API Spec 6D — Specification for Valves, 25th Edition — Includes Errata 1, 2 & 3 + Addenda 1, 2 & 3

About this publication

The API Specification 6D — Specification for Valves, 25th Edition is the American Petroleum Institute’s comprehensive specification establishing requirements for valves used throughout the petroleum, natural gas, pipeline, piping, and hydrogen industries.

This updated package includes the 25th Edition of API Spec 6D together with Errata 1, Errata 2, Errata 3, Addendum 1, Addendum 2, and Addendum 3, providing the complete published update sequence through March 2025.

API Spec 6D defines requirements covering the design, manufacturing, materials, welding, quality control, assembly, testing, marking, documentation, and process controls associated with industrial valves.

The specification applies to major valve types including:

• Axial valves

• Ball valves

• Check valves

• Gate valves

• Plug valves

These valves are widely used in pipelines, terminals, processing facilities, compressor and pumping installations, petroleum systems, natural-gas infrastructure, and other energy-industry applications where reliable pressure isolation and flow control are critical.

The 25th Edition represents a major modernization of API 6D and supersedes the previous 24th Edition. API also shortened the formal title from the earlier Specification for Pipeline and Piping Valves to Specification for Valves, reflecting the wider range of applications covered by the current standard.

API 6D addresses the complete valve manufacturing process rather than focusing only on dimensional requirements. Manufacturers must consider design verification, pressure-containing components, materials, welding, heat treatment, bolting, assembly, factory acceptance testing, marking, documentation, and controlled manufacturing processes.

The specification includes requirements affecting pressure-containing parts, valve bodies, closures, seats, stems, shafts, bolting, end connections, flanges, weld ends, cavity pressure relief, drive trains, actuators, coatings, corrosion protection, and product marking.

Material requirements are particularly important because valves may operate under high pressures, corrosive fluids, low temperatures, elevated temperatures, sour conditions, hydrogen environments, or other demanding service conditions. API 6D establishes requirements for metallic and nonmetallic materials and coordinates with numerous other API, ASTM, ASME, and ISO standards.

Testing is another central part of the specification. API 6D establishes requirements for factory acceptance testing, hydrostatic shell testing, seat testing, pressure testing, inspection, and verification of finished valve performance.

Quality control and manufacturing process controls are also integrated throughout the document. Requirements address activities such as material procurement, machining, welding, assembly, inspection, testing, marking, coating, corrosion protection, and final inspection.

Includes All Published 25th Edition Updates Through 2025

This package includes:

Errata 1 — December 2021

Corrects technical and editorial issues identified after publication of the 25th Edition.

Errata 2 — April 2022

Provides additional corrections and clarifications applicable to the 25th Edition.

Addendum 1 — April 2023

Addendum 1 introduced revisions across numerous requirements, including updates involving:

• Definition of date of manufacture

• Flow coefficient definitions

• Full-opening valve requirements

• Pressure-balance hole design

• Manufacturing and design provisions

• Testing and technical requirements

For example, the revised definition of the date of manufacture identifies it as the month and year in which factory acceptance testing is completed.

Errata 3 — October 2023

Errata 3 provides additional technical corrections affecting requirements including:

• Supplemental requirements

• Valve body marking

• Check-valve flow-direction marking

• Material designation requirements

• Applicable tables and notes

Addendum 2 — September 2024

Addendum 2 is one of the most significant updates to API Spec 6D because it formally expands the specification to address hydrogen gas service.

The revised scope covers valves used in:

• Petroleum industries

• Natural gas industries

• Hydrogen gas service

Addendum 2 introduces Specification Level for Hydrogen (SLH) requirements and a new Annex M containing supplemental provisions for valves intended for hydrogen applications.

Major hydrogen-related provisions address:

• Design validation

• High-pressure gas testing

• Fugitive-emission testing

• Metallic material requirements

• Nonmetallic material requirements

• Supplemental acceptance testing

• Fire-safe certification

• Antistatic design

• Additional nondestructive examination

• Hydrogen-specific valve reliability

• Factory acceptance testing

This update makes API 6D increasingly important for manufacturers and operators involved in emerging hydrogen pipeline and energy infrastructure.

Addendum 3 — March 2025

Addendum 3 provides the latest published revisions to the 25th Edition.

Important changes include updated normative references to API material and manufacturing specifications and revised requirements involving:

• API Spec 20A castings

• API Spec 20B open-die forgings

• API Spec 20C closed-die forgings

• API Spec 20E bolting

• Flange alignment and misalignment tolerances

• Valve cavity pressure relief

• Pressure-boundary bolting

• Check-valve flow marking

• Material specifications

Addendum 3 also clarifies cavity-relief requirements where trapped liquid could generate excessive internal pressure.

