Table of Contents

1.0 Disclaimer...............................................................................................................1

2.0 Nomenclature.........................................................................................................2

3.0 Codes and Standards...............................................................................................3

4.0 Results....................................................................................................................4

5.0 Design Of Bolt Holes In Joining Flange (work in progress)..................................5

6.0 Design of Joining Flange Connection to Clamping Shell....................................10

7.0 References............................................................................................................12

Appendix A – High Strength Bolts – Grade 8.8 (consultants, 2007)..............................13

Appendix B – Different Types Of Butt Weld (V.N.Vazirani,1985,p.g 71)....................14

Appendix C – Butt And Fillet Weld Size Illustration.....................................................15

Appendix D - Standard and Recommended Weld Preparation Details (AS1210-Figure 3.19.3(D).(c)(PP.170)......................................................................................................16

List of Figures

Figure 1: Joining flange connection to clamping shell......................................................4

Figure 2: A bolt subjected to full external load and full prying load................................5

Figure 3: General arrangement of joining flange and bolt holes.......................................6

Figure 4: Location of forces and bending moments at joining flange induced by internal pressure..............................................................................................................................6

Figure 5: Full penetration welded-on joining flange.......................................................10

Figure 6: Full penetration butt weld – Details.................................................................11

1.0 Disclaimer

This report has been written by an undergraduate student. Any information described

herein needs to be verified and approved by a professional engineer prior to be issued

for construction.

1

2.0 Nomenclature

A - outside diameter of joining flange (m)

A’b - total cross-sectional area of bolts required for operating conditions = W/Sb

Ab - cross-sectional area of bolt = π d2 (m2)

B - inside diameter of clamping flange (m)

C - bolt circle diameter (m)

d - bolt nominal diameter (m)

g0, g1 - thickness of clamping shell (m)

H - total hydrostatic end force (N)

HC - balancing reaction force outside the bolt circle in opposition to moments due

to loads inside the bolt circle (N)

hc - radial distance from bolt circle to outer edge of flange on which HC acts (m)

Le - effective length of the clamping shell (m)

MP - moment due to loads inside the bolt circle (Nm)

MC - moment due to HC

n - total number of bolts required for operating conditions

p - design pressure (Pa)

R - radial distance from bolt circle to point of intersection of clamping shell and

back of flange (m)

Sb - maximum permissible bolt design stress at design temperature (MPa)

W - minimum bolt load required for operating conditions (N)

2

3.0 Codes and Standards

This report should be read in conjunction with the following codes and standards:

AS 1210-2010 Pressure Vessels

AS 1554.1-2011 Part 1: Welding of Steel Structures

AS 3990-1993 Mechanical Equipment - Steelwork

Additionally, where there were no applicable Australian standards, the appropriate

British and American standards would be applied:

ASME BPV VIII-1 Rules for construction of pressure vessels - Flat Face

Flanges With Metal-To-Metal Contact Outside The Bolt

Circle

BSi-Enquire Case

5500/133 to PD

5500:2003

Specification For Unfired Fusion Welded Pressure Vessels -

Flat Unstayed Ends Of Non-Circular Shape And Associated

Flanges

3

4.0 Results

For rectangular metal-to-metal contact joining flanges, the total cross-section area of bolt holes required for operating condition would be determined by the following equation:

Ab' =

H +4 M c

( A−C )Sb

(1)

The number of bolts required would be:

n=Ab

'

Ab(2)

Details of joining flange connection to clamping shell have been illustrated as below:

Figure 1: Joining flange connection to clamping shell

4

5.0 Design Of Bolt Holes In Joining Flange (work in progress)

Since the leaking fluid would be sealed by injected sealant, there would be no gasket

required and, hence, the joining flange would be metal-to-metal contact. For flanges

with metal-to-metal contact outside the bolt circle, AS 1210-Clause 3.21.10 suggested

design method in Appendix Y, ASME BPV VIII-1, “Rules for construction of pressure

vessels”, as an equivalent method. It should be noted that the rules have applied to

circular flanged connections where the assemblage comprised of identical flange pairs,

and where the flanges were flat faced and were in uniform metal-to-metal contact across

their entire face during assembly before the bolts were tightened. This method assumed

the flanges were in tangential contact at their outside diameter. The analytical procedure

was based on the prying effect. Illustration of this effect has been shown in Figure 2:

Figure 2: A bolt subjected to full external load and full prying load

From Figure 2, due to the flange interaction beyond the bolt circle to resist the bending

moment developed by the external load, H , a bolt was not only subjected to the full

external load, H , but also the prying load, H R, or the joint would fail. Hence, the bolt

load would satisfy the following condition:

5

FB ≥ H +H R (3)

It was important to note that the operating bolt stress was relatively insensitive to

changes in prestress up to a certain point and that thereafter the two stresses were

essentially the same. In other words, the assembly stress in the bolts would have no

significant effect on the actual operating stress in the bolts.

