Thursday, March 12, 2009

Corrosion Monitoring

Corrosion is a natural phenomenon which will occur but will vary on the rate depending on the environment and the material. Corrosion not only taking place in industry generally or oil and gas specifically but also everywhere which are not really noticed by human being. For instance, many of car manufactures are having some sort of antirust which giving some coating on the surface of the car body to prevent from corrosion taking place. This antirust scheme is not a whole life guarantee given by them but just for some time only. What can be seen from here is that the coating mechanism only can sustain for limited time only and again need to be coat again with the presence of car polishing companies. So, even coating mechanism itself facing corrosion problem where they lose of the coating film on the car body. Here where the material taking the action but some other scenario where environment will take action. For example, those cars exposed to beach area more prone to corrode since the environment is corrosive.

Corrosion is everyone issue which need to be addressed by everyone, everywhere, and every time. However, the corrosion that taking place in industry is more severe compared to non-industry related. This is mainly because of the function of itself where in industries, corrosion like a culprit to production. If the corrosion persists, the production line has to be shut-down since the safety always become on the top priority even ultimate aim of industries are to make profit. Therefore, there lot initiatives have been taken and being done in all level to monitor the corrosion. This mainly to study the suitable material to be used in related industry and way of minimizing the rate of corrosion. There are lot of proprietary chemicals are being used as a corrosion inhibitor to inhibit the corrosion. Again this corrosion can behave very differently for different application and they need different chemicals as a corrosion inhibitor. There is detail study to be done when procuring any vendor chemicals to avoid any off-spec products which can cause billion dollars losses. Thus, corrosion monitoring is important to identify the behavior of the fluid exposed to the material (piping, vessel, etc.). There are many ways of monitoring and one of it has been discussed on corrosion coupon. In addition to that, electrical resistance (ER) and linear polarization resistance (LPR) also have been successfully applied and are used in an increasing range of applications.

ER probes can be thought of as “electronic” corrosion coupons. Like coupons, ER probes provide a basic measurement of metal loss, but unlike coupons, the value of metal loss can be measured at any time, as frequently as required, while the probe is in-situ and permanently exposed to the process stream.

The LPR technique is based on complex electro-chemical theory. For purposes of industrial measurement applications it is simplified to a very basic concept. In fundamental terms, a small voltage (or polarization potential) is applied to an electrode in solution. The current needed to maintain a specific voltage shift (typically 10 mV) is directly related to the corrosion on the surface of the electrode in the solution. By measuring the current, a corrosion rate can be derived.

1 comment:

  1. What is the good way for corrosion monitoring system for the subsea pipelines?