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AGENDA OF THE CEMA ENGINEERING CONFERENCE

SCREW CONVEYOR COMMITTEE MEETING

TUESDAY, JUNE 27, 2017, 8:30 – 10:00 A.M.

1. Call to order.

2. Attendance and introductions

3. Approval of minutes of June 21, 2016.

4. Old Business

a. Helicoid Flight O.D. Tolerance – Only (2) companies have submitted the survey results prior

to the spring meeting. What is current status?

b. Dimensional standards for 3‐15/16”, 4‐7/16”, and 4‐15/16” shafts have been approved by OR’s.

We, now, need to up‐date applicable areas of the 300 and 350 standards.

c. 350 Graphics and Photos – From the Spring meeting, some graphics have been added.

However, still missing images and information on descriptions from Chapter 1. Kevin from

Syntron MH, Bill Mecke from KWS, and Warren Knapp from Screw Conveyor Corp. to assist in

reviewing Chapters 1, 5, 6, and 7 for missing images and figures. Request either individual to

up‐date the engineering committee on progress. How can we help?

d. Inclined and Vertical Screw Conveyor Best Practices – Only (2) companies have

participated. David Stronczek from Martin Sprocket to up‐date and/or present

draft document to engineering committee.

e. Risk Assessment – OR’s would like the engineering committee to discuss incorporating the Risk

Assessment Technical Report CEMA TR 2015‐01 in the Screw Conveyor IOM manual (Std. #352).

5. New Business

a. Seal Bolting Pattern for Oversized Shafts – survey results to be distributed.

b. Election of Chair

c. Election of Vice Chair

6. Next meeting June , 2018

7. Adjourn

Trevin M. Berger Screw Conveyor Committee Chair

Conveyor Equipment Manufacturers Association

owner

Highlight

CEMA Technical Report 2015-01

Recommended

CEMA Risk Assessment Process

Provided as a service to the Conveyor Industry by CEMA Safety Committee

Conveyor Equipment Manufacturers Association 5672 Strand Court, Suite 2 Naples, Florida 34110‐3314

www.cemanet.org

Approved: January 26, 2015

Format edit July 1, 2015

CEMA TR 2015 ‐01 – Recommended CEMA Risk Assessment Process

DISCLAIMER

The information provided herein is advisory only.

These recommendations provided by CEMA are general in nature and are not intended as a substitute

for professional advice. Users should seek the advice, supervision and/or consultation of qualified

engineers, safety consultants, and other qualified professionals.

Any use of this video, CD, or publication, or any information contained herein, or any other CEMA

publication is made with the agreement and understanding that the user and the user’s company

assume full responsibility for the designs, safety, specifications, suitability and adequacy of any conveyor

system, system component, mechanical or electrical device designed or manufactured using this

information.

The user and the user’s company understand and agree that CEMA, its member companies, its officers,

agents and employees are not and shall not be liable in any manner under any theory of liability to

anyone for reliance on or use of these recommendations. The user and the user’s companies agree to

release, hold harmless and indemnify and defend CEMA, its member companies, successors, assigns,

officers, agents and employees from any and all claims of liability, costs, fees (including attorney’s fees),

or damages arising in any way out of the use of this information.

CEMA and its member companies, successors, assigns, officers, agents and employees make no

representations or warranties whatsoever, either expressed or implied, about the information contained

herein, including, but not limited to, representations or warranties that the information and

recommendations contained herein conform to any federal, state or local laws, regulations, guidelines

or ordinances.

CEMA TR 2015‐01 – Recommended CEMA Risk Assessment Process

1

RISK ASSESSMENT Risk can be defined as a combination of the probability of occurrence of harm and the severity of that harm. Risk assessment can be applied to personnel, property, environmental and societal events and their consequences. Reactively evaluating risk and dealing with the consequences through a variety of mitigation techniques is common in bulk material handling. What is not common is a standardized proactive approach to reducing risk through the use of a defined risk assessment and solution implementation process.

Figure 1 ‐ General risk assessment process


2

There are many terms used interchangeably with the term Risk Assessment. Risk Assessment in this book is defined as the process of reducing the probability and severity of harm to people, and/or the environment and/or property to an acceptable level through the use of a defined process. A defined risk assessment procedure is useful in identifying risks that can be mitigated at each stage of use of a product or service. Mitigating hazards by design or eliminating them by substitution is recognized as the most effective way to improve safety.

Figure 2 ‐ Effectiveness of risk mitigation methods

The risk assessment described here focuses eliminating risk through mitigating the hazard or hazardous

situation as it applies to systems, components and activities. Risk assessment is most commonly done by

a team of stakeholders and usually results in identifying and reducing risks that the manufacturer,

engineer, supervisor or worker may not identify or consider a serious hazard by themselves.

Each stakeholder at each stage of use of a product, system or service should perform a risk analysis. For

example the designer or manufacturer can assess risk on the equipment or activity as they foresee the

reasonable intended use of their product or service. However, the designer or manufacturer often does

not control the installation, integration of their equipment into a process, training on proper use or

maintenance or; the use of product or service on site, requiring further hazard identification and

mitigation. Job Safety Analysis is a form of risk analysis that is most effectively completed by those at

the point of installation, use or maintenance. It is often said that the fact that risk analysis is done is

more important than which risk assessment format that is used.

At the time of printing are no government mandated standards that must be used for risk reduction in

general bulk material handling. Therefore, it is up to each stakeholder’s management to establish and

implement a risk reduction methodology. In this document ANSI B11.TR3‐2000 and MIL‐STD 882* are

used as reference documents for developing an example risk assessment methodology with additional

suggestions for considering risks unique to your particular conveyor and conveyor installation.

*Note: ANSI B11.TR3‐2000 is available for sale from the Association for Manufacturing Technology. The

latest version of MIL‐Std 882 is available for free download from many online sources.


3

Acceptable Risk

The goal of a risk assessment is to reduce residual risks after analysis and implementation, to an

acceptable level. Zero risk is impossible to obtain. Acceptable risk is a subjective concept which is

defined by the risk assessment team often within established policy. Many risk assessment systems use

the concept of residual risk as being acceptable if it meets a test of “As Low As Reasonably Possible”,

ALARP

Determining ALARP is almost always a subjective judgment made by a team formed from a range of skill

sets within the context of their operation. If one member or group of the team dominates the judgment

on a particular point the result may not be reasonable so it is important to have a cross section of skill

sets in the risk assessment team with a method of reaching consensus. The team should reach some

definition of ALARP risk before starting the process. It is not necessary to address every risk that the

team identifies as some risks may be so remote or redundant that it would be a diversion from resolving

the significant risks.

