Pipeline operations are a varietal complex of underground arteries, terminals, compressor and pumping stations, all of which help to transport natural gas, crude oil, refined products, water, coal and many other commodities from producing areas to marketing areas. Major oil and gas pipelines crisscross continental United States with a total of over 750,000 miles of steel tubes that represent capital expenditures of billions of dollars and a source of work for thousands of skilled craftsmen. Since the oil and gas industries represent a major segment of the pipeline users, this discussion will center about such pipelines.

Pipeline welding is one of the major fields of endeavor in the welding industry and, conversely, welding is the outstanding factor in making modern pipelines economically possible. The economy of pipeline construction and operation demands that new developments in welding methods be applied to this work as soon as they can be adapted to the rigorous requirements of cross country operations.

The laying of gas and oil pipelines had a rather obscure beginning and it is really only since World War II that this industry has been brought to public attention. Actually, the first pipeline in this country, laid in 1821 near Fredonia, N. Y., was made of hollow logs but, since the line did not prove satisfactory for the carrying of natural gas, was almost immediately replaced. With the discovery of oil in Titusville, Pa., the need for faster and more economical transportation of this raw material to market was apparent, thus the first iron pipeline was laid in 1862.

Welding was still an undeveloped art, but in 1903 a blow pipe, using oxyacetylene, which could be applied to metal joining, was developed and adopted by industry. This torch could produce a localized temperature great enough to melt steel or iron and form a fusion welded joint between adjacent edges. Only eight years later, oxyacetylene welding was used on a pipeline to Philadelphia. Figure 1 shows a typical generator of these early days.

Electric arc welding, first discovered in 1885 but not developed until World War I, was barely out of the state of curiosity when, in 1920, it was also brought into the pipeline picture. Figure 2 illustrates one of the first electric generators used in pipeline welding. Pipelining moved forward at a rapid pace, with oxyacetylene welding as the common process for joining until the early 1930's when the reliability of electric arc welding, using covered electrodes, was accepted and started to supplant acetylene as the preferred welding process. While oxyacetylene declined as a process of welding for larger diameter line pipe, it still remained an important accessory to pipeline construction work as a source of heat for preheating and post heating and is still preferred as a welding process for small diameter pipe and tubing in the range of 2 in. OD and less.