Risk Analysis Considerations in Industrial Machinery Accident Investigations

Published April 2024
By: Marty Timm, PE

When a serious industrial machinery accident occurs, multiple parties want to know the causes and contributing factors of the accident.  A thorough investigation is important.  A “rush to judgement” may overlook significant underlying causes or contributing factors, while a thorough investigation may uncover these.  A thorough investigation should consider whether a risk analysis was performed for the machinery, whether the results of the analysis were used to reduce risk to the extent practicable, and whether the residual risk was fully communicated to the purchaser, operators, and maintenance personnel.

Failure of a machinery supplier to identify hazards, reduce risk to the extent practicable, and communicate the residual risk to the machinery purchaser may place the machine supplier in a weak position.  Being able to show that hazards were identified, risk was reduced, and residual risk was fully communicated can place the machine supplier and other third parties in a strong position.

Experienced legal and insurance professionals are familiar with the need to preserve evidence to aid in accident reconstruction and to avoid spoliation claims, the need to secure witness statements, the need to verify condition and functionality of safety features, and the need to obtain photos and videos of the equipment and scene as found, etc.  There are additional items that may be important to a machinery accident investigation depending on circumstances.  They may not be as obvious, but early consideration should be given to having them secured and copies obtained to aid in later analysis.  Broad categories of these items include:

  • Procurement Documents
  • Risk-related Documents
  • Supplier IOM Documents (Installation, Operation, Maintenance)
  • Owner IOM Documents
  • As-found condition of signage / warnings / alert devices
  • After-action reports from authorities or first responders

The following sections or this article will discuss each subject area.

Procurement Documents

Procurement documents are important in that they provide a roadmap to what was asked for, what was offered by the supplier(s), what promises, assurances, or guarantees were offered, and what was finally purchased and installed.

Procurement documents include, but are not limited to:

  • Requests for quotation (RFQs)
  • Supplier sales literature and specifications
  • Quotes / Purchase Orders / Contracts
  • Drawings and schematics
  • Text messages, e-mails, or correspondence between the parties that may address or touch on roles and responsibilities, especially as related to safety and training of personnel.

Comparison of these documents can identify potential issues, such as purchasers of equipment applying them in ways not disclosed during purchase negotiations and not approved by the manufacturer, suppliers failing to fully satisfy the customer requirements in the RFQ, scope between parties being left undefined, technical information provided by the supplier not matching what was actually shipped to the job site, resellers or integrators failing to pass on all safety related information from the supplier to the ultimate end-user, etc.  The electronic and written correspondence is especially important as it can provide insight as to how each party met their obligations as described in the RFQ and the supplier quote(s).  For example, did a supplier specify that the purchaser was to provide and install certain safety barriers or interlocks, but the purchaser overlooked or ignored this and did not install such devices?  If the supplier(s) stated they would comply with certain industry standards and government regulations, did they do so? 

Risk-Related Documents

Most machinery industry segments have recognized standards, best practices and RAGAGEP (recognized as generally accepted good engineering practices).  For example, the machine tool industry in the USA utilizes the “ANSI B11” standards.  One of the foundation documents in this series of standards is ANSI B11.0, Safety of Machinery[1].  It includes a formal method describing in detail how to conduct a risk assessment, and how to document it.  The robotics industry utilizes ANSI R15.06-2012, Industrial Robots and Robot Systems – Safety Requirements[2].  The packaging machinery industry utilizes ANSI/PMMI B155.1-2016, Safety Requirements for Packaging and Processing Machinery[3].  Each has similar requirements for risk analysis.

B11.0-2020 has been harmonized with an international standard, ISO 12100-2010, “Safety of machinery — General principles for design — Risk assessment and risk reduction”[4].  Compliance with B11.0 automatically assures compliance with ISO 12100-2010, but the opposite is not true, because the scope of ISO 12100-2010 is not as comprehensive as B11.0-2020.  Other standards developed by USA organizations have undergone similar international harmonization efforts.  Compliance with international standards does not automatically guarantee compliance with USA requirements, so “digging” may be required to identify possible gaps that may be relevant to an incident under investigation.

