AS 5714:2015 – Load restraint for LP Gas cylinder distribution.
2.3.4 Loss of esliuders through central support failure
For the cylinder truck design concept being covered in this Clause, 50% of side forces are resisted by the central support. The maximum length of the LP Gas storage space is 8.4 m; therefore, the central support shall resist the LP Gas clinder-related forces with a safety factor of 2.5. These forces arc—
(a) a shear force of 18, 500 N; and
(b) a bendinu moment force of 2, 510 Nm.
2.3.5 Other detailed design considerations to minlmiac the risk of failure
Where there is a sudden change in shape of a structural member, stress concentration will occur. The safety factor may be increased.
A weld joint shall be designed so forces are transferred through welds in shear. Ii is poor welding practice and not recommended that a weld be in pure tension.
For example, using rectangular hollow section (RI-IS) steel tubes for the central support for the headboard uprights, butt welding these against the top of the coaming rail and welding around the point of contact is not recommended, The minimum material that will resist the forces and provide the required safety margins is a 100 mm x 50 mm x 4 mm RI-IS tube with the 50mm dimension lined up with the 50mm width of the coaming rail.
The method in which this support is attached to the coaming rail is critical. The
100 mm x 50 mm x 4 mm RHS tube shall not be butted to the coaming rail and welded
around its circumference. Any internal weld defect may crack and fail as maximum loads
(tension plus shear plus bending moment) arc applied to that weld.
Plates, angles or other devices shall be used to ensure that the welds resisting failure arc not in tension.
Two possible arrangements are shown in Figure 2.2. with all edges and corners smoothed and rounded. Other detailed designs that achieve the same result may be used.
(g) The pins shall be welded at the top flange of the coaming rail to give maximum gale clearance to the ground, and the length of welds to the coaming rail on each side shall be at least 40 mm.
NOTE: The tubing forming the other part of the hinge should be at least 40 mm long and either heasy 15 mm nominal bore circular hollow section lC’llS) tube with an outsidc diameter of 21.3mm and a wall thickness of 3.2mm or machined tube with a minimum wall thickness of 4 mm.
(h) Suitable top latches that positively lock the gates shall be fitted at each end of the gales, Such latches shall have pins, barrels or bars at least 10 mm in diameter if in close to pure shear, or larger if subject to bending moments.
NOTE: If the locking part is a fiat plate style, it should be 40 mm widc and 4 mm dccp or alternately around 25 mm wide and 5 mm thick,
(I) (jaWs shall not exceed 3.2 m overall length.
lahlc 2.2 shows the centre of mass of the various types of 1.P Gas cylinders regularly carried and recommended locations of gate cross mcmbers These spacing are illustrated in Figure 2.3.
Gates shall he a minimum of 70/o of the height of the cylinders they arc used to contain or 55% of the height of any stillage they contain. Due consideration shall be given to ground clearance for gates that are hinged.
When in the ‘down’ position with a load of full cylinders and the suspension fully compressed, there shall be adequate clearance for the operator to close the gates and to provide ground clearance when manoeuvring the truck into depot load bays while the gates are down. For 45 kg cylinders, the optimum height is 900 mm.
For a 2000 mm long gate there shall be minimum two verticals between the two hinge verticals. The estimated weight of a 201)0 mm gale is nominal 16 kg.