In the SMR process gas cooler, the flow of the 1400^oF hydrogen stream is controlled by blade and butterfly dampers. The OEM furnised bearings supporting the damper shafts often seized, making the regulation of the process difficult. They were replaced with GRAPHALLOY grade GM GDG-2 bushings. Inspected after several years of trouble-free operation in this high temperature environment, the GRAPHALLOY bushings were found in excellent condition with the shafts free to rotate.

Lube oil stock mixed with MEK and toluene is fed through the chiller to crystallize the wax in solution. The interior scrapper assembly bushings are subjected to temperature swings and attacked by harsh chemicals. GRAPHALLOY works in this environment. It remains dimensionally stable under load and close operating clearance is maintained regardless of the temperature changes. At one refinery, GRAPHALLOY bearings have run four times longer with less than one-half the measurable wear of the original bronze bearings.

Excessive shaft vibration can cause repetitive mechanical seal failures in process pumps. A non-galling, close clearance GRAPHALLOY throat bushing lowers the shaft deflection and improves rotor stability. It also reduces flush liquid consumption. This application is recognized in the current API 682 standard.

Pumping recirculated creosote is always a maintenance headache. The liquid is hot, gritty and provides no lubricity to internal pump parts. One operator tried bronze, plain carbon and tungsten carbide for the idler bushing, but never obtained an operating period greater than 150 hours. Switching to GRAPHALLOY increased service life to over 400 hours.