Grid Mesh Basic Assessment Guidelines - Water Corporation · Grid Mesh Basic Assessment Guidelines P RINT D ATE: 29-A PR-14 W ARNING: D OCUMENT U NCONTROLLED W HEN P RINTED P AGE

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Grid Mesh Basic Assessment Guidelines

Doc ID aquaDoc #2141010

Custodian Snr OSH Consultant PoF, CSE & Rescue

Version Date 30 Apr 2014

Accountabilities Framework Level 1: Manage Occupational Safety and Health Level 2: Manage Hazards & OSH Incidents Next Review Date

30 Apr 2017

1 Purpose This guideline provides information as to the minimum requirements for existing grid mesh and support components.

Note: These guidelines are not Design Standards and should not be used for design purposes.

Content 1 Purpose ................................................................................................................................................... 1

2 Scope ...................................................................................................................................................... 1

3 Training .................................................................................................................................................... 2

4 Guideline ................................................................................................................................................. 2

4.1 Assessment Process ..................................................................................................................... 2

4.1.1 Grid Mesh Detailed Assessment ........................................................................................ 2

5 Records ................................................................................................................................................... 3

6 Definitions ................................................................................................................................................ 3

7 Compliance Mapping ............................................................................................................................... 3

8 References .............................................................................................................................................. 3

Appendix A Grid Mesh Summary ........................................................................................................... 4

9 Types of Grid Mesh ................................................................................................................................. 4

9.1 Steel and Aluminium Grid Mesh.................................................................................................... 4

9.2 Fibre Reinforced Plastic (FRP) ..................................................................................................... 4

9.3 Expanded Metal Mesh .................................................................................................................. 4

Appendix B Grid Mesh Basic Assessment Criteria ................................................................................ 6

Appendix C Checklist for Field Use ...................................................................................................... 10

2 Scope This guideline applies to all Water Corporation workplaces. It shall only be used to assess existing grid mesh sections that are metal or fibre reinforced plastic panel. Landings with chequer plate or timber decking shall be referred for detailed assessment as per Section 4.1.1. The guidelines shall only be used to assess landings that are subject to normal access by personnel. The guidelines do not provide sufficient guidance to assess the suitability of landings for placement of abnormal loads (such as pumps, motors or construction equipment during maintenance or construction, or large numbers of people). Where landings are required to support such loads, a detailed assessment is required as outlined in Section Error! Reference source not found. New grid mesh shall be designed and constructed to the Water Corporation’s Design Standard (DS100). The assessment of new grid mesh against the requirements of DS100 is out of scope of these guidelines.



3 Training For Water Corporation employees, this guideline is associated with a training qualification (SAP #Q13076), which serves as a record that an individual has read these guidelines. Refer to the OSH Training WaterNet page for guidance on how to record this qualification.

Contractors are responsible for maintaining their own employee qualification / training records in association with this guideline.

Course Name Mandatory for Roles Description Period of Validity

Grid Mesh Basic Assessment Guidelines SAP #Q13076

Persons involved in: issuing OSH permits (authorised

persons) conducting the reinstatement post work

assessment. This may be the responsible person or delegate.

This document provides guidance information as to the minimum requirements for grid mesh and support components

No expiry

4 Guideline This document provides guidance information as to the minimum requirements for grid mesh and support components.

4.1 Assessment Process An assessment of existing mesh is required for;

Post work reinstatement (grid mesh reinstatement permit) or, Where grid mesh hazards have been identified during normal operations

These guidelines can be referred to when assessing the conformance of the grid mesh. Appendix B sets out the conformance criteria for grid and expanded metal mesh. Panels where no deficiencies or non-conformances are detected against the criteria in Appendix B can be considered suitable for normal personnel access. Where any panel has deficiencies or non-conformances against any one of the criteria in Appendix B, the panel should be tagged with an Out-of-Service Tag in accordance with WC-OSH 109 Tagging and Isolation, and barricaded from access with one of the following actions taken: Where correction of the non-conformance with the assessment criteria is within the delegated authority

and competence of the person undertaking the basic assessment, then correction of the non-conformance should be arranged. Once all non-conformances on a panel have been corrected, the Out-of-Service Tag and barricades on that panel can be removed.

