AA_RP_000154 - CONVEYOR GUARDING

8/12/2019 AA_RP_000154 - CONVEYOR GUARDING

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COMPANY CONFIDENTIAL APPROVED Page 1 of 28

AA RP 0154 CONVEYOR GUARDING VERSION 102 FEBRUARY 2012

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CONVEYOR GUARDING

1 Scope 2

2 Definitions 2

3 Risk Management 2

4 Guarding of Conveyor Belts 4

4.1 Five Human Motions 4

4.2 Physical Hazards (Danger Points) 5

4.3 Safety Barriers 6

4.4 Typical Installation Requirements 10

5 Material Specifications 25

5.1 Primary Safety Barrier 25

5.2 Secondary Safety Barrier 26

5.3 Power Drive Unit 26

6

Maintenance 26

7 Removal of Guards 27

Appendix A: Reference Documents 28

Appendix B: Record of Amendments 28
mailto:[email protected]:[email protected]:[email protected]


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1 SCOPE

This document serves to provide the necessary guidelines on the safeguarding of belt

conveyor equipment. It outlines the interface between general human motion and knowndanger points on a belt conveyor installation.

2 DEFINITIONS

HIRA : Hazard Identification and Risk Assessment

Danger Points : This is identified as nip points and any rotating machinesor parts thereof that are a threat to the health and safetyof persons in the vicinity of belt conveyors.

Primary Safety Barrier : A guard installed to prevent human contact with a sourceof danger created by a rotating pulley or idler andeliminate the possibility of any person being drawn intothe nip point. Such guards include nip guards.

Secondary Safety Barrier : A guard, fence or barrier structure designed,manufactured and installed of such material and strengthas to afford the necessary protection against inadvertenthuman contact with a moving or rotating component of aconveyor belt system.

Tertiary Safety Measures : Such measures cover personal protective equipment(PPE).

Indirect Safety Measures : Such measures will include operator and personneltraining which is likely to move in the vicinity of a conveyorbelt.

3 RISK MANAGEMENT

All exposed machinery which, when in motion, may be dangerous to any person shall besecurely fenced off or effectively guarded. Efficient guards shall be provided to such partsof any machinery as may be a source of danger to any person.

The wording may be dangerous to any person and may be a source of danger to anyperson clearly implies that at places where persons may reasonably be expected to workor move about, machinery must be guarded of fenced off. It does not matter whether aperson has or has not any right to approach such items of machinery, for should anaccident result, the plea of safety by position will not normally be accepted in a court oflaw unless at least certain minimum requirements were complied with. Also implicit in thestatutory requirements, is the fact that it is not sufficient to act with hindsight but, as far asis humanly possible hazards must be identified before danger arises. Guards or fencesmust therefore be constructed to protect against unforeseen contingencies, not merelyagainst normally expected operational hazards.

The employer must take reasonably practicable measures to prevent persons from beinginjured as a result of them, the clothes being worn by them or any equipment being held


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by them coming into contact with or being drawn into any moving part of any machine.

The measures to be taken by the employer to prevent any person from coming intocontact with any moving part of machinery or any equipment attached thereto, mustinclude:

a) Effective physical barriers at the machinery such as screening, guarding or fencing;or

b) failsafe electric or electronic barriers interlocked with the machinery in such a waythat the machinery would be stopped before persons come into contact with movingmachinery or parts thereof; or

c) Effective barriers at a safe distance away from any machinery

Key Words : All Exposed; In motion; All sources of danger; Efficiently guarded, Source of

danger

Hazard is the Source of or exposure to danger

Risk is The likelihood that occupational injury or harm to a person will occur

Ergonomics is the Study of the relationship between man, the equipment with which heworks, and the physical environment in which this man -machine system operates.

Safety Objectives are:

a) Prevent any person from being injured at any belt conveyor installation

b) Guards must be adequately designed and installed

c) Do adequate maintenance on and around guards to prevent guard from beingineffective due to its design or any external influence such as spillage, impactdamage, etc.

d) Only persons authorised by the employer may start, operate and maintain beltconveyors.

e) Only persons permitted by the employer may be in the vicinity of any belt conveyorinstallation.

f) Belt conveyors may only operate if ALL safety guards, as determined by legislation

and Risk Assessment for the particular conveyor, is installed correctly andeffectively maintained for safety.

g) Persons may not wear loose clothing, or anything else that can be caught in theevent that the moving parts of a conveyor are exposed.

h) All stored mechanical, electrical, hydraulic, chemical or other forms of energy will beremoved from the conveyor installation before any safe guard is removed.

i) Barriers must be installed and so positioned at a safe distance away from movingmachinery or their parts.

The following serves to establish the requirements of effective guarding:

a) IDENTIFY all the danger points with regards to the belt conveyor installation.


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b) DESIGN - Determine the extent to which the danger point is to be safe guarded.

c) CONSTRUCT the guard to the required dimension using the correct material toensure and maintain safe guarding.

d) ISOLATE the belt conveyor installation following the correct lockout procedure andINSTALL the constructed guards.

e) MAINTAIN the safe guards according to correct installation, deterioration of guards.

f) REPLACE guards when they become ineffective in its function as a safety barrier.

ISOLATION & LOCKOUT When any repairs, maintenance, routine cleaning andcleaning of spillage is done on or in the vicinity of conveyor belt installation the powersupply of a conveyor belt installation shall be removed and when the belt conveyor hasbecome stationary this stationary conveyor belt installation shall be locked out.

4 GUARDING OF CONVEYOR BELTS

4.1 Five Human Motions

Mechanical danger points around the conveyor are identified by a risk assessmentprocess. Each of these danger points must be addresses in terms of the extent to whichthe danger point is to be guarded and followed by the specified materials used to safeguard such danger point. The extent to which such danger points are safe guarded isdependent on the five physical motions of a human being when in the vicinity of operatingmachines.