Minimal risks that evolve into significant risks in the future or new risks that are introduced can be

identified if risk assessment is considered a continuous improvement activity and performed

periodically. The absence of qualitative data in ranking risk is not as important as the team’s perception

of the risk and their solution because data on specific hazards is almost never available for bulk material

handling operations and those involved daily with the risk are often the most expert in resolving them.

Teams can always seek outside expert advice if they become deadlocked or need specific expertise.

MIL‐STD 882

MIL‐STD 882 can be downloaded for free and used as guide. There are many other risk assessment

approaches readily available. There is no right or wrong approach. The important point is to have a

defined system that works for your operation and make it part of your safety culture. The basic

approach in all risk assessment systems is to list all of the hazards, hazardous conditions or at risk

behaviors that the team can readily identify. Brainstorming techniques are useful in this part of the

process. Once a list is generated, each hazard is rated for severity and probability of occurrence. The

combination of severity and probability is given a rank. Alternative means of reducing the risk are

evaluated and scored until the ranking is within the team's ALARP definition. In some cases the risk

cannot be reduced to an ALARP level through design or substitution. In those cases, alternate

approaches such as additional training or engineering controls can be used to mitigate the risk.


4

Table 1 ‐ Severity categories (adapted from MIL‐STD 882)

Obviously, for the hazards identified in the assessment to be effectively mitigated, the solutions must be implemented for them to become effective. Documenting the results is strongly suggested so that improvements can be monitored and goals for mitigation of risks adjusted if necessary. The most effective systems implement changes as quickly as possible, often through empowerment of the risk assessment team to take immediate action.

Table 2‐ Suggested Mishap Probability Levels (adapted from MIL‐STD 882)

Probability

Severity

Catastrophic (I)

Critical (II)

Marginal (III)

Negligible (IV)

Frequent (A) 1 3 7 13

Probable (B) 2 5 9 16

Occasional (C) 4 6 11 18

Remote (D) 8 10 14 19

Improbable (E) 12 15 17 20

Table 3 ‐ Mishap risk assessment matrix results with numerical values (adapted from MIL‐STD 882)

Probability

Severity

Catastrophic (I)

Critical (II)

Marginal (III)

Negligible (IV)

Frequent (A) 1 3 7 13

Probable (B) 2 5 9 16

Occasional (C) 4 6 11 18

Remote (D) 8 10 14 19

Improbable (E) 12 15 17 20

Description Category Definition

Catastrophic I Could result in death or permanent total disability, loss exceeding $1,000,000 or irreversible severe environmental damage that violates law or regulation.

Critical II Could result in permanent partial disability, injuries or occupational illness that may result in hospitalization of at least three personnel, loss exceeding $200,000 but less than $1,000,000 or reversible environmental damage causing a violation of law or regulation.

Marginal III Could result in injury or occupational illness resulting in one or more lost work day(s), loss exceeding $10,000 but less than $200,000 or mitigatable environmental damage without a violation of law or regulation where restoration activities can be accomplished

Negligible IV Could result in injury or illness not resulting in lost work day, loss exceeding $2,000 but less than $10,000 or minimal environmental damage not violating law or regulation.


5

Example: Severity vs. Probability ALARP Matrix Management forms a risk assessment team and provides some guidelines. Management sets the as low as reasonably possible risk level as shown in Tables 4 and 5 below. The team determines that they will use a combination number and letter ranking rather than all numerical values as shown in Table 3. For example, a hazard or work practice that creates a hazardous situation with consequences judged by the team to have marginal consequences (Marginal III) and is judged by the team to probably occur (Probable (B)) over the life of the equipment would be ranked III‐B.

Probability of Event ”X” Occurring

Severity of consequences of event “X” Occurring

(Table 1)

Catastrophic (I)

Critical (II) Marginal (III) Negligible (IV)

Frequent (A) I-A II-A III-A IV-A

Probable (B) I-B II-B III-B IV-B

Occasional (C) I-C II-C III-C IV-C

Remote (D) I-D II-D III-D IV-D

Improbable (E) I-E II-E III-E IV-E

Table 4 ‐ Hazard risk assessment ranking

Management determines that for the matrix in Table 4 the following criteria apply:

Risk Ranking Scores Action

I-A, I-B, I-C, II-A, II-B, III-A Unacceptable: eliminate, substitute or redesign

I-D, I-E, II-C, II-D, III-B, III-C, IV-A, IV-B Undesirable: review risk reduction plan with management

II-E, III-D, III-E, IV-C, IV-D, IV-E Acceptable: management review if cost is > $10,000

Table 5 ‐ Management criteria for ALARP risk acceptance

As Figure 1 shows, risk reduction or elimination is an iterative process. In this hypothetical scoring system the team has, in effect, been tasked with reducing risks into the shaded area of Table 4 and given authority by management to incur up to $10,000 to reduce identified risks within the scope of the assignment.

The team decides to focus on the risks associated with the common practice in the plant of taking a short cut by crossing under a conveyor. The particular


6

crossing is located where it is necessary for some workers to duck to avoid contact with the structure moving belt. A return roller is located nearby but is 7 ft (2.1 m) from ground level.

Figure 3 ‐ Conveyor existing layout for risk assessment example The team developed a list of potential hazardous situations using brainstorming techniques and ranked them by severity and probability. It is more important that the hazard list identify the most consequential hazardous conditions and possible outcomes than it is to list every possible scenario. If good safety and design review processes are in place, there will be additional risk analysis reviews before the teams final proposal is accepted and implemented.

Hazard Resulting Event Severity Probability

1 Carryback accumulation under

conveyor Slip on carryback ‐ possible back injury II A


conveyor Trip on carryback ‐ reach for hand hold ‐possible

laceration or fall II A


conveyor Walk on pile ‐ return roll no longer guarded by position ‐

Nip point exposure I C

4 Low clearance catwalk structure Hit Head ‐ laceration possible if not wearing hard hat III B

5 Traffic along both sides of conveyor Walk into Traffic without yielding ‐ pedestrian/vehicle

accident I D

6 Belt overloaded or mistracking Falling material from above ‐ injury from falling material

and additional accumulation causing slips and trips II C

7 Poor visibility at night or severe

weather Slip or trip possibility of increased pedestrian/vehicle

accident I C

Table 6 ‐ Example risk assessment severity and probability list


7

Comparing the team’s assessment with management’s ALARP matrix, the team concludes that the cross‐under location needs to be moved and redesigned.

