Corrosion is a major cause of structural deterioration in marine and offshore structures. It affects the life of process equipment and pipelines, and can result in structural failure, leakage, product loss, environmental pollution and the loss of life. Pitting corrosion is regarded as one of the most hazardous forms of corrosion for marine and offshore structures. The total loss of the structure might be very small, but local rate of attack can be very large and can lead to early catastrophic failure. Pitting corrosion is a localized accelerated dissolution of metal that occurs as a result of a breakdown in the protective passive film on the metal surface. It has been studied for many years; however, the structural failure due to pit characteristics is still not fully understood. Accurate pit depth measurements, precise strength assessment techniques, risk analysis due to pitting, and the mathematical relationship of the environmental factors that causes pitting failure are also factors, which need further understanding. Hence this paper focuses on these issues. It reviews and analyses the current understanding of the pitting corrosion mechanism and investigates all possible factors that can cause pitting corrosion. Furthermore, different techniques employed by scientists and researchers to identify and model the pitting corrosion are also reviewed and analysed. Future work should involve an in-depth scientific study of the corrosion mechanism and an engineering predictive model is recommended in order to assess failure, and thereby attempt to increase the remaining life of offshore assets.

Modelling of pitting corrosion in marine and offshore steel structures – A technical review

Mathematical modelling of the diffusion controlled phase in marine immersion corrosion of mild steel

Ship-shaped offshore units are some of the more economical systems for the development of offshore oil and gas, and are often preferred in marginal fields These systems are especially attractive to develop oil and gas fields in deep and ultra-deep water areas and remote locations away from existing pipeline infrastructures Recently, the ship-shaped offshore units have been applied to near shore oil and gas terminals This 2007 text is an ideal reference on the technologies for design, building and operation of ship-shaped offshore units, within inevitable space requirements The book includes a range of topics, from the initial contracting strategy to decommissioning and the removal of the units concerned Coverage includes both fundamental theory and principles of the individual technologies This book will be useful to students who will be approaching the subject for the first time as well as designers working on the engineering for ship-shaped offshore installations

Ship-Shaped Offshore Installations : Design, Building, and Operation

A time-dependent corrosion wastage model for seawater ballast tank structures of ships

Models for the anaerobic phases of marine immersion corrosion

Corrosion data are reported for 20 structural ferrous metals exposed up to 16 yr in natural tropical waters, including seawater, fresh water and mean tide elevation. Time- corrosion curves derived from both weight loss and pitting are presented for many of the ferrous alloys and tabulated data for all metal environment combinations are included. These comprehensive long term results comprise the most extensive collection of accurate seawater and fresh water corrosion data presently available.

C R Southwell

Papers

Corrosion of metals in tropical waters, structural ferrous metals