For a guard or a fence to be effective it must be so constructed that a person is preventedfrom reaching the danger point. A person may normally be regarded as capable ofreaching upward, over, into, around or through a guard or fence and all five these aspectsmust be taken into account when considering the effectiveness of a guard or fence:

a) Reaching Upwards - Any rotating or moving equipment or machinery, includingpulleys and idlers which are installed and operated at a height above 3,5 m from theground or a working platform where persons might be positioned will be regarded aspositionally safe and need not to be guarded. The possible reduction of thisminimum safe clearance, due to a build-up of spillage or discharge of material, mustbe taken into account in the design of the guards. Risk Assessments must beroutinely conducted within the workplace to identify such areas of change.

b) Reaching Over Head and tail pulleys must be guarded on at least the two sidesand the top unless the guards or fences on the sides are carried to such a heightthat it is impossible to reach over it into the nip point. If the side guards only areprovided with a very small clearance between the edge of the carry belt and the sideguard, this may perhaps be regarded as adequate to prevent reaching over theguard and touching the nip point but this will not necessarily prevent tools or clothingfrom being caught in the nip point. If the head end is provided with a top guard itmust be high enough above the belt to ensure that the moving load will not impactand damaged the guard. Tail pulleys in addition to the sides must be guardedacross the rear end from the end of the one side-guard to the end of the other side-guard. Such guard must not be installed closer than 150 mm from the tail pulleycircumference.

c) Reaching Into The distance that the guard or fence is away from the side of thebelt will really determine the distance the guard or fence must be extended away


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from the nip point along the length of the belt. The distance from the guard to theedge of the belt must be a minimum of 150 mm while the side guard extends at least850 mm away from the position of the nip guard along the belt line.

d) Reaching Aroun d This really has the same meaning as into as far as theconveyor pulley guard is concerned but may also be applied to determine the lengthof the top section of the guard. The same minimum distance of 850mm must apply.

If there is a V-belt or chain drive associated with the conveyor installation a verycommon defect is often found where the V-belts or chains are perfectly guardedaround the perimeter and on one side, but the guard is so installed that the nippoints can easily be contacted by reaching around the section forming the perimeterguard.

e) Reaching Through - The protection afforded against injury by reaching throughthe guard will be determined by the shape and size of openings in the material usedfor construction of the guard or fence and is governed by this document.

4.2 Physical Hazards (Danger Points)

The following exposed hazards require ONLY a Secondary Safety Barrier

a) Electric motor shaft

b) Gearbox in- and output shaft

c) Gearbox external fan

d) High speed coupling and associated in-and output shafts (such as Fluid Couplingsor Semi-flexible Coupling)

e) Pulley shafts extending past the outside of both plummer blocks to which personscould be exposed to (could be idle or driving shafts)

f) Take-up carriage area

g) Take-up counterweight tower

h) Take-up rope, sheaves and winches

i) Belt turnover(s)

The following exposed hazards require ONLY a Primary Safety Barrier

a) Return Idler nip points When the belt is moving onto the face of the return idlerrolls and when access underneath the conveyor is possible, exposing such nippoints.

b) Where idlers are specifically designed and installed to restrict the upward movementof a conveyor belt during a start-up or run-down procedure

c) When the belt tension is such that the additional normal force and belt weightpressing down on idlers in a convex curve posses a significant risk to safety ofpersons.

d) In areas where idler sets or impact cradles are installed below a bunker, feeder-bin,

silo hopper or transfer chute to support a belt, eliminate spillage and improve theloading profile onto the belt and also applies, even more so, to belt on which hand


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sorting is performed.

The following exposed hazards require a Primary AND Secondary Safety Barrier

a) Pulley nip points Where belt moves onto the pulley face

The following point DO NOT require a Primary or Secondary Safety Barrier

a) Carry Idler nip point Where the belt is moving onto the carry wing idler roll surface.

4.3 Safety Barriers

4.3.1 Primary Safety Barriers

Definition

A nip point is created when a belt moves onto a rotating pulley or return idler and require aprimary safety barrier and is positioned with respect to the rotation of a pulley or returnidler. This guard extends over the whole width of the pulley or idler and may be regardedas a reasonable solution to prevent access to danger points. A person is not completelyprevented from reaching around it and therefore cannot, by itself, be regarded assufficient protection and it is therefore essential that guarded pulley nip points be furtherguarded or fenced off with a secondary safety barrier.

The nip point created by a carry idler cannot in all circumstances be regarded as a threatto life or limb. The mass of the belt, load and convex curve normal force will affect thedecision on whether or not carry idlers required guarding. This will be installation specificand each engineer must determine the necessity of such guards.

Positioning

At the point where a moving belt moves onto the pulley face of a rotating pulley or whereaccess underneath a conveyor is possible and the nip point, created by the belt movingonto a return idler(s), is exposed/reachable:

a) Belt onto Pulley - The entry point of the belt onto the pulley is known as a dangerousnip point. Any object making contact with any nip point while the belt is in motion willresult in the object being drawn into the nip point. An effective means to safe guardthis nip point is to install a primary AND secondary safety barrier.

HeadPulley

TailPulley


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Figure 1

b) Belt onto Idlers - The entry point of the belt onto the return idler is known as adangerous nip point. A dangerous condition exists when access underneath (h) therun of conveyor is possible and such nip point is less than 3, 5m and more than 1mabove the walking platform or ground where persons may be positioned or moving.

Any object making contact with this nip point while the belt is in motion will result inthe object being drawn into the nip point. An effective means to safe guard this nippoint is to install a primary OR secondary safety barrier. This will include a nip pointguard, fully or semi-enclosed guard or barricading the dangerous portion on bothsides of the conveyor to prevent access underneath the conveyor. Barricadinginclude cross bracing two or three 8 gauge galvanized steel wire rope with No -Entry signs on such bracing.

Figure 2

The positioning of pulley nip guards is illustrated in Figure 3. The belt running awayfrom the pulley surface is not shown in the figure. The figure therefore showsdifferent variations of angles at which the belt runs onto the pulley surface for allangles around the pulley and how the nip guard should be positioned. The tail pulleynip guard shown in green is the exception to the general orientation as indicated inblue.