Probability of Event ”X” Severity of consequences of event “X” Occurring (Table 2)

Occurring

(Table 14.34) Catastrophic (I) Critical (II) Marginal (III) Negligible (IV)

Frequent (A) I‐A II‐A III‐A IV‐A

Probable (B) I‐B II‐B III‐B IV‐B

Occasional (C) I‐C II‐C III‐C IV‐C

Remote (D) I‐D II‐D III‐D IV‐D

Improbable (E) I‐E II‐E III‐E IV‐E

Table 7 ‐ Example risk assessment severity and probability ratings.

The team recommends that the travel paths be controlled using handrails, a formal cross‐under with spill protection be installed, traffic control signs and guard rails installed and the area lighted at night. The result will be a minor inconvenience to workers traveling under the conveyor but it greatly reduces the severity and probability of accidents.

The team works with the maintenance department and comes up with a plan for making the changes that will take into account the needs of all that would use the cross under. The team also re‐evaluates the Severity vs. Probability matrix with the conclusion that their re‐design meets management’s requirement of ALARP risk. The process is documented and the changes are implemented.

Figure 4 ‐ Example risk assessment redesign to reduce severity and probability


8

Introduction to Appendices

ANSI B11.TR3‐2000 Risk Assessment and Risk Reduction ‐ A Guideline to Estimate, Evaluate, and Reduce

Risks Associated with Machine Tools, lists typical hazards and hazardous situations in the design,

installation, use and maintenance of machine tools.

There are hazardous and hazardous situations specific to typical bulk material and unit handling

systems, components and maintenance that need to be identified in addition to those listed in ANSI

B11.TR3‐2000.

Each design firm, manufacturer, installer, user and maintenance operation should develop a check list of

hazards and hazardous situations unique to their situation.

The following Appendices are provided as suggested starting points for developing a list of hazards that are common to most conveyors (Appendix 1) and that are unique to a particular type of conveyor (Appendices 2,3,4, and 5) and are not intended to be an all encompassing list. The list should be used as a supplement to other commonly available lists, such as those in ANSI B11.TR3‐2000 and MIL‐STD 882, and modified for each specific material handling operation. The ASME B20.1 and ISO 5045 Standards are recommended as sources of additional identified hazards.

There are often many types of process equipment and haulage systems in the proximity of conveyors that potentially represent significant hazards. The hazards they present should be considered in addition to simply analyzing the movement and storage of the material being conveyed on the conveyor. Regulations pertinent to the specific industry are another source of specified risks that can be added to check lists to customize the risk assessment process.


9

Appendix 1

Examples of Common Hazards and Hazardous Situations for All Conveyors and Conveying Systems

Ref # Hazard or Hazardous Situation, Item or Event

Site ConditionsFalling return idlers, components or conveyed productWet or slippery surfacesRelative location of Isle ways and pathwaysUntrained Personnel

Installation or Integration and Start upIncomplete specifications or instructionsMissing components or software for system or processInstallation labor not trained on specific requirementsWrong components delivered or parts missing Scheduling conflictsRun in issues with components or control systems

ComponentsFrictional heating from frozen component against moving beltIn running nip points between belt and rotating componentsCrushing between moving and fixed componentsApplying belt dressing to drive pulleyBackstop or holdback failureHot surfaces ‐ gearboxes and motorsSignificant quantity of bearingsKey seat or set screw snag points

System

Elevated systems and walk ways (egress per local and federal standards)Location of controlsCrossover or crossunder conveyorMoving transfer pointsPlugged chutes24/7 operationPortable conveyorsBelt tracking

1

2

3

4


10

MaintenanceWelding and cuttingManual lifting and positioning of heavy components in restricted spacesConfined spacesHigh pressure fluids and gasses usedLock Out Tagout (LOTO)

ControlsProper interlockingPull cord and E‐stop switchesRemote automated sequential startingLocal disconnect switchConvenience of LOTO locationUnexpected Startup ‐ Restoration of Energy after InterruptonSoftware Errors

CleaningStrains, slips and fallsLong handled and sharp toolsCompressed air or high pressure water used for cleaningRecovering of product from Return Belt or Pulleys with Conveyor OperatingLock Out Tagout (LOTO)

EnvironmentNoise and dustLow light conditionsBurns or scalding from contact with hot surfacesOther external influences (gravity, wind, etc.)

Guarding

Guard opening to hazard distanceGuard too heavy or has sharp edges

Guards at Nip Points: pulleys, idlers, convex curves, and take‐up and counterweight drop Guard size ‐ reach distance to hazardLubrication fittings external of guardUse of tools to removeColorWarning Labels

5

6

7

8

9


11

Electric ShockEnergized live exposed partsLack of earth groundingShorts, arcing, sparkingImproper wiringStatic buildup and discharge

Slip/Trip Falls

Fall from elevated work (fall protection)Miss‐use of climbing on conveyorFalling material from conveyor surfaceSpilled product or debrisUneven walking surfaces

Noise/VibrationNoise or sustained sound pressure levels > 85 dBANoise or instantaneous sound pressure level >120 dBAInterference with communicationsFatigue and alertness of operators

GeneralLock Out Tag Out Try Out procedureLoose clothing, hair, jewleryHeavy equipment with limited driver visibilityHigh voltage motors and electromagnetic fieldsPressure ‐ hydraulic or pneumatic component ruptureStructural members ‐ fatigue, corrosion, ruptureUnexpected Startup or Motion during Jam Clearing or MaintenanceLoss of communication with machine that affects stopping or control

13

10

11

12


12

Appendix 2

Examples of Hazards and Hazardous Situations in Bulk Belt Conveying

Ref # Hazard or Hazardous Situation, Item or EventBeltProtrusions, flaps or long sections of ripped conveyor belt Mechanical splices with protruding or loose components

Hypnotic effect of moving belt and rotating componentsWalking on stationary or moving beltRiding on beltStored energy, potential energy in belt, slack in the belt Static charge build up Sloped belt or belt splice failure

Belt mistrackingBelt fireMoving belt with no motion markersStored energy in pulling cable during belt installation Failure of belt clamp during installation or splicingEnergy stored in belt and components during clearing jams by jogging the belt

Vibration in steel cord belt

Bulk MaterialRespirable dustExplosive dust

Spontaneous combustionLarge lumps falling or projected from conveyorPotential energy of material accumulated on stationary belt, structure or in binsCaustic or acidic bulk materials

Site Conditions

Open top hoppers, bins, silosIn ground pits and receiving hoppers

Fire and/or explosion from accumulation of combustible finesElectrical classificationWaste water and drainage systemsUneven and/or unpaved surfaces