General arrangement of the assemblage has been shown in Figure 3:

Figure 3: General arrangement of joining flange and bolt holes

Location of forces and bending moments have been illustrated in Figure 4 below:

Figure 4: Location of forces and bending moments at joining flange induced by internal

pressure

6

According to ASME BPV VIII-1-Appendix Y-9, the total cross-secional area of bolts

required for operating conditions has been defined by the following equation:

Ab' =

H +2 M P

( A−C )Sb

(4)

The Equation 4 provided for circular flange. For rectangular flange, using Figure 4 and

Equation 3 for minimum bolt load required at operating conditions:

W =FB=H2

+H c (5)

in which H has been defined by Equation 15 (Semester 1-progress report),i.e.,

H=PB Le . Also,

H c=2 M c

A−C (6)

Substituing Equation (6) into Equation (5):

W =H2

+2 M c

A−C=1

2A

b

'

Sb (7)

The expression Ab' Sb multiplying by

12

indicated the bolt load in each joining flange.

Rearranging Equation (7) would yield the total cross-secional area of bolts required for

operating conditions for rectangular flanges:

Ab' =

H +4 M c

( A−C )Sb

(8)

7

Due to symmetry, the balancing moment M c developed by H c would be equal to half

the moment M P developed by H which could be expressed as

M c=H2

×C2=

M p

2 (9)

From Figure 3,

C=B+2 (g+R ) (10)

In which g could be obtained from Equation 2, semester 1- progress report; R should be

sufficient to provide clearance for washer seating,i.e., dimension ‘D’ Appendix A, and

welding at flange connection to clamping shell defined in Clause 6:

R ≥D2

+G (11)

Dimension ‘G’ could be seen in Appendix D as a reference.

From Figure 3,

A=C+2 hc (12)

The minimum and maximum distance from bolt centre to edge of flange have be

designed in accordance with AS3990–Clause 9.6:

hcmin=1.5d (13)

hcmax=12 g but not exceed 150 mm (14)

8

For bolt grade 8.8 described in Appendix A, the minimum tensile strength, Fuf ,would be

800 MPa and the minimum yield strength, FYf ,would be 640 MPa. According to

AS3990–Table 9.5.2 (PP.58), the maximum permissible stress, F tf , subjected to tension

would be the smaller of:

0.60 FYf=0.60 ×640=384 MPa (15)

0.45 Fuf=0.45 ×800=360 MPa (16)

Hence, the maximum permissible stress of the bolt, F tf=Sb, would be 360 MPa.

The number of bolts required would satisfy the following condition:

n ≥Ab

'

Ab(17)

Refering to Figure 3 and Equation 6, the prying force could be reduced, and hence the

bolt load, by increasing the distance hc, minimising the distance R. It has also been

shown that by increasing the joining flange thickness to make it more rigid, the prying

effect would be reduced or eliminated. Under these conditions the bolt would just react

to an external just the way it would if the external load were applied axially

(Bickford,1990).

9

6.0 Design of Joining Flange Connection to Clamping Shell

The welded joint between the flange and the clamping shell has been designed in

accordance with AS1210, AS1554.1, and AS3990. There have been many types of

flange attachement specified by AS1210-Figure 3.21.3(PP.189). It has been suggested

by Dave Landwehr that full penetration butt weld would be employed for the design.

The advantages of this type were that there would be no limit in maximum calculation

pressure and temperatures (AS 1210, Clause 3.21.3.3),i.e., it could be still applicable

when the design pressure and temperature were needed to be improved, and no

calculations were neccessary as the maximum permissible stresses would be the

minimum value pertaining the components jointed (AS 3990-Clause 9.8.2). However,

for butt welds, the members to be connected had to fit perfectly when they were lined

up for welding and edge preparation was also required,i.e., chamfering. Normally, a

backup plate was also temporarily required to ensure full penetration and a sound weld.

Hence, this attachment method would require more skilled supervision and be costlier.

