Safe load and proof limits

Yes — proof loads must be adjusted whenever stability or the structural competence of the equipment at a specific working radius would make the specified proof load unsafe. The rule requires that the proof loads specified in 1919.27 and 1919.28 be changed as necessary to account for any limitations based on stability or structural strength at particular radii, and that safe working loads be reduced accordingly (1919.29).

• Check the equipment at the actual boom radius/configuration intended for use. - If the equipment would be unstable or overstressed at that radius under the standard proof load, reduce the proof/load test value and the marked safe working load (SWL).

(See the requirement in 1919.29.)

"Particular radii" refers to the actual working radius or distance from the equipment's pivot/center to the load attachment point (for example, boom length and angle on a crane) at which the equipment will be used. The standard requires adjusting proof loads and reducing safe working loads for limitations that appear specifically at those radii (1919.29).

• Evaluate the equipment at the exact boom length/angle or configuration expected in service. - Do not rely only on a generic capacity if the structural strength or stability varies with radius. - Make adjustments where the load chart or structural analysis shows reduced capacity at a given radius.

(See 1919.29 for the requirement to adjust proof loads for limitations at particular radii.)

The employer must ensure a qualified or competent person evaluates stability and structural competence and determines any needed adjustments to proof loads and safe working loads. The regulation requires making adjustments where limitations exist (1919.29), and OSHA guidance indicates the employer assigns the "competent person" who can identify hazards and take corrective action (Competent person accreditation procedures, 1977-04-26).

• The competent person should have the technical knowledge to assess structural capacity and stability at specific radii. - Document the evaluation and any changes to proof-test values or SWLs.

(See 1919.29 and the 1977 OSHA letter on competent persons at https://www.osha.gov/laws-regs/standardinterpretations/1977-04-26.)

You must reduce the safe working load to reflect the weaker structural competence at that longer radius. The rule states safe working loads shall be reduced when proof loads are adjusted to meet limitations based on stability or structural competence at particular radii (1919.29).

• Mark or document the reduced SWL for that specific radius/configuration. - Ensure operators and riggers know the reduced ratings before lifting.

(See 1919.29 for the obligation to reduce SWL when proof loads are adjusted.)

No — you cannot skip proof testing; instead you must modify the proof test to reflect the actual, safe test load for the configuration and document the change. The proof loads specified in 1919.27 and 1919.28 are subject to adjustment where stability or structural competence at particular radii impose limitations, and 1919.29 requires proof loads be adjusted as necessary and SWLs reduced accordingly.

• Perform the proof test using the adjusted (reduced) load that is safe for the tested radius/configuration. - Record the adjusted proof load and the rationale so inspectors and users understand the basis for the reduced value.

(See 1919.27, 1919.28, and 1919.29.)

Adjustments should be based on objective evidence such as the manufacturer's load chart, structural calculations, engineering analysis, or stability tests for the specific configuration and radius. The regulation requires adjustment of proof loads where stability or structural competence is limited at particular radii (1919.29).

• Prefer manufacturer-provided load charts and engineering analyses when available. - If charts or calculations are not available, perform conservative stability/structural testing or obtain an engineer's assessment. - Document the method used to determine the adjusted load.

(See 1919.29 for the requirement to adjust proof loads for stability/structural limitations.)

Yes — any change in configuration that affects stability or structural load paths (such as adding a jib, counterweight, or different boom length) requires re-evaluation and, if necessary, adjustment of proof loads and safe working loads to reflect the new limitations (1919.29).

• Recalculate or retest for the new geometry and radii. - Update the SWL markings, load charts, or documentation to reflect any reductions. - Make sure operators are trained on the new ratings before using the equipment.

(See 1919.29.)

You must ensure the reduced safe working loads are clearly communicated to users; marking the equipment or maintaining readily available documentation that specifies the adjusted SWL for the relevant configurations are acceptable ways to comply. The rule requires safe working loads be reduced accordingly when proof loads are adjusted for stability or structural limitations (1919.29).

