In pipeline transportation, pigging is the practice of using pipeline inspection gauges or gadgets, devices generally referred to as pigs or scrapers, to perform various maintenance operations. This is done without stopping the flow of the product in the pipeline. These operations include but are not limited to cleaning and inspecting the pipeline. This is accomplished by inserting the pig into a "pig launcher" (or "launching station") — an oversized section in the pipeline, reducing to the normal diameter. The launching station is then closed and the pressure-driven flow of the product in the pipeline is used to push the pig along the pipe until it reaches the receiving trap — the "pig catcher" (or "receiving station"). Applications Pigging is used to clean large diameter pipelines in the oil industry. Today, however, the use of smaller diameter pigging systems is now increasing in many continuous and batch process plants as plant operators search for increased efficiencies and reduced costs. Pigging can be used for almost any section of the transfer process between, for example, blending, storage or filling systems. Pigging systems are installed in industries handling products as diverse as lubricating oils, paints, chemicals, toiletries, cosmetics and foodstuffs. Pigs are used in lube oil or paint blending to clean the pipes to avoid cross-contamination, and to empty the pipes into the product tanks (or sometimes to send a component back to its tank). Usually pigging is done at the beginning and at the end of each batch, but sometimes it is done in the midst of a batch, such as when producing a premix that will be used as an intermediate component. Pigs are also used in oil and gas industries to clean or clear pipelines. Intelligent or "Smart pigs" used to inspect pipelines to assess their condition and to prevent leaks, which can be hazardous or harmful to the environment. They usually do not interrupt production, though some product can be lost when the pig is removed. They can also be used to separate different products in a multiproduct pipeline and to clear slugs of liquid from multiphase gas//liquid pipelines. Pigging requires the pipeline to be designed to be pigged from the outset. If the pipeline contains topological variations including changes in diameter, butterfly valves, instrumentation, tight bends, pumps or reduced port ball valves, the pipeline cannot be traditionally pigged. In such instances, alternatives such as Ice Pigging may