Cm43A Adjustable Metal Scaffold

7/27/2019 Cm43A Adjustable Metal Scaffold

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Construction Manual No. 43A

(See Manual No. 43A-M for the Metric Version)

Adjustable Metal Scaffold

Rewritten July 2004By: D. Sullivan / A. Haynes

COPYRIGHT 2004BY

CHICAGO BRIDGE AND IRON CO.

All rights reserved

The information contained herein is proprietary and confidential. All documents remain theproperty of Chicago Bridge and Iron Company and are to be used only in connection with theperformance of work by Chicago Bridge and Iron Company. This manual, and anyinformation contained herein, shall not be disclosed to any person other than employees ofChicago Bridge and Iron Company or one of its affiliated companies. Reproduction in wholeor part is expressly forbidden.


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Manual No. 43A CB&I Use Only - ConfidentialAdjustable Metal Scaffold (AMS) Part TOC

Table of Contents Page 1

Original By: RDS Date: July 04 Rev: By: Date:

1.0 Introduction (A Formal General Description of the AMS)

1.1 History1.2 ClosingFigure 1-1 Hollow Polygon Made of 30 Trapezoidal PlatformsFigure 1-2 Minimum Annular SpaceFigure 1-3 Overall Bracket Length

2.0 Project Manager Decisions

2.1 Regulations Comparisons2.2 Cost Comparisons2.2.1 Labor Cost Comparisons2.2.2 Equipment Cost Comparisons2.3 Environmental Comparisons2.3.1 Wind Protection2.4 Shipping Cubage ComparisonsTable 2-1 Regulation ComparisonsTable 2-2 Sample Equipment CostsTable 2-3 Shipping Cubage for B&B Scaffold vs. AMSFigure 2-1 Two Shipping Racks Inside a 40 Flat Rack

3.0 Glossary & Figures

3.1 Glossary3.2 Figures of AMS PartsFigure 3-1 Plan View of a Complete Scaffold With (10) 3-Hinged Scaffold

SectionsFigure 3-2 3-Hinged Scaffold Section Set at the 12 Degree MinimumFigure 3-3 2-Hinged Scaffold Section Set at the 12 Degree MinimumFigure 3-4 Side View of AMS on Inside TankFigure 3-5 Side View of AMS on Outside Tank

Figure 3-6 Spacer and Tie DownFigure 3-7 Make-Up Section (Regular & Short)Figure 3-8 Trap Door Ladder AssemblyFigure 3-9 Lifting AssemblyFigure 3-10 Lifting BridleFigure 3-11 AMS Raising TrolleyFigure 3-12 Dual Handrail Post Support


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3.0 Glossary & Figures (continued)

Figure 3-13 Gate Strap AssemblyFigure 3-14 Long Handrail AssemblyFigure 3-15 Short Handrail AssemblyFigure 3-16 Make-up Handrail AssemblyFigure 3-17 End Gate Handrail AssemblyFigure 3-18 Shipping Rack AssemblyFigure 3-19 Crane Method Used For Jumping ScaffoldFigure 3-20A Trolley Method Used For Jumping ScaffoldFigure 3-20B Trolley Method Used For Jumping Scaffold

4.0 Erection Procedure

4.0.1 Preliminary4.0.2 Shell Attachments (Bracket Straps)4.1 Installation4.2 Splices Between Scaffold Sections4.2.1 Splice Between Scaffold Sections Without a Make-up Section4.2.2 Splice Between Scaffold Sections With a Make-up Section4.3 General for Jumping an AMS Section4.4 Jumping Methods (The Trolley Method and The Crane Method)

4.5 Jumping the First Section4.5.1 Preparations For Jumping4.5.2 Lifting the Section Out of the Lower Straps:4.5.3 Bracket Strap Clean-Up While on The Suspended Scaffold Section4.5.4 Stabbing the Bracket Into The Upper Straps4.5.5 Temporary Placement of the Make-up Section4.6 Jumping the Second Scaffold Section4.6.1 Preparations For Lifting4.6.2 Lifting the Section Out of the Lower Straps4.6.3 Bracket Strap Clean-Up While on The Suspended Scaffold Section4.6.4 Stabbing the Bracket Into The Upper Straps

4.6.5 Erect Tank Erection Ladders4.6.6 Placement of the Make-up Section or Connecting Section toSection

4.7 Jumping The Rest of The Scaffold Sections4.8 Jumping The AMS Scaffold Sections From Inside the Tank to

Outside The Tank4.8.1 Preliminary4.8.2 Shell Attachments (Bracket Straps)


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4.0 Erection Procedure (continued)

4.8.3 Installation of First Section4.8.4 Installation of Second SectionFigure 4-1 Shipping Rack AssemblyFigure 4-2 Scaffold Section HandlingFigure 4-3 Bracket Strap Lay OutFigure 4-4 Plan View of Chord LayoutFigure 4-5 Plan View of Arc LayoutFigure 4-6 Welding of Bracket StrapsFigure 4-7 Inside Scaffold Side View

Figure 4-8 Outside Scaffold Side ViewFigure 4-9 Completed Scaffold on 1

stRing

Figure 4-10 Splice Scaffold SectionsFigure 4-11 Splice Scaffold SectionsFigure 4-12 Side View Using 2L1-19-A Vert LadderFigure 4-13A Trolley Method For Scaffold Jumping (shown inside)Figure 4-13B Trolley Method For Scaffold Jumping (shown inside)Figure 4-14 Crane Method For Scaffold JumpingFigure 4-15 Scaffold with Make-up Pulled BackFigure 4-16 Prepare Scaffold Section For JumpingFigure 4-17 Side View of End Gate

Figure 4-18 Scaffold Section JumpingFigure 4-19 Scaffold Section Jumped to Upper StrapsFigure 4-20 Install Make-up Bracket in Upper StrapFigure 4-21 Second Scaffold Section To JumpFigure 4-22 Side View of End GateFigure 4-23 Trolley Method Scaffold Jumping (shown inside)Figure 4-24 Crane Method Scaffold JumpingFigure 4-25 Scaffold Section JumpingFigure 4-26 Jumped Second Scaffold SectionFigure 4-27 Complete Second Scaffold SectionFigure 4-28 Outside Bracket Strap Layout

Figure 4-29 Scaffold Section HandlingFigure 4-30 Scaffold Section Side ViewFigure 4-31 Scaffold Section Handling


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5.0 Quantity Calculation for Inside Tank Scaffold

Table 5-A AMS Quantity CalculationTable 5-B AMS Quantity Calculation With No Make-upsChart 5-A Quantities of AMS Scaffold SectionsChart 5-B Quantities of AMS Scaffold Sections With No Make-ups

6.0 Quantity Calculation for Outside Tank Scaffold

Table 6-A AMS Quantity Calculation

Table 6-B AMS Quantity Calculation With No Make-upsChart 6-A Quantities of AMS Scaffold SectionsChart 6-B Quantities of AMS Scaffold Sections With No Make-ups

7.0 Example Layouts For Inside Tank Scaffold

7.1 Example to Determine AMS Quantities for 103-3 13/16 ID Tank7.2 Example to Determine AMS Quantities for 106-10 11/16 ID Tank7.3 Example to Determine AMS Quantities for 136-3 ID TankFigure 7-1 Layout Sequence for 103-3 13/16 ID TankFigure 7-2 Layout Sequence for 106-10 11/16 ID Tank

Figure 7-3 Layout Sequence for 136-3 ID Tank

8.0 Example Layouts For Outside Tank Scaffold

8.1 Example to Determine AMS Quantities for 96-2 OD Tank8.1 Example to Determine AMS Quantities for 99-10 OD Tank8.3 Example to Determine AMS Quantities for 129-0 OD TankFigure 8-1 Layout Sequence for 96-2 1/2 OD TankFigure 8-2 Layout Sequence for 99-10 OD TankFigure 8-3 Layout Sequence for 129-0 OD Tank

9.0 Tool List Quantities & Weights

9.1 Tool List Quantity & Weight TableTable 9-1 Tool List Quantity & Weight


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10.0 Jobsite Photographs

10.1 Testing The Hinges10.2 Testing The Platform10.3 Scaffold Staged on Ground10.4 Scaffold Outside and Inside Hinges10.5 Scaffold Swinging Hinge Plates10.6 Dual Handrail Post Support at Rigid Handrail10.7 Spacer Installation10.8 Scaffold Jumping

10.9 Lifting D-Rings10.10 3-Hinged Scaffold Section Rigged for JumpingFigure 10-1 Scaffold Hinge Load TestFigure 10-2 Scaffold Platform Load TestFigure 10-3 Scaffold Staged on GroundFigure 10-4 Inside Adjustable Hinge & Outside HingeFigure 10-5 Splice Between Scaffold SectionsFigure 10-6 Dual Handrail PostsFigure 10-7 Spacer InstallationFigure 10-8 Jumping a 3-Hinged Scaffold SectionFigure 10-9 Scaffold Section Lifting D-Rings

Figure 10-10 Jumping a 3-Hinged Scaffold Section


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Manual No. 43A CB&I Use Only - ConfidentialAdjustable Metal Scaffold (AMS) Part 1

Introduction Page 1


1.0 Introduction

In general terms scaffolding is used to obtain temporary access to work areas. Therequirement of a good scaffold is that it provides safe and easy access to the work,complies with government regulations, and is easily erected and moved.