Figure 3 is as illustration of pulleys rotating in the counter clockwise rotation, butequivalent requirements will apply for clockwise rotation.

1m < h < 3,5m

Ground / Working platform


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Figure 3 Position of Nip guard when belt run onto pulley surface

General

On its own a nip guard is not regarded as sufficient or effective protection and it is a

requirement that all pulleys must be further guarded, barricaded or fenced off with asecondary safety barrier.

4.3.2 Secondary Safety barriers

Definition

Such barriers consist of a guard or fence and is designed, manufactured and installed ofsuch material and strength as to provide the necessary protection against inadvertenthuman contact with moving or rotating components of a conveyor system.

Positioning

Figure 4 illustrates the specific areas along a conveyor system which is most likely to be

90

270

0180

Third Quadrant (180 - 270) Forth Quadrant (270 - 360)

45

225

180

270

90

0

Second Quadrant (90 - 180) First Quadrant (0 - 90)

PULLEY

Tail pulley nipguard


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equipped with secondary safety barriers. The following locations typically requiresecondary safety barriers depending on the conveyor design layout:

a) A Head/Discharge End comprising of a driving or idling pulley(s)

b) Drive area which is located either at the Head End, Intermediately or Tail End

c) Return belt Take-up system situated behind the intermediate or head drive

d) The Loading Point where material is loaded onto the belt

e) Run of Conveyor consists of a conveyor stringer (structure) with the carry andreturn idler brackets and normal run of belt and are typically situated between:

1. The Head and Intermediate Drive, And / Or

2. The Head Drive and following Take-up, And / Or

3. The following Take-up and the last Loading Point

4. Between Loading Points

5. First Loading Point and Tail End

f) A Tail End comprising of a driving or idling pulley

For clear understanding and purpose, this specification will address each of theselocations in the following paragraphs in an attempt to understand the requirements ofprimary and secondary safety barriers.

Figure 4 Secondary Barriers

4.3.3 Tertiary Safety measures

Such safety measures are defined as personal protective equipment(PPE) and eachperson will at all times wear the appropriate PPE applicable to the conveyor installationsand other machines which the person will be exposed to. Persons in close proximity of

moving parts of machinery must not wear clothing or anything else that may be caught insuch moving parts.

Head End And/OrHead- Drive

location

IntermediateDrivelocation

FollowingTake-uplocation

Loadingpoint (s)

Tail End And/OrTail-Take-up

location And/OrTail-Drive

Run ofConveyor

4.2.1 / 4.2.2

4.2.2 4.2.3

4.2.4 4.2.5

4.2.6 / 4.2.3


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4.3.4 Indirect Safety measures

Such safety measures include the necessary personnel training and managementrequired to safely manage, operate and maintain belt conveyor installations. The followingmeasures must be adhered to:

a) Only authorised persons may start, operate and maintain belt conveyors

b) When moving parts of a conveyor belt installation or other such conveyorequipments poses a significant risk to any person, such movement will only be doneunder the direct supervision of a competent person.

c) Only persons authorised to do so may enter the area where belt conveyor operate.

d) Persons in close proximity of moving parts of machinery must not wear clothing oranything else that may be caught in such moving parts.

A properly guarded belt conveyor installation is not, in itself, inherently safe but withadequate training and proper awareness of dangers, an operator may use it with perfectsafety.

Operator training is usually the personal responsibility of the person in charge of theproper operation and running of the machinery. He must guard against the fact that overfamiliarity with the machines on his part and an over estimation of operator skills andknowledge does not result in and under estimation of the amount of instruction anddegree of supervision necessary for the safe execution of tasks. Comprehensive trainingschemes to ensure that operators are made familiar with the equipment with which theywill be associated, (which includes re-training) are essential.

4.4 Typical Installation Requirements

4.4.1 Head End

The head end of a conveyor installation typically consists of a head pulley and in somecases a snub pulley. The head pulley can either be driven or idling depending onoperational and design requirements.

In cases where the design of the head end is such that persons can move underneath thehead end, it is required that all pulleys, belting, material trajectory and material flow beeffectively guarded to prevent inadvertent contact with such moving equipment or material

flow and the construction of such guards will be such as to minimise or prevent the build-up of fugitive material on such guards. Due to the general elevation of the head end, it is,in most installations, not possible to access the pulleys and belting from beneath the headend as the chute and supporting structure generally covers this area. No gaps andopening may exist that would allow a finger or any part of limb of any person to reach anydanger points associated with the head end.

For the purpose of inspection and maintenance, a walkway platform is typicallyconstructed to move around the head end. Guarding around the head end must thereforeadhere to the following general requirements as referred to figure 5.

a) Dimension A1 The guard covering the sides of head and snub pulley shall extendupward above the head pulley circumference enough so that no person standing onthe working platform next to the head end is able to reach over the guard and touchthe nip point of the head pulley. If the top of the head end is guarded, the height of


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the side guards can be reduced such that this top guard will not be closer than 900mm from the head pulley circumference.

b) Dimension B1 The guard in front of the head pulley must be situated such that the

material trajectory will not impact directly onto the guard cover, unless the guardstructure has been designed with impact plates in order to ensure that safety guardsare not damaged by the impact from the trajectory.

c) Dimension C1 The guard covering the sides of head and snub pulley shall extenddownward up to the walking platform level in such a manner that it would beimpossible to reach the nip point of any pulley in the vicinity of the head end.

d) Dimension D1 - The guard covering the sides of head end shall extend a minimumof 850 mm along the belt line (Figure 5):

1. As measured from the circumference of the head pulley if the head end onlyconsist of on head pulley.

2. As measured from the circumference of the snub pulley if the head end isequipped with such a snub pulley out-bye of the head pulley.

e) Dimension E1 - The guards covering the sides of the head and snub pulleys shallnot be closer than 50 mm from the edge of the pulley shell.

f) Dimension F1 - The shaft of the head pulley and any other shaft extending throughthe main guard side panels shall be guarded such that the gap between the rotatingshaft and the side guard panels are inaccessible to any persons standing or movingon the working platform. Where the primary and secondary belt cleaning scraperframe-shaft extends through these side guard panels, the gap between the scraperframe-shaft and the guard panels is inaccessible to any persons standing or movingon the working platform.


