Load Test – Tower Cranes
Load Test – Derricks and Offshore
Load Test – Floating and Deck Cranes and High Pedestal
Portal Cranes
Introduction: In most cases it is a statutory requirement that all cranes be tested by a competent person before being taken into service and periodically thereafter. In addition, a further test may be required following any substantial alteration or repair to the crane. It is the purpose of the annual condition inspection to ensure that the overall structural, mechanical, and electric components of the equipment have been maintained in a safe and serviceable condition and are functioning properly according to the original equipment manufacturer's specifications.
Before any proof load test is carried out, it should be established that the design of the crane allows for the imposition of a proof load and the amount and position at which such load may be handled. It should be noted that the maximum load may be limited by the structural strength of the crane and not by the stability of the machine, in which case a structural failure might occur, e.g. the boom might collapse without warning before the crane starts to tip.
Before a test is carried out reference should be made to manufacturer’s specifications or an authority experienced in crane design and construction. Due account will then be made for the actual condition of the crane at the time of testing. It should be noted that a proof load test is not the sole criterion for assessing the safe working load of a crane.
Most regulations demand a test and thorough examination before first being taken into service, test and thorough examination every four years thereafter, test and thorough examination after substantial modification or repair, and a partial load test and thorough examination annually between proof load tests. While regulations do not always demand the use of a dynamic test load, generally accepted practice is the use of freely suspended loads.
Proof testing of the following equipment is described in this section:
- Tower Cranes
- Derrick Cranes
- Floating and Deck Cranes
- Offshore Cranes
- High Pedestal Portal Cranes
Note: Mobile cranes and overhead travelling cranes are covered in other sections.
The following procedure is established to provide a method which will meet the most stringent requirements that apply to this type of crane. The methods herein recommended are intended to provide a safe and effective means by which load tests can be conducted.
1. Pre-test Procedures (Back to Top)
1-1. Determine that lifting gear to be used with the crane in normal duties or for the purpose of testing the crane has already been tested independently. Check that all lifting attachments are clearly marked with their safe working load.
1-2. Review previous tests and inspection certificates and deficiency reports and determine that any necessary corrections have been made. Determine the appropriate standards by which the crane should be inspected and tested.
1-3. Review periodic inspection reports, maintenance records and documentation of repairs to determine that all work was in order.
1-4. Determine that the rated loads for the crane are presented on a chart or in the owners manual on the crane and select appropriate test loads from this data.
1-5. Check that an owner’s manual with operating instructions is available for the crane.
1-6. Choose appropriate loads for the test based on the manufacturer’s load ratings for the condition of use. A 25% minimum partial load, the rated load and proof loads exceeding the rated loads as required by the regulatory authority shall be used. Reeving configuration must be recorded.
1-7. Rigging should be arranged for the test loads which conforms to good rigging practice for a safe lift.
1-8. Barriers should be set up around the operating perimeter if there is any possibility that personnel or vehicles will intrude into the operating region.
1-9. A pre-test conference should be arranged with the operator, the riggers, and the signalman to establish how the test will be conducted and to review the signals to be used.
1-10. Inspect the crane in its entirety according to the checklist normally used for that type of crane. Particular attention should be given to the structural elements of the crane which will be subjected to stress during the load testing procedure. Any evidence of degradation among the structural elements should be evaluated and a determination made as to the suitability of the crane’s condition for load testing and the need for nondestructive testing or dismantling for detailed examination.
1-11. Conduct a visual examination of the crane supports, runway, track, power conductors, collectors and switch gear as applicable prior to commencing the test.
1-12. The crane should be operated without a load through its full range of operation and all safety devices should be checked. The 25% partial load should then be applied and required adjustments made for appropriate function. (i.e. limit switches, soft starts, etc.)
1-13. Foundations, walls and structures on which the crane is mounted or attached must be checked for soundness and freedom from sinkage, wastage or defects.
1-14. In the case of electric power operated equipment, all supply, current collecting systems, control gear, valves, “fail—safe” mechanisms, limit mechanisms, protective and running equipment must be examined for correctness, safety and proper operation.
2. Load Test – Tower Cranes (Back to Top)
2-1. A rail mounted crane should be positioned on a straight and level track with firm foundations and free from obstruction.
2-2. The rail and rail foundations must be straight, level and sound over the complete craneway before a load test is conducted.
2-3. The accuracy of marking on the load radius indicator, when the crane is so equipped, should be checked by measuring the radius for the appropriate safe working load.
2-4. Prior to the proof load test the maximum safe working load should be raised clear of the ground and the crane slowly operated through all its motions, as site and wind conditions permit.
2-5. Test for Horizontal Boom with Trolley
2-5-1. With the trolley set at less than maximum radius for the maximum load (not to be confused with the maximum radius of the crane), a proof load equal to 110% of maximum rated load should be raised clear of the ground, the trolley moved to maximum radius for the maximum rated load and the crane slowly operated through all its motions to ensure that the load is applied to all parts. The hoist brake should be proved to be capable of sustaining the proof load. The trolley must not be traversed out beyond the specified maximum working radius for the maximum load. The manufacturer’s recommendations must be followed for any loading beyond the rated load at a given radius and for over—riding safety alarms and devices.
2-5-2. With the trolley set at an intermediate radius, a 110% proof load for maximum radius should be raised clear of the ground and the trolley moved to maximum radius and the crane slowly operated through all its motions to ensure that the load is applied to all parts, as site conditions permit.
2-5-3. Where there are intermediate duties, each panel point and section track should be subject to the relevant excess proof load.
