oSIST prEN ISO 10426-1:2026

• Abstract:

  ISO 10426-1:2009 specifies requirements and gives recommendations for six classes of well cements, including their chemical and physical requirements and procedures for physical testing.; ISO 10426-1:2009 is applicable to well cement classes A, B, C and D, which are the products obtained by grinding Portland cement clinker and, if needed, calcium sulfate as an interground additive. Processing additives can be used in the manufacture of cement of these classes. Suitable set-modifying agents can be interground or blended during manufacture of class D cement.; ISO 10426-1:2009 is also applicable to well cement classes G and H, which are the products obtained by grinding clinker with no additives other than one or more forms of calcium sulfate, water or chemical additives as required for chromium (VI) reduction.

• Status: Not Published
• Public Enquiry End Date: 14-Jul-2026
• ICS: 75.180.10 - Exploratory, drilling and extraction equipment
• ICS: 91.100.10 - Cement. Gypsum. Lime. Mortar
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 21-May-2026
• Due Date: 08-Oct-2026
• Completion Date: 15-Jul-2026
• Ref Project: prEN ISO 10426-1 - Oil and gas industries including lower carbon energy - Cements and materials for well cementing - Part 1: Specification (ISO/DIS 10426-1:2026)

• Revises: SIST EN ISO 10426-1:2010/AC:2010 - Petroleum and natural gas industries - Cements and materials for well cementing - Part 1: Specification - Technical Corrigendum 1 (ISO 10426-1:2009/Cor 1:2010)
• Effective Date: 25-Feb-2026
• Revises: SIST EN ISO 10426-1:2010 - Petroleum and natural gas industries - Cements and materials for well cementing - Part 1: Specification (ISO 10426-1:2009)
• Effective Date: 25-Feb-2026
• Revises: SIST EN ISO 10426-1:2010/AC:2018 - Petroleum and natural gas industries - Cements and materials for well cementing - Part 1: Specification - Technical Corrigendum 2 (ISO 10426-1:2009/Cor 2:2012)
• Effective Date: 25-Feb-2026

oSIST prEN ISO 10426-1:2026 is the Slovenian draft adoption of ISO/DIS 10426-1:2026 from ISO for the oil and gas industries including lower carbon energy. It specifies requirements and recommendations for well cements used in well cementing, including chemical and physical requirements, physical testing procedures, and a supplementary GWP reporting requirement for manufacturers and users who qualify or specify these cements. As a draft International Standard, the text is still subject to change before publication.

What does oSIST prEN ISO 10426-1:2026 specify?

oSIST prEN ISO 10426-1:2026 specifies well cement requirements for eight classes: A, B, C, D, G, H, K and L. It focuses on the cement composition, the chemical and physical requirements, and the procedures used to test those properties in practice.

The scope covers well cements made from Portland cement clinker and related composite formulations. Classes A to D are based on Portland cement clinker, classes G and H are based on clinker with limited permitted additions, and classes K and L are composite well cements with specified composite constituents. Clause 4 is the technical core of the document, and it is divided into general requirements and GWP-related requirements.

The document is organized into four main clauses:

• Scope
• Normative references
• Terms and definitions
• Supplements to API Spec 10A, 25th edition (2019)

Clause 4 is the part that adds the ISO-specific provisions to the API base standard.

What are the key requirements of oSIST prEN ISO 10426-1:2026?

oSIST prEN ISO 10426-1:2026 requires users to start with API Spec 10A, 25th edition (2019), and then apply the exceptions and additions in this document. In practice, that means the API cement requirements remain the base, but this part adds extra obligations that must also be met.

• Clause 4.1 says the requirements of API Spec 10A apply unless this document states otherwise. For users, that means qualification and purchasing decisions need to check both documents together.
• The scope identifies the eight cement classes and their permitted manufacturing routes. That matters because product formulation has to match the class claimed on the product or in the specification.
• Classes A, B, C and D are Portland-cement-based products, with calcium sulfate permitted when needed, and class D allowing set-modifying agents during manufacture. This is the main formulation rule for these common well cements.
• Classes G and H are made from clinker with no additives other than forms of calcium sulfate, water, or chemical additives needed for chromium (VI) reduction. This restricts what can be added and helps users control conformity.
• Classes K and L are composite well cements made with specified composite constituents, either by intergrinding or by later blending. For manufacturers, that means the product route and constituent control both matter.
• The document covers chemical and physical requirements and physical testing procedures. In practice, this means compliance depends on test results, not only on the declared recipe.
• Clause 4.2 adds a GWP-related requirement: manufacturers shall maintain and provide on request a product-specific Type III Environmental Product Declaration (EPD). This gives buyers and specifiers a documented environmental profile they can request and compare.
• The EPD must conform to ISO 14025 and use ISO 21930 or EN 15804 as the framework, with cradle-to-gate A1-A3 Life Cycle Assessment (LCA) under ISO 14040 and ISO 14044. That means the environmental data must be structured, verified, and traceable to recognized rules.