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Figure 5 Guarding at the Head End

4.4.2 Drive

The drive can be located either at the head end, intermediately at a point along the lengthof the conveyor, at the tail or a combination of these locations. The location(s) of the drivelargely depends on the conveyor design and geometry.

The drive typically consists of the drive pulley(s) and associated snub pulleys to achievethe necessary drive pulley wrap angle(s).

The electric motor output shaft is mechanically connected to the gear reduction unit with ahigh speed coupling and in a lot of cases this high speed coupling unit serves as a start-up control device, better known as hydraulic (fluid) couplings. The output shaft of the gearreduction unit is then connected to the drive pulley shaft with a low speed coupling.

Primary safety barriers are required for the drive and snub pulleys whereas secondarysafety barriers are required to cover all pulleys, the low and high speed couplings, all

WORKING PLATFORM

C1

B1D1

A1

D1

B1

E1

F1

SIDE VIEW

PLAN VIEW

Primary Safety Barriers(Nip guards)

Pulleys

Conveyor Belt

ChuteStructure


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exposed shafts and cooling fans of both the electric motor and gear reducer.

The guarding of drive bend pulleys in the vicinity of walkways will be covered in thesection dealing with similar take-up bend pulleys.

Driving belts, chains and couplings between driving motors and gearboxes or drive pulleysmust be effectively guarded. Experience has shown that even when transmissions areapparently inaccessible they can still be a hazard. If the driving mechanism or any otherpart is fenced off completely in such a way that access thereto can only be obtainedthrough a gate or door forming part of the fencing, then this gate or door should beinterlocked so that the conveyor is stopped when this gate or door is opened.

Head Drives

The head chute structure is generally considered as the secondary safety barrier guarding

the pulleys and primary safety barriers (nip guards) will be installed accordingly. The driveunit(s) (motor, couplings & gear unit) will be either base plate mounted or shaft-hungmounted with a torque arm connected to the supporting structure and such units arelocated on the outside of the head chute structure in the walkway area and safe guardingof these drive units are therefore imperative. Figure 6 is a plan view of drive units in thehead area and where guarding is required.

For installations where access is required around the power drive unit(s) of a head pulley,it is necessary to ensure:

a) The electric motor cooling fan is effective guarded to prevent contact with the bladesor shaft of the fan.

b) The high speed coupling located between the electric motor and reducer iseffectively guarded. This guard shall not consist of any holes or openings and shallbe constructed of plate metal. No inspection doors or openings shall be allowed aspart of the design of the guard.

c) The cooling fan on the gear reduction unit is effectively guarded to prevent contactwith the blades or shaft of the fan.

d) The low speed coupling located between the reducer and head pulley shall beeffectively guarded to prevent contact with any part of the coupling.

e) All shafts forming part of the drive unit and pulley system shall be effectivelyguarded as to prevent any contact with any part of such shafts. A guard shall beinstalled to cover the gap between the pulley shaft and the chute when the minimumgap between the plummerblock and the bearing exceeds 100 mm.

f) If the head or any other pulley is equipped with an external low speed holdback(back stop) this unit will be guarded in such a manner that is would be impossible tocontact any part of the unit including its torque arm.

g) In the event of a V-belt or chain drive associated with the conveyor installation, suchdrives must be guarded on its perimeter and both sides that will prevent personsfrom reaching around the perimeter guard and contacting the danger nip points onsuch a drive.

h) All of these above mentioned guards will be secure to the component or supportingbase plate. The guard of any fluid coupling will be bolted on all four corners tomaintain safety in the event that a fusible plug is blown.


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Figure 6 Guarding of pulleys and power drive unit

Intermediate Drives

In some installations where the entire OR secondary drives and pulleys are situated at apoint along the run of conveyor, specific guarding requirements apply. There are twomethods of effective guarding of such drive areas:

a) Independent Guarding

This guarding method comprises of one guard frame to safeguard all drive pulleysand associated snub pulleys independent from the power drive unit. In this case thedrive pulley shaft will extend through the guarding toward the power drive unitssituated outside the guarded drive pulley system.

In this case, power drive units will be guarded in the same manner as explainedabove.

It will be required to install primary safety barriers (nip guards) on each pulleywhether they are accessible or inaccessible to human contact and such nip guardswill be positioned in accordance with figure 3.

When any person, standing or moving on ground level or on any elevated workingplatform, are required to move next to such pulleys, the following requirements applywith regards to secondary safety barriers in order to safe guard persons from suchpulleys (refer to figure 7):

Motor Gear Unit

Couplings

WalkwayPlatform

Legend : Guarding Required

Conveyor Belt

Bearing

Bearing

ChuteStructure

Pulleys

Cooling Fans

>100 mm


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1. Dimension A2 - The height of the side guard panels shall be such that noportion of any pulley or belting can be touch when standing on the groundlevel or working platforms. These side guard panels will be constructed fromground or working platform level in order to prevent any person reachingunderneath the guard and touching any part any pulley or belting. The heightof these guards will be restricted to a minimum height of 2, 5 m, unless theseguards have reached the bottom of the conveyor stringer. In such cases theside of the return stand will also be guarded up to the carry deck and a deckplate will be constructed between the carry and return strand long enough toextend at least 850 mm past the nip point of any reachable pulley in bothdirections of belt line.

2. Dimension B2 In most cases, this rear guard panel is not installed due to theintegration of the drive guarding with the take-up system guards. In the eventthat this drive pulley system is guarded independently from the take-upsystem, it is recommended to install this guard not closer than 150 mm as

measured from the closest pulleys circumference to this guard. The height of this rear guard will be restricted to a minimum height of 2, 5 m unless theguard has reached the bottom of a stringer.

