SIST EN ISO 7278-2:2023/A1:2026

• Status: Published
• Public Enquiry End Date: 23-Dec-2025
• Publication Date: 15-Jul-2026
• ICS: 75.180.30 - Volumetric equipment and measurements
• Technical Committee: NAD - Petroleum products, lubricants and related products
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 24-Jun-2026
• Due Date: 29-Aug-2026
• Completion Date: 16-Jul-2026
• Ref Project: EN ISO 7278-2:2022/A1:2026 - Petroleum measurement systems - Part 2: Pipe prover design, calibration and operation - Amendment 1 (ISO 7278-2:2022/Amd 1:2026)

• Amends: SIST EN ISO 7278-2:2023 - Petroleum measurement systems - Part 2: Pipe prover design, calibration and operation (ISO 7278-2:2022)
• Effective Date: 01-Sep-2026

SIST EN ISO 7278-2:2023/A1:2026 is the Slovenian adoption of EN ISO 7278-2:2022/A1:2026, published through SIST and based on ISO 7278-2. It is an amendment for petroleum measurement systems, focused on pipe prover design, calibration and operation. The amendment updates how spheres are inspected and sized, how leakage is checked before calibration, and what calibration observations must be recorded.

What does SIST EN ISO 7278-2:2023/A1:2026 specify?

SIST EN ISO 7278-2:2023/A1:2026 specifies changes to the base standard EN ISO 7278-2:2022 for pipe prover design, calibration and operation. The amendment is limited to the clauses and annex item listed below, so it should be read together with the base standard.

Location	What it covers
Clause 6.5.2	Deletes the earlier text on verifying sphere diameter
Clause 6.5.4	Adds new guidance for sphere inspection and sizing
Clause 11.2	Adds leak checking and safe sphere removal before calibration
Annex H, item j	Adds a calibration-report observation on temporary modifications

In practice, this means the document is about the condition, sizing and measurement of prover spheres, plus the checks and records needed when a prover is calibrated.

What are the key requirements of SIST EN ISO 7278-2:2023/A1:2026?

Sphere inspection and sizing

SIST EN ISO 7278-2:2023/A1:2026 adds a new Clause 6.5.4 for sphere inspection and sizing. New spheres and spheres removed from a prover are to be inspected in the same way, and the sphere supplier should be given the prover inside diameter and the expected oversize inflation.

This matters because the sphere has to fit the prover and remain compatible with the fluid and operating conditions. The sphere should also be checked for bulges, flats, cuts, abrasions, wear, degradation or softening, and a new sphere should be checked for an expiry date.

Measuring the sphere

SIST EN ISO 7278-2:2023/A1:2026 allows three usual measurement methods: an outside micrometre with a calibrated length standard, slip rings, or a diameter or circumference tape. The measuring instrument should be calibrated to a recognised standard, with suitable uncertainty, and checked and recalibrated at intervals based on use and experience.

This is important because the reported size must be traceable and repeatable. The sphere is measured across at least two perpendicular diameters, one across the filling valve(s), and the reported diameter is the smallest one measured.

Ovality and size acceptance

SIST EN ISO 7278-2:2023/A1:2026 uses multiple diameter measurements to judge ovality. The difference between the largest and smallest diameter should not exceed the limit referenced to API MPMS, chapter 4 section 9, part 2.

For users, this means a sphere is not accepted just because one diameter looks right. Ovality is part of the sizing check, and the amendment also notes that very large spheres can distort under their own weight.

Inflation condition in service

SIST EN ISO 7278-2:2023/A1:2026 states that sphere inflation is part of prover design, but it can be adjusted from operating experience or a product change. An underinflated sphere can leak, while an overinflated one can increase pressure loss, cause judder and give poor switch actuation.

In practice, inflation is not just a setup detail - it affects prover performance and should be controlled with the operating conditions in mind.

Checks before calibration

SIST EN ISO 7278-2:2023/A1:2026 adds to Clause 11.2 that, before calibration starts, the system should be checked for leakage. When appropriate, the four-way valve should be operated and leak checked, or a seal leakage test should be carried out on a piston prover.

This means calibration begins only after basic integrity checks. If a sphere displacer is removed, it should be taken out safely for inspection and, if needed, measured as found.

Calibration records

SIST EN ISO 7278-2:2023/A1:2026 adds an item to Annex H requiring temporary modifications used to help calibration to be recorded as observations in the calibration report. Examples include capping leaking drains or manually assisting a four-way valve to obtain a seal.

That helps the calibration report reflect the actual test condition. It gives the reader context for any unusual result or temporary workaround during calibration.

What terms does SIST EN ISO 7278-2:2023/A1:2026 define?

• Pipe prover - The prover used in petroleum measurement for design, calibration and operation requirements in this part.
• Sphere - The displacer inspected, sized and measured for fit and condition in the prover.
• Ovality - The difference between the largest and smallest measured sphere diameter, used to judge shape.
• Four-way valve - A valve that may need operating and leak checking before calibration.
• Piston prover - A prover type mentioned for seal leakage testing before calibration.
• As found diameter - The sphere diameter recorded before any adjustment after removal.
• Material compatibility - The match between sphere material, fluid and operating conditions.

Who uses SIST EN ISO 7278-2:2023/A1:2026?

