This document presents recommended practices for the gas tungsten arc welding (GTAW) process.(Footnote 1) Its purpose is to provide a fundamental explanation of the process@ describe basic practices and concepts@ and outline some advanced methods and applications of GTAW. These should enable welding personnel to determine the best applications of this process and evaluate its use compared with other joining processes. The section covering principles of operation will help the reader understand how the process works@ the general types of equipment needed@ and the advantages and limitations of the gas tungsten arc welding process. The basic concepts and practices include both general and specific recommendations and technical data for equipment@ consumables@ procedures@ variables@ applications@ and safety considerations. This standard makes use of U.S. Customary Units. Approximate mathematical equivalents in the International System of Units (SI) are provided for comparison in brackets [ ] or in appropriate columns in tables and figures. Footnote 1. - Gas tungsten arc welding is defined as an arc welding process that uses an arc between a tungsten electrode (nonconsumable) and the weld pool. The process is used with shielding gas and without the application of pressure. (Ref. AWS A3.0@ Standard Welding Terms and Definitions.)