16.K Portal, Tower, and Pillar Cranes.
16.K.01 All load bearing foundations, supports, and rail tracks must be constructed or installed as determined by a RPE with knowledge in this area, in accordance with the crane manufacturer's recommendations.
How tower cranes are built
16.K.02 Cranes must be erected/dismantled in accordance with the manufacturer's recommended procedures, (or if manufacturer procedures are not available, in accordance with procedures developed by a RPE with knowledge in this area).
- When erected/dismantled, written instructions by the manufacturer and/or RPE and a list of the weights of each component must be kept at the site.
- Erection and dismantling must be performed under the supervision of a QP.
- An AHA must be developed and procedures established before the erection/dismantling work commences to insure site-specific needs are considered. The analysis will include:
- (1) The location of the crane in relation to other tower cranes, adjacent buildings or towers, overhead power and communication lines, underground utilities;
- (2) Foundation design and construction requirements; and
- (3) When the tower is erected within a structure, clearances between the tower and the structure and bracing and wedging requirements.
- Wind velocity at the site at the time of erection/dismantling must be a consideration as a limiting factor that could require suspending the erection/dismantling operation and must be as determined by the manufactured or if this data is not available, by a QP.
- Before crane components are erected, they must be visually inspected for damage. Dented, bent, torn, gouged or otherwise damaged members must not be erected.
- Initially and after each climb, the crane must be plumbed and then held in the plumbed condition by wedges or other means. Cranes must be plumbed to a tolerance of 1:500 (1 in:40 ft; 2.4 cm:12 m) unless the manufacturer specifies otherwise.
16.K.03 Pre-operation tests must be performed when cranes are erected and after each climbing operation, before placing the crane in service. All functional motions, motion limiting devices and brakes must be properly tested for operation in accordance with the manufacturer's recommended procedures and ANSI/ASME B30.3 or B30.4, as applicable:
- Crane supports;
- Brakes and clutches, limit and overload switches, and locking and safety devices; and
- Load hoisting and lowering, boom hoisting and lowering, and swing motion mechanisms and procedures.
16.K.04 Climbing Procedures.
Prior to and during, all climbing procedures (to include inside and top climbing), the employer must:
- Comply with all manufacturer prohibitions;
- Have a RPE verify that the host structure is strong enough to sustain the forces imposed through the braces, brace anchorages and supporting floors;
- Ensure that no part of the climbing procedure takes place when wind velocity at the crane superstructure exceeds the limit set by the manufacturer or a QP, or 20 mph (9 m/s) at the crane superstructure if no such limit has been set. The characteristics of the gusts should be considered for their effect on the climbing operation; and
- The operator of a hammerhead tower crane must be present during climbing or telescoping operations.
16.K.05 Safety devices and operational aids.
Operations must not begin unless the operational aids are in proper working order, except where the employer meets the specified temporary alternative measures. In addition to those listed in 16.E.03, the following must be provided:
Note: The general requirements, as identified in Section 16.E.03 for Operational aids, do not apply to tower cranes. The devices listed in this Section are required on all tower cranes covered by this subpart, unless otherwise specified.
- Rail clamps, if used, must have slack between the point of attachment to the rail and the end fastened to the crane. Rail clamps must not be used as a means of restraining tipping of a crane display magnitude of load on the hook;
- Hydraulic system pressure limiting device;
- The following brakes, which must automatically set in the event of pressure loss or power failure, are required: hoist brake on all hoists, swing brake, trolley brake, rail travel brake;
- Deadman control or forced neutral return control (hand) levers;
- Emergency stop switch at the operator's station;
- Trolley travel limiting device prevents trolley from running into the trolley end stops;
- Ambient wind velocity device. This device must be mounted at or near the top of the crane. A velocity readout must be provided at the operator's station in the cab, and a visible or audible alarm must be triggered in the cab and at remote control stations when a preset wind velocity has been exceeded;
- Hoist line pull limiting device (limits lifted load).
16.K.06 Multiple tower crane jobsites.
On jobsites where more than one fixed jib (hammerhead) tower crane is installed, the cranes must be located such that no crane or its load may come in contact with the structure of another crane.
Cranes are permitted to pass over one another.
16.K.07 Weathervaning.
Tower cranes required to weathervane when out-of-service must be installed with clearance for boom (jib) and superstructure to swing through a full 360 degree arc without striking any fixed object or other weathervaning crane. The boom must be taken in the attitude dictated by its wind area balance. Non-weathervaning boom (jibs) must be taken in the least favorable attitude. Traveling cranes must also resist design wind level induced sliding.
Knowledge Check Choose the best answer for the question.
16-16. Cranes must be plumbed to a tolerance of _____ unless the manufacturer specifies otherwise.
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