Dust control

ComponentsFalling gravity takeupMagnetic fields from tramp metal magnets

Radiation exposure from nuclear measuring devices

3

1

2

4


13

SystemTunnels and enclosed galleries with limited space between belt and access

Spillage and carryback Build up of bulk materials on rotating components or tracks

De‐icingUnguarded portions of conveyor by rule i.e. skirtboard seal and beltExposed to weather extremes

Installation or Integration and Start upTest bulk material not same as production material

Stockpiles

Mobile equipment traffic patternsHighwall failuresCrusted bulk material with opening or void below

Open unguarded draw down into feederStockpile level control failureSlope stabiliztion during reclaim operations

Dust controlSpontaneous combustion of product

7

6

5


14

Appendix 3

Examples of Hazards and Hazardous Situations in Unit/Package Conveying


BeltProtrusions, flaps or long sections of ripped conveyor belt

Mechanical splices with protruding or loose components Hypnotic effect of moving belt and rotating componentsWalking on stationary or moving belt

Riding on beltStored energy, potential energy in belt, slack in the belt Static charge build up

Sloped belt or belt splice failureBelt mistrackingBelt fire

Stored energy in pulling cable during belt installation Failure of belt clamp during installation or splicingEnergy stored in belt and components during clearing jams by jogging the belt

2 Drawing‐in / Trapping ‐ Belt ConveyorCarrier belt and end pulley InterfaceCarrier belt and drive pulley interface

Carrier belt and snubber roller interfaceCarrier belt and take‐up roller interfaceDrive train belt / chain and sprocket interface

Drawing‐in / Trapping ‐Live Roller ConveyorDrive belt and carrier roller interface

Drive belt and end pulley InterfaceDrive belt and snubber roller interfaceCarrier belt and take‐up roller interface

Drive train belt / chain and sprocket interface

3

1


15

Pinch Point

Between moving parts and fixed objects of lifts and transfersBetween slats on a slat conveyorPopout rolls

Shearing /SeveringBetween parts that move in close proximity to each other

Controls

Electromagnetic Frequency Interference and Compatability

4

5

6


16

Appendix 4

Examples of Hazards and Hazardous Situations in Screw Conveyors


1 Bulk Material

Respirable dust

Explosive dust

Elevated temperature of the material being conveyed

Corrosiveness of the material being conveyed

2 Site Conditions

Open top hoppers or buns

in ground pits and receiving hoppers

Electrical classification

Wet or slippery surfaces

3 Drawing In

Exposed screws not properly guarded

Covers not in place or securely fastened

4 Shearing / Severing

Exposed screws not properly guarded

Access plates or Covers not in place or securely fastened


17

Appendix 5

Examples of Hazards and Hazardous Situations in Bucket Elevator

Conveyors

Ref # Hazard or Hazardous Situation, Item or EventBulk Material

Respirable dust

Explosive dust

Elevated temperature of the material being conveyed

Corrosiveness of the material being conveyed

Potential energy of material in buckets on carry side

Site Conditions

Open top inlet chutes

In ground pits and receiving hoppers

Electrical classification

Wet or slippery surfaces

Shearing / Severing

Between buckets and fixed housing walls

Access door covers not in place or securely fastened.

Ladders and Work platforms

Insure safe access to overhead motors, drives, head bearings, etc.

1

2

3

4

END OF DOCUMENT

CEMA STANDARD NO: 352-2012

SCREW CONVEYORSAFETY

OPERATIONAND

MAINTENANCEMANUAL

Provided by the Membersof the

Screw Conveyor and Bucket Elevator Sectionof the

Conveyor Equipment Manufacturers Associationas a service to the industry

ISBN: 978-1-891171-43-7

CEMA STANDARD NO: 352-2012Approved: September 19, 2012


DISCLAIMER

The information provided herein is advisory only.

These recommendations provided by CEMA are general in nature and are not intended as asubstitute for professional advice. Users should seek the advice, supervision and/or consultationof qualified engineers, safety consultants, and other qualified professionals.

Any use of this publication, or any information contained herein, or any other CEMA publicationis made with the agreement and understanding that the user and the user’s company assumefull responsibility for the designs, safety, specifications, suitability and adequacy of any conveyorsystem, system component, mechanical or electrical device designed or manufactured usingthis information.

The user and the user’s company understand and agree that CEMA, its member companies, itsofficers, agents and employees are not and shall not be liable in any manner under any theoryof liability to anyone for reliance on or use of these recommendations. The user and the user’scompanies agree to release, hold harmless and indemnify and defend CEMA, its membercompanies, successors, assigns, officers, agents and employees from any and all claims ofliability, costs, fees (including attorney’s fees), or damages arising in any way out of the use ofthis information.

CEMA and its member companies, successors, assigns, officers, agents and employees makeno representations or warranties whatsoever, either expressed or implied, about the informationcontained herein, including, but not limited to, representations or warranties that the informationand recommendations contained herein conform to any federal, state or local laws, regulations,guidelines or ordinances.

i.

Conveyor Equipment Manufacturers Association5672 Strand Court, Suite 2

Naples, Florida 34110-3314www.cemanet.org

CEMA Screw Conveyor Safety, Operation & Maintenance ManualCopyright - September 2012


SECTION A - SAFETY Page 1 PDF Page 5

SECTION B - INSTALLATION Page 4 PDF Page 8

SECTION C - OPERATION Page 10 PDF Page 14

SECTION D - MAINTENANCE Page 11 PDF Page 15

SECTION E - SHUTDOWN AND STORAGE Page 12 PDF Page 16

SECTION F - TROUBLESHOOTING Page 15 PDF Page 17

Bolt Torque Guide Page 16 PDF Page 19

TABLE OF CONTENTS

ii.


INTRODUCTION

The Screw Conveyor and Bucket Elevator Engineering Committee of the CEMA(Conveyor Equipment Manufacturers Association) Engineering Conference wasassigned the task of bringing together, under one cover, the accumulated experienceof many individuals and their companies in an effort to provide a common basis forthe safety, operation and maintenance of screw conveyors.

The CEMA Safety, Operation & Maintenance Manual contains instructions for thesafe installation, operation and maintenance of screw conveyors. The reliability andservice life depend on the proper care taken while installing and preparing theequipment for its intended use.

Read ALL instructions in this manual and manufacturer's manuals BEFORE installing,operating and maintaining the equipment.

iii.


SECTION A - SAFETY

Screw conveyor safety begins with a plan that considers every possible danger andpotential hazard. Operation and maintenance personnel must be thoroughly trainedin safe operating procedures, recognition of possible hazards, and maintenance ofa safe area around screw conveyors.

