dm4.A 3.5mm:= Minor diameter bolts

kN 1000N:= Conversion factor

p 0.7mm:= Pitch

β 60deg:= apex angle

φ atanp

π dm4.A⋅

:= Pitch angle

φ 3.6 deg=

µk 0.15:= Friction factor

ρ atanµk

cosβ2

:= * Friction angle

ρ 9.83deg=

Nm N m⋅:= Conversion factor

Page No. Report No.

Checked By

Drawing No.

Calculation conflat with pressure load File name: Conflat calculationLHCb VErtex LOcator

23/03/2005Prepared By L van Diepen

INPUT

bar 0.1N

mm2:= Conversion factor

k 1.5:= Safety factor

P 100bar:= Pressure

H2 18.5mm:= Diameter conflat knife

n 6:= Number of bolts

C 500N

mm:= Sealing force (C=300-500N/mm)

Cmin 300N

mm:= Minimum sealing force

dm4 4mm:= Diameter bolts

omtrek 58.1mm= circumferential conflat knife

Fseal C omtrek⋅:= Fseal 2.9 104× N= sealing force in bolts

Fseal.b

Fseal

n:= Fseal.b 4.8 103× N= sealing force per bolt

σFp.b Fseal.b+( )0.25 π⋅ dm4

2⋅:= σ 438.9

N

mm2= tensile stress per bolt

Fb.totaal Fseal.b Fp.b+:=Fb.totaal 5.5 kN= total force per bolt

Max.negative force in m4 bolt (12.9): 6,8 kN

Yield stress of m4 bolt (12.9): 1100 N/mm^2

Bolt strength is sufficient

Pn

M4

H2

CALCULATION

Internal pressurePn k P⋅:= Pn 15

N

mm2=

Pressure loadAp 0.25 π⋅ H2

2⋅:= flange surface

Fp Pn Ap⋅:= Fp 4 103× N= pressure load

Fp.bFp

n:= Fp.b 672 N= force per bolt

Sealing force

omtrek π H2⋅:=

(Leaking test with Helium 100 bara)2.4 10 6−⋅ mbarl

s⋅Leaking rate:

The conflat connection performed well at a pressure of 150 bara (water)

Leak test

Max. Torque on m4 bolt(12.9): 5.2Nm

Total torqueT 4.5 Nm=T Tt Tf+:=

Torque from frictionTf 2.2 Nm=Tf µk Fb.totaal⋅ 1.3⋅dm4

2⋅:=

Torque from turning Tt 2.3 Nm=Tt Fb.totaal tan φ ρ+( )⋅

dm4.A

2⋅

:=

Calculation of torque on the bolts

Fseal Fp− 2.5 104× N=

Fseal Fp− Fseal.min>

Fseal.min 1.7 104× N=Fseal.min Cmin omtrek⋅:=

Minimum Sealing force: