The tube and fittings is a scaffolding system made from many different lengths of 48.3 mm diameter tubes clamped together in such a way that a rigid structure is formed.
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The way the tube is clamped together is very important. If the tubes are not properly connected and adequately braced, the scaffold will not be safe. The scaffolding crew should have suitable experience and reliability to commensurate with the complexity of the scaffolding erection.
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These systems are assembled from three basic structural elements: |
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The Uprights or Posts, which rise from the ground or other solid support. |
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The Bearers, which supports the working platforms and/or provide transverse horizontal connections between the posts.
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The Runners, which attach to the posts directly below the bearers and provide longitudinal connections along the length of the scaffold. |
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These three elements are usually connected with double couplers which provide 90O degree connection in two places. These three elements from the basic structure are repeated in horizontal and vertical planes to build the scaffold to its desired size. |
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Bearers should be installed transversely between posts and must be securely coupled to the posts and bearing on runner coupler. When its necessary to couple directly to the runners, the coupler must be kept as close to the post as possible. |
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Bearers should be at least 100 mm but not more than 300 mm longer than the post spacing or runner spacing. Runners should be erected along the length of the scaffold, located on both the inside and the outside posts at even heights. They should be interlocked to form continuous lengths and coupled to each post. The bottom runners should be located as close to the base as possible. Runners should be placed not more than 2000 mm from the center.
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Tubes should never be thrown or dropped from the scaffolding. |
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Partially cut tubes should never be used. |
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Bent and damaged ends should be cut and bores removed. |
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Tubes must not be split, bent, badly corroded or distored. |
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Tubes not meeting BS requirements, i.e. thin gauge water pipes or rusty tubes, is totally unacceptable. |
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When dismantling scaffolding, always remove fittings from tubes, making for easy storage and less damage. |
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Fittings should never be dropped or bombed from any height. |
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Fittings must not be distorted and moving parts must be sound and lubricated. |
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Never try to pull material up the scaffold without the scaffold being tied to the building or a solid structure. |
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At the end of the working day, all materials should be stacked and placed in a neat and tidy fashion.
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Diagonal bracing is used to stiffen the structure as necessary, most importantly in the upright direction. Bracing is generally connected to the posts with "adjustable" or "swivel" couplers which have the facility of adjusting a full 360 degree so that two members in parallel planes are connectable at any angle. Cross bracing should be installed across the width of the scaffolding at least every third set of posts horizontally and every fourth runner vertically. Such bracing should extend diagonally from the inner and outer runners upward to the next outer and inner runners. Longitudinal diagonal bracing on the inner and outer rows of poles shall be installed at approximately a 45 degree angle from near the base of the first out post upward to the extreme top of the scaffolding. |
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Where the longitudinal length of the scaffold permits, such bracing must be duplicated, beginning at every fifth post. In similar manner, longitudinal diagonal bracing must also be installed from the last post extending back and upward toward the first post. Where conditions preclude the attachment of this bracing to the posts, it may be attached to the runners. |
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Nodes points are where a number of tubes converge on the structure. The degree of eccentricity should be minimized in order to avoid excessive eccentricities and bending in the tubes. |
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Braces should be connected as near as possible to the nodes where continuous diagonal brace tubes are used. It is essential that they connect at every node point. |
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The conditions shown in figure below illustrate, that the buckling load required to produce failure in figure (A) is much less than in (B), because the buckling lengths are longer. |
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