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{{short description|Method of inspection using remotely operated tools}}
{{refimprove|date=June 2016}}
'''Robotic
Robotic [[non-destructive testing|NDT]] tools can also be used for mandatory inspections in inhospitable areas (e.g., tank interiors, subsea petroleum installations) to minimize danger to human inspectors, as these tools are operated remotely by a trained technician or NDT analyst. These systems transmit data and commands via either a wire (typically called an umbilical cable or tether) or wirelessly (in the case of battery-powered tetherless crawlers).▼
▲Robotic [[non-destructive testing]] (NDT) is a method of inspection used to assess the [[structural integrity]] of petroleum, natural gas, and water installations. Crawler-based robotic tools are commonly used for in-line inspection (ILI) applications in [[pipelines]] that cannot be inspected using traditional [[Pigging#Intelligent_pigging|intelligent pigging tools]] (or unpiggable pipelines).
▲Robotic NDT tools can also be used for mandatory inspections in inhospitable areas (e.g., tank interiors, subsea petroleum installations) to minimize danger to human inspectors, as these tools are operated remotely by a trained technician or NDT analyst. These systems transmit data and commands via either a wire (typically called an umbilical cable or tether) or wirelessly (in the case of battery-powered tetherless crawlers).
== Applications ==
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** Pipe walls
** Girth welds
* [[Nuclear reactor safety system|Nuclear cooling systems]]
* [[Storage
** Floor plates
** Shell plates
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Pipeline conditions that may prevent or hinder a flow-driven pig inspection include:
* Some pipe fittings (e.g., small-radius [[
** Technicians can manually adjust robotic tool travel speed, orientation, and configuration to navigate fittings that might trap or damage a free-flowing pig.
* Product flow may not be conducive to pig travel.
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* Limited tool access may impact use of traditional tools – smart pigs require special entry and exit points (called launchers and receivers, respectively), which may be permanently or temporarily installed.
** Some crawlers can be inserted via removed fittings or cut-out spools as small as 24” in length, providing greater flexibility in launch and retrieval options – these tools do not require special fixtures.
** Some crawlers are designed to enter and exit natural gas lines via [[
** Even in pipelines that could feasibly accept a traditional smart pig, the ability of crawlers to perform short inspections inside specific areas of concern is much more efficient for pipeline operators than arranging a lengthy pig run just to reach the same small area.
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=== Untethered ILI crawler overview ===
[[File:Pipetel Explorer 30-36.jpg|thumb|Pipetel Explorer untethered NDT pipeline crawler, manufactured and operated by Pipetel Technologies
Untethered robotic ILI crawlers are powered by onboard batteries; these tools transmit sensor data wirelessly to the tool operator or store the data for downloading upon tool retrieval. Untethered crawlers have the following advantages over tethered crawlers:
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=== Electromagnetic Acoustic Transducers (EMAT) – milled steel ===
Main article – [[
[[File:DB EMAT.jpg|thumb|A transducer uses the direct beam method to discover anomalies in a pipe wall; the pink arrows represent the ultrasonic waves.]]
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=== EMAT – girth welds ===
[[Oxy-
One angle-beam EMAT method employs a set of nine [[
[[File:GWS diagram.jpg|center|The principle of angle-beam EMAT use in pipeline girth weld assessment.]]
[[File:GWS FTM scan.jpg|thumb|upright|The frequency-time matrix for a lateral cylindrical hole in a pipe
The tool merges each set of FT scans into a single frequency-time matrix scan to display weld conditions, with anomalies color-coded by severity.<ref name="GWS" /> This method of girth weld scanning is designed to detect the following [[
* Planar defects (e.g., lack of fusion, cracks)
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=== Video inspection ===
[[File:Pipeline video inspection - pitting corrosion.png|thumb|A high-resolution camera image of an internal corrosion pit in a pipe wall
Main article – [[
Robotic NDT tools employ cameras to provide technicians an optimal view of the inspection area. Some cameras provide specific views of the pipeline (e.g., straight forward, sensor contact area on the metal) to assist in controlling the tool, while other cameras are used to take high-resolution photographs of inspection findings.
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=== Laser profilometry ===
[[File:Laser profilometry - pitting corrosion.png|thumb|Laser profilometry assessment of the pipe wall corrosion pit shown in the previous image
Main article – [[surface metrology]]
Laser profilometers project a shape onto the object surface. Technicians configure the laser (both [[
=== Pulsed-Eddy Current (PEC) ===
Main article – [[Eddy-
Pulsed-eddy current (PEC) tools use a probe coil to send a pulsed magnetic field into a metal object. The varying magnetic field induces eddy currents on the metal surface. The tool processes the detected eddy current signal and compares it to a reference signal set before the tool run; the material properties are eliminated to give a reading for the average wall thickness within the area covered by the magnetic field. The tool logs the signal for later analysis.<ref>Robers, M.A. and R. Scottini. [http://www.ndt.net/article/ecndt02/251/251.htm Pulsed Eddy Current in Corrosion Detection]. June 2002. Web. Accessed 2 March 2016.</ref> The following diagram illustrates the principle of a typical PEC inspection tool.
