Who must determine the foundation and structural supports are installed in accord with their design?
Tower cranes present unique issues that are addressed in Section 1435. In general, all provisions of the standard apply to tower cranes unless Section 1435 specifies different or additional
Additional Requirements for Erecting, Climbing, and Dismantling
To reflect industry terminology, "erecting, climbing, and dismantling" are used instead of "assembly/disassembly" when referring to tower cranes. The following requirements apply in
addition to those specified in sections 1403-1406:
Tower crane foundations and structural supports (including both the portions of the structure used for support and the means of attachment) must be designed by the manufacturer or a
registered professional engineer.
The Assembly/Disassembly (A/D) director must determine that tower crane foundations and structural supports are installed in accord with their design.
The A/D Director must address the backward stability of self-erecting cranes or cranes on traveling or static undercarriages.
Always make sure the tower is erected plumb to the manufacturer’s tolerance or at least 1:500.
Wind must not exceed the speed recommended by the manufacturer or, where the manufacturer does not specify this information, the speed determined by a qualified person.
Towers must be erected plumb to the manufacturer's tolerance and verified by a qualified person. Where the manufacturer does not specify plumb tolerance, the crane tower must be plumb
to a tolerance of at least 1:500 (approximately 1 inch in 40 feet).
On jobsites where more than one fixed jib (hammerhead) tower crane is installed, the cranes must be located such that no crane can come in contact with the structure of another crane.
Cranes are permitted to pass over one another.
Prior to, and during, all climbing procedures (including inside climbing and top climbing), the employer must comply with all manufacturer prohibitions and have a registered professional
engineer verify that the host structure is strong enough to sustain the forces imposed through the braces, brace anchorages, and supporting floors.
Equipment must not be erected, dismantled or operated without the amount and position of counterweight and/or ballast in place as specified by the manufacturer or a registered professional
engineer familiar with the equipment. The maximum counterweight and/or ballast specified by the manufacturer or registered professional engineer must not be exceeded.
The size and location of signs installed on tower cranes must be in accord with manufacturer specifications. Where these are unavailable, a registered professional engineer familiar with
the type of equipment involved must approve in writing the size and location of any signs.
Particular Caution Required When Using Synthetic Slings
Synthetic slings must be protected from abrasive, sharp or acute edges, and configurations that could cause a reduction of the sling's rated capacity.
This requirement appears in section 1404(r) but bears repeating here: when using synthetic slings during erecting, climbing, and dismantling, you must follow the synthetic sling manufacturer's
instructions, limitations, specifications and recommendations. Synthetic slings must be protected from abrasive, sharp or acute edges, and configurations that could cause a reduction of the
sling's rated capacity, such as distortion or localized compression.
Different safety devices than those specified in section 1415 are required on tower cranes. Those required on tower cranes are:
boom stops on luffing boom type tower cranes
jib stops on luffing boom type tower cranes if equipped with a jib attachment
travel rail end stops at both ends of travel rail
travel rail clamps on all travel bogies
integrally mounted check valves on all load-supporting hydraulic cylinders
hydraulic system pressure limiting device
Jib stops are required on tower cranes.
the following brakes, which must automatically set in the event of pressure loss or power failure, are required:
hoist brake on all hoists
rail travel brake
deadman control or forced neutral return control (hand) levers
emergency stop switch at the operator's station
trolley end stops at both ends of travel of the trolley
Proper operation of these safety devices is required before operations can begin.
Is a boom angle indicator a required operational aid for a tower crane? Photo courtesy of Link-Belt Cranes
Different operational aids than those specified in Section 1416
are required for tower cranes. Those required on tower cranes are:
trolley travel limiting device at both trolley end stops
boom hoist limiting device that limits the range of the boom at the minimum and maximum radius
anti two-blocking device
hoist drum lower limiting device on tower cranes (manufactured after November 8, 2011)
load moment limiting device
hoist line pull limiting device
rail travel limiting device
boom hoist drum positive locking device and control
boom angle or hook radius indicator readable from the operator's station (required on all luffing boom tower cranes and on hammerhead tower cranes manufactured after November 8, 2011)
trolley travel deceleration device
boom hoist deceleration device
load hoist deceleration device
wind speed indicator
load indicating device on tower cranes (manufactured after November 8, 2011)
As with operational aids on other equipment, tower cranes may be operated for limited amounts of time with malfunctioning aids as long as the temporary alternative measures specified in the
standard are taken.
Additional inspection requirements for tower cranes are discussed under section 1412 (Inspections).
Derricks also present unique issues that are addressed in Section 1436. In general, all provisions of the standard apply to derricks unless Section 1436 specifies different or additional requirements.
Derrick operators need not meet the operator qualification/certification requirement of section 1427. However, you must train each derrick operator on how to operate the equipment safely.
Do you need to ensure the load chart is posted where it is visible for personnel operating a permanent derrick?
