Selecting the right sealing method can make the difference in both performance and cost when the fastening system is under attack by hydraulic or pneumatic, internal or external pressure, or when environmental contaminants are externally present. There are several wet and dry methods to explore, ranging from liquid thread sealing compounds, tapes, o-rings, and deformable washers, to APM Hexseal’s specially designed screw with an o-ring sealing system.