US Patent 6857668 Replaceable corrosion seal for threaded connections

The threaded connection between the pin and the box ends of two pipes is sealed externally and internally to protect the threads in the connection from exposure to corrosive fluids. Seals are provided at each axial end of the threads. External seals are formed by metal-to-metal engagement between the pin and box and a third metal body secured circumferentially about the pin. The metal body may be fashioned into a desired annular pin seal surface to mate with and seal with the box at full makeup of the connection. The metal body can be removed and replaced as required to repair or reconstructed the pin seal surface.