Standard for thickness of spectacle blind 1

[Redpipe]

Hi all,

Normally ANSI B31.3 specifies formula for thickness calculation of blind. However,when we specify only pipe size, pressure rating and flange face, mostly all vendors inform the same thickness. For example, thickness of spectacle blind 10" 600# RTJ will be 2.25" (57 mm.)as per information from many vendors.

When I see standard table from many vendors, there is no standard referred for specitacle blind.

Anyone know standard applied for spectacle blind?

Thanks,

Dave

 

[unclesyd]

I think all the information you need is here.

http://www.swecofab.com/spectacle/designspecs.htm

 

[jte]

Or, for a mere $58 you can own your very own copy of ASME B16.48 which, in Table 10 of the 1997 version (left the 2005 ed. at work) lists the thickness of a 10" NPS Class 600 female ring-joint figure 8 blank as... 2.25".

http://catalog.asme.org/Codes/PrintBook/B1648_2005_Line_Blanks.cfm

B16.48 takes the B31.3 formula and does the math for you. The 1997 ed. only covered carbon steel; the 2005 ed. upgraded that to cover more flavors. See the forward.

jt

 

[dcasto]

or for free just build a spreed sheet with the equations something like this:

ANSI 150, 300, & 600 FLANGE SKILLET DESIGN CALCULATIONS
======================================================

DESIGN PRESSURE--- 720 psig
PIPELINE NOMINAL DIAMETER-- 12.0 inches
PIPELINE ACTUAL OUTSIDE DIAMETER.. 12.750 inches
PIPE WALL THICKNESS--- 0.375 inches
PIPE INTERNAL DIAMETER.. 12.000 inches
OUTSIDE DIAMETER OF RAISED FACE.. 15.000 inches
"d" -max SPAN.... 13.500 inches
d = (internal + outside) / 2 = 13.5

"c" - FACTOR----------- 0.020
"S" MAXIMUM ALLOWABE STRESS--- 15,000 psi
MINIMUM REQUIRED THICKNESS SKILLET. 1.301 inches
d*(3/16*Design pressure/S)^0.5+ c = 1.301

 

[onrush]

Dear members,

- Up to 24", see ASME B16.48.
- For 26" & above, use ASME B31.3 formula.