Dimensions of spectacle blinds according to ASME B16.48

Spectacle also called as Figure-8 .

Spectacle blind flange-draws

1. Spectacle blind 2.Flanges 3.Gaskets 4.Stud bolts

Dimensions of spectacle blinds according to B16.48 for installation between B16.5 flanges.

Material Symbol C Mn P S Si Ni Cr Mo Cu N V Co
ASTM A105 0.35 0.60-1.05 0.035 0.04 0.10-0.35 0.4 0.3 0.12 0.4 _ 0.08 _
ASTM A350 LF2 0.3 0.60-1.35 0.035 0.04 0.15-0.30 0.4 0.3 0.12 0.4 _ 0.08 0.02
ASTM A182 F304 0.08 2 0.045 0.03 1 8.0-11.0 18.0-20.0 _ _ _ _ _
ASTM A182 F304L 0.03 2 0.045 0.03 1 8.0-13.0 18.0-20.0 _ _ _ _ _
ASTM A182 F316 0.08 2 0.045 0.03 1 10.0-14.0 16.0-18.0 2.00-3.00 _ _ _ _
ASTM A182 F316L 0.03 2 0.045 0.03 1 10.0-15.0 16.0-18.0 2.00-3.00 _ _ _ _
ASTM A182 F321 0.08 2 0.045 0.03 1 9.0-12.0 17.0-19.0 _ _ _ _ _
EN 10025 S235JR 0.2 1.4 0.045 0.045 _ _ _ _ _ 0.01 _ _
20Mn 0.17-0.23 0.70-1.00 0.035 0.035 0.17-0.37 0.3 0.25 0.25
20 0.17-0.23 0.60-1.00 0.03 0.02 0.17-0.37 0.25 0.25 0.25
16Mn 0.13-0.19 1.20-1.60 0.03 0.02 0.20-0.60 0.3 0.3 0.25
Material Symbol Tensile Strength, min, MPa Yield point, min, Mpa Elongation, min, % Reduction of area, min, % Hardness, max, HB Min. Impact Test Temperature, °C
ASTM A105 485 250 22 30 187
ASTM A350 LF2 485-655 250 22 30 20 -46
ASTM A182 F304 515 205 30 50
ASTM A182 F304L 485 170 30 50
ASTM A182 F316 515 205 30 50
ASTM A182 F316L 485 170 30 50
ASTM A182 F321 515 205 30 50
20Mn 450 275 24 50 197
20 410 245 25 55 156

Raised Face Joint Blanks

Raised Face Joint Blanks

Raised Face Joint Blanks

  • ASME B16.48 says: The gasket seating surface finish and dimensions for raised face line blanks shall be in accordance with ASME B16.5. A raised face may be specified at the option of the purchaser.
  • A Raised Face would add machining time and complexity so the price would be higher. Call this the Bugatti or Rolls Royce of the line blind world.
  • Personally, I have seen that version once or twice somewhere. The version without Raised Face is the default and is used everywhere.

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