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Draft 2, Section 5 – CasingMay 5, 2015

CEMA Bucket Elevator Book, Best Practices in Design1st Edition-Section 5, CASINGBucket Elevator CommitteeChair: Warren Knapp, SCC

Vice-Chair: Kris Gililland, KWS

ATTENTION: EDITORS / REVIEWERS, you must add your name and Draft number below if you are providing suggested edits and/or reviewing.

Contacts and ReferencesName Company Email AddressWarren Knapp, Chapter Owner Screw Conveyor Corp [email protected] Matheson Rexnord [email protected]

DRAFT / REVIEW* HISTORY

DRAFT's # (i.e. D-1, D-2, etc.) Submittal Name DateDraft 1 Warren Knapp, SCC 3/07/2014

Draft 2 Warren Knapp 6/13/2014

REVIEWER's # (i.e. R-1, R-2, etc.) Submittal Name DateREVIEW 1 Erik MathesonREVIEW 2

FINAL

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Chapter 5

CASING

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Figure 5.01 - XXXXX


INTRODUCTION

The elevator is usually enclosed in a steel casing, to provide a means of support and as a matter of safety and dust retention. The casing consists of boot section, inspection or service section, intermediate sections, head section and hood or bonnet. Casings can be single trunk casing or double trunk casing. The single trunk case are generally the industrial type operating at lower chain or belt speeds, while the double trunk is generally agricultural and belt type. They also operate at higher speeds. These are general classifications, the actual determination should be base on the diameter of the head pulley and elevator height. In most cases when the head pulley is larger than 36” a double trunk is more economical. And when the discharge height is over 100’ the added strength of the double trunk is desirable. Figure 5.01-xxxx is a graphic outline of these two different type of construction.

Figure 5.02 - XXXXX


DOUBLE TRUNK SINGLE TRUNK

Boot SectionElevator boot sections should be made of not less than 3/16" for elevators under 30' and 1/4" for elevators above 30'. In elevators, the boot section supports either part or all of the entire unit. Removable doors and side plates should be installed in boot sections, to make it easier to clean out the boot by hand, when and if required. In industries where products cannot be mixed or contaminated, the boots have to be cleaned out after each operation or run. In some cases, the entire sides of the casing are made removable for cleaning or pulley replacement.

Normally, the location of the point of inlet in a boot occurs between 4" and 6" for centrifugal types, and 20-26" for continuous types, above the centerline of the boot or shaft in its highest position. When using take-ups in the boot, and when handling materials that are mixed, say 1/4"

Figure 5.03 - Typical Boot Assembly


with 10% of lumps not exceeding 2", this point of inlet can be lowered to the centerline of the boot shaft without harm, but the capacity of the bucket may be slightly reduced, depending on the material handled. An allowance of at least 2” to 6" below the buckets, with the take-up in the lowest position, should be made for cleaning-out purposes.


The boot section generally contain the belt or chain take-up. The take-up can be screw type or counter-weight type. On belt elevators the take-up mechanism is external to the boot shell. On chain elevator the take-up mechanism can be external or internal.

Casing design is dependent on the structural conditions of the elevator, free standing, self supporting including drive or self supporting excluding drive. A casing can be made dust-tight, either by using a sealing medium, or continuously welding the comer angles to the plate. Figure YY shows details of dust-tight construction. These casings are regularly made with inspection cleanout doors. For free-standing elevators, structural considerations, such as strength of the sections and the size and number of anchor bolts to resist wind, often will dictate the narrow dimension of the casing and its composition.

Figure 5.04 - Boot Assembly For Internal Gravity Chain Take-Up

Figure 5.04-xxxxx


The service or inspection section is usually the first section of casing above the boot.This section has removable panels on the wide side (front) of the casing to allow for belt or chain installation. And smaller access doors on the narrow side of the casing to aid with bucket attachment to the belt or chain.

Figure 5.06 - Casing / Belt Accessories, Used on Double Trunk Elevators



Steel plates with comer angles provide a substantial support to the complete unit. Elevators are usually self-supporting up to 30', with some even up to, say, 80' above the boot. Above these heights, the casing should be structurally supported, and braced against the building or silo for heights over 30'.

