A Localized Corrosion Managing Clamp in a Crevice between a Clamp and Stainless Steel Tube

摘要

Fluid flowing austenitic 316/316L stainless steel (S31600/31603) tube lines are usually subjected to repeated impulses and vibrations. To support installed tube lines, plastic clamp systems have been widely used for various industries such as oil and gas industries, ship building and power plants. However, the plastic clamp system has high risk of corrosion failure of the pipe and tube underneath plastic clamp bodies which are supporting component for the clamp. Local failure (crevice and pitting corrosion) can occur by changes in local chemistry at the crevice (between a plastic clamp body and a tube). The localized corrosion in crevice is not predictable and once it is initiated, the corrosion is extremely accelerated. As a result it can develop leakages that may lead to abrupt failure of the tubing system. To prevent localized corrosion on the metal tube line underneath the clamp body, the galvanic effect was introduced by inserting sacrificial anode material in the clamp. In this paper, the crevice corrosion resistance of tube line clamped with sacrificial anode inserted plastic clamp was investigated based on the standard test methods. The corrosion characteristic of sacrificial anode was analyzed from lab test and field test results. Furthermore, the operational life time of the anode inserted in the clamp was estimated.