3. Dimension C2 This front guard shall not be closer than 150mm to any of thepulleys circumference. The height of this guard will be restricted to a minimumheight of 2, 5m unless the guard has reached the bottom of a stringer but willbe have sufficient as to prevent any person contacting any part of the pulley orbelt while standing on the ground level or working platform.

4. Dimension D2 Guards in this area are generally constructed on the outsideof support structural members, but these side guard panels must not be closerthan 150 mm as measured from the edge of the pulley shell.


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Figure 7

5. If any pulley shaft extends through the guards, such portion of the shaft will beeffectively guarded so that it would be impossible for any person to contactany part of that shaft.

6. In the event of a V-belt or chain drive associated with the conveyor installation,such drives must be guarded on its perimeter and both sides that will preventpersons from reaching around the perimeter guard and contacting the dangernip points on such a drive.

b) Fully Enclosed Guarding

Fully enclosed guarding involves fencing off the entire drive area. All associateddrive pulleys, power drive units and in some cases take-up systems are fenced offand access to the area can only be made through a door(s) or gate(s) and such

doors and gates must each be interlocked such that power is removed from thepower drive units once the door or gate of the fencing is opened. The opening ofsuch gates or doors will be such that they hinge on the sides and swing outwardly.

SecondaryDrive

Primary Drive

Ground level or working platform

A2B2 C2

SIDE VIEW

D2

B2 C2

Conveyor Belt

Pulleys

FrontGuardpanel

RearGuardpanel

Example of drive pulley layout


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It will be required to install primary safety barriers (nip guards) on each pulleywhether they are accessible or inaccessible to human contact and such nip guardswill be positioned in accordance with figure 3.

When any person, standing or moving on ground level, the following requirementswill apply to fenced-off guarding which forms part of secondary safety barriers:

1. The height of the fence shall be such that no portion of any pulley, belt, driveunit or take-up moving parts can be touch when standing on such ground leveloutside the fenced-off area. These side guard panels will be constructed fromground level in order to prevent any person reaching underneath or over theguard. The height of these guards will be restricted to a minimum height of 2,5m.

2. This guard shall not be closer than 150mm to any of the pulleys circumferenceand any part of the power drive unit(s) or take-up system.

3. The gate(s) or door(s) constructed to access such areas shall hinge on thesides of the panel and shall swing away from the fenced off area.

4. The guards covering the fan of both the motor and gear box will be presentand secure. In the event that a fluid coupling is used as the start-up controldevice, the entire fluid coupling will be guarded as explained previously.

Tail Drives

In the event that the tail end consists of a power drive unit, the same independentguarding requirements will apply with regards to the power drive unit and pulleys. Primaryand secondary safety barriers will comply as stipulated in the section covering guarding ofthe Tail End of conveyor installations. The nip point of associated snub pulley will also beequipped with a nip guard.

4.4.3 Take-up Area

The take-up system design of a belt conveyor largely depends on what the belt conveyorrequire for successful operation under starting, running and stopping conditions. For thisreason, the following list of typical take-up design layout exists:

a) Vertical Gravity Consist of a pulley-counterweight system moving vertically in atower.

b) Horizontal Gravity Consists of a pulley- carriage system moving horizontally onrails and a counterweight moving vertically in a tower.

c) Horizontal Automatic/Manual Winch Consist of a pulley-carriage system movinghorizontally on rails and an automatic or manual winch system also acting in thehorizontal plane.

d) Horizontal Screws Consists of a pulley plummer block arrangement which ismanually locked in position with screws acting on the plummer blocks in thehorizontal plane.

Due to the variety of take-up designs as mentioned, the specification will deal withguarding of counterweight towers, take-up carriages, screws, associated bend pulleys aswell ancillary take-up equipments such as rope, sheaves and winches.


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a) Counterweight towers

The counterweight tower can facilitate the operation of a counterweight box or acombination of a counterweight box with a pulley.

It will be required to install primary safety barriers (nip guards) on all pulleys whetherthey are accessible or inaccessible to human contact and such nip guards will bepositioned in accordance with figure 3.

For counterweight boxes operating less than 5m from ground level, it will berequired to install guarding around the tower starting from ground level to aminimum height of 3m or until it is impossible to reach over the guard and touch thecounterweight. For counterweight boxes operating higher than 5m from groundlevel, it will be required to install guarding around the tower starting from groundlevel to a minimum height of 2,5m or until it is impossible to reach over the guard

and touch the counterweight.

The guard shall not be closer than 250mm as measured from the counterweightbox, pulley, guide rolls or belt. If such guards consist of gates, such gates will bekept locked and interlock switch will be installed that will remove power from theconveyor installation once the gate is opened. The area inside and outside thecounterweight tower shall be kept clean to avoid damage to guards as a result ofbuild-up material.

For installations where elevated walkways provided movement next to suchcounterweight towers it will be required to install guarding on that portion of thecounterweight tower to a minimum height of 3m as measured from the elevatedwalkway level or until it is impossible to reach over the guard and touch thecounterweight and shall proceed around the tower to such extend as to preventcontact with any part of the counterweight box, pulley, guide rolls or belt inside thetower. If elevated platform levels exist around such a counterweight tower it will berequired to install such guards all around the tower to a minimum height of 3m oruntil it is impossible to reach over the guard and touch the counterweight.

b) Take-up Carriages

Take-up carriages consist of a moving trolley unit which supports the take-up pulleyand this unit will move on rails in a horizontal or inclined angle depending on the

conveyor layout design.

In the case where the top of the carriage remain unguarded, it is recommended thatthe guards surrounding the carriage extend from ground or working platform level toa minimum height of 2, 5m or until it is impossible to reach over the guard and touchany moving part of the carriage system. If the top of the carriage is guarded it isrecommended that the guard be at least 500mm above the circumference of thepulley and these guards shall be kept clean from material build-up. The side guardsof the carriage will not be closer than 150mm as measured from the carriagewheels. The guard at tail portion of the carriage system (upper limit of carriagemovement) shall not be closer than 3 times sheave outer diameter or 1m to thisupper limit, whichever is greatest and the height of this guard will be similar to the

height of the side guards.