In some cases, the head shaft supporting the complete chain and buckets is mounted on building steel, to take the load off the casing, which then acts simply as a cover, carrying only its own weight. Above 100-ft centers, the drive (motor and speed reducer) should be supported directly on the building steel, rather than on the elevator casing.

Figure 5.07 - Service Section Used for Single Trunk Elevators

Figure 5.08 - xxxxx


Head & Hood SectionElevator Head sections should be made of not less than 3/16" for elevators under 30' and 1/4" for elevators 30' to 100' and 3/8” or heavier above 100'.. In elevators the head section supports either part or all of the Head pulley, shaft, belt, buckets, bearings drive and belt tension of the unit. Removable doors or inspection panels should be installed in head section, to make it easier to inspect and service lagging and throat baffle. The hood or bonnet should be split aid in belt instillation and if necessary pulley replacement.

Normally, the point of discharge is located about 6” below the centerline of the head shaft, projected downward at 45° to 60°. An adjustable throat plate in the bottom of the discharge section is used to prevent materials from falling down the casing to the boot. When handling very fine and dry materials, the 6” vertical dimension should be 12”. The head section should be of dust tight construction which include a seal around the head shaft. Generally dust collection or pick points directly on the head section are a determinate to good discharge and should be located a short distance downstream of the head discharge flange.

High speed elevator heads require consideration of the material profile leaving the bucket.

Figure 5.09 - xxxxx

Figure 5.10 - xxxxx


Calculating the Casing ThicknessThe following is an example of the calculation required to design a self-supporting elevator casing.

The elevator legging is considered a light box section governed by thin compressive elements design for cold formed steel. The section we are going to consider is a box section 39" x 15" We will first consider a thickness of 10 Ga and no angle stiffeners. Prior to that loads must be determined.

LOADS

HP 150 P 39 Red 3968

BS 684 N 15 Base 1200

DH 188 pcf 5.5625 Pulley 1260

bwtft 7.68 cawt 3.19 Brgea 406

buwtea 4.82 wind 1.2 ShaftPF 130.9

n 2 PD 43 ShaftLG 6

Sp 10 Motor 2003 Rea 6000

T 1HP 33000

BS1.5

T 1 1.086104

Bwt DH bwtft

Bwt 1.444103

Buwt DH 12 buwtea n

Sp

Buwt 2.175103


Steel P12

DH 2 N12

DH 2 pcf 4 DH cawtN P( ) 4( ) PD 3( ) DH

10

12cawt wind

Steel 1.448104

Drive Motor Red Base

Drive 7.171103

ShaftWt ShaftPF ShaftLG

ShaftWt 785.4

LoadOnUpLeg T 1 Bwt Buwt Steel Drive2

ShaftWt2

Brgea

LoadOnUpLeg 3.334104

AngleLoad LoadOnUpLeg4

AngleLoad 8.335103

A 2 P .135( ) 2 N .135( )( )

A 14.58

t .135

I xt N2

63 P N( )

I x 668.25


f=maximum edge stress

I yt P2

6P 3 N( )

