PREMIUM TESTING SYSTEMS

Corrosion testing is often done in two types of environments: real field and laboratory. Weight loss tests are common in the field environment, where corrosion rate sensors are available for testing. In a laboratory, the testing environment can be easily modified to test a wider range of conditions, without disrupting production. However, it's important to be careful about the testing environment to ensure accurate results.

Broadly speaking stress corrosion cracking can be considered as a concept that includes for example stress corrosion cracking (SCC), sulfide stress cracking (SSC) and corrosion fatigue. Common for all these corrosion phenomena are three factors: material, stress and environment. SCC differs from universal corrosion or local corrosion, such as pitting corrosion, due to its latent destruction potential. A brittle fracture due to SCC can grow undetected at a fast pace until the construction fails.

There are various SCC testing methods. Deciding the testing method depends on the purpose of the test and the information required. Certain tests tempt to reproduce the service conditions to simulate the effect of the operating environment as closely as possible. Other tests are designed to study the mechanistic aspects of SCC. The specimens can be roughly divided into two categories: 1) smooth and 2) notched or pre-cracked specimens. Various loading modes are also available: slow strain, constant load, and cyclic fatigue tests. Smooth specimen tests cover the entire corrosion process, from the start of the crack to the moment it breaks. The results include data such as plastic strain, time-to-failure, and reduction of the specimen's cross-section area. Pre-cracked specimens are used to measure the crack growth rate or perform fracture mechanic tests.

SCC is a combination of material properties, stress, and environment. To get results that are representative and reproducible, it's important to carefully manage the testing environment and reduce deviations. This includes setting parameters for the operation, testing cell type, and accessories as part of the research plan. It's important to pay attention to the chemicals, liquids, and gases used, as well as the operating temperature and pressure. Make sure the specimen, specimen holders, and testing cell are all clean. If the operation requires high temperature and pressure, a pressure vessel should be used as the testing cell. Sometimes the operator needs to monitor and adjust the gas content, conductivity, and pH of the operation environment. All sensors and controlling devices should be calibrated regularly.