Where correction of the non-conformance is outside the delegated authority or competence of the person undertaking the basic assessment, then the panel should be listed for detailed assessment. The detailed assessment will determine whether the panel is suitable for access or whether modifications or work are required to make it so.

Note: the panel may have a non-conformance with the basic guideline assessment criteria, but detailed assessment may show that it is suitable without modification (e.g. it is a small or irregular shaped panel, but is assessed as having adequate support by a person competent to undertake a detailed assessment)

4.1.1 Grid Mesh Detailed Assessment

A detailed assessment shall be undertaken by a person with formal training in basic engineering principles (including forces, vectors, strength of materials, stress and strain) applying that knowledge together with these guidelines, relevant standards and manufacturer’s guidelines. The person conducting the detailed assessment should seek advice from a structural engineer or other relevant specialists where required.

http://waternet.watercorporation.com.au/hrw/osh/osh_training/osh_training_providers.asp

http://aqua/link/?doc=460862



Any Out-of-Service Tag and barricades on a panel marked for detailed assessment must not be removed until the person undertaking the detailed assessment has assessed the panel as suitable for access, which may require the completion of noted repairs or modifications.

5 Records Contractor records associated with the grid mesh reinstatement task shall be available for the duration of the task and then stored in an easily retrievable manner. Water Corporation records associated with the reinstated grid mesh assessment shall be available for the duration of the task and then stored in an easily retrievable manner. Records shall be filed in accordance with the Water Corporation Records Retention and Disposal Schedule, with the filing convention, retention period and disposition type outlined below:

Record To be retained by Filing convention Retained for

(time period) Disposition Type

Training and Competency records

SAP n/a n/a n/a

Branch Manager STAFF DEVELOPMENT - Training

Interim 2 years after last action

Destroy 7 years after last action

6 Definitions Term Description Grid Mesh Means steel, aluminium or fibre reinforced plastic (FRP) panels of the types detailed in Section 9 of

the Grid Mesh Basic Assessment guidelines.

Basic Grid Mesh Assessment Means an assessment for compliance with the criteria contained in Appendix A of the Grid Mesh Basic Assessment guidelines.

Detailed Grid Mesh Assessment

Means an assessment by a person with formal training in basic engineering principles including forces, vectors, strength of materials, stress and strain applying that knowledge together with these guidelines, relevant standards and manufacturer’s guidelines. The assessor should seek advice from a structural engineer or other relevant specialists where required.

7 Compliance Mapping Task Legislation

Grid Mesh Basic Assessment AS 1657 Fixed platforms, walkways, stairways and ladders – Design, construction and installation

8 References Document Number Title

DS100 Suspended Flooring - Grid Mesh and Chequer Plate

WC-OSH 036 Reinstated Grid Mesh Panel Assessments

Document Revision History

08 Jul 2009 Original version.

20 Aug 2013 Updated template. Linked to WC-OSH 036 and SAP training qualification.

30 Apr 2014 Updated to reflect July 2013 revision of DS 100 Suspended Flooring - Grid Mesh and Chequer Plate. Refer to MOC #10306441.











Appendix A Grid Mesh Summary

9 Types of Grid Mesh

9.1 Steel and Aluminium Grid Mesh The steel and aluminium grid mesh (Webforge or similar) panels used for landings generally consist of two elements - load bars and cross rods. The load bars are the larger bars of which the grating is primarily made, the cross rods are the twisted bar forged across the top of the load bars. The strength of the mesh is determined solely by the size and spacing of the load bars. The cross rods simply keep the load bars in position and provide a degree of non slip surface.

9.2 Fibre Reinforced Plastic (FRP) Fibre reinforced plastic (FRP) grid mesh panels generally have load bars in both directions, in a square pattern.

9.3 Expanded Metal Mesh Expanded Metal Mesh means the steel or continuous single sheet of mesh produced when a flat metal plate is sheared and stretched, but left intact at the “knuckles”. It is available in a variety of thicknesses with differing sizes and designs of apertures. See photograph below.