The specific scaffold that is used for building tanks is conveniently referred to as theTank Builders Scaffold, and for its design and use, CB&I uses those rules establishedby the U.S. Department of Labor, Occupational Safety & Health Administration (OSHA).

OSHAs definition of a Tank builders' scaffold is:

A supported scaffold consisting of a platform resting on brackets that are eitherdirectly attached to a cylindrical tank or attached to devices that are attached tosuch a tank.

Such scaffolds have been developed by CB&I. For tank building CB&I uses basically (3)three scaffolding methods:

1. Board and Bracket (B&B) Scaffold: The B&B scaffold is the most common type ofthe Tank builders scaffold. The use of this type scaffold is covered in RBS 155-6-9-2 and other Construction Manuals like Manual 13 or 17.

2. Wind-girder Scaffold: The Wind-girder Scaffold uses the tanks permanent wind-girder as a scaffold during tank erection. The use of the Wind-girder Scaffold isexplained in the second and third parts of Construction Manual 43.

3. Adjustable Metal Scaffold (AMS): The AMS is explained here in this ConstructionManual and the fabrication details of the AMS are shown in the 2L33 series of CB&Istandard drawings.

A Formal General Description of the Adjustable Metal Scaffold (AMS) is:

The AMS is a 30 wide scaffold platform resting and secured on standard tankbuilder brackets. The AMS is made up of at least (30) thirty trapezoidal platformsthat when placed end-to-end form a 30 wide platform with the shape of a hollowpolygon. This hollow polygon has inside and outside vertices and at thesevertices are hinges. Unless there is a make-up used, the distance betweenadjacent outside hinges is fixed at 10- 4 . Using sliding plates, the distancebetween adjacent inside hinges changes with the addition of trapezoidalplatforms. Rotation at the hinges allows the addition of platforms. The distance


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Introduction Page 2


from the hollow polygons center to the inside hinge is the inside radius, andfrom the center to the outside hinge is the outside radius. Adding additionalplatforms allows the AMS to inscribe any cylindrical tank with a diameter greaterthan 100, or to circumscribe any cylindrical tank with a diameter greater than92.75. See Figure 1-1.

A less formal way to understand the AMS is to compare the AMS to a carnival snakewith its ability to flex at each joint and curve sideways around a cylinder without saggingdownward. Sometimes the AMSs slang name is the Serpent.

The AMS can be used on the inside shell of any tank with an inside diameter equal to

or over 100-0.

The AMS can be used on the outside shell of any tank with an outside diameter equalto or over 92-9.

Figure 1-1Hollow Polygon Made of 30 Trapezoidal Platforms


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Introduction Page 3


Not including scaffold brackets, the minimum annular space that the AMS can fit into is37 . See Figure 1-2.

Figure 1-2Minimum Annular Space

When including scaffold brackets, the minimum annular space that the AMS can fit intois 41 . This is due to the overall length of the bracket. See Figure 1-3.

Figure 1-3Overall Bracket Length


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Introduction Page 4


1.1 HistoryBeginning in 1973 there was an effort by CB&I employees J.E. Vaughn fromConstruction Services-Houston and W.B. Dixon from New Castle, Delaware to developa re-useable metal scaffold for tank erection. The research was done, opinions made,and after many trials the company eventually applied for a U.S. patent.

The very first drawings of the scaffold carried the name Dixon Scaffold but duringpatent application the name was changed to Adjustable Metal Scaffold. The scaffoldis still today nicknamed the Dixon Scaffold, but its official name is the AdjustableMetal Scaffold.

In 1975 CB&I was granted Patent Number 3,908,793. The AMS design has notchanged much over the years, but renewed interest has led to certain improvements.Some of those few improvements were to:

1. Change to current material specifications.

2. Improve the durability of the hinges. It is important to note that hinges of all AMSassemblies must be fabricated to the current drawings.

3. Add a two-hinged scaffold section as a standard assembly. The original design onlyhad a three-hinged scaffold section.

4. Reduce the size of the make-up pieces and remove the make-up piece hinge. With

the addition of the two-hinged scaffold section, the make-up pieces were madesmaller and easier to handle. Note that make-up pieces are not always needed.

5. Provide rigging points on the hinges and remove any other lifting holes.

6. Provide another set of Lifting D-rings for the 2L33-16-A Lifting Assemblies that areused during the jumping of the AMS on the outside of the tank shell.

7. Add the option to use a rigid handrail.

8. Develop a Shipping Rack to hold at least (8) three-hinged scaffold sections.

1.2 ClosingThis manual deals only with the use of the Adjustable Metal Scaffold. When the AMS isused while erecting a tank it is expected that the tank erector will be a competentperson and that person will have the knowledge necessary to safely complete the tankerection. That competent person will provide all training necessary for the successfuluse of the AMS. Also, that competent person will be aware of the rules governing theguying of the tank shell for wind protection, as addressed in Manual 13, part 3.9, and itis understood that the use of the AMS will not alter those rules in any way.


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Project Manager Decisions Page 1


2.0 Project Manager Decisions

Every job is different and all the factors to consider when determining which type ofTank Builders Scaffold to use cannot be determined only from information in a manual.

The Project Manager will have to make this decision using what is known about aspecific job and using the guideline information presented in this part of the manual.

It has been the consensus that, when all other factors are equal and a tank is to be builtwith a permanent wind-girder that is wide enough to use as a scaffold, the Wind-girderScaffold method should be the first choice for the Tank Builders Scaffold.

The other two scaffold choices are the Board & Bracket (B&B) scaffold method and theAdjustable Metal Scaffold (AMS) method. Whether to use the B&B scaffold method orthe AMS method is the Project Managers choice.

2.1 Regulations Comparisons

The Tank Builders Board and Bracket (B&B) Scaffold is very prevalent and its use isexplained in Red Book Standard 155-6-9-2.

For quick reference the government regulations for Tank Builders Scaffold are listed in

Table 2-1. These regulations were written mostly with the thoughts of using a B&Bscaffold and some of the items in the regulations may not be applicable to the AMSeven though the AMS meets the definition of a Tank builders scaffold.

The right hand side of the table has comments on how the regulations apply to theAMS.

Table 2-1 Regulation Comparisons

The Tank Builders Board and Bracket(B&B) Scaffold Requirements

Adjustable Metal Scaffold (AMS)Applicability

1. Maximum spacing of 10'-6" betweenscaffold brackets and between handrailpost.

The spacing will vary but it shouldnever be over 10-5 1/2.

2. The work area below the scaffold must bebarricaded 6 feet from the shell on thescaffold side and "Danger - OverheadWork" signs must be posted at the tankaccess areas.

There are toe boards so a physicalbarricade is not needed but thesigns are still valid.


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Table 2-1 Regulation Comparisons (continued)The Tank Builders Board and Bracket

(B&B) Scaffold RequirementsAdjustable Metal Scaffold (AMS)

Applicability

3. Small tools and equipment must be kept insecured tool containers.

This is required but again there aretoe boards so risk is reduced.

4. CB&I Safety Rules require that a thirdhand-line be installed on all two boardinside scaffolds, and on outside scaffoldswhen gaps between the shell and plank aregreater than 12".

The third hand-line is not neededbecause the gaps between theAMS and the shell would never bemore than 12.

5. No more than two people are allowed onone board and no more than three peoplein one span at the same time.

There are no boards but thequantity of people in one spanwould remain the same.

6. All planking must be secured frommovement or overlapped.

There will be no movement andoverlapping is not an issue.

7. All hand-lines must be taut and they mustbe supported a minimum of 42" above theboard surface. California requires 45"minimum. Taut is defined as three inchesof deflection under hand pressure at mid-span.

This will still apply unless theoption to use a rigid handrail isused; the rigid handrail will easilymeet the taut definition.

