AS 5714:2015 pd free.Load restraint for LP Gas cylinder distribution.
2.3.2 Loss of clinders through gate opening
This may occur through two modes—
(a) failure of strapping, wrapping or mechanical restraint where the upper gate latching becomes loose resulting in a gap that a cylinder could pass through: or
(b) failure of strapping. wrapping or mechanical restraint where a cylinder becomes loose on the tray, or unrestrained, particularly small cylinders, which move around until an opening is found.
To avoid these circumstances, the following load restraint requirements shall he complied with:
(i) Gate latches shall positively lock in a manner that does not allow the latching mechanism to release during transit.
(ii) Stillages used for small cylinders shall have openings that are less than the diameter of the smallest cylinder.
(iii) Where small cylinders are not transported in stillages or cages, gates shall have openings that are less than the diameter of the smallest cylinder.
2.3.3 Loss of cylinders through gate failure
Loss of cylinders through gate failure may occur through two modes—
(a) failure of the gate at the lugs or hinges as a result of the shear forces and bending forces applied to the gate; or
(b) failure of the gate as a result of the gate bending outwards between the lugs or hinges and becoming detached at the locking points.
The gates and the headboard shall be designed to safely resist the forces in Table 2.1. It is normal practice to apply a safety factor of 2.5.
2.3.4 Loss of cylinders through central support failure
For the cylinder truck design concept being covered in this Clause. 50% of side forces arc 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 cylinder-related forces with a safety factor of 2.5. These forces are—
(a) a shear force of 18, 500 N; and
(b) a bending moment force of 2, 510 Nm.
2.3.5 Other detailed design considerations to minimize 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. It is poor welding practice and not recommended that a weld be in pure tension.
For example, using rectangular hollow section (RIIS) 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 RIIS tube with the 50 mm 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 RIIS 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) are applied to that weld.
Plates, angles or other devices shall be used to ensure that the welds resisting failure are not in tension.
Two possible arrangements are shown in Figure 2.2, with all edges and corners smoothed and rounded. Oilier detailed designs that achieve the same result may he used.AS 5714 pdf download.