Section 4 Spreaders and lifting beams

4.1.1 The safe working load of a spreader or lifting beam is to be the maximum load which the item is certified to lift. The SWL of the lifting appliance with which the spreader or lifting beam is to be used is to be adequate for the SWL of the beam plus its self-weight.

4.1.2 Steel used in the construction of the beam is to be of weldable quality in accordance with Ch 8, 1.2 Materials and construction. The grade of steel is to be selected in accordance with the requirements as provided in Ch 11, 1.2 General material requirements 1.2.2 , based on the minimum design temperature for the location where the beam will be used (see Ch 11, 1.2 General material requirements 1.2.4).

4.1.3 Special attention is to be paid to the structural continuity and abrupt changes of the section are to be avoided.

4.1.4 Adequate reinforcement is to be fitted in way of concentrated loads at lifting and load attachment points.

4.1.5 Welding and weld details are to be to the satisfaction of LR.

4.2.1 For beams and spreaders that are used solely in harbour situations, and where dynamic loading is minimal, they may be designed such that the maximum stresses do not exceed the following values when the beam is subjected to its unfactored SWL:

Intermediate values are to be determined by interpolation. Alternatively, they may be designed in accordance with Ch 8, 4.2 Loading and allowable stress 4.2.2.

4.2.2 For beams and spreaders that will be used in opensea, offshore or in conditions where there is significant dynamic loading, they are to be designed by factoring the SWL and selfweight by a hoisting and duty factor appropriate to the situation. The resulting stresses are to comply with the allowable stress criteria described in Ch 4, 2.17 Allowable stress – Elastic failure and Ch 4, 2.18 Allowable stress – Compression, torsional and bending members.

4.2.3 The wire ropes forming the slings for beams and spreaders are to have a minimum safety factor, SF, derived from Ch 4, 2.26 Rope safety factors and sheave ratio 2.26.1 or Ch 4, 3.9 Rope safety factors 3.9.1 (as applicable). The minimum breaking load of the sling is given by:

4.2.4 The beam and components of frames are to be designed to ensure adequate lateral stability under load.

4.2.5 Where the beam is designed as a frame lifted by an arrangement of slings, the structure is to be designed to resist the compressive forces which are generated. In this respect, the factor of safety of each component against compressive buckling under the appropriate test load is to be not less than 1,3. See Ch 12 Testing, Marking and Surveys for test loads.