8. Special ladders such as hook ladders andthe AGW access ladders must be designedto provide a first step no more than 24"above the boards.

This will still be the rule.

9. Temporary or permanent ladders used forscaffold access must have a provision forrest at 35 foot intervals or ladder climbingfall protection must be used. The provisionfor rest may be a trap door, a trap door and2 scaffold boards, or 2 scaffold boardsadjacent to the ladder. In all cases, a

double hand-line with all (4) cable endsindependently tied to the shell is required.Check your local Safety Supervisor forcurrent models of standard ladder climbingfall protection. Retractable Lifeline systems(sometimes called Yo-yo's) may be usedwith Safety Department approval of theequipment.

This will still apply, but there is acaged rest platform that hangs 6under the AMS that people standon just after or prior to goingthrough the trap door. For the AMSthis is the 2L33-13-A Trap DoorLadder Assembly.


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Table 2-1 Regulation Comparisons (continued)The Tank Builders Board and Bracket

(B&B) Scaffold RequirementsAdjustable Metal Scaffold (AMS)

Applicability

10. Training Requirements - Training isrequired for employees who work onscaffolds as well as those who build anddismantle scaffolds. The Steel PlateFabricators Association booklet titled TankBuilders Scaffold Guideline is intended foruse in training employees.

All the rules in the guideline thatcan apply will apply.

11. California Requirements The state ofCalifornia Code of Regulations, Title 8,Section 1645 (d) (6) requires that scaffoldplatforms on tanks larger than 40 indiameter be at least 30 wide.

This requirement is satisfied whenusing the AMS.


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2.2 Cost Comparisons

The other comparison that the Contract Supervisor must make is the cost.

2.2.1 Labor Cost Comparisons

A comparison study made by the CCT Department in February 1977 reported thefollowing:

o The B&B scaffold method spends an average of 0.38 man-hours/diameter (ft)/ring.

o The AMS scaffold method spends an average of 0.23 man-hours/diameter (ft)/ring.

An example would be that for a (6) six-ring 150 diameter tank, 342 scaffolding man-hours would be spent using the B&B scaffold method, or 207 man-hours would bespent using the AMS method.

The scaffold man-hours for the AMS method are 61% of the B&B scaffold method.

A more complete review may realize even a greater savings since the AMS raises three

brackets at once.

2.2.2 Equipment Cost Comparisons

The AMS also acts as a suspended scaffold. After an AMS section is removed from thebracket straps, the AMS is lowered below the straps and the employee, tied off to anindependent safety line, rides on the AMS section to remove the bracket strap from theshell. While the AMS section is being jumped and acting as a suspended scaffold, therules governing its use will be per Red Book Standard 155-6-9-4 Suspension ScaffoldSafety.

The standard plugging up buggy (2L24-1) would not be needed when using the AMS.

The following Table 2-2 is a sample equipment cost comparison between the AMS andthe B&B scaffold methods.


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Table 2-2 Sample Equipment Costs

Sample Scaffold Cost Comparison for 6 Ring 159-8 Diameter Tank; Scaffold Inside

Equipment B&B Method AMS Method

ItemLife

(jobs)Cost/ea

$Quantity

Cost/job$

QuantityCost/job

$

Std. Bracket 20 34.00 51 86.70 48 81.60

Key Channel* 30 30.00 49 49.00

Bull Pin* 10 3.75 98 36.75

Bracket Strap 1 0.76 369 280.44 144 109.44Handrail Post 10 35.00 49 171.50 48 168.00

Hand-line, 3/8 x 100' 1 51.93 6 311.58 6 311.58

12 Boards 6 26.18 98 427.61

J Hooks or Binders* 5 2.00 49 19.60

Plug Up Buggy 30 800.00 1 26.67

Scaffold trap door 30 150.00 2 10.00

AMS 3-hinged Section 30 390.00 14 182.00

AMS 3-hinged trap-door section w/ladder 30 390.00 2 26.00

AMS 3-hinged make-up 30 200.00AMS Trap Door Ladder Assembly 30 100.00 2 6.66

AMS Trolley 30 200.00 3 20.00

Total perjob=

$1420 $905

Notes:

1. * J hooks are probably replaced by binders but cost is based on the j-hook system assuming that the j hooksystem material costs are similar to the binder system costs

2. Costs are based on the 1998 CB&I master tool list3. A job is equal to the use during the erection of one tank

2.3 Environmental Comparisons

2.3.1 Wind Protection

o The B&B scaffold offers wind protection up to 40 mph.

o The AMS offers wind protection up to 90 mph.


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2.4 Shipping Cubage Comparisons

The Adjustable Metal Scaffold (AMS) 3-hinged and 2-hinged sections ship in the 2L33-22-A Shipping Rack.

Each Shipping Rack is designed to hold (8) scaffold sections and two Shipping Rackswill fit in the SEA Container known as the 40 Flat Rack. The cubage of each ShippingRack is 613 cf. See Figure 2-1.

Figure 2-1Two Shipping Racks Inside a 40 Flat Rack


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To compare the shipping cubage of the B&B scaffold to the AMS use Table 2-3

Table 2-3 Shipping Cubage for B&B Scaffold vs. AMS

Sample Scaffold Weight and Cubage Comparison for 6 Ring 159-8 Diameter Tank;Scaffold Inside

Equipment BB Method AMS Method

ItemWeight/

eaCube/ea Quantity

Weight/job

Cube/job QuantityWeight/

jobCube/job

Std. Bracket 32 2 51 1632 102 48 1536 96

Key Channel 20 0.67 49 980 33

Bull Pin 1 0.010 98 98 1

Bracket Strap 1 0.03 369 369 11 96 96 2.9

Handrail Post 11 0.12 49 539 5.9 48 528 5.8

Hand-line, 3/8 x 100' 40 4 6 240 24 6 240 24

12 Boards 80 2 98 7840 196

J Hooks or Binders* 1 0.15 49 49 7.4

Plug Up Buggy 1000 95 1 1000 95

Scaffold trap door 57 16 2 114 32AMS Shipping Rack 3447 613 2 6894 1226

AMS 3-hinged Section 928 73 14 12992 W/Rack

AMS 3-hinged trap-door sec 933 73 2 1866 W/Rack

AMS regular make-up 92 8 W/Rack

AMS Trap Door Ladder Assy. 140 56 2 280 112

AMS Trolley 96 8.5 3 288 25.5

20% Allowance for Gaps 102 298

Totalper job=

12861 609 24720 1792

Notes: LBS. CF LBS. CF

1. * J hooks are probably replaced by binders but cubage is based on the j-hook systemassuming that the j hook system volume is similar

2. One truck platform or chassis has probably 1800 CF available


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Glossary and Figures Page 1


3.0 Glossary & Figures

The following are definitions of the terms used in this manual and figures showing theparts of the AMS.

3.1 Glossary

AF The angle factor found in Chart 5-B. Used to determine the chorddimension BC.

6AF The angle factor found in Chart 5-B. Used to determine the chord

dimension 6BC.

ARF The angle factor found in Chart 6-B. Used to determine the arc dimensionBA.

BC The chord dimension used to lay out bracket straps on the inside of thetank shell.

6BC The chord dimension used to lay out every 7th

bracket strap on the insideof the tank shell. Represents the skipping of the 6 chords between the 1

st

and 7th

strap.

BMC The chord dimension used to lay out the bracket strap on the inside of thetank shell that supports the make-up section.

BA The arc dimension used to lay out bracket straps on the outside of the tankshell.

BMA The arc dimension used to lay out the bracket strap on the outside of thetank shell that supports the make-up section.

GAP The open space between a 3-hinged or 2-hinged scaffold sections that

must be bridged by the make-up section.

H2 A term used to represent the 2-hinged scaffold section (standard drawingmark 2L33-3-A). This section has one whole platform in the middle andtwo half platforms at each end.


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3.1 Glossary (continued)

H3 The term used to represent the 3-hinged scaffold section (standarddrawing mark 2L33-1-A or 2L33-2-A). This section has two whole platformsin the middle and two half platforms at each end.

ID The tank shell inside diameter.

IHC The distance between two adjacent inside hinge assemblies. These hingespivot and slide.

LayoutSequence

The term used to represent how many and in what order the 3-hinged, 2-hinged, and make-up sections should be installed on the tank shell.Examples are given in parts 7 & 8.

M The term for the make-up section that is used to bridge the GAP.

N The number of AMS platforms in an AMS ring.

OD The tank shell outside diameter.

