19.6 10-year major inspection
AS 2550.1 : Cranes, hoists and winches - Safe use - General requirements (non-Queensland Government link) specifies that cranes are to be subjected to a major inspection at the end of their design life or, where this is unknown, after 25 years for the structure and 10 years for the mechanical components. The 10 and 25-year periods are based on design parameters in AS 1418.1 : Cranes, hoists and winches - General requirements (non-Queensland Government link). While it is acknowledged that mechanical components may undergo greater wear and fatigue rates, this may not always be the case and structural items on cranes are generally easier to inspect. For this reason, this code does not state that a separate major inspection must be undertaken at 25 year intervals. Instead, the competent person is encouraged to inspect structural items during the 10-year major inspection.
AS 2550.1 : Cranes, hoists and winches - Safe use - General requirements (non-Queensland Government link) indicates that the 10-year major inspection is intended to assess the crane’s suitability for continued operation. The parameters of the 10-year major inspection should be considerably more comprehensive than the yearly inspection, due to the amount and severity of operation that a mobile crane will be exposed to after 10 years. Even if the crane has not been exposed to regular operation during the 10-year period, the crane may have deteriorated due to the way it has been stored or the environment it has been operated in (e.g. dirty or corrosive environments). The 10-year major inspection is to be certified by an engineer who has experience in the inspection of mobile cranes. The engineer may use the advice of other competent persons when preparing the inspection report.
An example of a Crane Safety Certificate for a 10-year major inspection is provided in appendix 7. This document may be used as evidence that the crane has received its 10-year major inspection by an engineer.
AS 2550.1 : Cranes, hoists and winches - Safe use - General requirements (non-Queensland Government link) does not provide specific detail on the parts of the crane to be examined; this is left to the responsibility of the crane manufacturer, or where this information is not available, the competent person. The extent of inspection performed during the 10-year inspection will largely depend on this information. However, a number of key items are to form part of the major inspection.
Prior to listing the key inspection items, the following is to be noted:
- Where the crane manufacturer specifies instructions for the 10-year major inspection, these instructions are to be followed and take precedence over the list below.
- The list only specifies some of the generic items requiring inspection. The actual list of items inspected will be considerably larger and will be based on the requirements of the crane manufacturer, or if these do not exist, the instructions of a competent person.
- Completion of a 10-year major inspection does not indicate that the components inspected will have an additional life of 10 years.
- It must not be assumed that the items included in the list only require inspection at 10-yearly intervals. All items will require some type of inspection and maintenance at more frequent intervals (i.e. at annual and other inspection intervals) in accordance with the crane manufacturer’s instructions.
Where there is documented evidence that the appropriate inspecting and testing has been carried out on a certain item within the preceding two years, this item does not have to be stripped down in the 10-year major inspection. However, the competent person must still inspect the safe operation of the item to certify that it is operating safely. In some cases the two year period may be extended based on the opinion of the competent person. However, the reasons justifying this decision are to be documented. This requirement applies to slew ring bolts, drive systems and braking systems.
19.6.1 Key items requiring inspection
The key items which are to form part of the 10-year major inspection are detailed below.
Slew ring
Slew ring bolts
Hook rollers
Drive systems
Braking systems
Hydraulic cylinders
Booms (hydraulic cranes)
Booms (lattice boom cranes)
Rated capacity limiters and load indicators
Steel wire ropes
Rope sheaves
The amount of clearance in the slew ring is to be quantitatively measured and compared to the maximum clearance specified by the crane manufacturer. The clearance should be measured at a minimum of four locations around the slew ring. If the clearance exceeds that specified by the manufacturer, the slew ring should be split. Where the slew ring is split, all components must be examined and replaced where they are damaged or worn. The backlash and teeth width in both the pinion drives and ring drive are to be measured and are to be within the crane manufacturer’s specification.
One of the following alternatives should be followed:
- Remove all bolts and replace with new bolts of the type specified by the manufacturer, installed in accordance with the crane manufacturer’s instructions (i.e. torque and tightening sequence).
- Re-torque slew ring bolts to the crane manufacturer’s specifications. Where any bolts fail, all bolts are to be removed and non-destructively tested and re-installed, or replaced with new bolts. Note: this alternative may only be selected where the crane manufacturer states that the procedure is an acceptable method of testing integrity of the slew ring bolts.
- Remove all bolts and non-destructively test for cracking or other imperfections. Re-install undamaged bolts in accordance with the crane manufacturer’s instructions (i.e. torque and tightening sequence). Note: this alternative may only be selected where the crane manufacturer states that the procedure is an acceptable method of testing integrity of the slew ring bolts.
- Remove a percentage of slew bolts in accordance with the crane manufacturer’s instructions. Non-destructively test removed bolts. If any damage is found, all bolts are to be removed and non-destructively tested or replaced with new bolts. Note: this alternative may only be selected where the crane manufacturer states that the procedure is an acceptable method of testing integrity of the slew ring bolts.
Non-destructively test hook roller mounts for cracking or other imperfections. Measure diameter of rollers and replace if under tolerance. Check rollers to ensure they are able to rotate freely and that there is no uneven wear.
