Approximately 75% of struck-by fatalities involve heavy equipment such as trucks or cranes. Safety standards must take into account the numerous ways to implement administrative controls and reduce risks from large machines like stretch presses, cranes, fork trucks, water jets, and more. ANSI B11.25-2022: Safety Requirements For Large Machines covers the execution of the risk assessment process and the application of risk reduction measures for large machines.
Risk Reduction for Large Machines
Large machines generally require much higher levels of training and administrative controls than similar smaller machines. Due to the dependence on proper procedures for the safety of personnel and equipment, operators of large machines tend to require additional training, greater discipline, and more experience with machinery. The fundamental concerns with large machines are 1) keeping people out of machine hazard zones when there is a risk of significant harm, and 2) keeping components, parts, tooling, and swarf from being ejected. ANSI B11.25-2022 addresses these safety concerns.
The ANSI B11.25-2022 Standard for Large Machines
As machines and machining centers increase in size, function and capacity, new hazards emerge and new risks are introduced; in particular, personnel are typically required to enter into the work envelope of large machines. Examples of large machines may include stretch presses, measurement machines, water jets, laser cutting machines, and specialty machines. In some instances, certification(s) of operators of large machines may be necessary (e.g., crane or rigging operations, fork truck operation, etc.).
ANSI B11.25-2022 applies to two specific subsets of machinery:
- Machine types that would be covered by machine specific, “type C” B11 standards (i.e., machinery safety standards that deal with detailed safety requirements for a particular machine or group of machines), but would be excluded by any size limitation in the scope of those standards.
- Machines that, by the nature of the size of the workpiece, tooling, or process travels, require entry into the work envelope, an area in which motion can occur due to part of the machine or workpiece moving within its normal operating range. Machines larger than a 2 m3 work envelope are often not enclosed and in many cases, there is an actual or perceived need that entry into the work envelope is required to perform certain tasks.
ANSI B11.25-2022 is intended to be used with both ANSI B11.0 and ANSI B11.19 (both of which are available in the Safety of Machinery Set on the ANSI Webstore) to execute the risk assessment process and apply risk reduction measures. It is worthy to note that ANSI B11.25-2022 is not intended for machines integrated into a machinery system, industrial robot cells, material handling systems, or other large systems whose size is due to the inclusion of many smaller machines or processes.
ANSI B11 Standards: Safety of Machinery
The ANSI B11 Standards (Safety of Machinery) devise and propose ways to eliminate or minimize risks of the potential hazards associated with the required tasks. This can be accomplished by manufacturing an appropriate machine design, restricting personnel or other individuals’ access to hazard zones, and devising work procedures to minimize personnel exposure to hazardous situations.
Changes Made in ANSI B11.25-2022
Here are the updates in the newest 2022 version of ANSI B11.25 since its predecessor ANSI B11.25–2015:
- General updating of text and alignment of terms with ANSI B11.0 and ANSI B11.19
- Added text in the Foreword and Introduction
- Substituted practicable for feasible
- Modified/clarified the scope and exclusions clauses
- Modified text on entrapment
- Modified text on whole body access
- Modified text on safety-related reset
- Modified text on maintenance
What Are Administrative Controls in ANSI B11.25-2022?
Various administrative controls are detailed in ANSI B11.25-2022 for risk reduction for personnel in the work envelope of large machines. These controls include the following:
- Troubleshooting, set-up or maintenance: the design of a large machine shall provide means to allow troubleshooting, set-up or maintenance tasks that require power to be performed with acceptable risk.
- Entrapment: Guards shall be designed and installed to prevent personnel from being entrapped anywhere within the machine envelope.
- Tripping hazards: A large machine shall be designed and constructed to minimize tripping hazards.
- Lighting: Adequate lighting shall be provided for all tasks associated with normal operations. Where facility (building) lighting is used to fulfill this requirement, minimum general illumination levels shall be specified.
- Concurrent tool changes: When a means of loading or unloading tooling concurrently with the operation of the machine is provided, a large machine shall allow concurrent tool changes without personnel having to enter the hazard zone or work envelope.
- Stopping time / distance: Where feasible, a large machine shall provide means to allow adequate stopping time. These can include engineering controls at a safe distance, or interlocked guards with guard locking such that a safe state is achieved prior to personnel being exposed to the hazard.
- Material and part transfer: Risk reduction measures shall be used to achieve acceptable risk when material and parts are transferred between work stations within the machine, and/or into and out of the machine. When feasible, provisions shall be made to accomplish this without personnel having to enter the machine.
- Moving work station: If an operator work station moves during the operation of the machine, risk reduction measures shall be provided to minimize pinch points, crush or other hazards.
- Points of entry: Where necessary as determined by a risk assessment, the point(s) of entry to a large machine shall be protected or controlled
ANSI B11.25-2022: Safety Requirements For Large Machines is available on the ANSI Webstore.