OHR The horizontal radius from the center of an AMS ring to the center of the

pin in the outside hinge assembly.

TBIR The inside radius of the tanks 1st

shell ring. Expressed in inches whenused in Calculation Tables 5-A and 5-B.

TBOR The outside radius of the tanks 1st

shell ring . Expressed in inches whenused in Calculation Tables 6-A and 6-B.

TTIR The inside radius of the tanks top shell ring. Expressed in inches whenused in Calculation Tables 5-A and 5-B.

TTOR The outside radius of the tanks top shell ring. Expressed in inches whenused in Calculation Tables 6-A and 6-B.

X The horizontal radial distance from the surface of the shell ring to thecenter of the pin in the outside hinge assembly. If there are NO make-upsto be used, the dimension X is found in Calculation Table 5-B or 6-B.


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3.2 Figures of AMS Parts

Figure 3-1Plan View of a Complete Scaffold

With (10) 3-Hinged Scaffold Sections


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3.2 Figures of AMS Parts (continued)

Figure 3-23-Hinged Scaffold Section Set at the 12 Degree Minimum

Figure 3-32-Hinged Scaffold Section Set at the 12 Degree Minimum


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Figure 3-4Side View of AMS on Inside Tank

Figure 3-5Side View of AMS on Outside Tank


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Figure 3-6Spacer and Tie Down

Figure 3-7Make-Up Section(Regular & Short)


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Figure 3-8


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Figure 3-9


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Figure 3-10Lifting Bridle


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Figure 3-11


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Figure 3-12

Figure 3-13


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Figure 3-14

Figure 3-15


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Figure 3-16

Figure 3-17


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Figure 3-18


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Figure 3-19Crane Method

Used For Jumping Scaffold


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Figure 3-20ATrolley Method

Used For Jumping Scaffold


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Figure 3-20BTrolley Method

Used For Jumping Scaffold(View from Figure 3-20A)


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Erection Procedure Page 1


4.0 Erection Procedure

4.0.1 Preliminary

a) Before beginning the layout be sure to complete the applicable Calculation Tables.The Tables to complete are either 5-A or 5-B in part 5, or 6-A or 6-B in part 6.

b) Make a note of the dimension IHC.

c) For inside tank scaffold, record the chord dimensions 6BC, BC, and BMC.

d) For outside tank scaffold, record the arc dimensions BA and BMA.

e) Make a sketch of the layout sequence. Examples of Layout Sequences can befound in Part 7 or 8 of this manual. CCT can provide this sketch if desired.

f) The scaffold sections should arrive at the jobsite in a 2L33-22-A Shipping Rack.One shipping rack will hold 8 sections. The rack should be lifted from the truck andhandled using the rigging provided with the rack. The lifting points are shown inFigure 4-1.

Figure 4-1Shipping Rack Assembly


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g) Unload the scaffold sections from the shipping rack and place the scaffold sectionsaround the perimeter of the tank as per the layout sequence. One of the 3-hingedsections must have a trap door, and if the tank diameter is over 150, you will needtwo 3-hinged sections with a trap door. Space the sections with a trap door onopposite sides of the tank. The shipping rack holds 8 sections and the top section inthe rack should be a 3-hinged scaffold section with a trap door. A RED Stripe shouldbe painted on the 3-hinged scaffold section with the trap door.

h) Remember the outside hinge will be closest to the shell when the AMS is usedinside the tank and the inside adjustable hinge will be closest to the shell when the

AMS is used outside the tank. See Figures 4-7 and 4-8.

i) When placing the sections around the tank, rig the sections using the 5-point liftingbridle with the middle sling attached to one of the D-rings in the middle of the 3-hinged section. The other 4 slings will be attached to the lifting eyes on the outboardhinge lugs. If lifting a 2-hinged scaffold section, the middle sling of the 5-point liftingbridle is not used. See Figure 4-2.

Figure 4-2Scaffold Section Handling


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j) After the sections are placed around the perimeter of the tank, the adjustable insidehinges with the sliding plates can be set at the dimension relative to the next insidehinge. This dimension is IHC. Each scaffold section should be adjusted until thedimension from an inside hinge to an inside hinge is set at the dimension IHC.After articulating the scaffold section and sliding the hinges into place, snug tight thebolts at the hinges.

4.0.2 Shell Attachments (Bracket Straps)

a) Scaffold alignment to bracket straps is critical. The ideal location for straps is

approximately 52 down from the top of the shell to the top of the strap.

Figure 4-3Bracket Strap Lay Out

b) For inside tank scaffold the bracket straps are laid out as a chord.

This chord dimension will be between 10- 5 for the minimum diameter tankand 10- 4 for the largest diameter tank. The exact chord to use is thedimension BC and it is found in Calculation Table 5-A or 5-B in part 5.

Use the dimension 6BC for laying out every 7th

bracket strap and then use thechord dimension BC to layout the 5 straps between the beginning of the firstchord and the end of the sixth chord. This method will reduce the cumulativeerror caused by laying out from chord to chord. It is also recommended to layout

of the circumference in one direction, and then layout in the reverse directionto eliminate cumulative error.

The 6BC dimension eliminates cumulative error but it is only used when thereare NO make-up chords (BMC) within the boundaries of the chord 6BC. Besure to include for BMC as the chords are being laid out around the tanksperimeter. Use the layout sketch to keep sections in the correct order.


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e) Bracket straps are to be welded only by qualified welders - not tackers.

f) Weld across the top of bracket straps as shown in Fig. 4-6. Make all welds in theorder and direction shown. Reverse the direction of welding on the ends of thewelds to fill the crater. Use a 3/16" fillet weld of E6010 (where permitted for the shellmaterial), E7018, or E71-T1 electrode. Use the electrode as specified in the weldingprocedure to weld the bracket to the structure.

Fig. 4-6Welding of Bracket Straps

g) If, for whatever reason, the welding of a bracket strap cannot be completed, it mustbe removed by breaking the attaching welds. Never leave a bracket strap that ispartially welded.

h) All welded bracket straps must be inspected by either the superintendent, pusher,weld supervisor, or a qualified person designated by the superintendent. The welderwho welds the strap must not be person that does the inspection. The slag must beremoved from the weld before inspection. To show that the bracket strap weld hasbeen inspected and correctly welded, it must be circled and initialed by the personinspecting the weld.

i) Bracket straps may be used a maximum of 2 times. If a bracket strap is being useda second time, turn it over and weld on the side that has not been welded on.

j) Brackets can be stabbed into their straps after the strap welds are cleaned,inspected, and circled.

k) The bracket at the make-up section has (2) two make-up bracket spacers (2L33-14-A). See Figure 4-11.


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4.1 Installation

a) Unless noted this procedure and the figures shown are applicable for scaffolds oneither the inside or the outside of the tank.

b) The AMS sections will allow about variation in the chord or arc dimensions, butthis variation is not cumulative. It is recommended that a section of scaffold beplaced on the brackets as soon as the brackets for that section are stabbed into thestraps.

c) Just before placing an AMS scaffold section on top of the brackets be sure the

2L33-12-9 Bars under the adjustable inside hinge are loosened and swung out ofplace. The Scaffold Outside Hinge Radius (OHR) will have already been set whenthe inside hinges were set using the dimension IHC, but IHC should again beverified while the scaffold section rests on the brackets. See Figures 4-7 & 4-8.

d) Slide the section on the brackets until the center of the AMS Outside Hinge Pins areX dimension from the shell. If there is a make-up in the complete scaffold ring, thedimension X at the 1

string will be 5 for an inside scaffold and X will be 3-1

(37.25) for an outside scaffold. If there are NO make-ups to be used, the dimensionX is found in Calculation Table 5-B or 6-B.

e) After the section is set properly on the brackets as per the above instructions, use awrench to tighten the bolts at the adjustable inside hinges.

f) Install the spacer on the bracket between the AMS hinge and the bracket post if thespace between is greater than 1. This space could be as little as 1/8 when X isat its maximum of 39 with the outside tank scaffold.

g) Install the tie-down around the bracket at the outside hinge.

h) Swing the bar at the adjustable inside hinges back into position and tighten thebolts.

i) The bar and tie-down capture the bracket making the bracket an integral part of theAMS.