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United States federal law requires baseline inspections to establish pipeline as-built statistics and subsequent periodic inspections to monitor asset deterioration. Pipeline operators also are responsible to designate high-consequence areas (HCAs) in all pipelines, perform regular assessments to monitor pipeline conditions, and develop preventive actions and response plans.<ref>[https://www.federalregister.gov/articles/2003/12/15/03-30280/pipeline-safety-pipeline-integrity-management-in-high-consequence-areas-gas-transmission-pipelines Pipeline Safety: Pipeline Integrity Management in High Consequence Areas (Gas Transmission Pipelines)]. Research and Special Programs Administration, 2003. Web. Accessed 1 March 2016.</ref>
State regulations for inspecting pipelines vary based on the level of public safety concerns. For example, a 2010 natural gas pipeline explosion in a [[
=== Tethered robotic ILI crawler application examples ===
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The federal [[Pipeline and Hazardous Materials Safety Administration]] (PHMSA) does not permit use of tetherless crawlers in HCAs due to the risk of getting stuck. Excavating buried pipelines to retrieve stuck tools beneath freeway crossings, river crossings or dense urban areas would impact the community infrastructure too greatly. Natural gas and oil pipeline operators therefore rely on tethered robotic ILI crawlers to inspect unpiggable pipelines.
Williams used a tethered robotic ILI crawler to inspect an unpiggable section of the [[
[[Alyeska Pipeline Service Company]] inspected Pump Station 3 on the [[Trans-Alaska Pipeline System]] after an oil leak was discovered in an underground oil pipeline at Pump Station 1 in 2011.<ref>DeMarban, Alex. [http://www.adn.com/article/20150705/crawling-robot-patrols-alaska-pipelines-formerly-unpiggable-pipes Crawling robot patrols Alaska pipeline’s formerly ‘unpiggable’ lines]. July 5, 2015. Web. Accessed 9 March 2016.</ref> The spill resulted in a consent agreement between Alyeska and PHMSA requiring Alyeska to remove all liquid-transport piping from its system that could not be assessed using ILI tools or a similar suitable inspection technique. Because other ILI tools could not navigate the pipeline geometry common to each of the eleven pump stations along the pipeline, Alyeska received approval to use a tethered robotic ILI crawler manufactured by Diakont to complete an inspection project at Pump Station 3. This tool allowed Alyeska to only remove a few small aboveground fittings to permit crawler entry into the piping, saving the time and expense necessary to excavate hundreds of feet of pipe (some of which was also encased in concrete vaults) to inspect by hand.
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Nuclear power plants in the United States are subject to unique integrity management mandates per the Nuclear Energy Institute (NEI) NEI 09-14, Guideline for the Management of Buried Piping Integrity.
* The [[Cooper Nuclear Station]] in Nebraska performed buried pipe inspections to comply with these industry mandates as part of a 2010 nuclear power plant license renewal. Part of the plant pipeline integrity management program included inspecting a high pressure coolant injection (HPCI) line using a tethered robotic ILI crawler manufactured by Diakont.<ref>Bremer, David. [http://nuclearplantjournal.com/uploads/digital/MA13.pdf Robotic Pipe Inspection to Meet License Renewal Commitments]. Nuclear Plant Journal.
* The [[South Texas Project Electric Generating Station]] performed an inspection of a service water pipe in 2014 using a [[GE Hitachi Nuclear Energy]] crawler.<ref>[http://www.neimagazine.com/features/featurepipe-surveying-solution-4562648/ Pipe surveying solution]. Nuclear Engineering International Magazine. April 27, 2015. Web. Accessed 10 March 2016.</ref>
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Natural gas pipeline operators can use tetherless robotic ILI crawlers for smaller distribution pipelines that are not located beneath critical infrastructure elements (e.g., freeway crossings).
* In 2011, [[Southern California Gas Company]] (SoCalGas) used a tetherless robotic ILI crawler manufactured by Pipetel to inspect an 8” natural gas pipeline whose product flow lacked the pressure to propel a traditional smart pig.
* [[Southwest Gas Corporation]] used the same tool in 2013 to inspect approximately one mile of a 6” natural gas line in Las Vegas, Nevada.<ref>[http://www.nysearch.org/news-info_012114.php Southwest Gas chooses Pipetel for Unpiggable pipeline inspection as part of its commitment to safety]. Northeast Gas Association. January 2014. Web. Accessed 9 March 2016.</ref>
* [[Central Hudson Gas & Electric]] used a similar crawler in 2015 to inspect a 3000’ section of a 16” natural gas line that included a roadway crossing.<ref>Welsh, Kathy. [http://hudsonvalleynewsnetwork.com/2015/10/08/central-hudson-tests-innovative-pipeline-inspection-robot/ Central Hudson Tests Innovative Pipeline Inspection Robot]. Hudson Valley News Network. October 8, 2015. Web. Accessed 15 March 2016.</ref>
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*** Real-time data monitoring allows daily reports and makes a preliminary report (containing only the most serious anomalies) possible.
