Abstract
Polytetrafluoroethylene (PTFE) coated fasteners have been commonly used in various industry applications for both its corrosion resistance and lubricity during bolt up. There is a wide array of different brands and various process methods to apply PTFE on fasteners, that offer similar performance. However, there is a resounding question regarding if lubrication is needed during bolt up of PTFE fasteners and if there are any benefits to corrosion resistance and break-out.
For this study, we used two applicators of Xylan 1424 and one applicator of Flurokote #1, all PTFE based coatings. The samples were subjected to salt spray environment in accordance with ASTM B117 at 1,500 hours, 2,000 hours, 2,500 hours, and 4,000 hours. The studs were torqued to load the ASTM A193 B7 fasteners to 50% of the minimum yield, where half of the studs were torqued without lubrication and the other half were lubricated with Jet-Lube 550 Extreme. At each of the time intervals, the percentage of red rust on the stud and two nuts were measured and the break-out torque was recorded.
Numerous observations were made as to the relationship between application of lubrication and without regarding both corrosion and break out torques. This paper will talk in depth as to the benefits of using lubrication on PTFE coated fasteners.
