One of the most affordable and simple loading devices for constant load tests is the Proof Ring, whose operating principle has been defined in NACE TM0177 Method A. Proof rings are available in 10-25 kN and 20-38 kN capacity options. The most common specimen type for Proof Ring testing is the round tensile specimen that is inserted through the test cell lids. Flat tensile specimen holders are also available, and custom specimen holders can be made upon request.
The Proof Ring is a specialized tool designed only for constant load tests, and it is not advisable to modify or instrument it too much. However, Cormet offers load cells for load measurement. A load cell allows for easy load level adjustment and can detect load decreases during operation due to specimen yielding. This is a useful feature, as NACE TM0177-2016 requires that the applied proof ring be monitored during testing.