A breakdown of the products and services provided by the Members will be found on the previous three pages. The following is an explanation of some of the less well known terms and items which are listed: 1."Utility pigs" are used for a variety of purposes such as internal pipe wall cleaning, condensate removal, water fill for pressure testing, gauging, dewatering, drying, commissioning etc. There are many different types available for use in uni-directional, bi-directional and multidiameter pipelines. Utility pigs have been divided into the four different forms in which they are made: a) "Mandrel pigs" are assembled from a number of component parts, and spare parts are available. b) "Foam pigs" are moulded from polyurethane foam with various configurations of solid polyurethane strips and/ or wire bristles, studs etc. permanently bonded to them. c) "Solid cast pigs" are moulded in one piece - usually from polyurethane. d) "Spheres" are hollow balls, usually made from polyurethane and inflated to the optimum diameter with water/ glycol. 2. "Hyperbaric spheres" and "High DP pigs" are used mainly on subsea pipelines as a temporary plug while the two ends of the line are welded together. 3. "Pig signals" indicate the passage of a pig. Intrusive types are mechanically actuated via a trigger or plunger which protrudes into the line. Non-intrusive and subsea signals may employ magnetic, ultrasonic or radioactive techniques. 4. "Pig locators" are used to locate a pig which may or may not be in motion. 5. "Sphere flow tees" are specially designed to allow a sphere to pass an offtake without stalling. They may be called simply "Sphere tees" or "Flow tees". 6. "Sphere lifters" are usually in the form of tongs or suction devices. 7. "Pig suspension systems" are designed to keep a pig in the centre of a pipeline. They usually comprise spring-loaded skids or wheels and are used for inline inspection tools, or other relatively heavy pigs, and in multi-diameter pipelines. 8. There are two main methods of finding metal loss (corrosion): Magnetic flux leakage (MFL) and ultrasonics (UT). Another emerging technology involves the use of eddy currents.
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