving), and the specific test requirements within API 6D and ISO 10497 (incrementally updated in each edition).
Summary
Standards are living documents and the valve industry’s regulatory framework is evolving faster than at any previous period, driven by decarbonisation, digitalisation and tightening environmental requirements. The engineer who knows the current edition of the applicable standards, understands where the gaps and ambiguities are (particularly for new applications like hydrogen), and keeps their project specifications updated accordingly is the engineer who produces specifications that hold up in procurement, in inspection, and in regulatory audit. Standards literacy isn’t optional for valve engineers — it’s the foundation of technically defensible engineering.