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Pipeline Operators Forum 2009 - Words and Nomenclatures

Pipeline Operators

Pipeline operators forum 2009 is a referenced document for the pigging inspection professionals for caliper, MFL or UT intelligent tool.

Some nomenclature are not typical terminology, yet they are particularly defined to easy the communique amongst all project team members. Pipeline Operators forum.


Above Ground Marker: A device near the outside of a pipeline that detects and records the passage of an ILI tool or transmits a signal that is detected and recorded by the tool. Reference magnets can be applied to serve identical purposes.

Anomaly: An indication, detected by non-destructive examination of an irregularity or deviation from base pipe or sound weld material, which may or may not be an actual flaw.

Arc strike: Localized points of surface melting caused by an electrical arc (also referred to as hot spot).

Buckle: A partial collapse of the pipe due to excessive bending or compression associated with soil instability, landslides, washouts, frost heaves, earthquakes, etc

Casing: A type of feature consisting of a larger diameter pipe placed concentrically around the pipeline, usually in high stress areas such as road crossings.

Certainty: For the purpose of this specification, the probability that the characteristics of a reported anomaly are within the stated tolerances.

Cluster: Two or more adjacent metal loss anomalies in the wall of a pipe or in a weld that may interact to weaken the pipeline more than either would individually.

Confidence level A statistical expression used to describe the mathematical certainty with which a statement is made

Corrosion: An electrochemical reaction of the pipe wall with its environment causing a loss of metal.

Crack: A planar, two-dimensional feature with possible displacement of the fracture surfaces.

Debris: Extraneous material in a pipeline which may interfere with the ILI tool.

Dent: Distortion of the pipe wall resulting in a change of the internal diameter but not necessarily resulting in localised reduction of wall thickness.

Detection threshold: Minimum detectable feature dimension.

Feature: Indication, detected by non-destructive examination, of a pipeline.

Geometry tool: Configuration pig designed to record conditions, such as dents, wrinkles, ovalities, bend radius and angle, and occasionally indications of significant internal corrosion, by sensing the shape of the internal surface of the pipe.

Grinding: Reduction in wall thickness by removal of material by hand filing or power disk grinding.

Gouge: Mechanically induced metal-loss, which causes localised elongated grooves or cavities.

Heat affected zone: The area around a weld where the metallurgy of the metal is altered by the rise in temperature caused by the welding process, but this is distinct from the weld itself. The width of the heat-affected zone is typically limited to a few mm only, depending on the welding process and parameters. For the purpose of this specification it is considered to be within 2A of the centre line of the weld, where “A” is the geometrical parameter related to the wall thickness.

In-Line Inspection (ILI): Inspection of a pipeline from the interior of the pipe using an In-Line Inspection tool.

In-Line Inspection tool: Device or vehicle, also known as an intelligent or smart pig that uses a non-destructive testing technique to inspect the pipeline from the inside.

Intelligent pig: See “In-Line-Inspection tool”.

Joint: Single section of pipe that is welded to others to make up a pipeline.

Lamination: Imperfection or discontinuity with a layered separation, that may extend parallel or angular to the pipe wall surface. Metal loss anomaly/feature: An area of pipe wall with a measurable reduction in thickness.

Mid wall feature: Any feature which does not run out to either the internal or external surface.

Measured wall thickness: Measured wall thickness that is representative for a whole pipe joint/component. For ultrasonic tools the value shall be based on direct wall thickness measurements, for magnetic tools on the inferred magnetic flux signals.

Measurement threshold: The minimum dimension(s) of a feature to make sizing possible.

Nominal wall thickness: The wall thickness required by the specification for the manufacture of the pipe.

Pig: Device that is driven through a pipeline for performing various internal activities (depending on the pig type) such as separating fluids, cleaning or inspecting the pipeline.

Pigging: Running of a pig or ILI tool in a pipeline.

Pig trap: An ancillary item of pipeline equipment, with associated pipework and valves, for introducing a pig into a pipeline or removing a pig from a pipeline.

Pipeline: A system of pipes and other components used for the transportation of products between (but excluding) plants. A pipeline extends from pig trap to pig trap (including the pig traps), or, if no pig trap is fitted, to the first isolation valve within the plant boundaries or a more inward valve if so nominated.

Pipe mill anomaly: An anomaly that arises during manufacture of the pipe, as for instance a lap, sliver, lamination, non-metallic inclusion, roll mark and seam weld anomaly.

Pipeline component: A feature such as a valve, tee, bend, weld, casing, marker, off take, wall thickness change, etc. that is a fitted part of a pipeline

Probability of Detection: The probability of a feature being detected by the intelligent pig.

Probability of Identification: The probability that an anomaly or a feature, once detected, will be correctly identified Reference magnet: See Above Ground Marker

Reference wall thickness: The actual undiminished wall thickness surrounding a feature, used as reference for the determination of the feature depth.

Reporting threshold: Parameter, which defines whether or not a feature will be reported.

Sizing accuracy: Sizing accuracy is given by the interval with which a fixed percentage of features will be sized. This fixed percentage is stated as the certainty level.

Spalling: Abrasion of the pipe surface resulting in shallow surface laps and possibly hardening of the material below.

Weld: The area where joining has been done by welding and where the material has undergone a melting and solidification process. This area is distinct from the heat-affected zone, but surrounded by it.

Weld anomaly: Anomaly in the weld or the heat affected zone.

Weld affected area: Area on both sides of a weld where ILI measurements are effected by the geometry of the weld (e.g. due to sensor dynamics).

Abbreviations Nomenclature

A - Geometric parameter related to the wall thickness AGM - Above Ground Marker D - Metal loss anomaly depth EC - Eddy Current EMAT Electro - Magnetic Acoustic Transducer ERF - Estimated repair factor GPS - Global Positioning System HFEC - High Frequency Eddy Current ILI - In Line Inspection L - Anomaly/feature dimension (Length) in the axial direction and length of crack in any direction MAOP - Maximum Allowable Operating Pressure MOP - Maximum Operating Pressure MFL - Magnetic Flux Leakage NDE/NDT - Non-Destructive Examination, Non-Destructive Testing POD - Probability Of Detection POI - Probability Of Identification Psafe - Safe operation pressure as per calculated defect assessment method T - Wall thickness UT - Ultrasonic Technique W - Anomaly/feature dimension (Width) in the circumferential direction and opening dimension for cracks (if applicable).

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