Practical Aspects of Pipeline Integrity Assessment
Pipeline integrity ensures a pipeline and all its related components are running properly and in good working condition. It involves and ensures that pipelines are designed, built and operated to be safe, reliable and sustainable. Pipeline integrity management is done through every aspect of the pipeline life cycle – from design and construction to operations, maintenance and retirement.
Practical aspects of pipeline integrity assessment include corporate objectives, risk, planning integrity programs, internal inspection tools, anomaly identification and analysis, repair, coating, and pressure testing.
The practice of inspecting pipelines utilises various tools that accurately detect a diverse range of pipeline anomalies. Today, The Code of Federal Regulations Title 49 Parts 192 (Transportation of Natural and Other Gas by Pipeline) and 195 (Transportation of Hazardous Liquids by Pipeline) prescribe three permissible methods by which a pipeline shall be assessed.
- Direct assessment
Due to today’s industry regulations and an ageing pipeline network, there is a growing demand for direct assessment. The 3 types of anomalies specifically inspected by direct assessment are external corrosion, internal corrosion and stress corrosion cracking. An inspection done by direct assessment involves a 4-step process; a Pre-Assessment, and Indirect Inspection, a Direct Examination and a Post-Assessment. The existence of the threat at other locations within the pipeline segment can be inferred based on the results of the direct assessments.
Through these four phases, the direct assessment process becomes a structured, iterative integrity assessment protocol used by pipeline operators to assess and evaluate the integrity of their pipelines. Direct assessment gives oil and gas pipeline owners, the confidence that they are receiving the best data to make the most precise integrity decisions.
- Hydrotest
Hydrotest (or Hydrostatic Pressure Testing), is a way of checking the integrity of pressure vessels such as natural gas pipelines, gas cylinders, boilers, storage tanks and fuel tanks. With the help of this test, pressure tightness, strength and any leakages are checked. This test ensures the safety of the cost intensive setup and the human life as there is a risk of explosion from pipelines if any leakage takes place.
During a hydrotest, the pipeline is filled with a medium (typically water) and the pressure is held at a predefined level (e.g., 125% of the maximum operating pressure) for a prescribed period of time (e.g., 8 hours). The hydrotest is designed to cause near critical defects to fail (i.e., leak), thus proving that the defects that remain in the pipeline (those that did not fail) are not critical and safe to operate at the maximum operating pressure (MOP).
Some of the other important parameters which can be identified using a hydrotest are; Existing material flaws, Flaws in the mechanical properties of the pipe and stress corrosion cracking (SSC), Presence of active corrosion cells, Presence of any hard spots that can cause failure in long run when they come in contact with hydrogen.
- In-Line Inspection
In-line Inspection (ILI) involves the evaluation of pipes and pipelines using “smart pigs” (both tethered and non-tethered) that utilize non-destructive examination techniques to detect and size internal damage. ILI measures and records irregularities in pipelines including corrosion, cracks, deformations, or other defects.
ILI is a common practice throughout the oil and gas industry and has proven invaluable for examining extensive pipelines. It makes inspecting the condition of long stretches of pipelines, a task that used to be incredibly expensive and time consuming, far more easy and economical.
ILI is the only inspection technology that provides detailed information about defects within the pipeline segment that are sub-critical (i.e., not an imminent threat to the integrity of the pipeline). They also allow for the pipeline to be inspected without interrupting operation of the pipeline.
Pipeline Integrity Assessment – Practical Aspects is a 3-day training course held 29 – 31 October 2018 (Kuala Lumpur) where participants will be introduced to the technical basis for determining pipeline integrity. The seminar will provide information, reinforced by case studies and exercises on pipeline defects, such as corrosion, cracking, and third-party damage. Methods will be discussed that can be used to make decisions on whether defects are fit for service. Participants will gain in-depth knowledge on practical aspects, corporate policies, regulation and standard practices of pipeline integrity assessment. For more information, please contact us at info@opuskinetic.com.
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