Cross Rods

Load Bars

Galvanised Steel

Long Way Mesh (LWM)

Short Way Mesh (SWM)



There are two basic types of expanded metal mesh: Raised expanded metal mesh is as it comes off the machine. The strands and knuckles are set at a

uniform angle to the plane of the sheet. This adds strength and rigidity, and distributes the load on the metal to the supporting frame.

Flat expanded metal mesh is manufactured by passing raised expanded metal mesh through a rolling

mill. This reduces the overall thickness. Flat expanded metal mesh is not suitable for walkways.



Appendix B Grid Mesh Basic Assessment Criteria Each individual panel of a mesh landing should be assessed for conformance with the criteria 1 - 21 below. Construction 1. Panels are manufactured from galvanised steel, aluminium or fibre reinforced plastic (FRP), and are grid

mesh as described in Section 9. OR

Panels are manufactured from galvanised steel or aluminium and are raised expanded metal mesh as described in Section 9.

2. Panels are rectangular or close to rectangular – irregular shapes require more detailed consideration of

supports

3. Grid mesh panels are supported under the ends of the load bars over at least 80% of the length of each of two opposite ends. Where support is less than 100% of an end, the ends must be supported to prevent overturning of the panel under load. ie - any unsupported portion should be distributed through the middle sections of the end of mesh

OR

Expanded metal panels are supported under the ends of the long way mesh over at least 80% of the length of each of two opposite ends. Where support is less than 100% of an end, the ends must be supported to prevent overturning of the panel under load. i.e. any unsupported portion should be distributed through the middle sections of the end of mesh.

4. The load bar ends (or ends of the long way mesh) have at least the following bearing on their supports: a. 25mm minimum for load bars 25 - 40mm deep b. 40mm minimum for load bars 45 - 65mm deep c. 30mm minimum for expanded metal mesh d. 40mm minimum for FRP grid mesh load bars

End/corner unsupported



i. Grid Mesh Expanded Metal Mesh 5. Panels are no less than 0.6m2 in area (eg 600mm x 1m, 800mm x 800mm, 1.5m x 400mm) – small

panels may need special consideration to ensure adequate support.

6. The span between supports is no greater than shown in the tables below (panels with load bar or mesh sizes not listed below should be referred for detailed assessment).

7. The panel is physically restrained from moving laterally off its supports by an immovable barrier such as an adjacent wall or floor, a vertical section of the support itself, or locating lugs which protrude below the panel. The clearance between the panel and its restraint is such that the panel is unable to move beyond the minimum bearing on its supports specified in 4 above. (examples below)

OR Fixings, location and spacing of Grid Mesh Flooring provide at least: One fixing at each corner no farther than 200mm from the corner. Four fixings per square metre of panel for panel spans equal to or greater than one metre; Six fixings per square metre for panel less than one metre; Fixings generally spaced no farther apart than 600 mm. . Welding and riveting should only be considered where: Vibration from plant operations is likely to dislodge other types of fixings and where grid mesh panels

are not required to be removed for operational and maintenance purposes; Fire hazard and ergonomics can be adequately managed on site in the instance of welding; Protective coatings of adjoining structures on site are not compromised by stray arc or welding

spatter. Expanded metal mesh should be welded every fourth strand.

25mm minimum for load bars 25 - 40mm deep 40mm minimum for load bars 45 - 65mm deep

Panels restrained by kick plate fixed to support, adjacent concrete floor and handrail stanchion base plates

Panel fitted with welded locating lugs which protrude below panel and bear against support



8. The panel does not rely on the fixing clips to support any vertical load (upwards or downwards).

9. Where the edges of adjacent panels of expanded metal mesh are not on a support, they are butt welded or overlap by one full mesh along the short way side.

10. There should be no openings in the panel (holes for access to valve spindles etc.) which are greater than 5000mm2 in area or 40mm wide (eg 40mm x 125mm, 20mm x 250mm)

Note: The following items (1-3) are included to enable the identification of hazards associated with mesh landings, but do not need to be referred for Detailed Assessment. Defects based on items 1 - 3 below should be reported and addressed through the Water Corporation’s hazard identification and reporting process (refer to WC-OSH 034 OSH Hazard Identification and Reporting).