CEMA has a comprehensive safety program that includes:• Warning and Safety Reminder for Screw Conveyors, Drag Conveyors and

Bucket Elevators - (CEMA Document: SC2004-01)• CEMA Safety Label Brochure - (CEMA Document: 201)• CEMA Safety Label Placement Guidelines:

• Screw Conveyor - (CEMA Document: SC-2)• Vertical Screw Conveyor - (CEMA Document: SC-3)

• Screw Conveyor Safety Poster - (CEMA Screw Conveyor Safety Poster)• Screw Conveyor, Drag Conveyor and Bucket Elevator Safety Video -

(CEMA Document: AV6) This video describes key safety practices thatpersonnel must follow when operating and maintaining screw conveyors,drag conveyors and bucket elevators.

Screw conveyor accidents can be avoided by implementation and enforcement ofan in-plant safety program. A number of safety precautions are included in thismanual. Carefully study and follow the safety precautions. Remember - accidentsare usually caused by negligence or carelessness.

1.


CEMA Document: SC 2004-01

WARNING AND SAFETY REMINDERS FORSCREW , DRAG , AND BUCKET ELEVATOR CONVEYORS

APPROVED FOR DISTRIBUTION BY THE SCREW CONVEYOR SECTION OF THECONVEYOR EQUIPMENT MANUFACTURERS ASSOCIATION (CEMA)

It is the responsibility of the contractor,installer, owner and user to install, maintainand operate the conveyor, components and,conveyor assemblies in such a manner as tocomply with the Occupational Safety andHealth Act and with all state and local lawsand ordinances and the American NationalStandards Institute (ANSI) B20.1 Safety Code.

In order to avoid an unsafe or hazardouscondition, the assemblies or parts must beinstalled and operated in accordance with thefollowing minimum provisions.

1. Conveyors shall not be operated unlessall covers and/or guards for the conveyor anddrive unit are in place. If the conveyor is to beopened for inspection cleaning, maintenanceor observation, the electric power to themotor driving the conveyor must be LOCKEDOUT in such a manner that the conveyorcannot be restarted by anyone; howeverremote from the area, until conveyor coveror guards and drive guards have been properlyreplaced.

2. If the conveyor must have an openhousing as a condition of its use andapplication, the entire conveyor is then to beguarded by a railing or fence in accordancewith ANSI standard B20.1.(Request currentedition and addenda)

3. Feed openings for shovel, front loadersor other manual or mechanical equipmentshall be constructed in such a way that theconveyor opening is covered by a grating. Ifthe nature of the material is such that agrating cannot be used, then the exposedsection of the conveyor is to be guarded by arailing or fence and there shall be a warningsign posted.

4. Do not attempt any maintenance orrepairs of the conveyor until power has beenLOCKED OUT.

5. Always operate conveyor in accordancewith these instructions and those containedon the caution labels affixed to theequipment.

6. Do not place hands, feet, or any part ofyour body, in the conveyor.

7. Never walk on conveyor covers, gratingor guards.

8. Do not use conveyor for any purposeother than that for which it was intended.

9. Do not poke or prod material into theconveyor with a bar or stick inserted throughthe openings.

10. Keep area around conveyor drive andcontrol station free of debris and obstacles.

11. Eliminate all sources of stored energy(materials or devices that could causeconveyor components to move without powerapplied) before opening the conveyor

12. Do not attempt to clear a jammedconveyor until power has been LOCKED OUT.

13. Do not attempt field modification ofconveyor or components.

14. Conveyors are not normallymanufactured or designed to handle materialsthat are hazardous to personnel. Thesematerials which are hazardous include thosethat are explosive, flammable, toxic orotherwise dangerous to personnel. Conveyorsmay be designed to handle these materials.Conveyors are not manufactured or designedto comply with local, state or federal codesfor unfired pressure vessels. If hazardousmaterials are to be conveyed or if theconveyor is to be subjected to internal orexternal pressure, manufacturer should beconsulted prior to any modifications.

CEMA insists that disconnecting and lockingout the power to the motor driving the unitprovides the only real protection againstinjury. Secondary safety devices are available;however, the decision as to their need and thetype required must be made by the owner-assembler as we have no informationregarding plant wiring, plant environment,the interlocking of the screw conveyor with

other equipment, extent of plant automation,etc. Other devices should not be used as asubstitute for locking out the power prior toremoving guards or covers. We caution thatuse of the secondary devices may causeemployees to develop a false sense of securityand fail to lock out power before removingcovers or guards. This could result in a seriousinjury should the secondary device fail ormalfunction.

There are many kinds of electrical devices forinterlocking of conveyors and conveyorsystems such that if one conveyor in a systemor process is stopped other equipmentfeeding it, or following it can also beautomatically stopped.

Electrical controls, machinery guards, railings,walkways, arrangement of installation,training of personnel, etc., are necessaryingredients for a safe working place. It is theresponsibility of the contractor, installer,owner and user to supplement the materialsand services furnished with these necessaryitems to make the conveyor installationcomply with the law and accepted standards.

Conveyor inlet and discharge openings aredesigned to connect to other equipment ormachinery so that the flow of material intoand out of the conveyor is completelyenclosed.

One or more warning labels should be visibleon conveyor housings, conveyor covers andelevator housings. If the labels attached to theequipment become illegible, please orderreplacement warning labels from the OEM orCEMA.

The Conveyor Equipment ManufacturersAssociation (CEMA) has produced an audio-visual presentation entitled “Safe Operationof Screw Conveyors, Drag Conveyors, andBucket Elevators.” CEMA encouragesacquisition and use of this source of safetyinformation to supplement your safetyprogram.

SEE NEXT PAGE FOR SAFETY LABELS

2.


CEMA Document: SC 2004-01

The CEMA safety labels shown below should be used on screw conveyors, drag conveyors, and bucket elevators. Safetylabels should be placed on inlets, discharges, troughs, covers, inspection doors & drive guards. See CEMA Safety LabelPlacement Guidelines on CEMA Web Site: http://www.cemanet.org

Exposed buckets andmoving parts cancause severe injury

LOCK OUT POWERbefore removingcover or servicing

CVS930012

CHR930001

Exposed movingparts can causesevere injury

LOCK OUT POWERbefore removingguard

CHS991026

Walking or standing onconveyor covers orgratings can causesevere injury

STAY OFF

WARNINGExposed screw andmoving parts can causesevere injury


CHR930011

Exposed conveyorsand moving partscan cause severeinjury


CVS930010

Exposed screw andmoving parts cancause severe injury


CVS930011

PROMINENTLY DISPLAY THESE SAFETY LABELSON INSTALLED EQUIPMENT

SEE PREVIOUS PAGE FOR SAFETY REMINDERS

Note: Labels alone do not substitute for a thorough in-plant safetytraining program centered on the hazards associated with

operating your installed equipment.

