Investigation of marine environmental related deterioration of coal tar epoxy paint on tubular steel pilings

Abstract

In the Arabian Gulf region, port and waterway authorities are becoming increasingly concerned about accelerated tidal and splash zone concentrated corrosion on marine tubular steel piles. The coating protection and maintenance of tubular steel pilings located in a marine environment can be difficult. The arid environment of Kuwait of the salt water and salt laden moisture and high temperature fluctuation with the marine growth on the marine structure creates a challenging maintenance problem. This premature failure investigation dealt with the delamination and peeling of coal tar epoxy coating system. The new pier project is around 2.5 km long with topside facilities supported by 2000 tubular steel pilings in two types 914 mm and 1016 mm in diameters. Prior to installation, the piles at vendor's premises in another country received a protective coal tar epoxy coating with a minimum dry film thickness of 450 microns. However, almost all of the coated steel pilings severely deteriorated after 4–8 weeks causing an estimated cost of maintenance work of $4 million. The failure case investigation was carried out to ascertain the cause of the aforementioned coating defect and to propose a possible solution to the coating failure. An accepted method of repair has been proposed, and therefore to create a barrier system in the form of jacket material with anti corrosion wraps, protecting the underwater or splash zone pilings and other structural elements from further deterioration. The failure analysis results along with laboratory evaluation of the effectiveness of four different types of jacket materials will be addressed.