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Figure 4-7Inside Scaffold Side View

Figure 4-8Outside Scaffold Side View


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j) The spacer is only pinned and it will be loose. When there is sufficient wind for theAMS to act as a wind-girder, the spacer will tighten as it binds between the AMS andthe bracket post.

k) Continue the sequential installation of the AMS sections on the 1st

ring using thelayout sequence sketch as the guide. Be sure to include for the GAP at the make-up(s).

l) After all AMS 3-hinged and 2-hinged sections are erected, the make-up sections areinstalled at the GAP(s). The make-up sections should be bolted at both ends to the3-hinged or 2-hinged sections for the AMS to act as a wind-girder.

m) A competent person shall do a visual inspection of the scaffold sections as they areinstalled.

n) If using rigid handrail, install the 2L33-17-A Dual Handrail Post Supports and thenthe handrails. A 3-hinged section uses 2 long handrails. A 2-hinged section uses 1long handrail. Unless next to a make-up section, a 2-hinged section or 3-hingedsection uses 2 short handrails. If next to a make-up section, a 2-hinged section or 3-hinged section uses 1 short handrail and 1 make-up handrail.

o) It is acceptable to use conventional scaffold posts with wire-rope hand line instead

of the rigid handrail. See part 4.3(p) and Manual 13 when using wire-rope hand line.

Figure 4-9Completed Scaffold on 1

stRing

4.2 Splices Between Scaffold Sections

4.2.1 Splice Between Scaffold Sections Without a Make-up Section

a) A 3-hinged scaffold section is made of two whole platforms in the middle and twohalf platforms at each end.

b) The 2-hinged scaffold section is made of one whole platform in the middle and twohalf platforms at each end.


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c) The scaffold section should ship with (4) four bolts temporarily installed on the rightend of the scaffold section.

d) To explain orientation, the right and left end is determined by standing in the centerof the scaffold ring.

e) The left end of a scaffold section has swinging hinge plates to cover up the splicebetween the sections.

f) Unless there is a make-up, the half platforms are spiced together using the detail

shown in Figure 4-10.

Figure 4-10Splice Scaffold Sections

4.2.1 Splice Between Scaffold Sections With a Make-up Section

a) Make-up sections are installed after the adjacent scaffold sections are in place.

b) Two 2L33-14-A Make-up Bracket Spacers should be installed on the bracket toprovide support for the make-up section.

c) Four bolts along with the (4) four 2A19 nuts should ship with each make-up section.


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d) The make-up section that is installed at the splice between half platforms is bolted tothe half platforms using the detail shown in Figure 4-11. The GAP that is bridged isno more than 49 and the make-up lap should be no less than 6.

Figure 4-11Splice Scaffold Sections


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h) Before jumping a scaffold section, remove all unneeded materials and place anyremaining material near the middle of the scaffold section. Only a total of 250Lbs. ofmaterial, tools, or scaffold parts are allowed on the scaffold section being jumped.

i) Before jumping check that all connections have been broken loose. Confirm that thescaffold can rise freely without hanging up and that no additional equipment ormaterial has been attached or hung from the section.

j) Employees on the scaffold section being jumped or adjacent to an open scaffoldsection shall use a Personal Fall Arrest System. For each person, a 20 retractablelifeline shall be provided along with the Over The Shell Tie Off Device (2L69-A) or

an approved equal tie-off device. See Figures 4-13A and 4-14.

k) Employees adjacent to an open scaffold section shall be aware of the pinch pointscreated between the stationary scaffold section and the scaffold being jumped.

l) Ensure that personnel on the scaffold section have clear access and a ready meansto get off of the section being jumped.

m) People on the suspended scaffold section as it is being jumped will be allowed onlyfor the following reasons:

o

To free the scaffold section from its bracket straps.o To break-off and clean up the bracket straps. Employees may use air-driven

grinders for clean up.o To maintain clearances as the scaffold section is being jumped.o To ensure that the section has been properly secured to the new bracket straps.

n) As the scaffold section is being jumped, access shall be limited to two (2) people onthe 2-hinged scaffold section and (3) people on the 3-hinged scaffold section. Anobserver will be available for emergency assistance.

o) Scaffold can be jumped using the rigid handrail method or using the conventional

handrail post and wire rope hand-line method.

p) If using the conventional post and hand-line method, then before jumping a scaffoldsection, loosen the hand-line cable clips and move about 20 of slack to the sectionbeing jumped. While jumping the section keep an eye on the hand-lines to be surethey slip freely though the pigtails on the posts. After the first scaffold section is

jumped, snug the hand-line and re-tighten the cable clips. Leave just enough slackso the remainder of scaffold sections can be jumped without having to loosen the


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cable clips again. When the scaffold ring is complete retighten the hand-lines.People on the scaffold with incomplete hand-line must be tied off.

q) Do not make adjustments or loosen hinge bolts during jumping the scaffold. If aproblem develops stabbing brackets into straps the shell could be out of round. Fixthe shell but do not adjust the scaffold.

r) When the AMS is secured in the bracket straps welded to the tank then the capacityof the scaffold between two brackets should be limited to two people and no morethan 200 Lbs of tools, material, etc.

s) A competent person shall do a visual inspection of the rigging just prior to jumpingscaffold sections.

t) No person shall ever be under the scaffold section as it is being jumped.

4.4 Jumping Methods

Two methods can be used to jump an AMS section. The Trolley Method or the CraneMethod:

a) The Trolley Method: This method uses trolleys, chain-falls, and the 2L33-16-A

Lifting Assemblies. The use of 2 or 3 trolleys/ chain-falls/ lifting assemblies dependson if a 2-hinged or 3-hinged section is being jumped. The trolleys used are CB&Isstandard 2L25A-1-A Trolley. The chain-falls are a minimum of 1-ton capacity with aminimum of 18 lift. The chain-falls can be manual, electric, or air-powered. CoffingHoists, Harrington Hoists, and J.D. Neuhaus Hoists are approved chain-fallmanufactures. The Lifting Assemblies attach to the D-rings on AMS and to thescaffold bracket. See the following Figures 4-13A & B.


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Figure 4-13ATrolley Method For Scaffold Jumping (shown inside)


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Figure 4-13BTrolley Method For Scaffold Jumping (shown inside)

b) The Crane Method: This method uses the crane used for tank erection and the5-point lifting bridle. When using the Crane Method, balancing the load is even moreimportant than when using the Trolley Method. The sections are rigged using the 5-point lifting bridle with the middle sling attached to one 2L33-16-A Lifting Assemblyin the middle of the AMS section and the other 4 slings attached to the lifting eyeson the outboard hinge lugs. The minimum length between the outboard hinge points

and the crane hook will be twenty (20) feet. The middle sling and two of the fouroutboard slings will have 1 ton come-a-longs when lifting a scaffold section. Abypass sling must be placed between the eye of the sling and the shackle in theevent of a come-a-long failure. Never lift an AMS scaffold section from any otherlifting points. If lifting the 2-hinged scaffold section the middle sling with its come-a-long is not used. See the following Figure 4-14.


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Figure 4-14Crane Method For Scaffold Jumping

(People signaling the crane shall have an unobstructed view of theScaffold & uninterrupted communication with the crane operator)


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d) For the section being jumped, leave the long handrails in place and remove of theshort and/or make-up handrail.

e) Lay the loose pieces of the handrail on the next scaffold section being jumped.

f) The of handrail left at the bracket posts is the 2L33-19-B End Gate Assembly.The End Gate is rotated turn, re-pinned to the bracket post, and a gate straplashes the gate to the bracket to create the scaffold end gate. See side view Figure4-17.

g) If the conventional post and wire rope hand-line method is used follow the

procedure outlined in part 4.3 (p).

h) Use a rope and tie the make-up bracket to the hook ladder. Reach from the scaffold,pull the bracket from its strap, untie it, and stage it on the scaffold being jumped.

i) Remove the strap and clean up the strap area while lying down on the scaffoldsection or bridge the GAP with at least an 8 long scaffold board and do the clean upwhile sitting on the board. Remember people must be tied-off to an independentsafety line when outside the scaffold handrail.

Figure 4-16Prepare Scaffold Section For Jumping


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Figure 4-17Side View of End Gate

j) If using the Trolley Method, place three trolleys on the shell. Even if the first lift is a2-hinged section, three trolleys will be needed for later sections of scaffold to be

jumped.

k) Check for any possible interferences.

l) Ensure that the bolts at the connection between scaffold sections are removed andthe cover plate is flipped out of position.

m) Remove all unnecessary material from the section. Any material that must remainon a section while it is jumped must be spread out evenly about the middle of thesection.

n) Clear access for personnel must be maintained.

o) Provide access to each side of the section being jumped. The access from theleading end will be from the hook ladder and the access from the trailing edge willbe from a hook ladder when lifting the first section or from the previous scaffoldsection jumped.


