Overview
CEN ISO/TR 13881:2011 (ISO/TR 13881:2000) is a Technical Report for the petroleum and natural gas industries that defines a risk-based approach to the classification and conformity assessment of products, processes and services. It describes two classification methods (a quantitative, calculation-based model and a judgement-based model) and a set of five conformity assessment systems (Systems A–E) from which the appropriate system is selected according to the assigned class. The report links risk of failure to the level of conformity assessment needed to give confidence that requirements are met.
Key topics
- Classification principles
- Class is determined over the full life cycle (from functional specification to decommissioning).
- Health, safety and environmental (HSE) requirements in all countries of use must be considered.
- Classification must be based on verifiable parameters.
- Two classification methods
- Calculation-based method - uses measurable probability and consequence data to calculate monetary risk. Example sub-model equation given:
T = (p0 · c0) + (p1 · c1) + (p2 · c2) (total risk expressed in monetary terms).
- Judgement-based method - qualitative assessment by experts where quantitative data are unavailable (annex provides guidance).
- Risk definitions
- Probability of failure, consequence of failure, and risk = probability × consequence.
- Conformity assessment systems
- Five systems (A to E) provide increasing or differing levels of confidence; classes 1–5 map to Systems A–E respectively (Class 1 = highest risk → System A; Class 5 = lowest risk → System E).
- Concepts such as design review, witness points, and hold points are included for implementation.
- Flexibility
- Alternative classification models are acceptable if results are consistent with the conformity assessment systems.
Applications
- Procurement and contracting: define required class and corresponding conformity assessment in functional/technical specifications (ISO 13879/13880).
- Supplier selection and quality assurance: determine supplier controls, inspection plans, witness/hold points and third‑party certification needs.
- Regulatory and HSE compliance: align conformity assessment intensity with safety and environmental consequence.
- Engineering and project management: plan design reviews, testing and verification activities to match risk class.
Who should use this standard
- Procurement and contract managers in oil & gas companies
- QA/QC and conformity assessment bodies
- Suppliers, manufacturers and service providers to the petroleum and natural gas sector
- Project, HSE and design engineers, and regulators involved in risk‑based assurance
Related standards
- ISO 13879 - Content and drafting of a functional specification
- ISO 13880 - Content and drafting of a technical specification
- ISO/IEC Guide 2 - General vocabulary for standardization and related activities
Keywords: CEN ISO/TR 13881:2011, ISO/TR 13881, petroleum and natural gas industries, conformity assessment, classification, risk-based classification, products processes services, design review, quality assurance.