• Best practice: update or add permanent markings or load charts on the equipment for each configuration and radius. - At minimum, keep clear written records that accompany the equipment and are available to operators and inspectors.

(See 1919.29 and the related proof-load rules in 1919.27 and 1919.28.)

No — you cannot rely solely on the manufacturer's rated capacity if site-specific conditions reduce stability or structural competence at the working radius. 1919.29 requires adjusting proof loads and reducing SWL where stability or structural strength impose limitations at particular radii.

• Manufacturer load charts are a primary reference, but you must confirm applicability for the exact site configuration and radius. - If site conditions (ground support, outriggers, attachments, or weather) affect stability, perform a separate assessment and reduce ratings as needed.

(See 1919.29.)

Document the reduced proof load with the following: the equipment identification, the specific radius/configuration tested, the adjusted proof-test weight used, the reason for reduction (stability or structural limitation), and the new SWL. The standard requires adjusting proof loads to meet limitations at particular radii and reducing SWLs accordingly (1919.29).

• Keep the test report with the equipment records and update any load charts or markings. - Ensure the report is available to operators and inspectors.

(See 1919.29.)

Yes — auxiliary attachments that change load geometry or increase radius must be evaluated and, if they cause a stability or structural limitation at a particular radius, the proof loads and SWLs must be adjusted downward for that configuration (1919.29).

• Evaluate the entire lift system (equipment plus attachments) at the intended radius. - If attachments reduce safe capacity, mark or document the lower SWL for the combined configuration.

(See 1919.29 and related proof-load rules in 1919.27 and 1919.28.)

Yes — ground or supporting conditions that affect stability must be considered when adjusting proof loads and SWLs at specific radii. 1919.29 requires adjustment for any pertinent limitations based on stability, and poor ground support is a common stability limitation.

• Inspect and document ground-bearing capacity and use appropriate mats or support if needed. - If ground conditions reduce stability, reduce proof-test values and SWLs for the affected radii and configurations.

(See 1919.29.)

Yes — operators must be informed and trained about any reductions in safe working loads or changed load charts for the configurations they use. The rule requires that SWLs be reduced accordingly when proof loads are adjusted for radius-related limitations (1919.29), and practical compliance requires that operators understand those limits before performing lifts.

• Provide training or briefings describing the new SWLs, affected radii, and any operational restrictions. - Keep documentation and markings clear so operators can apply the correct limits in the field.

(See 1919.29.)

You must decrease the proof load and SWL when a larger working radius reduces structural competence or stability. For example, if the standard proof test for a hoist is 10,000 lb based on a short radius, but an engineering check shows at the longer radius the structure can only safely support 7,500 lb, then the proof test and SWL for that longer radius must be reduced to a safe value (e.g., 7,500 lb) and documented as such (1919.29).

• Record the radius at which the reduced value applies. - Update load charts/markings and inform operators. - If uncertain, obtain engineering analysis or test data to justify the reduced value.

(See 1919.29 and the related proof-load specifications in 1919.27 and 1919.28.)

The employer is responsible for assigning a competent person to assess limitations and determine necessary adjustments; OSHA historically recognizes that the employer assigns or approves the competent person rather than requiring a specific accreditation for all tasks (1919.29 and the 1977 OSHA letter on competent persons). The 1977 interpretation explains that the employer assigns the competent person who can identify hazards and take corrective action (Competent person accreditation procedures, 1977-04-26).

• Use a person with the technical knowledge to evaluate structural competence and stability at the relevant radii. - Where standards or Part 1919 require accredited certification (for certain certificated devices), follow those specific accreditation rules; otherwise, document the competency of the person who made the evaluation.

(See 1919.29 and the competent-person guidance at https://www.osha.gov/laws-regs/standardinterpretations/1977-04-26.)