2-6. Luffing Boom
2-6-1. With the boom set at less than the maximum radius for the maximum rated load (not to be confused with the maximum radius of the crane), a proof load equal to 110% of maximum rated load should be raised clear of the ground, the boom lowered to maximum radius for the maximum rated load and the crane operated slowly through all its motions to ensure that the load is applied to all parts, as site conditions permit. The hoist brake and derrick brake should be proved capable of sustaining the proof load.
2-6-2. The same proof load should then be applied near the minimum safe working radius of the boom.
2-6-3. With the boom set near its maximum radius, a 110% proof load at that radius should be raised clear of the ground and the crane slowly operated through all its motions to ensure that the load is applied to all parts, as site conditions permit.
3. Load Test — Derricks and Offshore Cranes (Back to Top)
3-1. A rail mounted derrick should be positioned on a straight and level track with firm foundations and free from obstruction.
3-2. The rail and rail foundations must be straight, level and sound over the complete craneway before a load test is conducted.
3-3. The accuracy of marking on the load radius indicator and the load monitor, if so fitted, should be checked by measuring the radius and comparing the monitor reading to the test load value.
3-4. Prior to the proof load test the maximum safe working load
should be raised clear of the ground and the derrick slowly
operated through all its motions.
3-5. Proof loads should be determined as follows:
SAFE WORKING LOAD TEST LOAD*
Up to 20 tons SWL + 25%
20-50 tons SWL + 5 tons
Over 50 tons SWL + 10%
* Unless manufacturer recommends otherwise.
3-6. With the boom set at the maximum radius for the maximum load (not to be confused with the maximum radius of the derrick), a proof load exceeding the rated load as noted above (or such other proof load as the regulatory authority requires) should be raised clear of the ground and the derrick slowly operated through all its motions to ensure that the load is applied to all parts. The hoist brake and, where applicable, the derrick brake should be proved capable of sustaining the proof load.
3-7. The same proof load should then be applied at the minimum safe working radius of the boom.
3-8. With the boom set at less than maximum radius, a proof load exceeding the rated load as noted above (or such other proof load as the regulatory authority requires) at maximum radius should be raised clear of the ground, the boom lowered to maximum radius and the derrick operated through all its motions to ensure that the load is applied to all parts.
3-9. These tests should be repeated for each boom length.
4. Load Test – Floating and Deck Cranes and High Pedestal Portal Cranes (Back to Top)
4-1. A mobile crane mounted on a barge shall be properly secured to the barge.
4-2. Load ratings for mobile cranes mounted on barges shall be reduced to stay within the limits for list of the barge with a crane mounted on it and a revised load rating chart shall be provided by the crane or barge manufacturer, a competent registered engineer or a marine architect.
4-3. The accuracy of marking on any load radius indicator should be checked by measuring the radius for the appropriate safe working load.
4-4. Prior to the proof load test proper ballasting should be done, if required, by the appropriate authority. The maximum safe working load should be raised clear of the ground and the crane operated through all its motions. This lift should be made over land or stabilized deck works to allow the stability of the floating crane to be ascertained. An inclinometer shall be installed in the operator's cab to indicate list. (A tilting barge or vessel can result in a drastic increase in the radius, thus causing the barge or vessel to capsize.)
4-5. With the boom set at less than maximum radius for the maximum load (not to be confused with the maximum radius of the crane), a proof load equal to 110% of rated load (or such other proof load as the regulatory authority requires) should be raised clear of the ground, the boom lowered to maximum radius for the maximum load and the crane slowly operated through all its motions to ensure that the load is applied to all parts. The hoist brake and, where applicable, derrick brake should be proved capable of sustaining the proof load.
4-6. The same proof load should then be applied near the minimum safe working radius of the boom.
4-7. With the boom set near its maximum radius, a 110% proof load (or such other proof load as the regulatory authority requires) at that radius should be raised clear of the ground and the crane operated through all its motions to ensure that the load is applied to all parts.
4-8. These tests should be repeated for each boom length.
5. Post-test Inspection (Back to Top)
5-1. After the tests are completed, conduct a thorough examination to ensure that the crane has satisfactorily withstood the tests. Park the crane at the proper location for service access and relax all rigging and reeving to allow for inspection of the wire rope and reeving components. Open the main disconnect and install a safety lock-out device before mounting the crane.
5-2. Check all components of the crane for structural damage including cracks, weld separation, permanent deformation, paint flaking and loose fasteners.
5-3. Check the runway and/or supports for structural damage or distortion, loose or damaged fasteners, track alignment and secure attachment to the structural support.
5-4. Check the crane and runway electrical components for deterioration and proper condition. Verify the integrity of wiring, connections and enclosures, checking for neatness, security and conformance to appropriate electrical codes.
5-5. Check all sheaves, drums and wire rope for evidence damage or excessive wear. Open the wire rope and inspect the core at several points to determine any deterioration. Give particular attention to potential damage at end fittings and anchor points.
5-6. Check that all required guards are securely attached. Verify that all shafts, couplings and open gears that can be contacted by personnel are properly guarded.
5-7. Make note of any damage, deficiencies, or corrections that may be required.
5-8. For a high pedestal, portal and overhead traveling cranes, hoist the load blocks clear of personnel or obstructions and verify that the wire rope has wound properly on the hoist drums. For a floating/deck cranes, properly secure the load blocks. Open the main disconnect and leave the pendant, if any, in the designated location.
5-9. Complete the report and conduct an exit briefing, if appropriate.
