ISO 13879:1999

Overview

ISO 13879:1999 - Petroleum and natural gas industries - provides guidance on the content and drafting of a functional specification. It explains what a functional specification should contain, how it should be structured, and the drafting principles to ensure verifiable, unambiguous requirements. The standard clarifies when a functional specification is appropriate (e.g., for novel or performance-based procurements) and notes it may be unnecessary when acquiring known standard products or services.

Key topics and technical requirements

ISO 13879 outlines a clear framework and drafting rules, emphasizing that a functional specification must be:

• Verifiable - only include requirements that can be tested or demonstrated.
• Consistent and clear - use uniform terminology and avoid synonyms.
• Complete within scope - define limits of applicability and exclusions.
• Life-cycle aware - address operational, safety and maintenance aspects.

Core content elements recommended by the standard:

• Preliminary elements: title page, contents, foreword, introduction.
• Normative elements: scope, normative references (e.g., ISO 13880), terms and definitions.
• Functional normative elements:
  • Functional requirements - performance parameters, acceptance criteria, handling, storage, transport, preservative needs.
  • Operating environment - all known environmental conditions and constraints.
  • Boundaries, limits and exclusions.
  • Ergonomics (per ISO 6385) and safety/environment (per ISO/IEC Guide 51).
  • Documentation - records, certificates, commissioning/maintenance manuals, trial programmes.
• Supplementary elements: informative annexes and operational experience data.

Applications and practical use

ISO 13879 is practical for procurement and specification development across the petroleum and natural gas sector:

• Preparing performance-based procurement documents for equipment, systems, processes or services.
• Guiding project engineers, procurement specialists and technical authors in writing clear, testable functional specifications.
• Supporting innovation where standard components are not directly applicable (pilot tests, trials, packaged systems).
• Defining acceptance criteria and the documentation required to demonstrate conformity.

Who uses it:

• User/purchasers drafting functional specifications
• Manufacturers/suppliers preparing technical specifications (see ISO 13880)
• Project managers, systems engineers, QA/QC and regulatory compliance teams in oil & gas projects

Related standards

• ISO 13880 - Drafting and content of a technical specification (normative reference)
• ISO 6385 - Ergonomics principles (referenced)
• ISO/IEC Guide 51 - Safety aspects (referenced)
• ISO/IEC Directives - guidance on standards structure and terminology

ISO 13879:1999 is a practical drafting guide for producing clear, life-cycle focused functional specifications in the petroleum and natural gas industries.