Literature has been reviewed and circumferential butt welds in superduplex pipes have been tested to illustrate how secondary phases, in particular intermetallics, affect properties. Welding induced intermetallic precipitation can occur in weld metal and HAZ of duplex stainless steels. In the case of superduplex grades, it is difficult to avoid this precipitation in multiple reheated regions. Although, precipitates sometimes reduce corrosion resistance or toughness to such an extent that WPQ requirements cannot be met, some intermetallics can often be tolerated without unacceptable degradation of properties. Microstructural studies of superduplex weldments showed that s -phase can form in highly alloyed ferrite regions without significant redistribution of alloying elements. Consequently, no depleted zone will develop in the ferrite adjacent to these precipitates. A very narrow Cr and Mo depleted zone was, however, detected in the austenite but did not affect corrosion resistance significantly. It is concluded that a microstructural examination can provide useful information about the presence and location of secondary phases. However, qualification of welding procedures should mainly be based on direct measurement of mechanical properties and corrosion resistance.