This paper investigates the reliability of the existing design equations specified in AS/NZS 4600:1996 for flare-bevel and flare-vee welded connections in cold-reduced high-strength G450 sheet steels. The existing design equations are adapted from the AWS D 1.3 Structural Welding Code, which is based on the testing results on flare-bevel welded connections only in mainly mild sheet steels. In the present work, flare-bevel and flare-vee welded connections in 1.5-mm and 3.0-mm sheet steels were fabricated using different GMAW procedures and tested to failure. All the transverse flare-bevel welded connections failed in the HAZs of the parent material. The longitudinal flare-bevel and flare-vee welded connections in 1.5-mm sheet steel also failed in the HAZs of the parent material, while those in 3.0-mm sheet steel failed in the weld metal. Nevertheless, it was found that the existing design rules may be applied conservatively to transverse and longitudinal flare-bevel welded connections in G450 sheet steels provided the weld quality is comparable to that produced inhouse. On the other hand, it was found that the existing equations overestimate the capacity of flare-vee welded connections in G450 sheet steels. Ideally, flarebevel and flare-vee welded connections in 3.0-mm G450 sheet steel are design in accordance with AS 4100. A survey of arc welded connections produced by industry fabricators suggested that the quality of in-house welded connections is unlikely to be matched in practice.