MWM-Array Characterization of Mechanical Damage and Corrosion

JENTEK Sensors, Inc.
Waltham, Massachusetts 02453

To deliver a cost competitive, easy-to-use and reliable tool for “in-the-ditch” characterization of mechanical damage (MD) and stress corrosion cracking (SCC) for buried pipelines, as well as internal and external corrosion imaging through insulation and weather protection (called corrosion under insulation, (CUI) for exposed pipelines.  Specific technical challenges encountered during this and related projects included:  repackaging of the JENTEK MWM-Array technology (currently in use for commercial and military aircraft engine and spacecraft inspection) for field inspections of pipelines; detection of corrosion and SCC through coatings and insulation including internal corrosion, from outside the pipeline, and high-resolution imaging of mechanical damage including defect geometry and stress. 

The MWM-Array is an inductive sensor that operates like a transformer in a plane.  A rapid multivariate inverse method converts impedance data into images of surface geometry (from the lift-off response), stress and microstructure changes (based on the permeability response) and metal loss from a combination of lift-off and wall thickness images. Ongoing activities in DOT PHMSA programs are developing enhanced characterization capability for mechanical damage, low frequency internal corrosion imaging, enhanced SCC/corrosion imaging through coatings, weld inspection capability, transition plans, along with manuals and standards.

Funding for this R&D began with two DOT PHMSA SBIR Phase I contracts, and a third Phase I is now ongoing.  Follow-on work is also ongoing under two PHMSA Broad Agency Agreement (BAA) funded programs with substantial matching funds from Chevron, the Pipeline Research Council International (PRCI), pipeline operators and other oil majors.  Total DOT funding - $1,200,000, non-government funding - over $1,500,000 to date.  The matching fund programs are run separately with independent but complementary work plans. 

Accomplishments:  Demonstration of detection capability for CUI, MD, SCC and fatigue cracks (under DOT 304) and preliminary in-line inspection (ILI), i.e. inspection from inside the pipe, capability (under DOT 306), following SBIR funding.  The project also demonstrated successful development of initial mechanical damage characterization capabilities, including residual stress/microstructure imaging, magnetic profilometry, and SCC imaging with and without coatings as well as successful field demonstrations of mechanical damage imaging, as a feasible method for verifying and ranking ILI detections in-the-ditch.  Other equally important project achievements include:   field demonstrations for SCC cluster mapping, with ongoing development of crack depth estimation capability for SCC assessment, successful laboratory capability demonstration for CUI, with field trials planned for late 2011 (demo target is 2-in. insulation with metallic weather protection layer) and field pull-test demonstration of MWM-Array ILI tool prototype for metal loss. 

Benefits:  This research will advance pipeline safety by providing new methods for in-the-ditch ranking and verification of ILI indications, including mechanical damage, corrosion and SCC, CUI imaging for both internal and external corrosion from outside of above ground pipelines, to enable more frequent inspection at substantially reduced costs for both piggable and unpiggable lines, convenient, low-cost, durable in-the-ditch and above-ground packaging for field inspections and potential for development of a low cost (“cleaning tool integrated”) ILI solution.

Future activities: JENTEK Sensors will further develop the CUI capability targeting inspection through 2-in. insulation with weather protection, improve packaging and field hardness of the system, develop the low frequency MR-MWM-Array technology with solid state sensing elements for wall thickness imaging (for metal loss characterization), enhance characterization capability for MD, SCC, and CUI and complete several field trials supported by oil primes and pipeline operators.  Also, new efforts are focused on crack detection near welds at ERW pipelines.

Highlights:
Number of employees:  30
Market size ($amount): > $10 million
Number of Awards:  3 DOT Phase I Awards from PHMSA
Other highlights: Over 40 other SBIR awards; 2006 National Tibbetts Award
More Information: http://primis.phmsa.dot.gov/rd/articles/Success_JENTEK_DOT_460.pdf