TÍNH BỀN CƠ KHÍ CHO THÂN VÀ ĐÁY,NẮP THIẾT BỊ THEO AD2000 CODE (DIN)

TÍNH BỀN CƠ KHÍ CHO THÂN VÀ ĐÁY,NẮP THIẾT BỊ THEO TIÊU CHUẨN CHLB ĐỨC AD2000 CODE AD2000 code là bộ qui chuẩn tính toán kỹ thuật của hiệp hội kỹ sư Đức dựa trên những tiêu chuẩn DIN,DINISO để tính toán cơ khí cho thiết bị hóa học (đáy nắp, thân thiết bị)ContentI. IntroduceII. Calculation Method1. Parameter calculation2. Cylindrical Shell 2.1 internal pressure 2.2 external pressure3. End and headII. Example

TRƯỜNG ĐẠI HỌC BÁCH KHOA TP HỒ CHÍ MINH

KHOA KỸ THUẬT HÓA HỌC

BỘ MÔN QUÁ TRÌNH & THIẾT BỊ MÔN THIẾT KẾ CƠ KHÍ THIẾT BỊ HÓA

TIỂU LUẬN

ĐỀ TÀI: TÍNH BỀN CƠ KHÍ CHO THÂN VÀ ĐÁY,NẮP THIẾT BỊ

THEO TIÊU CHUẨN CHLB ĐỨC

AD2000 CODENhóm 11:

GVHD: Nguyễn Hữu Hiếu

Trương Thanh Tiến 61203843 Huỳnh Quang Tiên 61203793

 The AD 2000 Code of

practice for pressure vessels

is drawn up by the German

Pressure Vessel Association.

II Calculation Method

1 Parameter calculation (AD2000-B0)

 Calculate the length of the shell

 Symbols and units

a lever arm mm

b width mm

c1 allowance for minus thickness tolerance mm

c2 wear allowance mm

d diameter of an opening, flange, screw mm

da outside diameter of a tube, nozzle, flange mm

di inside diameter of a tube, nozzle, flange mm

dt pitch diameter mm

dD average gasket diameter mm

e wide side of rectangular or elliptical plate mm

f narrow side of rectangular or elliptical plate mm

p design pressure bar

Ps maximum allowable pressure bar

Pt test pressure bar

r generally radius, e.g transition radius mm

s required wall thickness includin allowances mm

se actual wall thickness mm

v factor indicative of the use of the allowable design stress in joints or factor allowing for weakening

x decay-length zone mm

A area mm2

Symbols and units

Calculate the length of the shell

- L = H (shells have fit flange and connected with two flat ends)

- L = H + h/3 (shells connected with two eliptical or spherical ends)

L = l (b < 0,1L)

L = l-b (b ≥ 0,1L)

(shells have stiffener ring)

I planar moment of inertia mm4

K design strength value at design

S safety factor at design pressure

S´ safety factor at test pressure

SD leak safety factor

SK safety factor against elastic cupping at design pressure

S'K safety factor against elastic cupping at test pressure

SL safety factor on the permissible number of load cycles

• If a pressure-bearing wall is subject to pressure and vacuum at the same time, the design pressure is equal to the pressure difference.

- Tmax < 20 °C => T = 20 °C

- Tw­ < ­10o c => see AD 2000Merkblatt W 10

- For unheated walls: T = Tmmax

- For heated walls:

- In the case of brick linings,

it shall be determined by calculation

in the case of protected walls, the maximum working temperature plus 20 K

in the case of directly heated walls, the maximum working temperature plus 50 K

Design temperature

Design strength value

• design temperature : W series of the AD2000

• time-dependent design : AD2000-S 6

Safety factor

• The safety factors shall be taken from Tables 2 and 3 unless differing or additional data are given in the individual AD 2000-Merkblätter

• For austenitic steels and non-ferrous metals,minus

tolerances are not taken into account only when there

is static loading due to internal pressure

• For ferritic steels => c1 = 0

• For austenitic steels and non-ferrous metals => c2 = 0

• For ferritic steels => c2 = 1 mm

The permissible design stress level

in joints

- v = 1

- For brazed joints

- Lapped soldered circumferential joints between copper

parts are acceptable provided the lapping is at least 10 se up

to a wall thickness of 6 mm and up to Da, p ≤ 2500 mm bar v= 0,8

- For soldered joints between copper plates with a continuous

strap of width ≥ 12 Se on both sides of the joint, Se ≤ 4 mm

and an allowable Pw ≤ 2 bar

Minimum wall thickness

• The minimum wall thicknesses specified in the B series

of AD 2000-Merkblatter are nominal wall thicknesses

2.1 Cylindrical shells subjected to

Calculation steps

Determine minimum

thickness S’ ?

