Flange thickness and bolting calculations for ASME Sec I for S Stamping Jobs

[Yogesh.Patil]

Hello All,

I have doubt on how to qualify a non standard fabricated flange for s stamping job.
My customer End connection is 4" #2500 RTJ Flange, I am matching his flange details as per ASME B16.5 flange details with bolting used as per ASME B16.5 only.

The counter flange I am offering has modification as I am using the end parts as a hub and welding a probe DSH to the flange, so it makes my flange non standard and S Stamp will ask detail calculation for the flange bolts and thickness.

My questions are, Can I declare the flange thickness and bolting as per B16.5? If not how should I validate it as per ASME Sec I.

If I do the calculations as per ASME Sec VIII DIv.1; Appendix-2; "Rules for Bolted flange connection with Ring type Gasket" then my available bolt area comes less than the required bolt area.

Please see below details for the calculations;
Using Equation 2 of Sec VIII Div1; Calculations of Wm2;
for estimating bo, I used Sketch 6 and Column I; so bo=w/8; W=16.7; bo=16.7/8=2.08
b=bo; so b=2.08;
y=150Mpa; G=157.18mm;
So; Wm2=154619.7
For Wm1=H+Hp
P=15.5132 MpaG
m=6;
Wm1=492905.3

Temperature is 562.2 degC
Bolt Material Considered A193 Gr. B16;
Sb=48.014 Mpa
Sa=172 Mpa

Am1=10265.87
Am2=898.9516
Am=10265.87
Now as per B16.5; Bolt Size is 1.5"; Qty 8;
So root area for 1.5" Bolt size (6 TPI considered)
=PI()/4*(1.5-(1.3/6))^2
=1.2935 Sq. Inch

So, Ab=1.2935*8=10.348 Sq. Inch = 6676 mm2

So this area is less than Am.

Am I following correct path? If yes, how should I proceed further to validate the design as per B16.5.

Can anyone guide me in this regard?

Best Regards,
Yogesh Patil
+91 9623715216