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TECHNICAL

INFO

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SAFETY

NETTING

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Safety nets are a knotless, woven net made from high tensile, multifilament, polypropylene. They are 50% lighter than traditional knotted nets and are, therefore, flatter in catenary which further reduces fall distance. The energy absorption characteristics are set within the construction of the weave itself, rather than depending on the random tightening of knots, this ensures consistent, reliable performance.

 

Removable test cords are woven into the safety nets for periodic on-going performance assessment. These cords are removed at the inspection interval (they have no bearing on the performance of the Safety net) and are tested in accordance with the European Standard. They are used to monitor the on-going performance of the hire fleet.

 

POSITIONING

& RIGGING

 

Safety nets should be positioned as close as possible to the working platform. Whilst it is tested for falls up to 6m, the objective is to guard the fall hazard, and to do this the safety net should be within 2m of the working platform.

The energy absorption of all nets relies on available net area. The minimum safety net size for the maximum fall height is 35m², and the shortest side length should be 5m. The maximum fall height within 2m of the fixed edge of the safety net, is 3m (this is to take account of the reduced effective area in a maximum fall).


 

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The clearance distance below the safety net must take into account the fall height, the initial sag (max. 10% of the longest side length), and the net deflection under load.

 

TIE ROPES &

ANCHORING POINTS

 

Tie ropes shall also comply with BSEN1263-1, and have a minimum breaking load of 30kN. Normally this results in a 12mm dia rope. Safety nets should be fixed to suitable anchorage points. The distance between the anchorage points shall be less than 2.5m. Each anchorage point shall have a load capacity of 6kN, applied at an angle of 45º. When considering a continuous supporting structure, the fall load is distributed between 3 No. anchorage's at 4kN, 6kN, and 4kN respectively.

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STAIR

TOWERS

Erection Sequence check sheet:

 

  1. Check the building offset for the base positioning noting the overhang.

  2. The pads are placed under jacks and all the bottom ledgers are level and square.

  3. The height is sufficient for the purpose.

  4. All the external faces have a diagonal bracing except the entrance and exit.

  5. The tower is tied off once every 2m or two ties every 4m.

  6. The bottom stair is clear of obstructions with a maximum of 300mm step.

  7. Double handrails will be in place to each side of every staircase.

  8. Double handrail to continue around the landing.

  9. The Climbing route is kept clear of tie off positions and fittings.

  10. The top step off is less than 300mm, and into a safe area.

  11. A Handover Certificate and Inspection Sheet are supplied.

Specific Additional Checks:

 

  1. All stair units and walk off planks are locked down.

  2. All internal handrail wing nuts are tightened.

  3. Perimeter protection (Safe Side) will be tied into the tower top.

  4. Where used the top standard support spigot will be tight.

  5. All pegs engaged and lightly driven home.

  6. NO materials to be stored causing an obstruction.

 

This includes access points.

 

TYING & BRACING

PATTERN

  • Where the is no design drawing or calculations the tower should be tied every 2m vertically on both standards.

  • Where this minimum tie pattern cannot be achieved then design input is required.

  • Where possible ties should be located as close as possible to the top step off of the tower.

  • If additional banners or sheeting of any type are to be fixed to the tower the design input is required.

  • Vertical braces are required on all faces in a zig-zag formation.

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LOADING/DUTY

& SAFE STAIR INSPECTION

The classification of this tower as specified in BS1139 PT 5 is:

  • It is an access route only and not for material storage

  • It does not require toe boards however they can be integrated if required

  • Class 2

  • Light Duty

Safe Stair should be inspected by a competent person:

  • Before being taken into use for the first time

  • After any substantial addition, dismantling or other alteration

  • After any event likely to have affected its strength or stability

  • At regular intervals not exceeding 7 days since the last inspection