Pig technology for oil pipeline service.

Анотація

A "pig" in the pipelineindustry is a tool that is sent down a pipeline and propelled by the pressureof the product flow in the pipeline itself, see Fig. 1.There are four main uses for pigs: 1.Physical separation between different fluids flowing through the pipeline2.Internal cleaning of pipelines3.Inspection of the condition of pipeline walls (also known as an Inline Inspection (ILI) tool)4.Capturing and recording geometric information relating to pipelines (e.g., size, position).One of the most common and versatile is the foam pig which is cut or poured out of open cell polyurethanefoam into the shape of a bullet and is driven through pipelines for many reasons such as to prove the inner diameter of, clean, de-water, or dry out the line. There areseveral types of pigs for cleaning in various densities from 2lb to 10 lb foam and in special applications up to 20 lb. Some have tungstenstudsor abrasive wire mesh on the outside to cut rust, scale, or paraffin waxdepositsoff the inside of the pipe. Other types are fully or criss-cross coated in urethane, or there are bare polyurethane foam pigs with a urethane coating just on the rear to seal and assist in driving the pig. There are also fully molded urethane pigs used for liquid removal or batching several different products in one line. Fig. 1. A pig in a pipelineInline inspectionpigInline inspectionpigs use various methods for inspecting a pipeline. A sizing pig uses one (or more) notched round metal plates as gauges. The notches allow different parts of the plate to bend when a bore restriction is encountered. More complex systems exist for inspecting various aspects of