Abstract: Method and apparatus for monitoring the corrosive effects of certain fluids by simulating the high temperature, high pressure, and flow conditions experienced in the production tubulars of oil and gas wells. A corrosion coupon constructed from an accurately machined tube is divided parallel to its axis and is held in place in a test chamber. A corrosive fluid is passed through the tube under simulated flow conditions at a controlled temperature and pressure. The tube is then dismantled for inspection so that loss of mass and the character of the loss from the divided sections due to corrosion may be determined.