Loading devices

Cormet provides various kinds of loading devices for stress corrosion cracking (SCC), sulphide stress cracking (SSCC), hydrogen induced cracking (HIC), fracture mechanical and fatigue studies.

Cormet’s workhorse for stress corrosion cracking tests is a PC operated electromechanical loading device. It can perform Slow Strain Rate Tests (SSRT), Constant Load (CL) tests and Low Frequency Cyclic Fatigue (LFCF) tests. The loading device can be used in ambient temperature, autoclave and high temperature gas environments. There are several models available of which the 10 kN, 25 kN and 50 kN instruments are the most popular. The operational principle of the versatile and flexible controlling software is based on sequenced load patterns that can be combined and connected in series.

The highest cyclic loading frequency of Cormet’s electromechanical instrument is about 0.1 Hz depending on the amplitude, loading mode and loading pattern. Servohydraulic or electrically operated loading instruments are needed for the higher cyclic frequencies. Cormet can integrate an autoclave into such a loading device or integrate the servohydraulic actuator with a Cormet autoclave.

The core of the HIC instrument is a glass container in which the specimens are assembled. However, the accessories including gas volume flow meters, water traps, draft cabinet, ventilation and gas neutralization tools make the instrument more complicated. The HIC testing procedures are described in NACE TM0284-2011.

Operation of four point bending (FPB) instruments is described in NACE TM0177-05 Method B, ASTM G 39-2011 and ISO 7539-2 (1989). The FPB tests are often performed in HIC testing containers.

Constant-load instruments are used for evaluation of critical stress in a given environment using the Time-to-Failure (TTF) value as a testing result. Standards NACE TM0177-05 Method A and ASTM G 47 – 98 (2004) describe how to perform the constant load tests. Cormet offers spring loaded and motor controlled constant load instruments.

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