Automated Ball Indentation®
The ABI® test is based on progressive indentation with intermediate partial unloadings until the maximum depth is reached. The nonlinear spherical geometry of the tungsten carbide indenter allows increasing strain as the penetration depth increases. Incremental values of load and plastic depth are converted to true-stress and true-plastic-strain values according to established elasticity and plasticity theories — yielding critical mechanical properties without removing material from service. The same ABI® test simultaneously provides fracture toughness results which are verified and compared against J-integral data from destructive tests, ensuring robust accuracy.
Measurable Properties
What ABI® Measures
The ABI® test is a direct measurement mechanical test. The force required to indent the material to increased depth values is measured with a load cell. Periodic partial unloadings determine the elastic strain, which is subtracted from the total strain to give the plastic strain. The following key mechanical properties are measured:
The Science
How ABI® Works
The ABI® test uses progressive cyclic loading with multiple partial unloadings of a spherical indenter into the material. The indentation load-depth data is collected continuously during the test by a 16-bit data acquisition system. The entire test is fully automated (computer-controlled) where the spherical indenter is driven into the test surface at a desired speed which controls the strain rate.
Tests are typically performed using a 0.030-inch (0.762 mm) diameter tungsten carbide indenter at a speed of 0.0008 in/s (0.02 mm/s). The current stress at any point is a function of the current indentation force. Elastic strain is subtracted from total strain to give plastic strain. The incremental values of true-stress and true-plastic-strain are calculated from the force-depth data and plotted to form a true-stress versus true-plastic-strain curve.
The ABI® test can also be performed without intermediate partial unloadings — in a single cycle of continuous loading. This approach is preferred for high-temperature or high-strain-rate testing to avoid indentation creep and nonlinear unloading slopes.
Nondestructive by Design
Ball indentations are shallow, with smooth edges, and produce compressive stresses in the material that retard crack initiation. The remaining ABI® depression is similar to one from shot-peening or sandblasting — no sharp edges or stress-concentration sites. Each ABI® test is similar to a single shot peen, albeit slightly larger.
Weld & HAZ Testing
The ABI® test is a macroscopic (bulk) technique that measures properties on a small volume of material, making it valuable for mapping property gradients in welds and heat-affected zones (HAZs). It can measure the strength profile along a line traversing from one base metal through the HAZ, weld metal, and through the other base metal. The minimum indenter diameter ensures indentation covers at least three grains to measure macroscopic properties.
Test Procedure
Fast & Efficient Field Testing
Pipes as small as 5.5 inches to as large as full flat plate can be tested with the magnetic base. The ergonomic design features powerful electromagnets for quick attachment and removal, with rope access lift points for offshore and at-height applications.
Remove Coating & Prepare Surface
Coating is removed and sandblasted, then a 12" x 4" surface is polished using 120 grit so the magnets can properly attach.
Polish Test Area
A smaller 3" surface is polished at 220 grit to provide a smooth surface for indentation (63 RMS finish).
Perform ABI® Tests
Six indentation tests are performed using a 0.030-inch tungsten carbide indenter with progressive cyclic loading and partial unloadings, captured by a 16-bit data acquisition system.
View Analyzed Results
Once the final test is complete, analyzed results showing the API 5L material grade, fracture toughness values, and full stress-strain curves are displayed — all in under 30 minutes.
Business Impact
Make Informed Capital Asset Decisions
Enhance Fitness-for-Service Assessments
Use direct measurements of key mechanical properties to assess whether an asset can continue operating safely despite defects or aging. Instead of replacing entire components, operators can make informed decisions on whether a structure can remain in service or needs repair, reducing unnecessary downtime.
Prevent Unexpected Failures
Use fracture toughness data to determine a material's ability to resist crack propagation. By understanding this, engineers can predict and prevent sudden failures in pipelines, pressure vessels, and drilling equipment. Materials with insufficient toughness can crack under stress, leading to leaks, shutdowns, and costly repairs.
Optimize Maintenance Schedules
Shift from reactive maintenance (fixing failures after they occur) to predictive maintenance (anticipating failures before they happen). This allows for better planning of inspections and repairs, minimizing unplanned downtime and reducing maintenance costs.
Improve Material Selection & Design
Selecting materials with appropriate fracture toughness for specific operating conditions ensures equipment can withstand extreme pressures, temperatures, and corrosive environments. Engineers can design components with higher durability, reducing the risk of failure and extending service life.
Key Advantages
Why Choose ABI® Over Conventional Testing?
Traditional destructive testing requires sample removal, machining, and lab analysis — taking weeks and permanently consuming material. ABI® provides equivalent data in minutes, on-site, without affecting component integrity.
Nondestructive
No material removal. Leaves only a shallow spherical depression with compressive residual stress — retards crack initiation rather than causing damage.
In-Situ Capable
Test on operating equipment without disassembly or shutdown. Designed for rope access teams to eliminate scaffolding costs for offshore and at-height applications.
Multi-Property
One test yields yield strength, UTS, strain hardening, fracture toughness, reference temperature, and master curve analysis.
Fast & Portable
Complete field testing in under 30 minutes per location. Ergonomic design with powerful electromagnets for quick deployment on pipes from 5.5" to full flat plate.
Standards-Based
Procedures aligned with ASTM E636-14, with precision data from a six-laboratory interlaboratory study (L52280).
Proven Accurate
Validated against destructive testing across carbon steels, stainless steels, nickel superalloys, aluminum alloys, and more. ABI® tests replace both tensile and fracture toughness tests.
Applications
Where ABI® Testing Is Used
Originally developed for applications within the nuclear industry, ABI® testing has expanded to pressure vessels, forgings, coke drums, offshore platforms, and oil and gas pipelines — deterministically assessing structural integrity following normal and accident service conditions.
Pipeline material verification and pipe grade determination
Pressure vessel integrity after fire or thermal events
Offshore platform and subsea component assessment
Nuclear reactor vessel embrittlement surveillance
Weld and heat-affected zone property mapping
Life extension evaluations for aging components
Fitness-for-service per API 579/ASME FFS-1
Hydrogen embrittlement and damage detection
Component assessment for coke drums and forgings