The gap where steel ropes move through the guard will be covered such that no


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contact with this gap is possible while the conveyors power drive unit(s) isenergised.

c) Manual Screws

If the take-up tension is maintained through the application of a manual screw, it willbe required that the screw and take-up pulley be fully enclosed. If the top of thetake-up pulley remains unguarded the guards will extend around the pulley to amaximum height of 2, 5m. If the top of the pulley is guarded, this top guard shall notbe closer than 500mm above the pulley circumference and these guards shall bekept clean from material build-up. The side guards will not be closer than 150mmfrom the screw. The guard at the back of the pulley shall not be closer than 150mmto the pulley circumference.

d) Take-up and Drive Bend pulleys

It will be required to install primary safety barriers (nip guards) on all pulleys whetherthey are accessible or inaccessible to human contact and such nip guards will bepositioned in accordance with figure 3.

On installations where walkways or platforms are constructed next to inclineelevated conveyors, it is often found that drive or take-up snub pulley are in areachable distance from such walkways or platforms. Guards must be constructedsuch as to extend at least 850mm before and after such snub pulleys in the directionof belt line. Guards must not be closer than 150mm from the pulley shaft edge and iffor some reason it is required that a pulley shaft extend through the guard it must beguarded such that contact with such shaft is impossible. The extension of suchpulley shaft through guarding will not cause any tripping hazard for persons walkingon such elevated walkways.

For the portion where walkways are situated next to these snub pulleys it is requiredto install deck plates beneath the carry and return belt strand to prevent personsstanding on the walkway to reach over guards an contact pulley danger points.

e) Ancillary Take-up Equipment

Such equipment includes winches, ropes and sheaves. Danger points associatedwith such installed equipment is:

1. Nip point between rope and sheaves

2. Nip point between rope and winch

3. Nip point between rope and surrounding structure, guards or brackets.

For the purpose of simplicity it can be stated that such equipment and associateddanger points shall be guarded such that it will be impossible to contact any suchequipment or danger points unless energy has been removed from the power driveunit of that conveyor installation. The guards will be so constructed such that it willnot contact the rope or sheave during operation.

If mesh guarding is to be used, such guarding will be at least 150mm away fromsuch equipment to prevent finger contact with danger points. Caution should be


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taken as material build-up inside such guards will render the take-up systemineffective and compromise safety of the installation.

4.4.4 Run of Conveyor

The run of conveyor can be defined as the normal conveyor comprising of the carry- andreturn belt, idlers and structure and does not include the head, drive, take-up, loading ortail section.

The danger points associated with regards to the run of conveyor becomes evident whenpersons are required to cross over or underneath the belt conveyor structure, when thebelt is pressing down on rolls in a convex curve or when pressing rolls are used to preventbelt liftout in specific areas.

Trip Wire & Switches

When faults, accidents or blockages occur, it is normally necessary to bring the conveyorto an immediate halt. A continuous trip -wire stretching over the whole length of theconveyor, to actuate the stop switch of the conveyor, is an effective and essential safetydevice. With such a facility available the operator will be less tempted to try and rectifyfaults with the conveyor turning. It must however stretch the full length of the conveyor. Ifthe belt conveyor is so installed that persons can walk along the conveyor on either sideof it then a trip-wire must be installed on both sides of the conveyor. It is alsorecommended that a lockout facility be provided on this trip wire arrangement.

Carry Belt Convex Curves

When the profile of the belt shapes in a convex curve, the tension in the belt will furtherincrease the force exerted on a carry idler roll in the convex curve and when excessive,can cause severe harm to a human hand when caught in the nip point between the beltand carry idler. When it is known the curve could/will experience high belt tensions andmaterial loads resulting in the nip points causing harm, it will be required to guard suchidlers for the length necessary to safeguard persons in that vicinity of the conveyorinstallation.

Carry Belt Pressing Rolls

Although it was stated that it is essential that head tail and snub pulleys of belt conveyor

installations, which are within reach, should be guarded, accidents have happened oncarrying idlers with serious consequences, particularly where the distance the belt can liftoff the idlers is restricted. The danger at idlers is even more evident when fixed hoppersor skirt plates under which the hand can be trapped, are fitted directly above the idlers. Ifthis is the case the danger points must be very carefully guarded or completely enclosed.This also applies, even more so, to belts on which hand-sorting is performed.

Some conveyor installations incline upward and the conveyor structure will form aconcave curve. Under some operating tensions the conveyor belt could lift-out of thecurve. When such lift-out occurs in the vicinity of the loading points or fixed hoppers orwhere some other structural member or equipment is situated above the belt, it becomesnecessary to press the belt down in order to prevent such lift-out. This is done by installingpressing rolls on the sides of the conveyor belt. These rolls then present dangerous nip-points and will cause severe harm to limbs. In such cases it is recommended to install


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guards along the portion of the conveyor equipped with such pressing rolls and suchguards must extend at least 850 mm outside the first and last pressing rolls. The guardsmust be such that it will be impossible to reach over such guards and make contact withsuch nip points under any belt running condition, whether starting, running or stopping.

Elevated walkways

In cases where walkways are fitted on elevated conveyors, adequate hand and knee railsmust be installed on the outside of such walkways. Kick/toe boards shall be provided onthe hand rail and conveyor stringer side to keep movement of feet restricted to thewalkway platform. Walkways must have and even, non-slip surface, be properly drainedand free from obstructions.

Inclined shafts

Another condition exists on the walkways next to inclined shaft conveyors. Spillage onwalkways can cause persons to slip or loose footing and to prevent such person grabbinghold of the conveyor structure or other dangerous equipment, it is imperative that someform of handrail be constructed to aid persons walking on such walkways.

Cross-Over Bridges

It is often necessary for an attendant to cross a conveyor at various points. It isdangerous to climb over any belt. Where it is impossible to establish safe passagewaysunderneath the belt, cross over bridges with handrails, must be provided. The position ofthese bridges will depend on conditions at the belt conveyor installations but, unless asufficient number are installed they will not always be used. Access to the cross overbridge must be provided by means of stairs equipped with handrails. Vertical laddersshould be avoided. The cross over bridge should also be equipped with a toe -board andan intermediate or knee rail.