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4.5.2 Lifting the Section Out of the Lower Straps:

a) If the Crane Method is being used, it is acceptable to attempt lift the section out ofthe straps without people on the scaffold. Using the crane, apply tension to therigging and continue lifting only if the scaffold immediately clears the bracket straps.If the scaffold does not freely move out of the straps, then with tension on therigging, use people on either side of the section to attempt to dislodge the scaffoldby vibrating the section being raised. Some additional minimal tension can beapplied to the rigging at this time. If the scaffold section lifts, continue lifting at asteady rate. If the section slows or stops, immediately cease lifting. If the sectionhas stopped or has not begun to lift and vibration from the sides does not dislodge

it, personnel will then have to access the section being jumped. Before people geton the section, lower the cranes hook slightly but not enough to cause any visibleslack in the rigging.

b) When jumping a 3-hinged section, the lifting device in the middle of the centersection must always be under tension. This is applicable for the Trolley Method andthe Crane Method.

c) When accessing the section, no more than 2 people are allowed on a 2-hingedscaffold section as it is being jumped. No more than 3 people are allowed on a 3-hinged scaffold section as it is being jumped.

d) Use either lifting device (the chain-fall from the Trolley Method or the come-a-longfrom the Crane Method) to lift and loosen the brackets slightly from their straps. Itmight be necessary to loosen the bracket by using a bar, hammer, or anothermechanical method. Loosen one bracket at a time, starting with the middle bracketwhen jumping a 3-hinged scaffold section.

e) After the first bracket has moved, check and loosen the other bracket(s). Once thebrackets are free, lift them out of their straps with the crane or the chain-falls.

f) If, for any reason, the section stops rising or begins to go out of level, STOP. Re-

level the section with the lifting device and repeat the above.

g) After raising the section about one (1) foot, with the scaffold level and unrestrained,visually confirm that it is clear of all obstructions and hanging freely.

h) If not already on the scaffold, access is required for visual confirmation.


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4.5.3 Bracket Strap Clean-Up While on The Suspended Scaffold Section

a) Lower the scaffold to comfortable position below the straps. Remove the straps fromthe tank shell and perform the necessary clean up of the strap location. If clean uprequires pick-up welding or NDE, the proper precautions should be made as statedin RBS 155-6-6-4. When doing welding be sure to remove electrodes from holderswhen not welding and take care of leads on the scaffold. No more than two peopleare allowed on the suspended 2-hinged scaffold section.

Figure 4-18Scaffold Section Jumping

b) After the lower straps are removed, jump the section up to an elevation slightlyabove the upper straps. Stay clear of all obstructions.

4.5.4 Stabbing the Bracket Into The Upper Straps

a) Adjust the sections levelness as required using the lifting devices at the brackets.

b) Move the scaffold section into contact with the shell directly over the upper bracketstraps.

c) Verify that all brackets align with their mating straps.


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d) Each bracket pin should be checked to ensure its engagement in the matingopening of the bracket strap.

e) If the alignment is not correct, the strap will have to be removed, its proper positionmarked on the shell, and a new strap will have to be welded on the shell. This re-work will have to be done with people working on the suspended scaffold section.Diligence must be used when laying out straps so this re-work in an awkwardposition is avoided.

f) Determine which bracket is closest to its strap, which is second closest, and which isthird closest when applicable. Begin lowering the brackets into their straps.

g) Keep your hands free of pinch points and lower the section very slowly whilemonitoring the closest bracket. Use a bar only and move the first bracket so it willstart stabbing into the strap opening.

h) The lifting devices can be used to raise or lower the bracket elevations to assist instabbing the bracket into its strap.

i) As the brackets stab their respective straps, care must be used so the scaffoldsection remains level and the bracket does not bind in its strap.

j) Once the first bracket is started continue lowering the assembly.

k) Continuously monitor the brackets until they all start stabbing into their strapopening.

l) If the section hangs up or begins to tilt, stop lowering immediately.

m) Raise the section slightly to level and remove the hang up, and then begin loweringwhile repeating the above.

n) Lower the section until it is completely seated in its straps.


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Figure 4-19Scaffold Section Jumped to Upper Straps

4.5.5 Temporary Placement of the Make-up Section

a) If there is a make-up at the leading end of the scaffold section jumped, then thebracket that supported the make-up is now installed into its new upper strap. The

bracket was jumped with the scaffold section and it should now be stabbed into theupper bracket strap.

Figure 4-20Install Make-up Bracket in Upper Strap


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4.6.1 Preparations For Lifting

a) Check the bracket straps for the new level of scaffold and ensure these are installedcorrectly.

b) When at the trap door section, the straps for the new position of tank erectionladders should be installed before jumping the scaffold. Check that the location ofthe straps is correct to keep the ladders in their proper alignment.

c) The Trap Door Ladder Assembly must be installed so the employee is facing theshell while climbing the ladder

d) Advance a hook ladder to the leading end of the section to be jumped. The scaffoldcan be jumped in the clockwise or counter-clockwise direction.

e) For the section being jumped, leave the long handrails in place and remove of theshort and/or make-handrail.

f) Lay the loose pieces of the handrail on the next scaffold section to be jumped.

g) The of handrail left at the bracket posts is the 2L33-19-B End Gate Assembly.The End Gate is rotated turn, re-pinned to the bracket post, and a gate strap

lashes the gate to the bracket to create the scaffold end gate. See Figure 4-22.

Figure 4-22Side View of End Gate


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j) Check for any possible interferences. When lifting the trap door section, check thelifting clearances from the Trap Door Ladder Assembly. Remove the upper 4 of tankerection ladder from the shell and set it on the platform in the Trap Door LadderAssembly.

k) Ensure that the bolts at the connection between scaffold sections are removed andany cover plates are flipped out of position.

l) Remove all unnecessary material from the section. Any material that must remainon a section while it is jumped must be spread out evenly about the middle of thesection.

m) Clear access for personnel must be maintained.

n) Provide access to each side of the section being jumped. The access from theleading end will be from the hook ladder and the access from the trailing edge willbe from the previous scaffold section jumped.

4.6.2 Lifting the Section Out of the Lower Straps

a) If the Crane Method is being used, it is acceptable to attempt lift the section out ofthe straps without people on the scaffold. Using the crane, apply tension to the

rigging and continue lifting only if the scaffold immediately clears the bracket straps.If scaffold does not freely move out of the straps, then with tension on the rigging,use people on either side of the section to attempt to dislodge the bracket byvibrating the section being raised. Some additional minimal tension can be appliedto the rigging at this time. If the scaffold section lifts, continue lifting at a steady rate.If the section slows or stops, immediately cease lifting. If the section has stopped orhas not begun to lift and vibration from the sides does not dislodge it, personnel willthen have to access the section being jumped. Before people get on the section,lower the cranes hook slightly but not enough to cause any visible slack in therigging.

b) When jumping a 3-hinged section, the lifting device in the middle of the centersection must always be under tension. This is applicable for the Trolley Method andthe Crane Method.

c) When accessing the section, no more than 3 people are allowed on a 3-hingedscaffold section as it is being jumped. No more than 2 people are allowed on a 2-hinged scaffold section as it is being jumped.


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d) Use either lifting device (the chain-fall from the Trolley Method or the come-a-longfrom the Crane Method) to lift and loosen the brackets slightly from their straps. Itmight be necessary to loosen the bracket by using a bar, hammer, or anothermechanical method. Loosen one bracket at a time, starting with the middle bracket.

e) After the first bracket has moved, check and loosen the other bracket(s). Once thebrackets are free, lift them out of their straps with the crane or the chain-falls.

f) If, for any reason, the section stops rising or begins to go out of level, STOP. Re-level the section with the lifting device repeat the above.

g) After raising the section about one (1) foot, with the scaffold level and unrestrained,visually confirm that it is clear of all obstructions and hanging freely.

h) If not already on the scaffold, access is required for visual confirmation.

4.6.3 Bracket Strap Clean-Up While on The Suspended Scaffold Section

a) Lower the scaffold to comfortable position below the straps. Remove the straps fromthe tank shell and perform the necessary clean up of the strap location. If clean uprequires pick-up welding or NDE, the proper precautions should be made as statedin RBS 155-6-6-4. When doing welding be sure to remove electrodes from holders

when not welding and take care of leads on the scaffold. No more than three peopleare allowed on the suspended 3-hinged scaffold section.


