ABSTRACT
Oil and gas production in offshore areas has shown a marked increase, resulting in a growing network of underwater pipelines. The methods of laying offshore pipeline are many and the type of pipe considered is the steel pipe conforming to the API specification and not the flexible one. Following are the different pipe laying methods: Pull or tow method, bottom pull method, bottom pull method, flotation method and off-bottom tow method. In off-bottom tow Method, the pipeline is floated at a height a little above the ocean floor by adjusting buoyancy with weights and floats. Offshore pipelines are used for produced hydrocarbons that have undergone varying degrees of treatment, and give rise to the need for routine pigging programmes. The common reasons for pigging offshore trunklines are: Inspection, waxing and sedimentation of oil lines and liquid hold-up in gas pipelines.
