| One third (540,000 km / 335,000 miles) of pipelines worldwide are considered unpiggable because of access and valve restrictions, multi-diameter designs, impassable fittings and a myriad of other configuration issues. Notwithstanding these obstacles, many countries and operators are re-evaluating how pipeline condition assessments need to be performed in the future; and regulations are likely to emerge, as they have in the US, that will require these pipelines to be inspected on a continuing basis.
In response to this increasing demand for inspection and assessment of unpiggable pipelines (particularly in sensitive areas where there is consequential risk to the public or the environment), GE Energy has taken the initiative to invest in technologies that will help the global industry by providing a range of alternatives including both appropriate and cost-effective solutions to the unpiggable pipeline dilemma.
The industry is familiar with common and emerging integrity assessment methods such as in-line inspection (ILI), hydrostatic testing and Direct Assessment (DA), but the strengths and weaknesses of each alternative vary depending on a pipeline's particular situation.
Pipelines are generally classified as “unpiggable” if the original construction did not include launch and receive facilities, but there are many other reasons why a pipeline cannot accommodate ILI.
When unpiggable lines are involved (especially in the case of mid to large-diameter pipelines where retrofit/modification is not economically viable), operators face a “technology gap” between their increasing integrity needs and the limited level of information attainable through Direct Assessment and Hydrostatic testing.
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In theory, no pipeline is unpiggable – they can all be retrofitted to eliminate restrictions and allow ILI access. In practice, however, this is not always realistic. In addition to the historically significant capital costs (equipment, engineering and design, site availability, etc.), the potential for lost revenue or penalties from supply interruptions or re-light costs all present considerable financial barriers that have forced many operators to compromise pipeline integrity for many years.
For example, unpiggable challenges are often associated with diameter changes in a single pipeline section. |
Traditionally, a typical solution was to adapt a single-diameter MFL tool to inspect the nominal-diameter pipe sections and traverse through other diameters without collecting information. The limitation to this approach is largely due to the existing MFL technology – because the tools’ magnets are stationary and designed for a specific diameter pipe, data collected on other diameters is usually compromised and unreliable. Ultrasonic wall measurement ILI tools have performed better in these situations but often require costly tool modifications to fit the particular diameter.
Conventional ILI
ILI attains by far the best results, but traditional methods are inhibited if there are no launchers or receivers, if there are reduced-bore fittings, multi-diameter pipe or if service interruptions are not possible due to cost or critical end-user impact. Operators often consider retrofitting full-bore, single-diameter pipelines to perform ILI as a viable option, in particular for smaller lines or segments without supply constraints. These procedures introduce significant cost implications.
Direct Assessment
DA then becomes a logical alternative, although it can be cost prohibitive due to road and water obstructions. In addition, highly experienced vendors are required to avoid unnecessary and costly digs.
Pressure Testing
Hydrostatic testing typically involves the most costly service interruptions and the least descriptive data for future planning. Supplemental inspection methods are necessary for a complete threat analysis. |
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After much research and development by a dedicated multi-national team, GE Energy is now able to resolve many of the practical challenges of unpiggable pipelines. We have developed innovative and best-cost methods including a new hot-tap entry and exit procedure, enhanced bend-passing capabilities, video inspection and pre-inspection systems.
Our new SmartScan™ technology takes a giant step forward – innovating a practical ILI solution and making advanced pipeline integrity an attainable goal for operators worldwide.
SmartScan 20” x 26” MFL tool.
SmartScan effectively unlocks, for the first time, the multitude of valuable information lying inside previously unpiggable pipelines. Reliable, high-resolution inspection is no longer cost prohibitive or disruptive of service. The fleet of SmartScan tools offers a level of flexibility and collapsibility never seen before in ILI technology; they are shorter than conventional tools, can be deployed using existing launch and receive traps or injected into the line using temporary equipment.
For more information on SmartScan, click here.
Direct Assessment
Our integrated External Corrosion Direct Assessment (ECDA) and Internal Corrosion Direct Assessment (ICDA) services apply extensive modeling and statistical algorithms, rigorous region definition and data integration that reduce project cycle time and achieve confidence levels approaching those of our in-line inspections. In addition, our years of experience in SCC detection and modeling can further enhance your DA program when used in a coordinated fashion through which improved DA effectiveness levels are achieved.
For more information on our DA services, click here.
Hydrostatic Testing
We recognise that hydrostatic testing may prove to be the only viable alternative for some unpiggable pipeline segments. Where this is the case, we will mobilise the necessary resources and manage their activities as part of an overall unpiggable inspection program. Complementary above-ground coating inspection surveys can be used to augment the effectiveness of hydrostatic testing by investigating the potential for third-party damage.
Retrofit and Integrated Remediation
Our engineers have extensive experience retrofitting pipelines with the traditional launchers and receivers necessary to accommodate in-line inspection. For post-inspection remediation we offer a full range of repair best practices and installation assistance.
The bottom line is that, as governments worldwide place more emphasis on pipeline integrity, the industry must respond. Traditional definitions of “unpiggable” are no longer sufficient. Conventional inspection and assessment methods cannot overcome many of the issues now faced.
Investment in new technologies like SmartScan will be an imperative part of the industry’s ability to control costs, maintain the safety and integrity of aging pipelines – and move forward beyond these challenging times.
Steve Biagiotti, PE
Unpiggable Solutions Product Manager
Steve.Biagiotti@ge.com
To download a brochure of Solutions for Unpiggable Pipelines, please click here.
To download the SmartScan fact sheet, click here.
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