A thorough accident investigation should include review of how hazards and risks were evaluated and documented, whether the supplier complied with B11.0-2020 or other appropriate industry safety standards.  The review should evaluate whether the hazards were fully identified, and whether the risk reduction measures, and engineering controls identified in the risk analysis were fully implemented in the machinery as installed and as maintained up to the time of the accident.  Risk reduction measures include cautions and warnings in the manuals and procedures, and signage and labeling installed on the equipment.

Standards have evolved over time.  The versions referenced above may not have existed at the time the machinery was procured and installed.  Engineering experts examining compliance with standards will typically start with the standards that were in effect at the time the equipment was originally procured and installed and will explore whether the machinery was upgraded (or should have been upgraded) to comply with later standards if it was moved, modified, or repurposed.

Supplier IOM Documents (Installation, Operation, Maintenance)

Suppliers provide a wealth of information to purchasers regarding the safety features, intended use, operation, and maintenance of the equipment being supplied.  The information transfer typically takes the form of written documentation, often augmented by on-site training.  IOM documentation can include, but is not limited to:
Supplier Manuals and collateral materials, including:

    1. Detailed descriptions of what is included/provided
    2. Recommended operating procedures
    3. Recommended maintenance procedures and schedules
    4. Recommended troubleshooting procedures
    5. Safety cautions and warnings
  • Drawings (Process, mechanical, pneumatic, hydraulic, electrical, site layout, etc.)

Section 8.2 and Annex D in B11.0-2020[1] describe the requirements around content of manuals, including that the manual(s) conform with requirements of ANSI Z535.6, Product Safety Information In Product Manuals, Instructions And Other Collateral Materials[5]Demonstrating that a supplier complied with these standards and requirements can help defend against any suggestion that the manuals and safety warnings were less than adequate.

B11.0-2020 requires that the supplier analyze the risk involved in operation and maintenance of the machinery being supplied, that they reduce the risks to a tolerable level, and that they communicate the risk, residual risk, and protective measures and engineering controls that are being provided in the supplier IOM materials.  A thorough machinery accident investigation will consider how hazards were identified by the supplier, how the risks were reduced, whether the residual risk met the risk tolerance of the purchaser and the supplier, and whether the residual risks were fully communicated in the supplier manuals and collateral materials.

The title block of drawings and schematics usually contain dates and version numbers.  Early versions of drawings and schematics may contain markings such as “not for construction”.  A thorough investigation should include review of these title blocks against equipment actually supplied to determine if the drawings and schematics were accurate and “up to date”.  Did the version of drawings and schematics provided by the supplier match the equipment actually supplied?  Are drawings found in or near the machinery the “up to date” versions?  If the drawings and schematics were out-of-date or for a similar but not identical model, is the discrepancy relevant to the sequence of events of the accident?  If modifications were made to the machinery during commissioning activities, were the changes captured on “as-built” versions of the drawings and schematics?

Owner IOM Documents

Industrial sites with stationary machinery will typically have multiple written administrative procedures that provide guidance and job execution requirements to their employees.   Many of these relate to OSHA regulatory requirements.  Site specific administrative procedures typically include:

  • Lock-out tag-out [6]
  • Confined space entry [7]
  • Electrical safety [8], [9]
  • Hazardous or “hot work” permits [10]
  • Lone workers [11]

A thorough accident investigation will identify if any of these administrative procedures is relevant to the accident.  If so, further review should be done to determine if the procedure was followed.  For example, if a hazardous work permit was taken out for work during one shift, but the work was incomplete and needed to continue into the next shift, were procedures strictly adhered to for communicating status and transferring responsibility to the workers coming in on the new shift?  If an arc-flash accident occurs during maintenance on electrical equipment, was the worker wearing the level of personal protective equipment required in the electrical safety administrative procedure?  If deviations from the site administrative procedures occurred at the time of the accident, did the deviations contribute to the cause or sequence of events of the accident?  If an accident occurred during cleaning or maintenance of machinery, had the lock-out tag-out procedures been strictly adhered to?