*** The inspection crew can stop the tool’s forward progress to re-examine findings in order to gather additional data and confirm defect identity/severity.
*** The ability to monitor tool function ensures tool [[data integrity]] for the entirety of the inspection.
* The compact footprint of these tools allows them to be deployed at customer convenience rather than limited to pre-established endpoints (i.e., pig launcher/receiver).
** This makes tethered tools less likely to get stuck, and easier to retrieve if stuck/damaged.
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** The inspection crew can adapt tool travel to accommodate fixtures (e.g., tees, bends, tank roof supports) as well as findings (e.g., dents, corrosion pits) to prevent the tool from becoming damaged or stuck.
** The inspection crew can also manipulate the tool to maximize sensor reception in areas where the tool’s normal travel path would impact readings.
* Many inspection areas pose significant safety hazards to human occupants that can be eliminated or greatly reduced by robotic NDT tools:
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** Tension on a tethered crawler’s cable may limit tool movement after passing too many bends in pipeline applications, or after wrapping around roof supports during tank floor inspections.
* Many self-propelled pipeline inspection tools are slower than pigs that can flow with product.
* Unlike some [[
** Regulatory requirements often specify that inspection data must be gathered, analyzed, and collated for reporting by technicians who are certified as experts in the applicable inspection technology by an independent organization (e.g., the [[American Society for Nondestructive Testing]], the [[American Society of Mechanical Engineers]]).
* Many crawlers require the inspection area to be taken out of service and cleaned before operations.
** Continuous air-quality monitoring may be necessary during operations, up to provision of a blanket of inert gas (e.g., nitrogen) if the area contains especially flammable/explosive fumes.
** Loose debris (e.g., [[ferromagnetic]] dust, [[
** These services can often be performed during scheduled outages, but special shut-down may be necessary if regulatory requirements do not align with other planned service outages.
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* [https://www.gpo.gov/fdsys/granule/CFR-2010-title49-vol3/CFR-2010-title49-vol3-sec192-921 US federal baseline pipeline assessment – 49 CFR 192.921]
* [https://www.gpo.gov/fdsys/granule/CFR-2010-title49-vol3/CFR-2010-title49-vol3-sec192-937 US federal pipeline integrity evaluation process – 49 CFR 192.937]
* [
* [http://www.pipelineoperators.org/ Pipeline Operators Forum]
* [[American Petroleum Institute]] (API) [http://www.api.org/publications-standards-and-statistics/standards/whatsnew/publication-updates/new-refining-publications/api_std_653
* [http://www.api.org/Publications-Standards-and-Statistics/Standards/WhatsNew/Publication-Updates/New-Pipeline-Publications/API_Std_1163 API 1163]
* [https://www.asme.org/products/codes-standards/b318-2014-gas-transmission-distribution-piping The American Society for Mechanical Engineers (ASME) B31.8]
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== External links ==
* [http://www.diakont.com/
* [https://www.innerspec.com/integrated/applications/volumetric-inspection/composites-and-forgings/ Innerspec - Robotic Inspection Systems]
* [http://pipetelone.com/ Pipetel Technologies - pipeline ILI]
* [http://www.applusrtd.com/en/new/Applus_RTD_&_Delta_Subsea_unveil_pioneering_deepwater_NDT_Technology-1340242470561 Applus - subsea pipe inspection]
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* [http://invertrobotics.com/ Invert Robotics – tank shell inspection]
* [http://www.structint.com/competency/nondestructive-examination/technologies/sipec Structural Integrity Associates - pipeline ILI]
* [http://www.smartpigs.net/ Inline Inspection and Pipeline Pigging Resource]
* [https://www.nde-ed.org/AboutNDT/SelectedApplications/PipelineInspection/PipelineInspection.htm Introduction to Inline Inspection]
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* [http://www.silverwingndt.com/oil-gas-testing/storage-tanks/ndt-shell-inspection-equipment Silverwing – remote-control tank shell inspection vehicle]
* PHMSA
** [
** [https://primis.phmsa.dot.gov/comm/FactSheets/FSMaterialWeldFailure.htm Weld Failure fact sheet]
* [https://www.asnt.org/MajorSiteSections/Certification American Society for Nondestructive Testing certification]
* [https://www.asme.org/ American Society of Mechanical Engineers]
* [http://www.astm.org/ American Society for Testing and Materials]
* [https://ndtcs.com/ NDT Consultancy Services Inc.]
[[Category:
[[Category:Nondestructive testing]]
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