We couldn’t open our clamp because the bolt and nut were fused together. What happened?
Following best practices means ensuring that you’re using the right clamp for the application. For example, if you’re using the wrong clamp for your application, its bolt and nut can become bound or locked together, making it hard or impossible to open the clamp to service the connection. This is known as galling.
Galling can occur in clamps in which both the bolt and nut are made of stainless steel. Note that galling and coldwelding are not mutually exclusive; both can occur on steel parts. When accidentally over-torqued, either manually or mechanically, these separate pieces of metal can fuse or bind to each other so that they cold-weld together. In some cases, maintenance personnel will need to cut the clamps off before the piping can be removed.
For these applications, we recommend the use of clamps with an anti-galling option. Anti-galling is ensured by using a resident nitronic 60 stainless-steel alloy for the bolt and a slightly softer 316-grade steel for the wingnut or hex nut. If the nut is damaged by over-torquing, it can be replaced easily and inexpensively. Anti-galling options are available for bolt/nut combinations on clamps and are ideal for frequent disassemble/cleaning/assembly lines.