f y 33000

I y 2.875103

f b 0.6 f y

r xI xA

r x 6.77

f c f b

f c 1.98104

r yI yA

r y 14.042

1550

f b

11.015

w 1 P

w 1t

288.889

3250

f b

23.097


w 2 N

w 2t

111.111

4020

200089.89

b 18000

f c

1 1748w 1t

f c

t

b 1 7.345

b 28000

f c

1 1748w 2t

f c

t

b 2 6.817

b 3 b 1 0.10( )w 1t

60 t

b 3 4.255

b 4 b 2 0.10( )w 2t

60 t

b 4 6.127

L 2256

k 1b 3w 1

k 1 0.109


Lr x

333.233

k 2b 4w 2

k 2 0.408

Lr y

160.665

A e 2 b 1 b 2 t

QA eA

A e 3.824

Q 0.262

24200

Q f y260.129

F a 0.515Q f y

Q f y Lr x

47500

2

F a 770.663

F b 0.515Q f y

Q f y Lr y

47500

2

F b 3.6 103


P F a A

P 1.124104

P F b A

P 5.249104

P 1 10.5( ) 25 20 1020 25 10 5

20 35 10 15

20 35 10 5

20 45 10 15

20 45 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20 55 20 10

2055 20 10

2055 20 10

2045 20 10

20

P 1 5.46104

P 2 10.5( ) 25 10 520 35 10 15

20 35 10 5

20 45 10 15

20 45 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20 55 20 10

2055 20 10

2045 20 10

20

P 2 5.197104

P 3 10.5( ) 35 10 520 45 10 15

20 45 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20 45 20 10

20

P 3 4.856104

P 4 10.5( ) 45 20 1020 45 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20

P 4 4.41104

P 5 10.5( ) 45 20 1020 55 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20

P 5 3.938104

P 6 10.5( ) 55 20 1020 55 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20


P 6 3.465104

P 7 10.5( ) 55 20 1020 55 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20