1. The gap to adjacent panels should not exceed 10mm. 2. Adjacent panels should be at the same level (no tripping hazards) 3. Where panels are cut out around pipes etc there should be:

no sharp edges banding bars 5 mm thick welded to the cut ends no gaps greater than 40mm wide without toe-boarding

Installation Each panel should be installed in the following manner:

11. Correctly positioned on its supports

12. Fixings are correctly positioned and installed in a manner which retains the panel in its intended position

13. There are adequate fixings in place – see above under “construction”

Maximum gap of 40mm without toe-boarding in place

Banding bar 5mm thick

Butt Welded Overlap one full mesh




14. Fixings are tight and at 900 to the supports.

Condition Each panel and its supports should be in the following condition:

15. The panel is not bent indicating overloading (no visible bending)

16. Load bars are not twisted along their length

17. The panel is not twisted such that it does not sit properly on its supports

18. There is no corrosion on the mesh, its supports or the fixings of the supports which has reduced their cross sectional area i.e. - no significant pitting corrosion.

19. FRP panels have no exposed fibres, no cracks to the resin and no visible deterioration of the material around the cut ends of load bars.

20. The retaining fixings are not bent and are correctly engaging the mesh

21. The panel has not been cut or modified so that it no longer conforms to the construction criteria above.

Reference Tables for Span Between Supports - Steel and Aluminium Grid Mesh Panels

Load Bar Cross Section

mm

Maximum span in mm for load bars at 30mm spacing


Steel Aluminium Steel Aluminium 20 x 3 1000 N/A 900 N/A 20 x5 N/A 1000 N/A 900 25 x 3 1200 950 1100 800 32 x 3 1500 1100 1400 950 25 x 5 1300 1100 1200 900 32 x 5 1600 1300 1500 1100 40 x 5 1900 1500 1750 1300 45 x 5 2100 1700 1900 1400 50 x 5 2300 1800 2100 1500

Reference Tables for Span Between Supports - FRP Grid Mesh Panels


mm


25 x 6 750 38 x 6 1050

Reference Tables for Span Between Supports – Expanded Metal Mesh Panels (Figure 15)

Nominal Mesh Size mm SWM x LWM

Strand Measurement Maximum Span mm

Thickness mm

Width mm Steel Aluminium

45 x 135 5 8 750 500 45 x 135 5 11 850 600 34 x120 5 6.4 800 550 34 x120 5 8.4 900 650 34 x120 5 9.6 1000 750 34 x120 6 10.4 1100 800 30 x 75 5 7.5 800 550 30 x 75 5 10.5 1000 750 30 x 75 6 11.0 N/A 800 25 x 60 5 5.6 600 N/A

Note: Other sizes of expanded metal mesh are generally not suitable for walkways but are designed for security or decorative applications. If mesh is other than one of the sizes listed above refer for detailed assessment.



Appendix C Checklist for Field Use Note: This checklist provides a summary of the criteria outlined in Appendix A, for ease of reference. Construction Material - galvanised steel, aluminium or fibre reinforced plastic (FRP) Mesh type - as per photos overleaf - Figures 1, 2 & 3 Shape - rectangular or close to rectangular Support

o under the ends of the load bars or long way mesh – Figure 4 o over at least 80% of the length of each of two opposite ends – Figure 5 o No overhangs (ends supported) o The load bar ends have at least 25mm bearing on their supports (40mm for load bars >40mm deep,

30mm for expanded metal mesh, 40mm for FRP grid mesh load bars) - Figures 6 & 7 Panel size is no less than 0.6m2 in area (eg 600mm x 1m, 800mm x 800mm, 1.5m x 400mm) Span no greater than shown in the tables overleaf (Figure 15, 16 & 17) Fixing

o physically restrained by surrounds such as walls, floors, , or by locating lugs welded to the panel (Figures 10 & 11) OR

o Fixings, location and spacing of Grid Mesh Flooring provide at least: One fixing at each corner no farther than 200mm from the corner. Four fixings per square metre of panel for panel spans equal to or greater than one metre; Six fixings per square metre for panel less than one metre; Fixings generally spaced no farther apart than 600 mm.

