Q: I need fasteners for an exhaust duct where I want to use bolts to act as a stopper for a blast gate. The max temperature 1650F. Any suggestions?

A: In this type of environment, Inconel 625 bolts would be one of the strongest and most temperature resistant materials you could use at that temperature. There are not too many materials that would be better.

Q:  I have an application, which will be heated by radiant heat from below to 700°C to 900°C. The problem I am trying to solve is that the screws tend to fuse to the plate they are fastening. Black Oxide alloy steel is the best we’ve tried, but still very problematic. Any suggestions?

A: We definitely have some options that will help you. Probably the best option you have are Inconel 625 fasteners. This is a high temperature nickel alloy that is stable at temperatures over 900C. This will perform significantly better than the stainless steel you currently using, as you are readily oxidizing the materials causing them to fuse to your base plate.  You should not have this problem with Inconel 625 screws.

In addition I would recommend using a molybdenum disulfide anti-seize lubricant.  We offer one that is designed for high temperatures and will aid in the screws being more easily removed.

Q: What stud and nut material should I use with a ANSI 600# Alloy 800 HT pipe class max temperature 1650°F.

A: Given that you are at a high temperature and pressure I would recommend going with an Inconel 625 stud. This will provide the best combination of high temperature strength. Inconel 625 bolting can be used to temperatures of about 1800°F. These fasteners also offer 144ksi ultimate tensile strength. Inconel 625 fasteners are known for their resistance to corrosive environments as well.