Trent Burns discusses the important particulars of lattice and telescopic boom inspection.
Why should telescopic and lattice booms be regularly inspected? The answer is two-fold. The first reason is to prevent damage and destruction from the collapse of the boom. The second reason is to maintain regulatory compliance under the federal OSHA law.
The proper boom inspection of mobile cranes requires an up-close and personal approach. The inspector needs to be close enough to see the entire boom in detail. If the boom cannot be lowered to the ground, an aerial lift may be needed. The crane’s load chart should be consulted before attempting to lower the boom to the horizontal, as not all cranes can attain low angles without tipping. Once the inspector has access to the entire boom from base to tip, the inspection can begin.
Lattice boom inspection
Traditional lattice boom cranes are defined as being fabricated from high-strength steel, and by their booms, which will have four main chords pinned and welded together with lacings that are either tubular or angular. These serialized boom sections typically come in 10, 20, 30 and 40-foot long sections, and are matched to the crane per the manufacturer’s specifications and recommendations. Many times, the serial numbers on the boom sections can be extremely difficult to locate, especially if the crane has been painted multiple times.
On the boom, the shortest section should be installed closest to the crane itself, graduating to the longer sections towards the top. The connecting pins should be installed from the inside and pointing out, secured with cotter pins, not hitch pins, thereby increasing safety during disassembly. All sections of the boom should be free of structural damage including, but not limited to, nicks, corrosion, gouges, bent components, broken welds, any type of deformation or heat damage. If any of these items are found, the damage needs to be recorded, and the crane is to be tagged out until the manufacturer has been consulted and/or the damage repaired. If no issues are present, the qualified inspector, starting at the base and working forward, will check the straightness of each boom section and confirm that each section is square.
The sheaves, located at the boom tip, need to be inspected for anything that could inhibit rotation, lubrication, wear, or any damage that may have an impact on the wire rope. There also needs to be a close-fitting guard on each sheave that will keep the wire rope in place when installed. Auxiliary components installed on the boom need to be inspected per the manufacturer’s guidelines, as well as all safety devices and operator aides, such as anti-two block devices, load moment indicators, scales, etc.
Once the boom structure and added components have been checked, the pendant system must be evaluated.
Pendants can be fabricated of wire rope or solid steel with articulating systems pinned together. The crane’s manual will describe the system required for each crane, and the manufacturer will have guidelines for inspection. If the pendant line is made of wire rope, it should be inspected for diameter, broken wires, kinks, corrosion and structural damage. Should the pendant lines be made of solid steel, they need to be inspected for any type of deformation, including cracks, bends, or twists, missing connectors, etc.
Located on the top side of the boom, the rope guides, rollers or wear pads (on which the hoist rope ride), should be checked for wear due to metal-on-metal contact. Once the entire structure of the boom has been inspected, the boom hoist system must be evaluated. Each sheave of the system should be inspected in the same manner as the boom tip sheaves. This may require the sheaves to be completely unloaded and slack left in the lines. Inspectors generally find wear on the outer bale assemblies from excessive rotation while in motion. Once completed, keep tension on the lines while the crane is boomed, checking the accuracy of the boom angle indicator throughout the crane’s range.
Telescopic boom inspection
Telescoping crane booms differ from lattice boom cranes in style but require just as much, if not more, scrutiny. Even though many of the components are inspected in the same manner as lattice booms – boom tip, operator aides and safety devices – the boom itself has major differences.
Telescoping booms are made up of multiple “shell” sections that become progressively narrower the further they scope out from the crane. Through a system of hydraulic cylinders, in conjunction with roller chains or wire rope, each section will slide out as the boom is lengthened.
Once the inspector has access to the entire boom length, the inspection should begin with the base section at the hinge pins and the boom cylinder. The pins should be sized to the crane, without any gaps or play where they attach, and the cylinder should be free of leaks and damage. Each boom section should also be inspected closely for any structural damage, with the boom fully extended. If an inspection reveals structural damage, nicks, corrosion, gouges, bent components, broken welds or any type of deformation, the damage needs to be recorded, and the crane is to be tagged out until the manufacturer has been consulted and/or the damaged repaired. Any deformation in this type of boom can lead to a collapse, even without a load on the crane.
Wear pads, which prevent metal on metal contact and excessive movement on each section, will need to be inspected and adjusted or replaced if worn. There should be a lite coat of lubricant on the boom where the pads make contact,reducing friction and easing the extension/retraction of the boom.
Along the boom there will be sight windows, allowing for inspection of the crane’s telescoping system. The inspector should check for hydraulic leaks, damaged hoses, corrosion, worn parts, loose roller chains and anything else of question. The inspector will also be able to view the extension/retraction cylinders. Any hydraulic issues should be addressed immediately. Damage found in this section may need disassembly for repair.
Should inspection of any type of the crane’s boom show a deformation, excessive sag, structural damage, or raise a question about the safety of a crane, the inspector shall document it, and the manufacturer would need to be contacted.
The manufacturer’s report will let you know if the equipment needs to be repaired or replaced. If the deficiency can be repaired, the manufacturer’s procedures must be followed and documented accordingly by a qualified person.
The boom is a critical component that doesn’t require major damage to become dangerous. Everyone that works around cranes should be trained to know what to look for, and all mobile crane inspections should be completed thoroughly and by a qualified person.
A visual inspection of all booms is required before operating the equipment by a competent person. A comprehensive inspection is required annually by a qualified person and must be documented, maintained and retained for a minimum of 12 months. A well-documented and thorough inspection is a relatively inexpensive way of ensuring the health and well-being of everyone at a worksite along with protecting the hundreds of thousands of dollars invested in the crane.