The weld seam in fire sprinkler piping is highly susceptible to accelerated corrosion rates.
The current ASTM standards for fire sprinkler piping does not require heat treatment of the weld seam in the piping to reduce the risk of corrosion in the heat-affected zone around the weld seam. As a result, the weld seam in fire sprinkler piping is highly susceptible to accelerated corrosion rates relative to the remainder of the pipe.
Weld seams under trapped pools of water in dry (pre-action) fire sprinkler systems almost always experience high rates of corrosion and are frequently the point of failure.