What is the difference between a blind flange and a flange blank?
What is the difference between a blind flange and a flange blank?
(OP)
ASME B31.3 defines in 304.5.2 the calculation of thickness for a blind flange. I can see why you would use a blind flange, which would be when you want to close off the end of a pipe. However, in 304.5.3 the code defines the thickness calculation for a flange blank. Fig. 304.5.3 illustrates blanks, but what exactly are they and what are they used for? It looks like they are used for isolating two pipes when they are joined by flanges.
Thanks.
Thanks.





RE: What is the difference between a blind flange and a flange blank?
"Flange Blanks" are also called "Spec Blind", "Figure 8 Blind" and "Disk-and-Donut".
Go here and you will see various examples:
http://ww
You asked "what are they used for?"
You also answered your own question: "It looks like they are used for isolating two pipes when they are joined by flanges."
That is correct.
The primary motive behind the use of this type of device is Safety.
RE: What is the difference between a blind flange and a flange blank?
You use a spec blind to provide a visual reference of the flow path. The best use I ever saw of spectacle blinds was on a 2/3 stage compressor. To make it a 2 stage you would turn several blinds to flow and several to no-flow. To make it a 3-stage you reversed all the blinds. It is very easy to verify the number of compression stages by looking at the spec blinds.
David
RE: What is the difference between a blind flange and a flange blank?
The term "Skillet Blind" is just another name for the "Disk" part of the "Disk-and-Donut"
RE: What is the difference between a blind flange and a flange blank?
Or,it is that can not see and the other has no facial expression.