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f) Determine which bracket is closest to its strap, which is second closest, and which isthird closest. Begin lowering the brackets into their straps.

g) Keep your hands free of pinch points and lower the section very slowly whilemonitoring the closest bracket. Use a bar only and move the first bracket so it willstart stabbing into the strap opening.

h) The lifting devices can be used to raise or lower the bracket elevations to assist instabbing the bracket into its strap.

i) As the brackets stab their respective straps, care must be used so the scaffold

section remains level and the bracket does not bind in its strap.

j) Once the first bracket is started continue lowering the assembly.

k) Continuously monitor all 3 brackets until all start stabbing into the strap opening.

l) If the section hangs up or begins to tilt, stop lowering immediately. Raise the sectionslightly to level and remove the hang up, and then begin lowering while repeatingthe above.

m) Lower the section until it is completely seated in its straps.

4.6.5 Erect Tank Erection Ladders

a) Install the next tank erection ladder. The length of this ladder should be as long asthe height that the scaffold was jumped.

b) Remove the 4 tank erection ladder from the Ladder Assembly platform and install itin its straps.


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Figure 4-27Complete Second Scaffold Section

4.7 Jumping The Rest of The Scaffold Sections

a) The previous procedure used for the jumping of the first and second section shouldbe followed for all subsequent AMS scaffold sections.

b) The AMS is complete when the scaffold ring has all the handrails back in place andall the scaffold sections along with any make-ups are bolted together. A completeAMS will act as a wind-girder section capable of withstanding a 90 mph wind.

4.8 Jumping The AMS Scaffold Sections From Inside the Tank to OutsideThe Tank

4.8.1 Preliminary

a) If there is a need, after jumping the inside scaffold sections to the top of the tank, tojump the scaffold sections to the outside shell then another layout sequence sketch

must be made with the scaffold on the outside. Most likely the outside layoutsequence will have one more scaffold section than the inside and maybe anothermake-up.

b) Before beginning the layout of the straps on the outside shell complete CalculationTable 6-A or 6-B. Make a note of the dimension IHC. For the outside scaffold,record the arc dimensions BA and BMA.


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c) Do the Table 6-A or 6-B calculations using the outside diameter of the one shellring. The AMS will only be jumped to one ring on the outside therefore use the samedimension for TBOR and TTOR in all calculations.

d) Make a sketch of the layout sequence. Examples of Layout Sequences can befound in Part 8 of this manual.

e) Stage the additional scaffold section needed on the ground at the perimeter of thetank.

f) While the section is on the ground the adjustable inside hinges with the sliding

plates should be set at the dimension relative to the next inside hinge. Thisdimension is IHC. The scaffold section is adjusted until the dimension from aninside hinge to an inside hinge is set at the dimension IHC. After articulating thescaffold section and sliding the hinges into place, snug tight the bolts at the hinges.

g) Remember the inside adjustable hinge will be closest to the shell when the AMS isused outside the tank.

4.8.2 Shell Attachments (Bracket Straps)

a) Use the arc dimension BA and begin installing bracket straps. The ideal location

for straps is approximately 52 down from the top of the shell. Use the layoutprocedure mentioned in subpart 4.0.2 (c) of this manual.

Figure 4-28Outside Bracket Strap Layout

b) Proceed with the arc layout while working out of a shell buggy. Remember to includefor BMA, the arc dimension at the make-up.

c) As the straps are welded to the shell, brackets can be stabbed into their straps.


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4.8.3 Installation of First Section

a) After enough brackets are stabbed into their respective straps, installation of thescaffold section that is staged on the ground can begin.

b) Just before placing the scaffold section on top of the brackets, be sure the barsunder the adjustable inside hinge are loosened and swung out of place. TheScaffold Outside Hinge Radius (OHR) will have already been set when the insidehinges were set using the dimension IHC, but IHC should again be verifiedbefore hoisting up the section.

c) Rig the scaffold sections on the ground using the 5-point lifting bridle with the middlesling attached to one of the D-rings in the middle of the 3-hinged section. Theother 4 slings will be attached to the lifting eyes on the outboard hinge lugs. If liftinga 2-hinged scaffold section, the middle sling of the 5-point lifting bridle is not used.See the following Figure 4-29.



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place. The Scaffold Outside Hinge Radius (OHR) will need to be set by adjustingthe inside hinges to the dimension IHC. This adjustment should be an increase ofno more than .

i) Rig the scaffold section using the 5-point lifting bridle with the middle sling attachedto one of the D-rings in the middle of the 3-hinged section. The other 4 slings willbe attached to the lifting eyes on the outboard hinge lugs. If lifting a 2-hingedscaffold section, the middle sling of the 5-point lifting bridle is not used. See Figure4.31



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j) Using a shell buggy on the outside, brackets will need to be stabbed into the strapsbefore the scaffold section is jumped over the shell.

k) Jump the scaffold section from the inside to the outside.

l) Repeat the process of attaching the scaffold section to the bracket.

m) Bolt the sections together as they are jumped over the shell.

n) After a scaffold section is jumped from the inside to the outside, use a shell buggy

on the inside to remove brackets and pass them to the buggy on the outside forinstallation into straps.

o) The handrail sections that are removed during jumping are passed over the shell forinstallation on the other-side as the scaffold is jumped over the shell.

p) Complete the scaffold ring as explained in the previous manual parts 4.1 to 4.7.

End of Part 4


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Quantity Calculation for Inside Tank Scaffold Page 1


5.0 Quantity Calculation for Inside Tank Scaffold

To determine how many and what type of Adjustable Metal Scaffold (AMS) sections areneeded, begin with Calculation Table 5-A and proceed through the steps. The table actsas a flow chart and if the tank size does not require make-ups you will be quicklydirected to Calculation Table 5-B for an AMS of a fixed size.

The definitions of the abbreviations (such as TBIR, TTIR, OHR, IHC, etc.) can be foundin part 3 of this manual.

The logic to determine how many scaffold sections are needed is to first understand

that the outside perimeter of the AMS, without make-up sections, is a fixed lengthdetermined by the number of trapezoidal platforms. Since this perimeter length is fixed,the radius from the center of the AMS to the outside hinge pin is fixed. For the scaffoldto be useable on the inside of a tank shell, the distance from the inside of the shell tothe center of the outside hinge pin is allowed to vary between 4.47 and 7.5. Thisvariable means that the AMS without make-ups is usable on only tanks with the insidediameters listed in Chart 5-B.

The use of the AMS without make-ups is 14% possible.

If a tanks diameter is not listed in Chart 5-B then the AMS used will require make-ups.

For an AMS with make-up sections, the distance from the 1

st

ring tank shell to thecenter of the scaffolds outside hinge pin is fixed at the optimum distance of 5. The 5distance is set at the first ring, but as the AMS is jumped the dimension to the shell willincrease as the thickness of the shell decreases and the supporting bracket slidesunder the scaffold. The tanks inside radius minus 5 is used to calculate the neededoutside perimeter of the AMS. The possible length of all scaffold sections is subtractedfrom the calculated perimeter to determine the length to make-up. The individual lengthof a make-up section could require that up to three make-ups are needed since onemake-up GAP should never exceed 49. Make-ups are never placed next to each otherand are always separated by a 3-hinged or 2-hinged scaffold section.

The use of the AMS with (1) one make-up section is 36% possible.The use of the AMS with (2) two make-up sections is 39% possible.The use of the AMS with (3) three make-up sections is 11% possible.

For the computation of Calculation Tables 5-A & 5-B, spreadsheet software can beused and is suggested. CCT can provide these spreadsheets or CCT can determinethe quantities if requested. The exact inside diameter of the tank shells first and topring will be required to begin the calculations.


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Table 5-A AMS Quantity CalculationCalculation Table 5-A

For Adjustable Metal Scaffold Inside Tank

1. From Tank Drawings record Tank ID at 1st ring in Decimal Feet xxx.xxxx'

(1st ring) ID =

See Chart 5-A and Record M & N

M =

N =

2. From Tank Drawings record Tank ID at top ring in Decimal Feet xxx.xxxx'

(Top ring) ID =

See Chart 5-A and Record M & NM =

N =

3. If "M" equals 0 at the 1st ring & the top ring STOP HERE & go to Calculation Table5-B

4. Re-Enter Tank ID that uses most make-ups, "M", in Decimal Feet xxx.xxxx'

If "M" is the same at both the 1st ring & top ring then record 1st ring I.D.

