9.1 Introduction

Oilfield pipelines are insulated mainly to conserve heat. The need to keep the product in the pipeline at a temperature higher than the ambient could exist for the following reasons including:

• Preventing formation of gas hydrates

• Preventing formation of wax or asphaltenes

• Enhancing product flow properties

• Increasing cool-down time after shutting down

• Meeting other operational/process equipment requirements

In liquefied gas pipelines, such as LNG, insulation is required to maintain the cold temperature of the gas to keep it in a liquid state. This chapter describes commonly used insulation materials, insulation finish on pipes, and general requirements for insulation of offshore and deepwater pipeline.

9.2 Insulation Materials

Polypropylene, polyethylene, and polyurethane are three base materials widely used in the industry for pipeline insulation. Their thermal conductivities are given in Table 9.1 (Carter et al., 2003).

Depending on applications, these base materials are used in different forms resulting in different overall conductivities. A 3-layer polypropylene applied to pipe surface has a conductivity of 0.13 BTU/hr-ft- F, while a 4-layer polypropylene has a conductivity of 0.10 BTU/hr-ft- F. Solid polypropylene has higher conductivity than polypropylene foam. Polymer syntactic polyurethane has a conductivity of 0.07 BTU/hr-ft- F, while glass syntactic polyurethane has a conductivity of 0.09 BTU/hr-ft- F. These materials have lower...