During the early 1990s, several offshore operators experienced intermetallic precipitation in the heat affected zones (HAZs) of thin walled superduplex pipes. However, this experience appeared contrary to the time-temperature-transformation (TTT) diagrams available and an estimate of the total thermal history of such joints. To investigate this disparity, the current paper describes research undertaken in two parts. The first involved a matrix of HAZ thermal simulations on three grades of superduplex steel with subsequent metallography, impact and pitting corrosion tests. The second comprised gas tungsten arc welding (GTAW) of thin walled tubes supplied in different heat treatment conditions. Evaluation consisted of metallography and pitting corrosion tests. Conclusions are drawn on the cause of the HAZ intermetallic precipitation and their practical implications are discussed.