Bolts for Bromine
Bolts for Bromine
(OP)
Can anyone tell me the material of choice for bolting dual laminate (teflon/fiberglass) pipe flanges both flange to flange pipe and flange to steel(glass lined) vessel nozzle. Operating conditions are 100 psig, @ ambient, outdoors exposed to weather, pumping 100% bromine in the line. Currently using and ASTM 193 B7 but expeiencing rapid corrosion due to permeation of Br throught the teflon gasket.





RE: Bolts for Bromine
Timothy C. Odom, CEO
Odom Industries, LLC
Phone: 513-777-3773
Fax: 513-777-7223
RE: Bolts for Bromine
RE: Bolts for Bromine
RE: Bolts for Bromine
RE: Bolts for Bromine
Coated carbon steel bolts may not work for you. The coating may not stop the Br, and it can be abraded during assembly leaving no protection. I would recommend using more resistant material such as stainless steel or titanium. I have no direct experience with Br, so I will assume it behaves similarly to Cl. Titanium alloys are nearly impervious to Cl corrosion, so I would consider them first.
If you do choose to coat the existing bolts, then you need to change the torque based upon the friction coefficient. The preload developed from a given input torque is directly proportional to friction coefficient. I would estimate the bare friction coefficient at 0.20-0.25, and PTFE would be around 0.10. Therefore, you should use about 1/2 the original torque. If this is a critical application, I would perform testing to confirm the friction coefficient levels.
Cory
cpadfield@omnimetalslab.com
RE: Bolts for Bromine
Why don't you try for sleeved bolting like one does for insulating flanges in the Pipelines, this may prevent a direct exposure with Br.
Naeem