Ceramic Beads Are What Let a PWHT Pad Wrap a Weld and Still Stay Alive

Ceramic Beads Are What Let a PWHT Pad Wrap a Weld and Still Stay Alive A post-weld heat treatment pad looks like a pink mat with two camlocks on the end. The part that actually makes it usable on a pipe is the ceramic beads. Take the beads away and you have a hot wire and a short. Keep the beads right and you have a flexible heater that can sit on a butt weld at 600–750°C without cooking the leads or flashing over to the vessel. The construction is simple on purpose. Multi-strand nickel-chromium wire — usually 80/20, sometimes 60/16 — snakes through interlocking sintered alumina beads....