Super-duplex wrought products are often welded with near-matching composition welding
products, which may require post weld heat treatments for use in aggressive environments.
When duplex field welds are exposed to the demanding conditions encountered in
geothermal energy production, without a heat treatment, an over-matching nickel-chromiummolybdenum-
tungsten welding product is required for optimum corrosion resistance. Welding
procedures are known to have a significant effect on the corrosion resistance and mechanical
properties of the welded pipe. Thus a study was undertaken to optimize welding procedures
and then verify that the resulting welded pipe was fully resistant to the conditions of service.
Details of the welding procedures are reported along with the work conducted to evaluate
them. This work is then correlated with results from extensive examinations of welded pipes
and fittings taken from service. Effects of service exposure on corrosion and mechanical
properties of different weld filler metals are shown.