Miniature specimen techniques enable the measurement of a materials strength and performance in support of estimating the service life of pressure equipment.
Samples are removed from in-service components, for example steam pipes, and these samples are referred to as “Scoops” or “Boat-shaped” samples and are taken from the surface of components without effecting the component integrity and capability.
Specific test specimens are then cut from the sample in support of tests such as tensile, bend, compression, fatigue, impact and hardness. The test results are used to quantify the material's current strength and mechanical robustness.
Through periodic scheduled sampling and testing, the results data can be fed into finite analysis software and lifetime and performance predictions can be made using extrapolation techniques.
Tinius Olsen has developed a series of testing systems capable of carrying out the tests on the miniature specimens. Miniature specimens require exacting testing techniques to ensure accurate application of testing forces and measurements of movement (Strain) under load. In particular extraneous loading forces not in the precise axis of required loading would cause erroneous errors in results and effect measurements of uncertainty across batches of same type tests and between interval batches over time.
As an example Tinius Olsen implements the tensile test of miniature specimens using a linear bearing system to ensure no “out of axis” loading;Pictured Tinius Olsen model 161-002 Miniature Steel Tensile Dumbbell shaped specimen holder which incorporates a linear bearing system.
Using a Tinius Olsen system application of the tensile load, measurement of strain and reporting of results is all conducted under software control.
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