ID =

Re-Record M & N

M =

N =

5. Calculate TBIR in Inches xxx.xx"

TBIR = (ID at 1st ring /2) x 12 =

6. Calculate TTIR in Inches xxx.xx"

TTIR = (ID at top ring /2) x 12 =

7. Calculate OHR in Inches xxx.xx"

OHR = TBIR - 5 =

8. Calculate "X" at top ringX = TTIR - OHR =


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Table 5-A AMS Quantity Calculation (continued)Calculation Table 5-A

For Adjustable Metal Scaffold Inside Tank (continued)

9. Is "X" at Top ring between 4.47" & 7.5"

Yes = Continue

No = Consult CCT

10. Calculate Angle A between Sections w/o Make-ups (xx.xxxx) (degrees)

A = (ASIN (62.25/OHR)) x 2 =

11. Calculate Angle B between Sections w/ Make-ups (xx.xxxx) (degrees)

B = (360 - ((A) x (N-M)) / M =

12. Calculate Gap Angle GA (x.xxxx) (degrees)

GA = B - A =

13. Calculate Gap (xx.xx) (inches)

GAP = 2 x ((TAN (GA/2) x (OHR x (COS (B/2))) =

14. Is GAP < 49" ?

Yes = Continue

No = Consult CCT

15. Calculate IHC (distance between adjacent inside hinges) (inches)

IHC = ((OHR- (30.75/(COS (A/2)))) x (SIN (A/2))) x 2 =

16. Calculate Angle C to Make-up Bracket (x.xxxx) (degrees)

C = B/2 =

17. Calculate Chord between Section Bracket Straps (inches)

BC = (TBIR x SIN (A/2)) x 2 =

18. Calculate Chord between 1st

strap and 7th

Strap (6 spaces) (inches)

6BC = (TBIR x SIN (3 x A)) x 2 =

19. Calculate Chord at Make-ups (inches)

BMC = (TBIR x SIN (C/2)) x 2 =


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Chart 5-A Quantities of AMS Scaffold SectionsCHART 5-A

FOR ADJUSTABLE METAL SCAFFOLD INSIDE TANK

Tank Inside Diameter(ft)

# OfMake-

ups "M"

Total # ofPlatforms

"N"

# Of 3-Hinged

SectionsH3

# Of 2-Hinged

SectionsH2 Layout Sequence

From To

100.00 100.51 0 30 10 0 10(H3)

100.52 101.38 1 30 10 0 10(H3) + M

101.39 102.68 2 30 10 0 5(H3)+M+5(H3)+M

102.69 103.29 3 30 10 0 4(H3)+M+3(H3)+M+3(H3)+M

103.30 103.80 0 31 9 2 9(H3)+2(H2)

103.81 104.68 1 31 9 2 9(H3)+2(H2)+M

104.69 105.98 2 31 9 2 9(H3)+M+2(H2)+M

105.99 106.58 3 31 9 2 5(H3)+M+4(H3)+M+2(H2)+M

106.59 107.10 0 32 10 1 10(H3)+H2

107.11 107.98 1 32 10 1 10(H3)+H2+M

107.99 109.27 2 32 10 1 10(H3)+M+H2+M

109.28 109.88 3 32 10 1 5(H3)+M+5(H3)+M+H2+M

109.89 110.40 0 33 11 0 11(H3)110.41 111.28 1 33 11 0 11(H3) + M

111.29 112.57 2 33 11 0 6(H3)+M+5(H3)+M

112.58 113.18 3 33 11 0 4(H3)+M+4(H3)+M+3(H3)+M

113.19 113.69 0 34 10 2 10(H3)+2(H2)

113.70 114.57 1 34 10 2 10(H3)+2(H2)+M

114.58 115.87 2 34 10 2 10(H3)+M+2(H2)+M

115.88 116.48 3 34 10 2 5(H3)+M+5(H3)+M+2(H2)+M

116.49 116.99 0 35 11 1 11(H3)+H2

117.00 117.87 1 35 11 1 11(H3)+H2+M

117.88 119.17 2 35 11 1 11(H3)+M+H2+M

119.18 119.77 3 35 11 1 6(H3)+M+5(H3)+M+H2+M


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Chart 5-A Quantities of AMS Scaffold Sections (continued)CHART 5-A (continued)



# OfMake-

ups "M"

Total # ofPlatforms

"N"

# Of 3-Hinged

SectionsH3

# Of 2-Hinged


From To

119.78 120.29 0 36 12 0 12(H3)

120.30 121.17 1 36 12 0 12(H3) + M

121.18 122.47 2 36 12 0 6(H3)+M+6(H3)+M

122.48 123.07 3 36 12 0 4(H3)+M+4(H3)+M+4(H3)+M

123.08 123.59 0 37 11 2 11(H3)+2(H2)

123.60 124.47 1 37 11 2 11(H3)+2(H2)+M

124.48 125.77 2 37 11 2 11(H3)+M+2(H2)+M

125.78 126.37 3 37 11 2 6(H3)+M+5(H3)+M+2(H2)+M

126.38 126.89 0 38 12 1 12(H3)+H2

126.90 127.77 1 38 12 1 12(H3)+H2+M

127.78 129.06 2 38 12 1 12(H3)+M+H2+M

129.07 129.67 3 38 12 1 6(H3)+M+6(H3)+M+H2+M

129.68 130.19 0 39 13 0 13(H3)130.20 131.07 1 39 13 0 13(H3) + M

131.08 132.36 2 39 13 0 7(H3)+M+6(H3)+M

132.37 132.97 3 39 13 0 5(H3)+M+4(H3)+M+4(H3)+M

132.98 133.48 0 40 12 2 12(H3)+2(H2)

133.49 134.37 1 40 12 2 12(H3)+2(H2)+M

134.38 135.66 2 40 12 2 12(H3)+M+2(H2)+M

135.67 136.27 3 40 12 2 6(H3)+M+6(H3)+M+2(H2)+M

136.28 136.78 0 41 13 1 13(H3)+H2

136.79 137.66 1 41 13 1 13(H3)+H2+M

137.67 138.96 2 41 13 1 13(H3)+M+H2+M

138.97 139.57 3 41 13 1 7(H3)+M+6(H3)+M+H2+M


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# OfMake-

ups "M"

Total # ofPlatforms

"N"

# Of 3-Hinged

SectionsH3

# Of 2-Hinged


From To

139.58 140.08 0 42 14 0 14(H3)

140.09 140.96 1 42 14 0 14(H3) + M

140.97 142.26 2 42 14 0 7(H3)+M+7(H3)+M

142.27 142.87 3 42 14 0 5(H3)+M+5(H3)+M+4(H3)+M

142.88 143.38 0 43 13 2 13(H3)+2(H2)

143.39 144.26 1 43 13 2 13(H3)+2(H2)+M

144.27 145.56 2 43 13 2 13(H3)+M+2(H2)+M

145.57 146.17 3 43 13 2 7(H3)+M+6(H3)+M+2(H2)+M

146.18 146.68 0 44 14 1 14(H3)+H2

146.69 147.56 1 44 14 1 14(H3)+H2+M

147.57 148.86 2 44 14 1 14(H3)+M+H2+M

148.87 149.47 3 44 14 1 7(H3)+M+7(H3)+M+H2+M

149.48 149.98 0 45 15 0 15(H3)149.99 150.86 1 45 15 0 15(H3) + M

150.87 152.16 2 45 15 0 8(H3)+M+7(H3)+M

152.17 152.77 3 45 15 0 5(H3)+M+5(H3)+M+5(H3)+M

152.78 153.28 0 46 14 2 14(H3)+2(H2)

153.29 154.16 1 46 14 2 14(H3)+2(H2)+M

154.17 155.46 2 46 14 2 14(H3)+M+2(H2)+M

155.47 156.07 3 46 14 2 7(H3)+M+7(H3)+M+2(H2)+M

156.08 156.58 0 47 15 1 15(H3)+H2

156.59 157.46 1 47 15 1 15(H3)+H2+M

157.47 158.76 2 47 15 1 15(H3)+M+H2+M

158.77 159.37 3 47 15 1 8(H3)+M+7(H3)+M+H2+M


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# OfMake-

ups "M"

Total # ofPlatforms

"N"

# Of 3-Hinged

SectionsH3

# Of 2-Hinged


From To

159.38 159.88 0 48 16 0 16(H3)

159.89 160.76 1 48 16 0 16(H3) + M

160.77 162.06 2 48 16 0 8(H3)+M+8(H3)+M

162.07 162.67 3 48 16 0 6(H3)+M+5(H3)+M+5(H3)+M

162.68 163.18 0 49 15 2 15(H3)+2(H2)

163.19 164.06 1 49 15 2 15(H3)+2(H2)+M

164.07 165.36 2 49 15 2 15(H3)+M+2(H2)+M

Cm43A Adjustable Metal Scaffold

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