Hydrogen Gas Service — Major 2024 Expansion

One of the strongest reasons to use the updated API 6D package rather than the original November 2021 publication alone is the addition of specific hydrogen gas service requirements.

Hydrogen can create design and material challenges that differ from conventional petroleum and natural-gas service. Addendum 2 therefore adds additional requirements intended to address valve integrity and reliability when hydrogen service is specified.

These include additional consideration of:

• Hydrogen compatibility of metallic materials

• Elastomers and thermoplastics

• Fugitive emissions

• High-pressure gas testing

• Valve sealing performance

• Fire-safe performance

• Antistatic features

• Additional NDE

• Design validation

For manufacturers and engineering organizations entering the hydrogen infrastructure market, these updated API 6D requirements are increasingly significant.

Valve Types Covered

API Spec 6D covers requirements applicable to:

Ball Valves

Widely used for positive shutoff in pipeline and process applications.

Gate Valves

Commonly used where full-bore flow and low pressure drop are important.

Check Valves

Designed to prevent reverse flow and protect pipeline systems and equipment.

Plug Valves

Used for isolation and flow-control applications across petroleum and natural-gas systems.

Axial Valves

Included within the current API 6D scope for applicable petroleum, natural-gas, and hydrogen service.

Major Areas of Coverage

API Spec 6D provides requirements involving:

• Valve design

• Design validation

• Design documentation

• Pressure-containing components

• Body and closure design

• End connections

• Flanged ends

• Weld ends

• Materials

• Castings

• Forgings

• Bolting

• Nonmetallic components

• Welding

• Heat treatment

• Assembly

• Valve seats

• Stems and shafts

• Drive trains

• Cavity pressure relief

• Factory acceptance testing

• Hydrostatic testing

• Seat testing

• Fugitive emissions where applicable

• Inspection

• Nondestructive examination

• Quality control

• Marking and identification

• Documentation

• Coating and corrosion protection

• Manufacturing process controls

Why This Standard Matters

The updated API Spec 6D, 25th Edition with Errata 1–3 and Addenda 1–3 is an essential reference for professionals involved in valve design, manufacturing, procurement, testing, inspection, and operation, including:

• Valve manufacturers

• Mechanical engineers

• Pipeline engineers

• Piping engineers

• Petroleum engineers

• Natural-gas professionals

• Hydrogen-system engineers

• Pipeline operators

• Oil and gas companies

• EPC contractors

• Valve design engineers

• Materials engineers

• Welding engineers

• QA/QC professionals

• API inspectors

• NDT personnel

• Procurement specialists

• Equipment manufacturers

• Pipeline integrity professionals

• Technical standards libraries

Product Features

• Official API Specification 6D

• 25th Edition

• Includes Errata 1 — December 2021

• Includes Errata 2 — April 2022

• Includes Addendum 1 — April 2023

• Includes Errata 3 — October 2023

• Includes Addendum 2 — September 2024

• Includes Addendum 3 — March 2025

• Provides all currently published API 6D updates through March 2025

• Covers axial valves

• Covers ball valves

• Covers check valves

• Covers gate valves

• Covers plug valves

• Covers petroleum industry applications

• Covers natural-gas industry applications

• Adds hydrogen gas service

• Includes new hydrogen Specification Level (SLH)

• Includes hydrogen-service Annex M

• Covers valve design and manufacturing

• Covers materials and bolting

• Covers welding

• Covers quality control

• Covers assembly

• Covers factory acceptance testing

• Covers pressure and seat testing

• Covers marking

• Covers documentation

• Covers process controls

• Includes updated cavity-relief requirements

• Includes updated flange-alignment requirements

• Includes current API material-standard references

• Supports API Monogram manufacturing applications

Product Details

Title: API Specification 6D — Specification for Valves
Publisher: American Petroleum Institute (API)
Edition: 25th Edition
Publication: November 2021
API Publication Date: November 10, 2021
Base Standard Pages: 173
API Product Number: G6D025
Language: English
Status: Current 25th Edition with published updates
Supersedes: API Spec 6D, 24th Edition

Updates Included:

• Errata 1 — December 2021

• Errata 2 — April 2022

• Addendum 1 — April 2023

• Errata 3 — October 2023

• Addendum 2 — September 2024

• Addendum 3 — March 2025

Subject: Valves / Pipelines / Petroleum / Natural Gas / Hydrogen / Oil & Gas Equipment / Valve Manufacturing / Pipeline Equipment

Current Edition Note

The 25th Edition remains API's current published edition of Specification 6D.

API's current standards plan identifies the base 25th Edition as published November 10, 2021, followed by:

• Addendum 1 — April 3, 2023

• Addendum 2 — September 5, 2024

• Addendum 3 — March 5, 2025

This product includes those addenda together with the three published errata, providing a substantially more current working reference than the original 2021 publication alone.