The austenitic stainless steels of type 304L are alloys which have carbon content below 0.03%. Applications of this stainless steel includes tubing for cooling systems in the automotive industry. The present study was conducted to evaluate the effect of variables involved in welding operations by the GTAW process of an austenitic stainless steel pipe grade 304L on characteristics as penetration and mechanical properties. Some variables to consider are travel speed and shielding gas mixture. An analysis of variance was used to determine which variable promotes the greatest impact in this process. According obtained results, hydrogen content has an important effect on penetration; mechanical properties were not affected by changing considered variables.