Abstract
repair method that can be applied from the inside of a gas transmission pipeline (i.e., a trenchless repair) is an attractive alternative to conventional repair methods since the need to excavate the pipeline is precluded. This is particularly true for pipelines in environmentally sensitive and highly populated areas. The objectives of the project are to evaluate, develop, demonstrate, and validate internal repair methods for pipelines; develop a functional specification for an internal pipeline repair system; and prepare a recommended practice for internal repair of pipelines. The purpose of this survey is to better understand the needs and performance requirements of the natural gas transmission industry regarding internal repair. A total of fifty-six surveys were sent to pipeline operators. A total of twenty completed surveys were returned, representing a 36% response rate, which is considered very good given the fact that tailored surveys are known in the marketing industry to seldom attract more than a 10% response rate. The twenty survey responses produced the following principal conclusions: (1) Use of internal weld repair is most attractive for river crossings, under other bodies of water (e.g., lakes and swamps) in difficult soil conditions, under highways, under congested intersections, and under railway crossings. All these areas tend to be very difficult and very costly if, and where, conventional excavated repairs may be currently used. (2) Internal pipe repair offers a strong potential advantage to the high cost of horizontal direct drilling (HDD) when a new bore must be created to solve a leak or other problem in a water/river crossing. (3) The typical travel distances required can be divided into three distinct groups: up to 305 m (1,000 ft.); between 305 m and 610 m (1,000 ft. and 2,000 ft.); and beyond 914 m (3,000 ft.). In concept, these groups require pig-based systems; despooled umbilical systems could be considered for the first two groups. For the last group a self-propelled system with an onboard self-contained power and welding system is required. (4) Pipe size range requirements range from 50.8 mm (2 in.) through 1,219.2 mm (48 in.) in diameter. The most common size range for 80% to 90% of operators surveyed is 508 mm to 762 mm (20 in. to 30 in.) diameter, with 95% using 558.8 mm (22 in.) diameter pipe.
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Published on 01/01/2003
Volume 2003, 2003
DOI: 10.2172/824951
Licence: CC BY-NC-SA license
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