Contact CEMA or Your Equipment Manufacturer for ReplacementLabels

CONVEYOR EQUIPMENT MANUFACTURERS ASSOCIATION5624 Strand Court, Suite 2., Naples, Florida 34110

239-514-3441http://www.cemanet.org

CEMA Safety Labels

3.

http://www.cemanet.org



http://www.cemanet.orghttp://www.cemanet.org





CEMA Safety Labels Placement Guidelines

Product: Bulk Handling Equipment

Equipment:

NEAR SIDE

FAR SIDE

USE LABEL “A” ON BELT GUARDUSE LABEL “B” ON ENDS OF TROUGH, MIDDLE OFCOVERS AND AT INLET OPENING.USE LABEL “C: ON TOP OF COVERS

CHR930001



“A”

Exposed screw andmoving parts cancause severe injury


CVS930011

“B”

CHS991026

Walking or standing onconveyor covers orgratings can causesevere injury

STAY OFF

“C”

Screw Conveyor

“C” “C”“C”

To be placed on inlets anddischarges, troughs, cov-ers, and inspection doorsof screw conveyors toprovide warning againstexposed moving partswhile in operation.

To be placed onremovable guards towarn that operation ofthe machinery withguards removed wouldexpose chains, belts,gears, shafts, pulleys,couplings, etc. whichcreate hazards

SC-2


http://www.cemanet.orghttp://www.cemanet.org

4.


CEMA Safety Labels Placement Guidelines

Product: Bulk Handling Equipment

Equipment:

To be placed onremovable guards towarn that operation ofthe machinery withguards removed wouldexpose chains, belts,gears, shafts, pulleys,couplings, etc. whichcreate hazardsCHR930001



“A”

USE LABEL “A” ON BELT GUARD

USE LABEL “B” ON ENDS OF TROUGH,ON INTAKE INSPECTION DOOR,ANDBOTH SIDES OF DISCHARGE SPOUT

NEAR SIDE

FAR SIDE

Exposed screws andmoving parts cancause severe injury


CVS930011

"B"

To be placed on inletsand discharges, troughs,covers, and inspectiondoors of screw convey-ors to provide warn-ing against exposedmoving parts while inoperation.

SC-3

Vertical Screw Conveyor

"A"

"B"

"B"

BOTHSIDES



5.


6.


SCREW CONVEYOR COMPONENTS

Item Descripton1 Screw2 Screw with Bare Pipe at Discharge3 Coupling Bolts (Not Shown)4 Coupling Shaft5 Hanger with Bearing6 Tail End Trough End7 Trough End for Screw Conveyor Drive8 Trough End for Screw Conveyor Drive9 Trough with Discharge Spout

10 Seal11 Bearing12 Tail Shaft 13 Flanged Cover14 Flanged Cover with Inlet15 Buttstrap

16 Screw Conveyor Drive Unit with Motor Mount, V-Belt Drive, and Guard

Bill of Materials

7.


SECTION B - INSTALLATION

RECEIVING

1. Screw conveyors may be ordered as individual components with all the assembly operations performed in the field,or assembled completely by the manufacturer, with drawings and bill of materials.

2. Immediately upon receipt all items in the shipment should be checked against shipping papers for shortages andinspected for damage.

3. Items to be inspected include troughs, screws, covers and drive units.4. DO NOT ATTEMPT TO INSTALL DAMAGED COMPONENTS OR ASSEMBLIES.

LIFTING AND MOVING

1. Extreme care must be taken to prevent damage when moving assembled conveyors or components.2. Spreader bars with slings are the recommended support method for lifting.3. Unsupported span should be no greater than 12 feet.4. NEVER LIFT A CONVEYOR WITH ONLY ONE SUPPORT POINT.5. Unusually heavy items such as drives or gates shall be considered when choosing support points because of load

balance and their bending effect.6. Shop assembled conveyors are typically match marked and shipped in the longest sections for practical shipment.

ASSEMBLY

1. The mounting surface for supporting the conveyor must be level and true.2. Screw conveyor troughs must be assembled straight and true with no distortion.3. Place troughs in proper sequence with discharge spout properly located.4. Connect the joints loosely. DO NOT TIGHTEN BOLTS.5. Assemble each trough end to proper end of conveyor.6. Attach piano wire full length of conveyor at centerline. Make sure piano wire is pulled tight. Refer to Figure 1 at the

end of this section.7. Tighten trough flange bolts keeping the trough assembly true to piano wire. Alignment must be checked in both

horizontal and vertical directions. Maximum deviation in either direction at any point along the length of theconveyor is 1/8". Torque bolts to proper torque rating per Chart A.

8. Anchor trough assembly to mounting surface. Make sure entire length of trough is straight and true. CEMArecommends supporting trough assemblies every 10 to 12 feet. Saddles and feet may be required.

9. Mount drive or thrust unit on correct trough end. Drive or thrust units are normally located at discharge end ofconveyor. Make sure drive or thrust unit is centered in seal and trough end openings. Torque bolts to proper torquerating per Chart A.

10. Place the first screw section in the trough starting at the drive or thrust end. Install screw so end lugs are oppositecarrying side of flight.

11. Insert screw onto drive shaft and install coupling bolts. DO NOT TIGHTEN COUPLING BOLTS.12. Insert coupling shaft into opposite end of screw and install coupling bolts. DO NOT TIGHTEN COUPLING BOLTS.13. Pull screw section away from drive or thrust unit to seat thrust connection.14. Insert hanger onto coupling shaft.15. Raise hanger and screw section until hanger top bar is flush with top of trough. Make sure correct clearance exist

between outside diameter of screw and inside of trough. Match mark and drill troughs to mount hanger assembly.Insert hanger assembly bolts and hand tighten.

16. Assemble screw sections, couplings and hangers until all are installed by repeating steps 10 through 15. Install screwsections so flighting is 180-degrees from end of flighting of previous screw section.

8.


17. Center hanger bearings between screw sections. Torque hanger assembly bolts to proper torque rating per Chart A.18. Assemble seal and bearing to opposite trough end. Make sure end shaft is centered in seal and trough end openings.

Torque bolts to proper torque rating per Chart A.19. Insert end shaft through end bearing and into last screw section and install coupling bolts. DO NOT TIGHTEN

COUPLING BOLTS.20. Rotate entire screw assembly to check alignment and adjust hanger assemblies as required.21. Torque ALL coupling bolts to proper torque rating. Over tightening of coupling bolts could result in failure in tension.