Such structures must be adequately designed and constructed of steel members andinclude suitably inclined access stairs of non-slip platforms made from steel grid plate andfitted with handrails on both sides to a minimum height of 1,2m.

The handrails and stanchions must be bolted to the support steel members. Kick/toeboards and and intermediate or knee rail must be fitted on both sides of the walkingplatform. The number and position of such bridges must be determined by a Risk

Assessment and based on the maintenance and inspection requirements for such belt.Vertical ladders must be avoided. The cross over bridge must elevate to a minimumheight of 1, 4m above the ground or working platform level on which the conveyor issupported, before extending across the conveyor.

Crossing Underneath Belts

On belt conveyors, the return belt and idlers may also present a hazard especially atspecific places where persons regularly pass through or works underneath the belt. Atsuch places it is recommended that the underside should be guarded.

In areas where persons or mobile machinery are permitted to cross underneath conveyorbelt installations, the following must be complied with:


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a) All passageways and roadways shall be conspicuously sign-posted to indicate theirpurpose i.e. men and/or machinery.

b) Height restrictions through such passageways and roadways must be prominently

displayed on both sides.c) If the return idler or any pulley is less than 3,5 m from the ground or working

platform level, such return idlers or pulleys must be guarded such to provide safepassage to any person or machine operator whilst crossing below such conveyorbelt. The passageway must extend to a minimum of 1 m beyond both sides of theconveyor structure. Crossing at other places which are not properly guarded mustprevented with No -Entry sig ns on a barricade, even if only two or three strands of 8gauge galvanized wire is used along the outside of the supporting framework toachieve this purpose. For the purpose of complete safeguarding, it is recommendedto construct a canopy over the road/walkway below the return belt to protect personsand vehicles whenever belt sags, snaps or for cases of spillage which falls from thebelt onto the road.

Under no circumstances will the crossing under or over conveyor belts bepermitted at any point along its length unless via the approved passagewayreferred to above.

Belt Turnovers

On some conveyor installations it is required to turn -over the return belt in order to runthe non-carry side of the belt in contact with return idler sets in order to reduce spillageand material build-up known as carry-back.

Mangle rolls are typically double flat idler rolls which gradually changes the twisting angleof the belt in order to turn the belt over 180. These turnover sections must be fullyenclosed and effectively guarded to prevent any contact with any of these mangle rollsets. Side guard panels must extend to a minimum height of at least 2, 5m and must notbe closer than 150 mm from the rolls end disk.

4.4.5 Loading Point

At the loading point material is fed onto the conveyor by means of a transfer chute.Danger point associated with the loading point is:

a) Point(s) of impact in the transfer chuteb) Point of impact on the moving conveyor belt

c) Material settling zone

d) Nip point between conveyor belt and chute structure

e) Maintenance and inspection doors on the transfer chute

To safeguard persons in the vicinity of the loading point it is required that the flow ofmaterial be guarded with a transfer chute in a manner that no person can contact theflowing stream of material in the chute while standing next to the conveyor installation,whether on ground level or other designated walkways or platforms. The construction ofthe chute will also prevent the escape of material from the chute and any rapiddeterioration of the chute due to material flow will be re-engineered to prevent such rapiddeterioration.


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The loading portion of the chute shall act as the safe guarded to prevent persons fromreaching the material impact zone on the belt and the chute shall extend in the direction ofbelt travel for the distance required for material to settle in order to prevent unsettledlumps from falling off the belt due to loading conditions.

The chute nip point is the gap that exists between the rear end of the chute and the carrybelt surface. This gap shall be minimized to not more than 50mm.

The design of the conveyor shall prevent belt lift-out in the loading area.

Maintenance and inspection doors shall be positioned outside the normal trajectory ofmaterial flow and such doors shall be kept closed and secured under belt starting, runningand stopping conditions.

4.4.6 Tail End

Non-Driven

The tail end will always be situated behind the loading point and will redirect the belt runfrom the return run direction to the carry run direction.

For any tail end constituting only of an idling pulley, the following danger points exist:

a) Nip point between the return belt and the tail pulley.

b) Rotating shafts

It will be required to install primary safety barriers (nip guards) on each pulley whetherthey are accessible or inaccessible to human contact and such nip guards will bepositioned in accordance with figure 3.


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Figure 8

A secondary guard will be constructed around the rear end of the pulley starting at least850mm (B3) in front of the tail pulley or snub pulley nip guard, whichever is closes to theloading point, and will cover all around the rear end of the pulley to the other side of thepulley to a distance of 850mm (B3) in front of the tail pulley or snub pulley nip guard.These guards shall extend vertically ground or working platform level to a minimum heightwhere the guard covering the pulley will be at least 400mm (A3) above the circumferenceof the pulley, whichever is closes to the loading point. The vertical guard on the rear endof the pulley shall not be closer than 150mm (D3) from the circumference of the pulley.The side guards will be constructed not closer than 150mm (E3) from the edge of thepulley shell. This is illustrated in Figure 8.

If shaft extend through any of the above mentioned guards, such shaft shall be guarded insuch a manner that will prevent any contact with any part of such rotating shaft.

In the event that the tail end is integrated with the take-up system, the associated pulleysand take-up equipment shall be guarded in accordance with the take-up guardingrequirements as stipulated in section 4.4.3.

Driven

Tail ends which are equipped with power drive units will be guarded in accordance to therequirements as stipulated in section 4.4.2 in the paragraph covering tail drives.

C3

B3D3

A3

B3

E3SIDE VIEW

PLAN VIEW

Primary Safety Barriers(Nip guards)

Conveyor Belt

Secondary SafetyBarrier

D3


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4.4.7 Belt Cleaning Devices

Lateral movement of the belt is usually caused by a build-up of material at the head andtail pulleys, the carrying idlers or snub pulleys. The manual removal of build -up is slow,complicated and often dangerous. In order to keep the pulleys and rollers clean, suitablemechanical devices must be installed. The manual removal of build-up should not bepermitted whilst the belt conveyor is in motion.

