Benchmark Site Services specializes in custom fabricated and stock flanges, Blinds, Paddle Blinds, Vented Paddle Blinds, EZ Vent Blinds, Ring Spacers, Spectacle Blinds, Bleed Rings, Blind Flanges and more.
We manufacture and machine our blinds in Canada and ship worldwide. Our prices are among the most competitive in the world. Since our materials are made and modified in Canada they are certified quality.
Single Blinds or Blanks are positive shut-off devices that prevent flow through a pipeline. Ring spacers or Open Blinds are used to fill the space of Single Blinds when they are removed from the piping system. With space, weight, and other pipeline requirements permitting, it may be more convenient and cost-effective in specific situations to use a Spectacle Flange, which is a combination of the two that can be rotated to function as Single Blind or a Ring Spacer.
A small problem is that we basically can not see, or a Spade or a Spacer mounted between the flanges. Therefore the handles are often specially marked, or both have a different design; a customer often provides its own specification.
What should never lack is, that in the handle, the diameter and the Pressure Class of a Spade or Spacer is engraved; this applies also for the Spectacle Blind.
The sealing surfaces of a Spectacle Blind, Spade or Ring Spacer are usually conducted in accordance with the Face Finish from the flange. The diameter always is slightly larger than the Raised Face of a flange; by a correct assembly, the bolts are just not touched by the Blind or Spacer.
The diameter of them, is depending on the flange size, and the thickness from the Pressure Class of a flange.
Dimensions from Spectacle Blinds, Spades and Ring Spacers, you will find in the main Menu “Flanges”
ASME B16.48 covers pressure-temperature ratings, materials, dimensions, dimensional tolerances, marking, and testing for operating line blanks in sizes NPS 1/2 – NPS 24 for installation between ASME B16.5 flanges in the 150, 300, 600, 900, 1500, and 2500 Pressure Classes.
Spectacle Blinds, Spades and Ring Spacers should be made from a plate or forging specification, approved for use by ASME B31.3, of essentially the same chemical composition as the mating flanges and piping involved.