pipe welding position

Welding is the simplest and easiest way to join sections of pipe. The need for complicated joint designs and special threading equipment is eliminated. Welded pipe has reduced flow restrictions compared to me- chanical connections and the overall installation costs are less. The most popular method for welding pipe is the shielded metal-arc process; however, gas shielded arc methods have made big inroads as a result of new advances in welding technology. Pipe welding has become recognized as a profes- sion in itself. Even though many of the skills are com- parable to other types of welding, pipe welders develop skills that are unique only to pipe welding. Because of the hazardous materials that most pipelines carry, pipe welders are required to pass specific tests before they can be certified In the following paragraphs, pipe welding positions, pipe welding procedures, definitions, and related infor- mation are discussed. PIPE WELDING POSITIONS You may recall from chapter 3 of this manual that there are four positions used in pipe welding (fig. 3-30). They are known as the horizontal rolled position (1G), the horizontal fixed position (5G), pipe inclined fixed (6G), and the vertical position (2G). Remember: these terms refer to the position of the pipe and not to the weld PIPE WELDING PROCEDURES Welds that you cannot make in a single pass should be made in interlocked multiple layers, not less than one layer for each 1/8 inch of pipe thickness. Deposit each layer with a weaving or oscillating motion. To prevent entrapping slag in the weld metal, you should clean each layer thoroughly before depositing the next layer. 7-25