CEMA recommends tightening coupling bolts to 75-percent of the values given in the Bolt Torque Guide to eliminateover tightening of coupling bolts.

22. Adjust seals as required.23. Remove all debris from conveyor.24. Install covers in proper sequence starting at inlet end and attach with provided fasteners.25. Lubricate drive and all bearings in accordance with manufacturer's instructions. DRIVES GENERALLY SHIPPED

WITHOUT OIL.26. MAKE SURE ALL CEMA SAFETY LABELS ARE IN PROPER LOCATIONS.

Figure 1 - Piano Wire Setup Diagrams

CEMA COMMONLY USED PIANO WIRE SETUPPIANO WIRE ATTACHED TO TOP OF CONVEYOR ON SIDE

OPTIONAL PIANO WIRE SETUPPIANO WIRE ATTACHED TO CENTERLINE OF CONVEYOR ON SIDE

9.


SECTION C - OPERATION

BEFORE INITIAL START-UP:

1. LOCKOUT/TAGOUT ALL POWER.2. Lubricate all bearings in accordance with manufacturer's instructions.3. Lubricate all gear reducers in accordance with manufacturer's instructions. Gear reducers are normally shipped

without lubrication.4. Check conveyor to ensure all tools and foreign materials have been removed.5. Turn drive unit by hand to check for alignment and obstructions.6. Check conveyor to ensure all covers, guards and safety devices are installed and operating properly.7. Attach gates to inlet and discharge chutes, where applicable.

INITIAL START-UP (WITHOUT MATERIAL):

1. Reenergize power to conveyor.2. Start conveyor momentarily to check for proper conveyor rotation. If conveyor rotation is NOT correct, quickly

shutdown and have qualified electrician change wiring.3. Operate conveyor without material for several hours as a break in period. Observe for excessive bearing tempera-

ture, unusual noise or drive misalignment. If these conditions occur refer to Troubleshooting Section of thisdocument.

4. Stop the conveyor and LOCKOUT/TAGOUT ALL POWER.5. Remove covers and check tightness of coupling bolts. Torque bolts to proper torque rating. Over tightening of

coupling bolts could result in failure in tension. CEMA recommends tightening coupling bolts to 75-percent of thevalues given in the Bolt Torque Guide to eliminate over tightening of coupling bolts. Replace covers.

6. Check all assembly and mounting bolts. Torque bolts to proper torque rating.7. Check conveyor discharge. Discharge must be clear to ensure that material flow out of conveyor will not be

impeded.

INITIAL START-UP (WITH MATERIAL):

1. Reenergize power to conveyor.2. Start conveyor and operate without material for several minutes.3. Feed material gradually until design capacity is reached.4. DO NOT EXCEED CONVEYOR SPEED, CAPACITY AND MATERIAL DENSITY.5. Start and stop conveyor several times. Operate conveyor for several hours with material.6. Check motor amperage when conveying at design capacity and compare to full load amperage of motor. Prob-

lems may exist if amperage is excessive. Check voltage to ensure that it is within normal operating limits.7. Stop the conveyor and LOCKOUT/TAGOUT ALL POWER.8. Remove covers and check tightness of coupling bolts. Torque bolts to proper torque rating. Over tightening of

coupling bolts could result in failure in tension. CEMA recommends tightening coupling bolts to 75-percent of thevalues given in the Bolt Torque Guide to eliminate over tightening of coupling bolts.

9. Check hanger bearings and realign if necessary.10. Replace covers.11. Check all assembly and mounting bolts. Torque bolts to proper torque rating per Chart A.

10.


SECTION D – MAINTENANCE

Practice good housekeeping. Keep area around conveyor clean and free of obstacles to provide easy access and to avoidinterference with the function of the conveyor.

Establish routine periodic inspection of the entire conveyor to ensure continuous maximum operating performance.LOCKOUT/TAGOUT ALL POWER BEFORE INSPECTION OF CONVEYORS. Periodic inspections should be made of thefollowing:

• Bearings – Check for proper lubrication. Lubricate all bearings in accordance with manufacturer’s instructions.Check hanger bearings for proper alignment and excessive wear. Replace hanger bearings when wear exceeds 1/8inch.

• Gear Reducers – Check for proper lubrication. Lubricate all gear reducers in accordance with manufacturer’sinstructions.

• Drives – Check for wear on belts and proper tension. Check for lubrication on chains and proper tension. Replacebelts or chains as necessary.

• Screws – Check for damage, excessive wear and material buildup. Replace screw sections as necessary.• Troughs – Check for damage, excessive wear and material buildup. Check trough alignment using piano wire as

described in Assembly Section of this document. Replace trough sections as necessary.• Shafts – Check for bolt hole elongation and wear. Check for run-out. Replace shafts when wear exceeds 1/8 inch.• Seals – Check for leakage. Adjust seal or replace packing as necessary.• Coupling Bolts – Check for wear. Replace worn coupling bolts as necessary. It is recommended to replace

coupling bolts and lock nuts when replacing screw sections. Torque ALL coupling bolts to proper torque rating.Over tightening of coupling bolts could result in failure in tension. CEMA recommends tightening coupling boltsto 75-percent of the values given in the Bolt Torque Guide to eliminate over tightening of coupling bolts.

• Assembly Bolts – Check for tightness. Torque ALL assembly bolts to proper torque rating per Chart A.• Guards – Check for clearance and bolt tightness. Check oil level on oil-tight guards.

REPLACING SCREW CONVEYOR COMPONENTS:

1. LOCKOUT/TAGOUT ALL POWER2. Removal of a screw section must proceed from the end opposite the drive or thrust unit.3. Remove trough end, screw sections, coupling shafts and hangers until the damaged screw section is reached and

removed.4. Reassemble conveyor components in accordance with the Assembly Section of this document.

NOTE: Quick disconnect screws can be removed at intermediate locations without first removing adjacent sections.

11.


EMERGENCY SHUTDOWN

An emergency shutdown may be necessary to clear obstructions or to replace damaged or worn components.

1. LOCKOUT/TAGOUT ALL POWER.2. Remove all covers.3. Remove all obstructions and product from conveyor.4. Inspect all components for damage or wear. Check conveyor components in accordance with the Maintenance

Section of this document.5. Replace all damaged or worn components. Replace conveyor components in accordance with the Assembly

Section of this document.6. Turn drive unit by hand to check for alignment and obstructions.7. Replace all covers and guards.8. Restart conveyor in accordance with the Operation Section of this document.