Choose actual thickness Se ?

Check permissible

stress ?

Calculate stiffener

ring ?Choose material ?

 Step 1: choose material

• Design temperature T

• Design pressure P

• External diameter Da

• Design strength value K

• Wall thickness tolerances C1 (mm)

• Wear allowance C2 (mm)

• Weld joints safety factor v

• Safety factor

- The safety factors for plastic deformation are given in Table 1

- The safety factor for elastic buckling, irrespective of the

 Step 2: Calculate minimum thickness S’ ?

• Ceamless, welded or brazed cylindrical shells

Design calculations for elastic buckling

n: the number of buckling ridges

D n

l S c c

=

− −

3 2

 − − 

Design calculations for plastic deformed

e

a a

a e

K P

Where the circumference is oval:

Where the circumference has a flattened portion:

For tubes:

D: governed by the manufacturing conditions

max min max min

Shell length against elastic

buckling after reinforcement

EI p

2.2 Cylindrical and spherical shells

subjected to internal overpressure

(AD2000-B1)

Calculation steps

Minimum wall

thickness S’ ?

Choose actual thickness Se ?

Required wall thickness S ?

Check permissible

stress ?Choose material ?

Step 1: Choose material

• Design strength value K (N/mm2 )

Step 2: Minimum wall thickness S’ (nominal wall thicknesses)

• Seamless, welded or brazed cylindrical shells

Step 4: Required thickness S

+

 1,2<Da /Di ≤1,5 : Cylindrical

(Da/Di>1,35 : S= 1,4 (over 200 oC))

Step 5: Check permissible stress

 Wall with no considerable temperature difference

Stress intensity on the inner σ i and outer σ a surface :

Wall with considerable temperature difference

Thermal stresses :

Maximum stress on the inner σi and outer σa surface

,

3 End and head

Domed ends objected to internal or external pressure

(AD2000-B3)

• The length of the cylindrical part is: a) For torispherical ends : h1 ≥ 3,5s b) For semi-ellipsoidal ends : h1 ≥ 3s

Calculate steps

Calculate minimum

thickness S’ ?

Calculate actual thickness

S ?

Check permissible pressure ?

P ≤ [p]

Choose material ?

Step 1: choose material

Step 2 : Minimum wall thickness S’

•Domed ends : s=2mm

•Domed ends made of aluminium and its alloy: s=3mm

•For castings the minimum wall thickness, among other parameter, is determined by the manufacturing technique

Step 3: Calculation required wall thickness

•K : design strength value at design temperature

•safety factor at design pressure

+

1 2

40.K.v ( a 1).

•Thickness of knuckle and hemisphere connection :

• S : safety factor at design pressure

•β : the design factors B shall be taken form Fig 7 and Fig 8

.

a kah

K

v S

Step 4 :Check permissible pressure

 Internal pressure :

The maximum pressure allowed of torisphecal ends:

The maximum pressure allowed of knuckle and hemisphere connection :

e

K

S p

a

K v s c c P

D p β

− −

=

Safety factor:

•The safe factor Sk against elastic buckling of the end under external pressure :

•if PT>1,3p:

0, 002 3

K

S ≥ Sk

s c c

E p

3.2 Conical shells subjected to internal and external overpressure

 Safety factor

 Safety factor S shall be taken from tables 2 and 3 of

AD 2000-Merkblatt B 0.

 In case of stressing by external overpressure the safety factor

according to 4.1 shall be increased by 20 % The safety factors for grey cast iron remain unchanged

 The safety factors to prevent elastic and plastic inward buckling

of the cone shall be taken from AD 2000-Merkblatt B 6

Calculate minimum thickness S’

•Conical shell is : s’=2mm

•Conical shell made of aluminium and its alloys is s’=3mm

•Exception to the requirement of 9.1 and 9.2 are possible as specified in 10.2 of AD 2000- merkblatt B0

Calculation required thickness s

•Tapler length (inside the tapler area ) :

a l

a l

x D s c c

D s c c x

• Required wall thickness outside of taper area :

•Requires wall thickness inside of taper ares :

20 .

k g

D p

K

v p S

K v

=

Shallow convergent conical shells ( > 70°)

'For shallow conical shells having a knuckle radius r> 0,01 Da1, the required wall thickness is:

III Example

Thank you for your attention