Line blinds are used to isolate a section of line between a valve and a vessel or other equipment, typically for maintenance or replacement. The Figure 8 blind, or spectacle blind, is a one piece or welded assembly with a blank side and a spacer side. With this type of blind its location is easily recognized in the piping run and whether the line is “open” or “blocked off”.
The figure 6A paddle blind and figure 6B paddle spacer are similar to the spectacle blind except it is made in two pieces and with a handle to protrude from the associated flange for identification. These can many times be easier to handle than the figure 8 blind, or spectacle blind, due to weight considerations. Larger sizes are furnished with lifting rings.
Figure 7 bleed rings, or drip rings, are for permanent installation in a line such that it can be drained prior to servicing associated equipment. It can also be used for sampling.
These items are available in mill finish, machined finish, or female ring type joint (RTJ). Male RTJ design is not recommended due to the potential for damage to the machined facing during handling and installation.
Pressure ratings for the blinds and bleed rings are from 150# to 2500#. Blind and spacer dimensions conform to ASME B16.48.
Line blinds and bleed rings are available in many materials including carbon steel, stainless steels, and various alloys.