Feature

Flanges and bolting, designed with the exchanger.

The girth flanges and their bolts are part of the exchanger design in PlutoHX, rather than a calculation done on the side.

Side elevation of the reference exchanger with its three bolted girth joints highlighted, and a section of the tubesheet joint with the tube side and shell side pressures acting on it. — Open the drawing at full size

Three flange pairs

Front end, tubesheet, and rear end.

An AET exchanger has three bolted girth joints: the channel cover to the channel, the channel to the stationary tubesheet and the shell, and the shell to the shell cover. PlutoHX designs each flange pair and its bolting automatically.

The joint at the tubesheet carries both the tube side and the shell side pressure, so its bolting is designed for whichever case governs, the higher one.

A true calculation

The girth flange, to Mandatory Appendix 2.

The girth flange of the reference exchanger, as the PlutoHX flange calculation works it out.

Girth flange, ASME Section VIII, Division 1, Mandatory Appendix 2

A true PlutoHX calculation, from the girth flange example.

Inputs

Type: Integral flange
A: 46.75 inFlange outside diameter
B: 40 inFlange inside diameter
C: 44.875 inBolt circle
g0: 0.75 inHub, small end
g1: 1.5 inHub, back of flange
h: 2.75 inHub length
Bolts: 60 of 1 in
m: 3Gasket factor
y: 10,000 psiGasket seating stress
b0: 0.25 inBasic gasket seating width
P: 464 psiDesign pressure
Sb: 25,000 psiAllowable bolt stress, operating and seating

Calculation
Step	Formula	Result
Effective gasket width	b = b0 (b0 not over 1/4 in)	0.25 in
Gasket reaction diameter	G	42.38 in
Pressure end force	H = (π/4) G² P	654,400 lbf
Gasket load, operating	Hp = 2 b π G m P	92,650 lbf
Bolt load, operating	Wm1 = H + Hp	747,000 lbf
Bolt load, gasket seating	Wm2 = π b G y	332,800 lbf
Required bolt area	Am = max(Wm1 / Sb, Wm2 / Sb)	29.88 in²
Bolt area provided, 60 × 1 in	Ab	33.06 in²
Flange thickness	found by the engine	1.875 in