Various type of the butt welds could be seen in Appendix B as a reference. The typical

arrangement of full penetration welded joining flanges has been shown in Figure 5:

Figure 5: Full penetration welded-on joining flange

(AS 1210, pg.189, Figure 3.21.3 (c))

In which t n (or go) was the nominal clamping shell thickness. In such connection, the

joining flange was considered to be the equivalent of an integral structure and the clamp

shell was considered to act as a hub. However, this design provided for circular flanges.

Design for rectangular flanges could be refered to AS/NZS1554-Clause 3.2 in which the

joining flanges were attached to the clamping shell to form a T-joint. As specified by

this clause, weld size would be the thickness of the joining flanges, which was also

10

known as throat thickness. The effective length of the weld could be taken as the length

of the joining flange in which a continous full-size weld was achieved. The effective

area would be the product of the effective length and the design throat thickness. For

this type of joint, a small fillet weld of 6 mm size was also superimposed on each

welded face. Definitions of size of butt and fillet weld could be refered to Appendix C.

Weld preparations have been designed in accordance with AS1210-Figure 3.19.3.(D).

(c)(PP.170) which could be seen in Appendix D. Details of the full penetration butt

weld have been shown in Figure 6:

Figure 6: Full penetration butt weld – Details

11

7.0 References

Committee ME-001, Pressure Equipment. 2010. As 1210. Standard Australia Limited

Committee ME-001, Pressure Equipment. 2008. As 1548-Fine Grained, Weldable Steel

Plates for Pressure Equipment. Standards Australia

Committee ME/5, Cranes. 1993. As 3990-Mechanical Equipment-Steelwork. Standards

Asutralia (Standards Association of Australia)

Consultants, PDC. 2007. High Strength Bolts – Grade 8.8.

Engineers, The American Society of Mechanical. 2004. Rules for Construction of Pressure Vessels.

Bickford, John H. 1990. An Introduction To The Design And Behaviour Of Bolted Joints. USA: Marcel Dekker.

V.N.Vazirani, M.M.Ratwani. 1985. Steel Structures and Timber Structures: Analysis, Design and Details of Structures. Vol. 3. Delhi: Khanna.

Bickford, John H. 1990. An Introduction To The Design And Behaviour Of Bolted Joints. USA: Marcel Dekker.

V.N.Vazirani, M.M.Ratwani. 1985. Steel Structures and Timber Structures: Analysis, Design and Details of Structures. Vol. 3. Delhi: Khanna.

V.N.Vazirani, M.M.Ratwani. 1985. Steel Structures and Timber Structures: Analysis,

Design and Details of Structures. Vol. 3. Delhi: Khanna.

V.N.Vazirani, M.M.Ratwani. 1985. Steel Structures and Timber Structures: Analysis,

Design and Details of Structures. Vol. 3. Delhi: Khanna.

12

Appendix A – High Strength Bolts – Grade 8.8 (consultants, 2007)

Size A B C D E FX

(Min.)

Min.

Length

M12 18 20 8 28 4.6 32 24 25

M16 27 31 11 34 4.6 32 28 40

M20 32 37 14 39 4.6 38 32 40

M24 41 47 16 50 4.6 44 36 50

M30 50 58 20 60 4.6 57 42 75

M36 60 69 24 72 4.6 57 48 90

Note: All dimensions in millimetres.

13

Appendix B – Different Types Of Butt Weld (V.N.Vazirani,1985,p.g 71)

14

Appendix C – Butt And Fillet Weld Size Illustration

15

Appendix D - Standard and Recommended Weld Preparation Details (AS1210-

Figure 3.19.3(D).(c)(PP.170)

LEGENDS

α = 50o min.

S2 = 0 to 3 (mm)

g2 = 3 (mm) min.

Dimensions E, F and G have been designed based on the reccomended α of 50o, S2 of 3

mm, and g2 of 3 mm and defined by the following expressions:

E=t f −3

2

F=E × tan (500 ) (18)

G=E+F (19)

16

Tabulation of E and F corresponding with various commercial plate thicknesses has

been shown in table below:

Flange thickness, t f

(mm)E (mm) F (mm) G (mm)

14 6 7 13

16 7 8 15

18 8 9 17

20 9 11 20

22 10 12 22

25 11 14 25

28 13 15 28

30 14 17 31

32 15 18 33

36 17 20 37

40 19 22 41

45 21 25 46

50 24 28 52

55 26 31 57

17