This amendment is used by people who design, calibrate, inspect and operate pipe provers in petroleum measurement. It is relevant to metrology and calibration technicians, maintenance teams, prover manufacturers, and quality managers who need calibration records that reflect actual operating conditions.

It also matters to buyers and inspectors who specify prover condition, sphere replacement, or calibration evidence.

What changed in SIST EN ISO 7278-2:2023/A1:2026 from the previous edition?

SIST EN ISO 7278-2:2023/A1:2026 is Amendment 1 to EN ISO 7278-2:2022. The amendment:

• deletes the earlier text in 6.5.2 on sphere diameter verification
• adds Clause 6.5.4 on sphere inspection and sizing
• adds pre-calibration leak checking to 11.2
• adds Annex H item j on recording temporary modifications in the calibration report

Which standards are used with SIST EN ISO 7278-2:2023/A1:2026?

• EN ISO 7278-2:2022 - the base standard that this amendment modifies.
• ISO 7278-2:2022/Amd 1:2026 - the international amendment text approved by CEN without modification.
• API MPMS, chapter 4 section 9, part 2 - the cited reference for the ovality criterion used in sphere assessment.

What does the SIST EN ISO 7278-2:2023/A1:2026 document contain?

The document contains the European foreword, the endorsement notice, and the amendment text for the base standard. Its technical content is concentrated in revised wording for sphere inspection and sizing, leak checking before calibration, and calibration-report observations.

It also gives practical measurement guidance, including ways to measure diameter or circumference, how to judge ovality, and how to handle overinflation and valve leakage checks. For users, the value of the document is in the detailed operating and reporting steps that support consistent prover calibration.

SLOVENSKI STANDARD
01-september-2026
Merilni sistemi za nafto - 2. del: Načrtovanje, kalibracija in delovanje merilnika cevi
- Dopolnilo 1 (ISO 7278-2:2022/Amd 1:2026)
Petroleum measurement systems - Part 2: Pipe prover design, calibration and operation
- Amendment 1 (ISO 7278-2:2022/Amd 1:2026)
Mineralölmesssysteme - Teil 2: Auslegung, Kalibrierung und Betrieb von
Rohrprüfgeräten - Änderung 1 (ISO 7278-2:2022/Amd 1:2026)
Systèmes de mesurage des produits pétroliers - Partie 2: Conception, étalonnage et
fonctionnement des tubes étalons - Amendement 1 (ISO 7278-2:2022/Amd 1:2026)
Ta slovenski standard je istoveten z: EN ISO 7278-2:2022/A1:2026
ICS:
75.180.30 Oprema za merjenje Volumetric equipment and
prostornine in merjenje measurements
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 7278-2:2022/A1
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2026
EUROPÄISCHE NORM
ICS 75.180.30
English Version
Petroleum measurement systems - Part 2: Pipe prover
design, calibration and operation - Amendment 1 (ISO
7278-2:2022/Amd 1:2026)
Systèmes de mesurage des produits pétroliers - Partie Mineralölmesssysteme - Teil 2: Auslegung,
2: Conception, étalonnage et fonctionnement des tubes Kalibrierung und Betrieb von Rohrprüfgeräten -
étalons - Amendement 1 (ISO 7278-2:2022/Amd Änderung 1 (ISO 7278-2:2022/Amd 1:2026)
1:2026)
This amendment A1 modifies the European Standard EN ISO 7278-2:2022; it was approved by CEN on 7 June 2026.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for inclusion of
this amendment into the relevant national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This amendment exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7278-2:2022/A1:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 7278-2:2022/A1:2026) has been prepared by Technical Committee ISO/TC 28
"Petroleum and related products, fuels and lubricants from natural or synthetic sources" in
collaboration with Technical Committee CEN/TC 19 “Gaseous and liquid fuels, lubricants and related
products of petroleum, synthetic and biological origin” the secretariat of which is held by NEN.
This Amendment to the European Standard EN ISO 7278-2:2022 shall be given the status of a national
standard, either by publication of an identical text or by endorsement, at the latest by December 2026,
and conflicting national standards shall be withdrawn at the latest by December 2026.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 7278-2:2022/Amd 1:2026 has been approved by CEN as EN ISO 7278-2:2022/A1:2026
without any modification.
International
Standard
ISO 7278-2
Second edition
Petroleum measurement systems —
2022-11
Part 2:
AMENDMENT 1
Pipe prover design, calibration and
2026-06
operation
AMENDMENT 1
Systèmes de mesurage des produits pétroliers —
Partie 2: Conception, étalonnage et fonctionnement des tubes
étalons
AMENDEMENT 1
Reference number
ISO 7278-2:2022/Amd.1:2026(en) © ISO 2026

ISO 7278-2:2022/Amd.1:2026(en)
© ISO 2026
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ii
ISO 7278-2:2022/Amd.1:2026(en)
Foreword
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This document was prepared by Technical Committee ISO/TC 28, Petroleum and related products, fuels
and lubricants from natural or synthetic sources, Subcommittee SC 2, Measurement of petroleum and related
products, in collaboration with the European Committee for Standardization (CEN) Technical Committee
CEN/TC 19, Gaseous and liquid fuels, lubricants and related products of pet
...