P 7 2.888104

P 8 10.5( ) 55 20 1020 55 20 10

20 55 20 10

20 55 20 10

20

P 8 2.31104

P 9 10.5( ) 55 20 1020 55 20 10

20 55 20 10

20

P 9 1.732104

P 10 10.5( ) 55 20 1020 55 20 10

20

P 10 1.155104

P 11 10.5( ) 55 20 1020

P 11 5.775103

w 55

l 960


E 29000000

max 10

c

max w l4

8 E II

I w l4

8 E max

I 2.014104

P 1 10.5( ) 25 20 1020

P 1 2.625103

P 2 10.5( ) 25 10 520 35 10 15

20

P 2 3.413103

P 3 10.5( ) 35 10 520 45 10 15

20

P 3 4.463103

P 4 10.5( ) 45 20 1020

P 4 4.725103

P 5 10.5( ) 45 20 1020

P 5 4.725103


P 6 10.5( ) 55 20 1020

P 6 5.775103

P 7 10.5( ) 55 20 1020 55 20 10

20 55 20 10

20 55 20 10

20 55 20 10

20

P 7 2.888104

P 8 10.5( ) 55 20 1020 55 20 10

20 55 20 10

20 55 20 10

20

P 8 2.31104

P 9 10.5( ) 55 20 1020 55 20 10

20 55 20 10

20

P 9 1.732104

P 10 10.5( ) 55 20 1020 55 20 10

20

P 10 1.155104

P 11 10.5( ) 55 20 1020

P 11 5.775103


A 2 75 .1875( ) 2 23 2 .1875( ) .1875( )( ) 4 0.94

A 40.369

t .1875

I xt 232

63 75 23( ) 448.94

I x 4.549 103

I yt 752

675 3 23( ) 5123.82

I y 3.044104

f y 33000

f b 0.6 f y

f c f b

f c 1.98104

r xI xA

r x 10.615

r yI yA

r y 27.458


1550

f b

11.015

w 1 75

w 1t

400

3250

f b

23.097

4020

200089.89

w 2 23

w 2t

122.667

b 18000

f c

1 1748w 1t

f c

t

b 1 10.329

b 28000

f c

1 1748w 2t

f c

t

b 2 9.58

b 3 b 1 0.10( )w 1t

60 t

b 3 3.954


b 4 b 2 0.10( )w 2t

60 t

b 4 8.405

L 120

k 1b 3w 1

k 1 0.053

Lr x

11.305

L 120

k 2b 4w 2

k 2 0.365

Lr y

4.37

A e 2 b 2 b 3 t 4 .94

QA eA

A e 8.835

Q 0.219

24200

Q f y284.755

F a 0.515Q f y

Q f y Lr x

47500

2


F a 3.717103

F b 0.515Q f y

Q f y Lr y

47500

2

F b 3.719103

P F a A

P 1.5 105

P F b A

P 1.501105

with corner angle 3 x 3 x 1/4, area = 1.44

I= 1.2, s= .58, x or y = .84, r = .59

A 2 80 .135( ) 2 16 .135( ) .135( )( ) 4 1.44

A 27.943

t .135

I 7 1.3 1.4432.162

I 7 1.491103

I xt 132

63 66 13( ) 189.72

I x 992.048


I yt 662

666 3 13( ) 5964

I y 1.626104

f y 33000

f b 0.6 f y

f c f b

f c 1.98104

r xI xA

r x 5.958

r yI yA

r y 24.119

1550

f b

11.015

w 1 66

w 1t

488.889

3520

f b

25.016

4020

2000028.426

w 2 13


w 2t

96.296

b 18000

f c

1 1748w 1t

f c

t

b 1 7.48

b 28000

f c

1 1748w 2t

f c

t

b 2 6.685

b 3 b 1 0.10( )w 1t

60 t

b 3 1.69

b 4 b 2 0.10( )w 2t

60 t

b 4 6.195

L 120

k 1b 3w 1

k 1 0.026

Lr x

20.14


L 120

k 2b 4w 2

k 2 0.477

Lr y

4.975

A e 2 b 2 b 3 t 4 1.44

A e 8.021

QA eA

Q 0.287

24200

Q f y248.641

F a 0.515Q f y

Q f y Lr x

47500

2

F a 4.862103

F b 0.515Q f y

Q f y Lr y

47500

2

F b 4.878103


P F a A

P 1.359105

P F b A

P 1.363105

A 2 75 .1875( ) 2 23 2 .1875( ) .1875( )( ) 4 1.94

A 44.369

t .1875

I xt 232

63 75 23( ) 935

I x 5.035 103

I yt 752

675 3 23( ) 10583

I y 3.59104

f y 33000

f b 0.6 f y

f c f b

f c 1.98104

r xI xA


r x 10.652

r yI yA

r y 28.443

1550

f b

11.015

w 1 75

w 1t

400

3250

f b

23.097

4020

2000028.426

w 2 23

w 2t

122.667

b 18000

f c

1 1748w 1t

f c

t

b 1 10.329

b 28000

f c

1 1748w 2t

f c

t


b 2 9.58

b 3 b 1 0.10( )w 1t

60 t

b 3 3.954

b 4 b 2 0.10( )w 2t

60 t

b 4 8.405

L 120

k 1b 3w 1

k 1 0.053

Lr x

11.265

L 240

k 2b 4w 2

k 2 0.365

Lr y

8.438

A e 2 b 2 b 3 t 4 1.94


A e 12.835

QA eA

Q 0.289

24200

Q f y247.682

F a 0.515Q f y

Q f y Lr x

47500

2

F a 4.896103

F b 0.515Q f y

Q f y Lr y

47500

2

F b 4.914103

P F a A

P 2.172105

P F b A

P 2.18 105

A 2 75 .1875( ) 2 23 2 .1875( ) .1875( )( ) 4 2.86

A 48.049

t .1875


I xt 232

63 75 23( ) 1399.28

I x 5.499 103

I yt 752

675 3 23( ) 15603

I y 4.092104

f y 33000

f b 0.6 f y

f c f b

f c 1.98104

r xI xA

r x 10.698

r yI yA

r y 29.181

1550

f b

11.015

w 1 75

w 1t

400


3250

f b

23.097

4020

200089.89

w 2 23

w 2t

122.667

b 18000

f c

1 1748w 1t

f c

t

b 1 10.329

b 28000

f c

1 1748w 2t

f c

t

b 2 9.58

b 3 b 1 0.10( )w 1t

60 t

b 3 3.954

b 4 b 2 0.10( )w 2t

60 t

b 4 8.405

L 120


k 1b 3w 1

k 1 0.053

Lr x

11.217

L 240

k 2b 4w 2

k 2 0.365

Lr y

8.225

A e 2 b 2 b 3 t 4 2.86

A e 16.515

QA eA

Q 0.344

24200

Q f y227.226

F a 0.515Q f y

Q f y Lr x

47500

2


F a 5.813103

F b 0.515Q f y

Q f y Lr y

47500

2

F b 5.838103

P F a A

P 2.793105

P F b A

P 2.805105

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