Goodyear used pressurised anhydrous ammonia as a cooling
fluid in a shell and tube heat exchanger at their synthetic rubber plant in Houston, Texas. The process chemicals to be
cooled were pumped through the tubes inside the exchanger
while the ammonia was circulated shell-side. On June 10, 2008 operators closed an isolation valve on the shell-side so that they could replace a burst rupture disk. Closing the isolation valve also closed off a pressure relief valve that was located there to prevent pressure build up of the ammonia on the shell-side. At the conclusion of the rupture disk replacement, the isolation valve was not re-opened. The next day another operator closed a block valve on the ammonia shell-side loop