EXTENDED SHUTDOWN

An extended shutdown may be necessary if the conveyor is not in operation for a long period of time.

1. Operate conveyor until all product is removed.2. LOCKOUT/TAGOUT ALL POWER.3. Remove all covers.4. Remove all obstructions and product from conveyor.5. Inspect all components for damage or wear. Check conveyor components in accordance with

the Maintenance Section of this document.6. Replace all damaged or worn components. Replace conveyor components in accordance with the Assembly

Section of this document.7. Lubricate drive and all bearings in accordance with manufacturer’s instructions.8. Coat all exposed metal surfaces with rust preventative.9. Rotate screws by hand every week. Screws may sag and permanently deform if not rotated.

NOTE: When operation is to resume, restart conveyor in accordance with the Operation Section of this document.

STORAGE

1. Protect conveyor from weather, moisture and extreme temperatures. DO NOT use coverings that promotecondensation.

2. Coat all exposed metal surfaces with rust preventative.3. Rotate screws by hand every week. Screws may sag and permanently deform if not rotated.

NOTE: When operation is to resume, restart conveyor in accordance with the Operation Section of this document.

SECTION E – SHUTDOWN AND STORAGE

12.


SECTION F – TROUBLESHOOTING GUIDE

13.

PROBLEM CAUSE REMEDY

FLIGHT THICKNESS TOO LIGHTINCREASE FLIGHT THICKNESS. USE ABRASION RESISTANT METERIALS OR HARDFACING

RPM TOO HIGH OR TROUGH LOADING TOO HIGH

REDUCE SPEED. CONSULT CEMA 350 BOOK TO DETERMINE RECOMMENDED SPEED AND TROUGH LOADING.

INCORRECT ALIGNMENTREALIGN TROUGH ASSEMBLY AND HANGERS IN ACCORDANCE WITH ASSEMBLY SECTION OF THIS DOCUMENT.

IMPROPER SPEED AND TROUGH LOADING

CONSULT CEMA 350 BOOK TO DETERMINE RECOMMENDED SPEED AND TROUGH LOADING.

IMPROPER HANGER BEARING MATERIAL

CONSULT CEMA 350 BOOK TO DETERMINE RECOMMENDED BEARING MATERIAL.

EXCESSIVE BEARING WEAR REPLACE HANGER BEARING.

TROUGH THICKNESS TOO LIGHT

INCREASE TROUGH THICKNESS.USE ABRASION RESISTANT MATERIAL. CONSULT CEMA 350 BOOK TO DETERMINE RECOMMENDED TROUGH THICKNESS.

SCREW DEFLECTIONCONSULT CEMA 350 BOOK TO DETERMINE PROPER PIPE SIZE AND SCRW LENGTH.

BENT SCREW STRAIGHTEN OR REPLACE SCREW.

INSUFFICIENT NUMBER OF COUPLING BOLTS

INCREASE NUMBER OF COUPLING BOLTS

CONVEYOR SUBJECT TO FREQUENT STOP/START

FREQUENT OVERLOADS

5. DRIVE SHAFT BREAKAGE EXCESSIVE TORQUECONSULT CEMA 350 BOOK TO DETERMINE PROPER TORQUE RATING.

CEASE FREQUENT STOP/START. INCREASE BEARING CAPACITY OF SHAFT AND/OR INCREASE NUMBER OF COUPLING BOLTS

1. ACCELERATED FLIGHT WEAR

2. HANGER BEARING FAILURE

3. PREMATURE TROUGH FAILURE

4. SHAFT HOLE ELONGATION


SECTION F – TROUBLESHOOTING GUIDE - Continued

14.

PROBLEM CAUSE REMEDY

MOTOR UNDERSIZEDCONSULT CEMA 350 BOOK TO DETERMINE PROPER HORSEPOWER REQUIREMENTS.

UPSET LOADING CONDITIONEMPTY TROUGH, CONTROL FEED AND OPERATE UNDER DESIGN SPECIFICATIONS.

BEARING CONTAMINATIONUPGRADE OR REPLACE SEAL. CHANGE TO OUTBOARD BEARING.

INSUFFICIENT LUBRICATIONLUBRICATE IN ACCORDANCE WITH MAINTENANCE SECTION OF THIS DOCUMENT.

IMPROPER SHAFT RUNOUTCHECK SCREW STRAIGHTNESS AND REPLACE AS NECESSARY.

EXCESSIVE TORQUECONSULT CEMA 350 BOOK TO DETERMINE PROPER TORQUE RATING.

INCORRECT ALIGNMENTREALIGN TROUGH ASSEMBLY AND HANGERS IN ACCORDANCE WITH ASSEMBLY SECTION OF THIS DOCUMENT.

EXCESSIVE SHAFT WEAR REPLACE COUPLING SHAFT.

7. TROUGH END BEARING FAILURE

8. COUPLING SHAFT BREAKAGE

6. MOTOR OVERLOAD


CHART A - BOLT TORQUE GUIDE

Formula: T= K x D x P

• T Target tighten torque (the result of this formula is in inch pounds, dividingby 12 yields foot pounds)

• K Coefficient of friction (nut factor), always an estimation in this formula• D Bolts nominal diameter in inches• P Bolt's desired tensile load in pounds (generally 75% of yield strength)

[P(lbs) = (75%) Yield Strength * Tensile Stress Area]

Bolt Torque Guide is for fasteners used to assemble screw conveyors and does not include coupling bolts. Overtightening of coupling bolts could result in failure in tension.CEMA recommends tightening coupling bolts to 75-percent of the values given in the Bolt Torque Guide toeliminate over tightening of coupling bolts

END OF DOCUMENT

15.

All bolted applications should be evaluated to determine optimum tightening torque.K factor in the formula below is considered an estimate.The most commonly used K factor is 0.20 for plain finished bolts.

Bolt Dia. (inches)Threads Per Inch

(UNC) SAE 2 SAE 5 SAE 818-8 & 316

Stainless Steel

1/4 20 5 9 12 6

5/16 18 11 18 25 11

3/8 16 18 31 44 20

7/16 14 28 49 69 29

1/2 13 44 73 105 40

9/16 12 63 108 149 52

5/8 11 96 147 212 86

3/4 10 158 252 351 115

7/8 9 219 389 552 180

1 8 316 589 784 240

GENERAL BOLT TIGHTENING TORQUE (Ft. lbs.)

CONVEYOR EQUIPMENT MANUFACTURERS ASSOCIATION

5672 Strand Court, Suite 2Naples, Florida 34110-3314

Tel: 239-514-3441


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