Special Requirements for Design
The safety and health department has recognized incident trends relating to below the hook lifting devices. The focus of this bulletin is to highlight some of the common uses of below the look lifting devices during steel erection and reinforcing steel activities and some of the basic, governing standards. The following are some illustrations of below the hook lifting devices our members and contractors should recognize to prevent failure of below the hook lifting devices.
Considerations for Below the Hook Lifting Devices
The process of hoisting prebuilt rebar curtain wall sections or panelized joists requires the use a specially designed below the hook lifting device. When designing and fabricating these lifting devices, the employer must refer to the ANSI B30.20 Standards. These devices must be designed by a qualified person to accommodate the intended load of panelized joists, rebar assemblies or other structural members. Additionally, performing any activities using these devices also requires a qualified rigger, a rigger who is also a qualified person, to inspect the rigging equipment before each shift.
Rated Load Markings and General Construction
Structural and mechanical lifting devices are required to be marked on the main structure where it is visible. The ANSI standard requires the lifting device “to withstand the forces imposed by its rated load, with a design factor of 3, based on yield strength, for load bearing structural components.” All welding on components of lifting devices must be in accordance with ANSI/AWS D1.1 Standards. A nameplate or other permanent marking must display:
- Manufacturer or employer name
- Serial number
- Rated load capacity
Before initial use, the erector must inspect all new, altered, modified or repaired lifting devices by a qualified person to recognize deficiencies and ensure compliance with applicable ANSI Standards. Inspection procedure for lifting devices in regular service is divided into two general classifications. These inspections consist of visual examinations by a qualified person or other designated personnel.
The two general classifications are designed as frequent and periodic, with respective intervals between inspections as defined below.
- normal service – monthly
- heavy service – weekly to monthly
- severe service – daily to weekly
- special or infrequent service – as recommended by a qualified person
Items to Look for:
- structural deformation, cracks, excessive wear
- lose or missing components
- maladjustments interfering with operator
Requirement for Rated Load Testing
All new, altered, modified, or repaired lifting devices should be tested and inspected by or under the direction of a qualified person confirming the load rating of the lifting device. The load rating should not exceed 80 percent of the maximum load sustained during the test. Test loads shall not be more than 125 percent of the rated load, unless otherwise recommended by the manufacturer.
The employer should establish a preventative maintenance program based on the frequency of use and recommendations of a qualified person or the manufacturer of the lifting device. When making adjustments and repairs to the lifting device, a qualified person must be consulted to verify service procedures and modifications.