For permanently installed derricks with fixed lengths of boom, guy, and mast, a load chart must be posted where it is visible to personnel responsible for the operation of the equipment.
For derricks that are not permanently installed, the load chart must be readily available at the job site to personnel responsible for operating the equipment. Load charts must contain at least the:
rated capacity at corresponding ranges of boom angle or operating radii
specific lengths of components to which the rated capacities apply
required parts for hoist reeving
size and construction of rope (or may be included in the operating manual)
Derricks must be constructed to meet all stresses imposed on members and components when installed and operated in accord with the manufacturer's/builder's procedures and within its rated
capacity. Load anchoring data developed by the manufacturer or a qualified person must be used.
Specific additional construction requirements are specified for:
gin pole derricks
chicago boom derricks
Does a new hoist need to be load tested? If so, it should be tested to what minimum rated capacity?
Derricks must be constructed to meet all stresses imposed on members and components when installed and operated in accord with the manufacturer's/builder's procedures and within its rated capacity.
Load anchoring data developed by the manufacturer or a qualified person must be used.
Specific additional construction requirements are specified for:
gin pole derricks
chicago boom derricks
Swingers and Hoists
The boom, swinger mechanisms, and hoists must be suitable for the derrick work intended and must be anchored to prevent displacement from the imposed loads.
Hoists must meet the following requirements:
Base mounted drum hoists must meet certain specified requirements of ASME B30.7-2001 ("Base-Mounted Drum Hoists").
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New hoists must be load tested to a minimum of 110% of rated capacity, but not more than 125% of rated capacity, unless otherwise recommended by the manufacturer. This requirement is met where the manufacturer has conducted the testing.
Hoists that have had repairs, modifications, or additions affecting their capacity or safe operation must be evaluated by a qualified person to determine if a load test is necessary. If it is, load testing must be conducted in the manner specified in the standard.
The operational aids requirements listed in section 1416 apply to derricks except when 1) a boom hoist limiting device (required by section 1416 for other equipment) is not required
for derricks, and 2) alternative requirements to those in section 1416 are specified for the following two operational aids:
Boom angle or radius indicator: Such a device is not required, but if the derrick is not equipped with a functioning one, the employer must ensure that either:
The boom hoist cable is marked with caution and stop marks. The stop marks must correspond to maximum and minimum allowable boom angles. The caution and stop marks must be in view of the operator or a spotter who is in direct communication with the operator; or
An electronic or other device that signals the operator in time to prevent the boom from moving past its maximum and minimum angles, or automatically prevents such movement, is used.
Load weight/capacity device: Derricks manufactured after November 8, 2011 with a maximum rated capacity more than 6,000 pounds must have at least one of the following:
load weighing device
load moment indicator
rated capacity indicator
rated capacity limiter
Post-Assembly Approval and Testing
The following requirements apply to new or reinstalled derricks:
Post-assembly should you perform a functional test of the derrick before lifting a load?
Anchorages: Anchorages, including the structure to which the derrick is attached (if applicable), must be approved by a qualified person.
Functional test: Prior to initial use, new or reinstalled derricks must be tested by a competent person with no hook load to verify proper operation. This test must include the following:
lifting and lowering the hook(s) through the full range of hook travel
raising and lowering the boom through the full range of boom travel
swinging in each direction through the full range of swing
actuating the anti-two-block and boom hoist limit devices (if provided)
actuating locking, limiting, and indicating devices (if provided)
Load test: Prior to initial use, new or reinstalled derricks must pass a load test conducted by a competent person. Test loads must be at least 100% and no more than 110% of the rated capacity, unless otherwise recommended by the manufacturer or qualified person, but in no event must the test load be less than the maximum anticipated load. The test must consist of:
hoisting the test load a few inches and holding to verify that the load is supported by the derrick and held by the hoist brake(s)
swinging the derrick, if applicable, the full range of its swing, at the maximum allowable working radius for the test load
booming the derrick up and down within the allowable working radius for the test load
lowering, stopping, and holding the load with the brake(s)
Test documentation: The functional and load tests must be documented. The document must contain the date, test results, and name of the tester. The document must be retained until the derrick is retested or dismantled, whichever occurs first. All such documents must be available during the applicable document retention period to all persons who conduct required inspections (see section 1412).
Load Testing Repaired or Modified Derricks
Derricks that have had repairs, modifications, or additions affecting the derrick's capacity or safe operation must be evaluated by a qualified person to determine if a load test is
necessary. If it is, load testing must be conducted and documented.
Power Failure Procedures
If power fails during operations, the derrick operator must safely stop operations. This must include setting all brakes or locking devices and moving all clutch and other power controls
to the off position.
The process of jumping a derrick must be supervised by the Assembly/Disassembly (A/D) director.
This is a video by Lee Sheppard on the operation of a digger derrick.
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