Oil & Gas
What is it?
This test method describes the procedure for the laboratory immersion corrosion testing of metals.
Why do we use it?
Corrosion inhibitors are injected as far upstream as possible to offer the best protection to the pipework, processing plants etc. Typically corrosion inhibitors are water soluble and are injected in a continuous process but they can also be oil soluble. Oil soluble corrosion inhibitors are used in batch injections and these formulations are injected to coat the pipes forming a protective film.
There are two key parameters to look for in a corrosion inhibitor and these are a corrosion rate of <0.1 mm/year and an efficiency versus the blank of >90%. Corrosion inhibitors are chosen firstly based on their performance and secondly against any side effects they may have (i.e. foaming, stabilising emulsions etc.).
How does it work?
A test piece and a test brine solution are prepared in the laboratory prior to the test. The test is carried out at 60ºC. The test piece is weighed and is then immersed in the prepared brine solution for a set period of time. The test piece is then weighed once removed from the solution as well as being physically examined for signs of corrosion.
Assuming that localised or internal corrosion is not present, the average corrosion rate is calculated.