Flash-butt welding technology as applied to marine pipeline construction can result in lay barge production rate increases of approximately 50% over existing methods. Welding equipment and welding quality have been evaluated in over 1,000 welds in 36-inch 0.0. × ½- to 1-1/8-inch-wallthickness line pipe. Weld quality has been very consistent with the fully automatic system, and has typically exceeded the requirements of API Standard 1104. Real-time monitoring of welding process parameters with a six ' channel, strip-chart recorder has provided an effective means of quality assurance.
Program progress from 1979 to 1985 is discussed, including acceptance of flash-butt welding by the API-AGA Joint Committee on Oil and Gas Pipeline Field Welding and the design and operation of an internal flash-butt welding machine for welding 28- to 36-inch diameter offshore pipelines. It is also shown that the flash-butt welding process is advantageous to both horizontal and vertical offshore pipeline construction.
Flash-butt welding has been used for many years in the United States to make automotive Wheels, bearing races, aircraft landing gear, and propeller blades. More recently it has been used to make oil drilling pipe, continuous railroad rails, and gas turbine components1. Recent technological advances in the Soviet Union have made it practical to fieldweld large-diameter pipe, such as the 56-inch diameter pipelines which transport gas from the extensive Siberian Gas Fields2
In August 1977, engineers from McDermott Incorporated witnessed the operation of a Soviet-built flash-butt welding machine at the E. O. Paton Electric Welding Institute in Kiev, U.S.S.R. The machine appeared to be readily adaptable to joining segments of pipelines offshore and capable of substantially increasing production rates over conventional manual and semi-automatic methods. After technical evaluations, economic evaluations, and contract negotiation, the Paton Welding Institute built and delivered an internal flash-butt welding machine to McDermott for welding 36- to 40-inch diameter pipe. The Soviet Model K775 FlashButt Welding Machine was brought to New Orleans in June 1981 after acceptance testing, and since that time over 1,000 full-sized pipe welds have been made and evaluated.
The K775 machine was demonstrated to the APIAGA Joint Committee in 1982, and after very thorough evaluation of 36-inch 0.0. test welds in API 5LX pipe, flash-butt welding was approved for inclusion in API Standard 1104.
Due to the success of the K775 machine, a smaller machine sized for 28- to 36-inch 0.D. pipe was designed and engineered by McDermott. This machine, intended for offshore pipeline construction, is scheduled for operation in 1985.
Some of the advantages of flash-butt welding of marine oil and gas pipelines are:
The equipment is truly automatic, so no adjustments are required by the operator during welding.
The process is weather tolerant, and lends itself very well to use in arctic climates.
Weld quality is very consistent from weld to weld because of preset machine parameters and adaptive control.
Only one weld station is required to make the weld.