OR o Expanded metal mesh welded every fourth strand (Figure 12)

Fixingsdo support any vertical load (upwards or downwards). o Expanded metal mesh panels butt welded to, or overlap one full mesh with, adjacent panels on

short way side (Figures 13 & 14) Other openings in panel – no greater than 40mm wide and 5000mm2 area (eg 40mm x 125mm, 20mm x

250mm) Note: Also check for these hazards (do not constitute a non-compliance with the Guidelines.)

o Maximum gap of 10mm to adjacent panels o Adjacent panels at same level – no tripping hazard o Cut outs in panels – Figure 7 overleaf

no sharp edges banding bars 5 mm thick welded to the cut ends (Figures 8 & 9) no gaps greater than 40mm wide) without toe-boarding (Figure 8)

Installation Panel correctly positioned on its supports Fixings are correctly positioned and installed in a manner which retains the panel in its intended position There are adequate fixings in place Fixings are tight and at 900 to supports. Condition Panel not bent indicating overloading – no visible bending Load bars not twisted along their length Panel is not twisted such that it does not sit properly on its supports Corrosion - no significant pitting corrosion on the mesh, its supports or the fixings of the supports FRP panels have no exposed glass fibres and no obvious cracks to the resin. Retaining fixings not bent and correctly engaging the mesh



Panel has not been cut or modified so that it no longer conforms to the criteria above. Galvanised Steel or Aluminium Fibre Reinforced Plastic (FRP)

Figure 1 Figure 2

Figure 4 Figure 5

Figure 6 Figure 7

Cross rods

Load bars

25mm minimum for load bars 25 - 40mm deep 40mm minimum for load bars 45 - 65mm deep

End/corner unsupported

Figure 3

Long Way Mesh (LWM)

Short Way Mesh (SWM)



Figure 8

Figure 9

Maximum gap of 40mm without toe-boarding

Banding bar 5mm thick

Figure 12

Figure 13 Figure 14

Welded every 4th Strand

Butt welded Overlap one full mesh

Panel fitted with welded locating lugs which protrude below panel and bear against support

Panels restrained by kick plate fixed to support, adjacent concrete floor and handrail stanchion base plates

Figure 10 Figure 11

Figure 12

Welded every 4th strand



Reference Table for Span Between Supports - Steel and Aluminium Grid Mesh Panels Figure 15

Load Bar

Cross Section mm Maximum span in mm for load

bars at 30mm spacing Maximum span in mm for load bars

at 40mm spacing Steel Aluminium Steel Aluminium

25 x 3 1200 950 1100 800 32 x 3 1500 1100 1400 950 25 x 5 1300 1100 1200 900 32 x 5 1600 1300 1500 1100 40 x 5 1900 1500 1750 1300 45 x 5 2100 1700 1900 1400 50 x 5 2300 1800 2100 1500

Reference Table for Span Between Supports - FRP Grid Mesh Panels Figure 16


mm Maximum span in mm

for load bars at 38mm spacing 25 x 6 750 38 x 6 1050

Reference Tables for Span Between Supports – Expanded Metal Mesh Panels Figure 17

Nominal Mesh Size mm

SWM x LWM Strand Measurement Maximum Span

mm

Thickness mm Width mm Steel Aluminium 45 x 135 5 8 600 500 45 x 135 5 11 750 600 34 x120 5 6.4 750 550 34 x120 5 8.4 900 650 34 x120 5 9.6 1000 750 34 x120 6 10.4 1100 800 30 x 75 5 7.5 800 550 30 x 75 5 10.5 1000 750 30 x 75 6 11.0 N/A 800 25 x 60 5 5.6 600 N/A

Note: Other sizes of expanded metal mesh are generally not suitable for walkways but are designed for security or decorative applications. If mesh is other than one of the sizes listed above refer for detailed assessment.

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Grid Mesh Basic Assessment Guidelines - Water Corporation · Grid Mesh Basic Assessment Guidelines P RINT D ATE: 29-A PR-14 W ARNING: D OCUMENT U NCONTROLLED W HEN P RINTED P AGE