VISTA TECH

 Pigging in the maintenance of pipelines refers to the practice of using pipeline inspection gauges or ''''''''''''''''''''''''''''''''pigs'''''''''''''''''''''''''''''''' to perform various operations on a pipeline without stopping the flow of the product in the pipeline. Pigs get their name from the squealing sound they make while traveling through a pipeline. These operations include but are not limited to cleaning and inspection of the pipeline. This is accomplished by inserting the pig into a Pig Launcher - a funnel shaped Y section in the pipeline. The launcher is then closed and the pressure of the product in the pipeline is used to push it along down the pipe until it reaches the receiving trap - the ''''''''''''''''''''''''''''''''pig catcher''''''''''''''''''''''''''''''''. Pigging has been used for many years to clean larger 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 pigging can be used for almost any section of the transfer process between, for example, blending, storage or filling systems. Pigging systems are already installed in industries handling products as diverse as lubricating oils, paints, chemicals, toiletries, and foodstuffs. Pigs are also used in oil and gas pipelines: they are used to clean the pipes but also there are "smart pigs" used to measure things like pipe thickness along the pipeline. They usually do not interrupt production, though some product can be lost when the pig is extracted. They can also be used to separate different products in a multi-product pipeline

The schematic shown here is for a horizontal pig launcher. A horizontal pig receiver would be almost identical to this schematic, except for the position and size of certain nozzles such as drain, kicker line and PSV nozzle.