Drive systems (including hydraulic motors, gearboxes and drive-shafts)
Where catastrophic failure of the drive system can result in the load or boom dropping in an uncontrolled manner, carry out the following:
- Remove and strip down all parts of the drive system. Ensure all components are within manufacturer’s tolerance. Replace worn components including valves, shafts and bearings.
- Non-destructively test parts of the drive system that may be prone to cracking. Particular attention must be given to components, the failure of which will have a catastrophic effect. Since significant fatigue damage can occur in the microstructure of these components without evidence in non-destructive testing, the competent person must consider the replacement of such components.
- Hydraulic motors and valves are to be pressure and performance tested prior to re-entering service.
Where catastrophic failure of the drive system will not result in the load or boom dropping in an uncontrolled manner, carry out the following:
- Inspect the drive system for vibration, fluid leakage and correct operation.
- Where damage or malfunction can be observed, remove and repair or replace defective part.
- Hoist and luff brakes are to be removed from the crane and dismantled. Pins, springs, valves and bearings are to be checked for correct tolerance. Rubber seals are to be replaced and pistons checked for correct operation.
- Any welds in braking systems, including band brake weld terminations, are to be crack tested by NDT. Non-destructively test parts of the braking system that may be prone to cracking. Particular attention must be given to components that will have a catastrophic effect if they fail.
- Since significant fatigue damage can occur in the microstructure of these components without evidence in non-destructive testing, the competent person must consider the replacement of such components.
- Hydraulic systems are to be checked for leaks prior to re-attachment to the crane.
- Brake linings are to be checked for wear limits.
- After re-installation brakes are to be adjusted and actuated a number of times to ensure correct operation.
Hydraulic cylinders (all cylinders, including outrigger cylinders)
- Hydraulic cylinders are to be checked for external leakage and creep. Where leakage is observed, or creep exceeds manufacturer’s specifications, hydraulic cylinders are to be removed and stripped down.
- Seals are to be replaced and rams re-chromed where necessary.
- NDT crack test welds on rod ends and caps.
- Re-assembled cylinders are to be pressure tested and checked for operation and leaks.
Booms (hydraulic cranes)
On all hydraulic booms:
- Perform creep test on telescopic function with boom extended and raised to maximum amount permitted on load chart. Where creep exceeds the crane manufacturer’s specifications, and this is caused by leakage in telescoping cylinder, disassemble boom and remove hydraulic cylinder for repair or replacement.
- Check boom straightness in both planes to manufacturer’s specifications. Where boom deflection exceeds manufacturer’s tolerances, remove and dismantle boom and repair or replace.
- Check wear pad clearance and replace worn wear pads.
- Check boom condition for corrosion and damage. Non-destructively test accessible welds on both boom sections and slew ring upper.
- Where pin type locks are used (i.e. instead of rope or chain type extensions), the effective operation of the locking mechanism is to be inspected. Note: in some cases, manufacturers of these boom types may require disassembly of the boom at pre-determined intervals.
There are additional requirements where the boom has internal boom extension wire ropes or chains, or where boom extension is activated by screw drive:
- Remove and disassemble boom. Inspect wire ropes to AS 2759 : Steel wire rope – Application guide (non-Queensland Government link), and chains to manufacturer’s tolerance. Replace worn ropes and chains.
- Inspect wire rope and chain anchorages and non-destructively test welds on anchorages.
- Where screw drives are used, measure all screw threads and non-destructively test any welds on assembly.
- Boom NDT for cracks—
- all welds connecting male and female clevises (on the ends of every boom section);
- welds on boom butt section;
- welds on boom head;
- minimum of 10% of lacing welds (all welds if cracks are found).
- Chord thickness testing (ultrasonics)—all chords on boom sections.
- Thickness testing of plate used on butt section (i.e. near water drain holes).
- Check boom for straightness, damage and corrosion.
Rated capacity limiters and load indicators
Rated capacity limiters and load indicators are to be checked and calibrated for correct operation. The accuracy of these systems is to be within the tolerance specified by the crane manufacturer or AS 1418.5 Cranes, hoists and winches - Mobile cranes (non-Queensland Government link). A calibration certificate is to be completed by the competent person testing the equipment. However, it should be noted that rated capacity limiters and load indicators are to be calibrated at much more frequent intervals than at the 10-year major inspection.
All hoist, luff, pendant, trolley and counterweight ropes must be inspected for wear to ensure they do not exceed the discard criteria specified in AS 2759 : Steel wire rope – Application guide (non-Queensland Government link). If the competent person considers that the rope will require replacing within the next three months, the rope should be replaced with one that passes the inspection criteria of AS 2759: Steel wire rope – Application guide. Ropes must only be replaced with the type of rope specified by the crane manufacturer unless a professional engineer specifies otherwise.
The pins and terminations on pendant ropes must also be inspected.
All rope sheaves must be removed and inspected for cracking, alignment and damage. The sheave groove size must be checked and the sheave replaced if it is outside of the manufacturer’s specification. Bearings must be replaced if necessary. Synthetic sheaves should be replaced if recommended to do so by the sheave manufacturer.
Last updated 21 August 2008
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