5 MATERIAL SPECIFICATIONS

Primary and secondary safety barriers will comply with the following materialspecifications:

a) Manufactured from a non-corrosive material or galvanized steel to prevent acorrosive environment from rendering the guard ineffective due to excessive

material loss during operation.b) The completed guard must be manufactured from a material of adequate strength

and design to safely support the mass of an 85kg person distributed over an area of2m.

c) A guard must not weigh in excess of 30kg to ensure that one person will capable ofremoving or installing such a guard. If guard weigh in excess of 30kg, they must bea permanent feature to the structure with hinges on the side that will allow theopening of such guard by swinging it outwardly.

d) Colour-coded such guards with ORANGE paint to create an awareness that if suchguard is not in its correct position it will be conspicuous by its absence and alertpersons that it has been inadvertently removed.

e) Guards shall be securely fixed in position with fasteners or other suitable devices,and which ensures that the guard cannot be altered or detached without the aid of atool or key.

f) Guards must be installed such that adjustments will not allow a loss of protection orthe modification of guards.

g) Guards must be such that they do not need to be removed for inspection.

h) The design, material and construction of guards must be such that they present noburrs, sharp edges or pinch points that may be a hazard to safety.

5.1 Primary Safety BarrierThe minimum material dimensions for all nip guards must be 120mm x 120mm x 10mmgalvanized angle members.

With regards to the tail pulley, the guard must be secured to the base of the plummerblocks in order to ensure that they follow the pulleys when repositioned.

These guards must be bolted to the conveyor structure so as to create a minimumclearance of 8 mm from the pulley circumference and 20mm from the belt. No welding willbe allowed to remove or replace such nip guards.


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5.2 Secondary Safety Barrier

It may be assumed that there is no reach through an opening of 10mm x 10mm or less as

fingers cannot normally be admitted. If the opening is such that it will admit one, two orthree fingers the reach is restricted by the roots of the fingers, a distance normally notexceeding 150mm.

When the opening is sufficient to admit the whole arm and the small portion of theshoulder the reasonable safe distance is based on the distance from the fingertips to thearmpit, which may be assumed to be 850mm.

Screening material with openings in excess of 80mm x 80mm should not be used in theconstruction of guards or fences. Preference should be given to materials with openingsnot exceeding 25mm x 25mm.

ELONGATED OPENINGS (Openings with parallel sides):

a) Openings up to 6mm wide may be disregarded. The guard or fence so constructedmay virtually be regarded as a sheet and a working clearance of approximately 25mm is all that is required.

b) Openings greater that 6mm but less that 13mm will admit part of a finger andrequires at least 50mm clearance from danger points.

c) Openings in excess of 13mm but not greater than 80mm are subject to the followingformula:

X = 10Y where X = reasonable safe distance from danger point in mm.Y = width of opening in mm.

5.3 Power Drive Unit

Driving belts (V-belts), chains, high and slow speed couplings installed between electricmotors and gearboxes or transmission assemblies fall into the category of exposedmachinery and must be effectively guarded. All such exposed machinery must be totallyenclosed on all sides with guards manufactured from solid steel plate with a minimumthickness of 3mm. They must be bolted securely in position.

Holdback or brakes can be guarded with mesh guarding but such guards will not be closerthan 150mm to any part of the hold back or brake and the extend of such guards will besuch that no part of the holdback or brake can be touched.

6 MAINTENANCE

Safety at belt conveyor installations may be further enhanced by creating the optimumworking environment including not only adequate ventilation, illumination, absence ofundue noise and adequate dust control, but also sufficient clearance around theinstallation and along walkways. Walkways should have an even non-slip surface, beproperly drained and free from obstructions.

Any build-up of spillage material on guards must be removed to prevent deflection of suchguard that would compromise its position relative to the danger point and thereby present


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possible human contact with such danger points. Dimensions given in the best practicemust be maintained at all times.

Primary barrier guards which have been damaged, corroded or bent in any way that wouldyield the barrier ineffective shall be replaced with a new guard.

If secondary barrier guards are in any way damaged, corroded or bent or mesh openingsor any other openings increased to sizes greater than stipulated in this document, suchguards shall be replaced immediately to cover the danger points and present a safeconditions for persons positioned or walking in the vicinity.

Maintenance, travelling and access ways along, around, over or under conveyor belt driveand tail-end installations must be adequately illuminated, kept dry and free of obstructionsor tripping hazards and allow sufficient clearance for routine maintenance and inspectionsto be conducted in a safe manner.

Minimum clearances of 1m must be maintained for the above purpose. Areas where suchclearances cannot be maintained must be suitably barricaded to prevent the unsafe entryof maintenance personnel.

The COP as required by the Inspectorate for the Operation and Maintenance all ConveyorSystems at any Mine or Plant must be reviewed and updated annually to ensure thesafety of all persons who are required to work in close proximity to such equipment.

Every person who by the nature of his/her work requires training to be competent in theoperation or maintenance of conveyor systems must at all times be briefed and updatedon the requirements of this BPG and subsequent revisions.

Man-riding of conveyor belts are strictly prohibited.

7 REMOVAL OF GUARDS

Under no circumstances may any guard be removed, repositioned or modified unless thebelt conveyor has come to a COMPLETE stand still, power to the drive has been removedand the correct lock-out procedure completed.


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APPENDIX A: REFERENCE DOCUMENTS

AA RP 000154, Conveyor Guarding

None

APPENDIX B: RECORD OF AMENDMENTS

Version 0 : New document (P. Nel, May 08)

Version 1 : Document Revised (C. Stensby, December 2011)

AA BPG 375001 document number changed to AA RP 0154 reflectthe new Anglo American document numbering system. (November

2013)

AA_RP_000154 - CONVEYOR GUARDING

Documents

Transcript of AA_RP_000154 - CONVEYOR GUARDING