Overview
EN ISO 3171:1999 (identical to ISO 3171:1988) covers recommended procedures for automatic pipeline sampling of petroleum liquids, principally crude oil and liquid petroleum products conveyed by pipeline. It does not apply to liquefied petroleum gases (LPG) or liquefied natural gas (LNG). The standard’s main aim is to provide guidance for specifying, testing, operating, maintaining and monitoring automatic samplers so that collected samples are representative for determination of composition, total water, sediments and other quality attributes.
Key topics and technical requirements
- Scope and purpose: Guidelines to obtain representative samples for composition, water and sediment content, density and other properties (with precautions for specific tests).
- Sampling principles: Need for homogeneity at the sampling point; preference for automatic sampling when pipeline conditions vary; role of sample integrity and conditioning.
- Sampler types: Definitions and differences between intermittent (grab) and continuous samplers; the requirement for proportional sampling (time‑proportional or flow‑proportional).
- Sampling point selection & stream conditioning: Guidance on locating probes, use of mixers (static, powered, variable-geometry) and ensuring adequate dispersion upstream of the probe.
- Profile testing: Multi‑point sampling across a pipe diameter to verify cross‑sectional uniformity and suitability of a sampling location.
- Probe, sampler and control design: Requirements for probe geometry, sampler installation, control equipment and maintaining proportionality to pipeline flow.
- Flow measurement & sample receivers: Considerations for accurate flow-proportional sampling, receiver and container design to preserve sample integrity.
- Sample handling & safety: Conditioning, transfer, division and transport practices and precautions for hazardous fluids.
- Validation & uncertainty: Procedures for proving sampling systems (field tests) and methods to estimate overall sampling‑system uncertainty; performance classification is included.
Practical applications and users
- Pipeline operators and terminals use EN ISO 3171:1999 to design and validate automatic sampling systems for crude oil and refined product transfers.
- Oil companies and traders rely on representative samples for quality control, analytical results (water, sediments, density) and commercial reconciliation.
- Equipment manufacturers and system integrators reference the standard when designing probes, samplers, mixers and control systems.
- Laboratories and quality assurance teams implement sample handling and conditioning requirements to preserve sample integrity.
- Regulatory and safety teams use the safety and procedural guidance when sampling hazardous petroleum liquids.
Related standards
- ISO 3170 - Petroleum products - Liquid hydrocarbons - Manual sampling
- ISO 3165 - Sampling of chemical products for industrial use - Safety in sampling
Keywords: EN ISO 3171:1999, automatic pipeline sampling, petroleum liquids, crude oil sampling, pipeline sampling, sample integrity, profile testing, sampler validation, flow‑proportional sampling.