Essential Factors in Pipe inspection
A good pipe inspection will take into account not just pipe materials, but ground conditions, the product being transported and utilize key testing methods.
Pipelines are an integral part of our daily lives and keep our cities and towns functioning day and night. Potable water, gas, telecommunication and electric lines, conveyed via a network of pipes originating at source bring convenience at our fingertips with the turn of a tap or the click of a switch.
On the other hand, sewer pipes carry wastewater or sewage from homes and businesses safely away in a closed system that keeps our societies clean and habitable.
One of the sectors that require extensive use of pipelines is the oil and gas industry. The industry not only provides employment to millions, but it is also the lifeblood of industries that help provide resources to meet the growing demands of a growing population.
Pipelines have made transport of liquid and gas products economical and safe compared to transport by road, rail and sea. Lately, oil, gas and water pipelines have become a vital resource-sharing method for various countries. It leaves no doubt that the world cannot do without pipelines. However, with all the benefits that pipelines offer, the biggest challenge that the industry faces is maintenance.
With thousands of miles of pipelines installed, some serious problems such as corrosion, leakages, and burst pipelines are commonplace. However, are these problems avoidable? Though not entirely avoidable, proper inspection, monitoring and regular maintenance can drastically reduce such incidents.
Importance of Pipe Inspection
Pipeline safety regulations require the operator to ensure that the pipeline is maintained in an efficient state and working order, and in good repair. It is assumed that some deterioration mechanisms are active in any pipeline, which over time can compromise the integrity of the pipe. Therefore, conducting regular inspections can help locate problem areas and rectify them before they become incidents or accidents.
The US Department of Transportation Pipeline and Hazardous Materials Safety Administration notes that pipelines fail due to a variety of reasons, such as:
- External and internal corrosion.
- Stress corrosion cracking.
- Damage due to excavation or natural force.
- Weld or material failure.
- Equipment failure.
- Improper operation.
According to industry trends, 65% of all offshore and onshore pipeline failures are caused by corrosion. It continues to be a major concern for all stakeholders interested in the pipeline installation industry.
To minimize pipeline failure risk, contractors should adhere to strict standards to build and maintain these critical infrastructures. (Read also: Pipe Inspection: Where It Goes Wrong (and How It SHOULD Be Done)
Essential Factors in Pipe Inspection
Pipe inspection is conducted during production or installation to examine for metal loss and to ensure that the pipe is fit for purpose and is not at risk for failure. Pipelines are also inspected regularly after commissioning to check for problems with joints and welds, to check for leaks, cracks or corrosion, and to ensure its structural stability.
A pipeline inspector evaluates the condition of the pipeline and anticipates problems that could arise and escalate into serious issues compromising its integrity. Different techniques are used for pipe inspection such as:
- Ultrasonic testing
- Magnetic particle testing
- Liquid penetrate
- Radiographic test techniques
These inspection methods can be deployed onshore and offshore using handheld tools or remote inspection tools like robots or crawlers. Pipelines in accessible locations can be inspected using specialized inspection tools. Remote inspection tools including robot-controlled cameras are very useful for inspecting pipelines that are difficult to access due to human risk or limitations such as in difficult terrain, presence of hazardous chemicals, high temperature and pressure.
What to Inspect
A pipeline inspection involves checking for leaks, cracks, corrosion, misalignment of pipes, change in wall thickness, change in pipe shape and change in diameter. Pipeline Integrity checks are conducted regularly for examining pipelines for suspected defects. Integrity digs are conducted by excavating a section of the buried pipeline, cleaning it and examining it. If a defect is detected, the pipeline is repaired, recoated and buried again.
To check pipe internals, in-line inspection tools called smart pigs are inserted into the pipeline and allowed to travel and scan the pipe interior. The ultrasonic technology in the smart pig allows the pig to scan about 3 meters per second to measure pipe thickness, metal loss, cracks and signs of corrosion.
The inside of the pipelines are cleaned using rotating wire brushes attached to a smart pig. As the pig moves through the pipeline, it cleans the pipeline and allows application of corrosion inhibitors if required. A clean pipeline will help the product to flow smoothly through the pipe and prevent build up and corrosion.
A Knowledgeable Pipeline Inspector
Pipelines are carefully designed based on design assumptions and the product it will convey. However, improper installation can prevent the pipe from performing adequately. The responsibility for this lies with the contractor and the inspector. (Read also: QUIZ: Think You're A Pipeline Inspection Expert?)
Ideally, the inspector should be a part of the project team from the time of project inception so that he or she is fully aware of all aspects of the project including soil geology and site topography. Even the type of pipe product being used, whether a commodity product (products purchased from a catalog with standard and conservative design assumptions) or an engineered product (pipes designed with specific tolerances, assumptions and criteria) will make a difference.
The inspector should also be made aware of factors that are important for the particular project such as trench width, material gradation, lift height, and compaction or consolidation methods. This will help the inspector to understand what the pipe will experience during installation. Being aware of the design criteria and the allowable tolerances, the inspector can make informed decisions and minimize pipe failure risk.
The presence of an inspector can also help avoid mishandling of product pipe during installation, improper bedding, improper compaction, and the use of improper fittings to secure pipes. All these factors can greatly affect the life cycle of the installed product, however perfect the pipe design may be.
Benefits of Pipeline Inspection
Pipeline inspection has no drawbacks and only does well for the contractor and the client. Some great benefits include:
- Extended service life of the pipeline.
- Reduced maintenance cost.
- Reduced business downtime for maintenance runs.
- Prevents extended periods of service disruptions.
- Reduced risk of undesirable accidents such as injury and death to people and wildlife.
- Reduced risk to environment from leakages and pipe bursts.
- Compliance with rules and regulations of governing authorities.
Trenchlesspedia uses high-quality sources to support the facts within our content including peer-reviewed studies, academic research institutions, professional organizations, and governmental organizations.
- Key Factors Involved in Pipeline Monitoring Techniques Using Robots and WSNs: Comprehensive Survey. Journal of Pipeline Systems Engineering and Practice, (2018). P. 9 (2).
- Pipeline Failure Causes. (2018).