Chapter 1 - External topside offshore corrosion

Abstract

This chapter discusses eight case studies on material selection and corrosion prevention for industrial valves in the topside or atmospheric zone of the offshore oil and gas industry. Case study 1.1 discusses the material selection of SS316 instead of coated carbon or cast iron for the gear boxes of manual valves. Case study 1.2 proposes minimizing the use of low-alloy steel bolts and carbon steel nuts in industrial valves to prevent the risk of corrosion. Case study 1.3 provides a material selection guideline for the assembly of mechanical joints, which are connectors used to save weight and space. Case study 1.4 provides reasons for why the use of 17-4 PH stems should be avoided in offshore industrial valves. Case study 1.5 discusses corrosion under insulation and its prevention through the use of a coating. Case study 1.6 discusses pitting and chloride stress cracking, two major types of corrosion that are of concern in the offshore industry, and their mitigation through a combination of material selection and coating application. Case study 1.7 reviews the use of austenitic stainless steels for industrial valve parts like the handwheel, gear box, name plate, and locking device. Finally, Case study 1.8 discusses the use of tubing for piping, instrumentation, and actuators as well as tubing material selection according to the fluid service, operating temperature, and clamping application.