Critical lifts also include the lifting of personnel with a crane, lifts where personnel are required to work under a suspended load, and operations with special personnel and equipment safety concerns beyond normal lifting hazards.
Each installation shall develop a process to identify critical lifting operations and lifting devices or equipment that must meet critical lift requirements. Input shall be gathered from facility, program, user, and quality assurance personnel. The results of the process shall be documented and approved, as a minimum, by the installation lifting devices and equipment manager (LDEM). The LDEM is appointed by the installation director and has a background in lifting devices, lifting operations, lifting equipment industry standards and an understanding of lifting safety. The LDEM is responsible for overall management of the installation LDE program and chairs an installation-wide committee to make sure the lifting standard is understood and applied.
Specific written procedures shall be prepared and followed for all critical lifts. During critical lifts there shall be one person present (NASA or contractor) that is designated as responsible for the safety of the operations. That person may be a safety professional, a supervisor, an engineer, or a task leader.
A recognized safety hazard analysis, such as fault tree analysis, failure mode and effect analysis (FMEA), operating and support hazard analysis (O&SHA), shall be performed on all cranes used for critical lifts. The analysis shall, as a minimum, determine potential sources of danger, identify failure modes, and recommend resolutions and a system of risk acceptance for those conditions found in the hardware-facility-environment-human relationship that could cause loss of life, personal injury, and loss of or damage to the crane, facility, or load. The analysis shall be done as part of the initial evaluation process for critical lift compliance and prior to use in a critical lift, included in the crane documentation, and updated as required to reflect any changes in operation and/or configuration.
Design requirements
For cranes used for critical lifts, two holding brakes shall be provided, each capable of bringing a rated load to zero speed and holding it. Holding brakes shall be applied automatically when power to the brake is removed. If the control brake and holding brake are designed to operate as a system and cannot independently stop and hold a rated load, then another means of braking is required for cranes used for critical lifts (e.g., emergency brake).
Speed reduction from the motor to the drum on the hoist should be achieved by enclosure in a gear case. If open gears are required, they shall be guarded with a provision for lubrication and inspection.
Remote emergency stops are required for cranes used for critical lifts where the crane operator’s view is restricted or obstructed. When provided, this independent remote emergency stop should be located such that the independent remote emergency stop operator can clearly see the critical lift area. The remote emergency stop circuit shall be separate from and take precedence over the operator control circuit. The control, when activated, shall cause all drives to stop and the brakes to set. Hand-held remote emergency stop pendants should be standardized and should include power and circuit continuity indication.
For those cranes required to make critical lifts that have not been modified to provide a remote emergency stop, handling procedures shall be developed and implemented to minimize the risk.
Dual upper limit switches are required for cranes used for critical lifts. Initial upper limit switch electrical contacts shall not inhibit movement in the lowering direction. After a final upper limit switch has been activated, movement of the load will require action (resetting) at the final upper limit switch level. An inspection shall be made to determine the cause of failure of the initial upper limit switch.
Stopping crane motion by the above design configuration may result in a hazardous suspended load condition. The crane design should include a means of detecting limit switch failure and allow for safe inspection and repair. For example, a system may be equipped with two different colored annunciator lights, one for each limit switch. A reset button may be included so that when a final upper limit switch is tripped, the load can be lowered immediately.
Lower limit switches to prevent reverse winding of the wire rope shall also be provided.
Testing
Three types of tests are required for cranes: proof load tests, periodic load tests, and operational tests. The proof load tests and operational tests shall be performed prior to first use for new cranes, or for existing cranes that have had modifications or alterations performed to components in the load path. The periodic load and operational tests shall be performed at least every 4 years. Cranes used frequently for critical lifts shall be load tested annually. Cranes used infrequently for critical lifts shall be load tested before the critical lift if it has been more than a year since the last test.
In particular for critical lift cranes, the final upper limit switch shall be independently verified and adjusted as described above at installation and after modifications that could affect switch operation. The switch can be tested periodically by manually tripping it and verifying that all hoist motion is precluded.
The operational test of critical lift cranes’ two holding brakes must demonstrate each brake’s ability to stop and hold a rated load. This can be done in one of three ways. First, each brake’s ability to hold shall be statically tested (under no load) with 150 percent of the rated load hoisting torque at the point of brake application. Second, each brake shall be tested for its ability to stop and hold a rated load in both the raising and lowering modes. (It must be possible to quickly reenergize the out-of-circuit brake or provide other safety measures to perform this test safely.) Third, other methods may be used if they are approved by the LDEM with agreement from the responsible safety, engineering, operations, and maintenance organizations.
Operation
Only certified (licensed) and trained operators shall be authorized to use/operate powered hoists and winches except for platform hoists where procedural controls can be provided in a technical operating procedure. A training, examination, and licensing program shall be established or made available. The operator certification program will be reviewed at least annually.
Operations where critical lifts are involved will require a more rigid operator certification program than those operations that involve more routine lifts that do not involve critical hardware or unique hazards.
Noncritical lift operators includes hands-on and classroom training. Classroom training includes safety, lifting equipment emergency procedures, general performance standards, requirements, pre-operational checks, and safety-related defects and symptoms (for initial certification and as needed). Candidates would need to pass a physical examination, written examination, operational demonstration and a periodic recertification. Licenses or certifications shall expire at least every 4 years.
A body should be set up to manage the licencing system and revoke licenses for negligence, violations of safety requirements, or failure to meet medical standards.
Besides the training, examination, licensing, and renewal requirements for noncritical lifts, operators that are being certified to perform critical lifts must be trained in the specific hazards and special procedures associated with the lift. Operators must also demonstrate proficiency and operating finesse with the hoist using a test load as appropriate for the initial certification or alternately be immediately supervised by a certified operator during the first initial lifting period. The licenses will indicate specific hoists for which the operator is certified.