What terms does oSIST prEN ISO 10426-1:2026 define?

API Spec 10A is the base cement standard that this document supplements for well cements and materials for well cementing.

EPD means Type III Environmental Product Declaration, a product-specific environmental declaration that is independently verified and published through a Program Operator.

GWP means Global Warming Potential, the environmental metric addressed in Clause 4.2 for well cements.

LCA means Life Cycle Assessment, the method used here to build the EPD from cradle to gate.

PCR means Product Category Rules, the rules that define how the LCA and EPD are prepared for a product category.

Cradle-to-gate means the assessment covers raw materials through factory output, which is why the document uses A1-A3.

CaSO4 means calcium sulfate, the material named in the formulation rules for several cement classes.

Who uses oSIST prEN ISO 10426-1:2026?

oSIST prEN ISO 10426-1:2026 is used by well cement manufacturers, drilling and completion fluids specialists, laboratory personnel, quality managers, buyers, and specifiers in the oil and gas industries including lower carbon energy. They use it to select a cement class, confirm the product formulation, run physical tests, and prepare or request environmental documentation such as the EPD. It is also relevant when products are being qualified, purchased, or documented for technical review.

What changed in oSIST prEN ISO 10426-1:2026 from the previous edition?

oSIST prEN ISO 10426-1:2026 cancels and replaces ISO 10426-1:2009 and its Technical Corrigendum 1 (2010). The foreword says the main change is the addition of “Determining The Global Warming Potential (GWP) of Well Cements.” It also updates the document to the current API Spec 10A, 25th edition (2019), including Addendum 1 and Addendum 2.

Which standards are used with oSIST prEN ISO 10426-1:2026?

• API Spec 10A, 25th edition (2019) - provides the base requirements that this document supplements.
• ISO 14025 - gives the framework for Type III EPDs.
• ISO 21930 - gives the core rules for environmental product declarations of construction products and services.
• EN 15804 - gives the core rules for construction product EPDs.
• ISO 14040 - gives the principles and framework for LCA.
• ISO 14044 - gives the requirements and guidelines for LCA.

What does the oSIST prEN ISO 10426-1:2026 document contain?

The document contains a foreword, scope, normative references, terms and definitions, and Clause 4 on supplements to API Spec 10A. The technical focus is on cement class coverage, application of the API base requirements, and the added GWP-related EPD and LCA requirement. It does not reproduce the underlying API test methods, but it points readers to the base standard and to the environmental standards used for the new reporting requirement.

SLOVENSKI STANDARD
01-julij-2026
Naftna in plinska industrija, vključno z nizkoogljično energijo - Cementi in materiali
za cementiranje vrtin - 1. del: Specifikacija (ISO/DIS 10426-1:2026)
Oil and gas industries including lower carbon energy - Cements and materials for well
cementing - Part 1: Specification (ISO/DIS 10426-1:2026)
Öl- und Gasindustrie einschließlich kohlenstoffarmer Energieträger - Zemente und
Materialien für die Zementation von Tiefbohrungen - Teil 1: Anforderungen (ISO/DIS
10426-1:2026)
Titre manque - Partie 1: Titre manque
Ta slovenski standard je istoveten z: prEN ISO 10426-1
ICS:
75.180.10 Oprema za raziskovanje, Exploratory, drilling and
vrtanje in odkopavanje extraction equipment
91.100.10 Cement. Mavec. Apno. Malta Cement. Gypsum. Lime.
Mortar
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 10426-1
ISO/TC 67/SC 3
Oil and gas industries including
Secretariat: UNI
lower carbon energy — Cements
Voting begins on:
and materials for well cementing —
2026-04-28
Part 1:
Voting terminates on:
2026-07-21
Specification
ICS: 75.020; 91.100.10
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Reference number
ISO/DIS 10426-1:2026(en)
DRAFT
ISO/DIS 10426-1:2026(en)
International
Standard
ISO/DIS 10426-1
ISO/TC 67/SC 3
Oil and gas industries including
Secretariat: UNI
lower carbon energy — Cements
Voting begins on:
and materials for well cementing —
Part 1:
Voting terminates on:
Specification
ICS: 75.020; 91.100.10
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
BE CONSIDERED IN THE LIGHT OF THEIR
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
POTENTIAL TO BECOME STANDARDS TO
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or ISO’s member body in the country of the requester.
NATIONAL REGULATIONS.
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RECIPIENTS OF THIS DRAFT ARE INVITED
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TO SUBMIT, WITH THEIR COMMENTS,
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NOTIFICATION OF ANY RELEVANT PATENT
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RIGHTS OF WHICH THEY ARE AWARE AND TO
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Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 10426-1:2026(en)
ii
ISO/DIS 10426-1:2026(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Supplements to API Spec 10A, 25th edition (2019) . 2
4.1 General requirements .2
4.2 Determining The Global Warming Potential (GWP) of Well Cements .2

iii
ISO/DIS 10426-1:2026(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
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with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives,
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