In addition to the “site wide” administrative procedures, owners will often extract the operating and maintenance procedures from the supplier manual(s) and write their own custom procedures for the equipment at their site.  Whether or not this was done for machinery involved in an accident should be clearly identified.  When such site specific (or multi-site) procedures have been created by the owner, careful review should be done by the reviewing expert(s) to determine if all the risk-related information in the supplier manuals and procedures was carried over into the owner-written procedures.  If risk information, cautions, or warnings are missing in the owner-written procedures, is this finding relevant to the accident?

Owner IOM documents include records such as work orders and “down time” reports showing what maintenance or modifications were actually done on the machinery since it’s installation.  If recommended maintenance was skipped or deferred, was it relevant to the accident?  If the machinery was modified by the supplier or someone other than the supplier, was the modification relevant to the accident?  If “near misses” occurred before the accident being investigated, was management aware of them, and were appropriate corrective actions taken?

As-found condition of signage / warnings / alert devices

CFR 1910.145, Specifications for Accident Prevention Signs and Tags, has specific requirements for danger signs, caution signs, and safety instruction signs [12].  All three types of signs are commonly found on or near industrial machinery.

Machinery always has some extent of:

  • labeling on controls indicating their function
  • safety signage at key locations where there is residual risk (possibility of injury)
  • safety signage indicating need for personal protective equipment such as safety glasses or hearing protection
  • Visual and/or audible indicators and annunciators (horns and lights)
  • Etc.

A thorough investigation will include evaluation of these items, to determine if they are present, if they are legible / audible, if their format is consistent with industry and regulatory standards, and if they are in a language that could be understood by the person(s) involved in the accident.  If horns or other audible indicators are used to warn workers of an immediate or impending hazard, are they audible above the background noise present in the workplace?  Is signage or labeling peeling away or covered in dirt to an extent rendering them illegible?  Are control switches and indicator lights clearly labeled as to their function and meaning? 

After-action reports from authorities or first responders

Authorities such as OSHA or first responders such as fire departments may issue reports or findings after an incident.  Obtaining copies of these documents can be useful to ascertain whether these authorities uncovered facts or took photos which may be useful in fully understanding conditions at the site, particularly in the time frame between the occurrence of the accident and the start of formal investigation activities.


The relevancy of the various issues discussed here will depend on the specifics of a particular machinery accident.  It is in the interest of each party with a stake in the outcome of the investigation to have as complete an understanding as possible of the actual causes and contributing factors that led to the sequence of events resulting in an injury or worse.  The understanding should include how hazards were identified, risks were reduced, and residual risk and safeguards were communicated.  If no discrepancies or shortcomings are found in these areas, focus can shift to other facts of the accident.  If discrepancies or shortcomings are found, they can be further scrutinized.  Just because there is a discrepancy, it doesn’t mean it is relevant to the causal factors of the accident.  Opinions of engineering experts can help interested parties identify issues that are relevant to causation of the accident.


[1]       B11.0 Subcommittee, “ANSI B11.0-2020 ‘Safety of Machinery.’” ANSI / B11 Standards Inc., Houston, TX, 2020.

[2]       RIA, “ANSI/RIA R15.06-2012 Industrial Robots and Robot Systems – Safety Requirements.” RIA, Ann Arbor, Michigan, 2012.

[3]       PMMI, “ANSI/PMMI B155.1-2016 Safety Requirements for Packaging and Processing Machinery.” ANSI / PMMI, Herndon, VA, 2016.

[4]       ISO/TC199, “ISO 12100:2010 Safety of machinery – Genergal principles for design – Risk assessment and risk reduction”.” ISO, Geneva, Switzerland, 2010.

[5]       NEMA, “ANSI/NEMA Z535.6-2011 (R2017) Standard for Product Safety Information in Product Manuals, Instructions and Other Collateral Materials.” ANSI / NEMA, 2011.

[6]       OSHA, 29 CFR §1910.147 The control of hazardous energy (lockout/tagout). 2011.

[7]       OSHA, 29 CFR §1910.146 Permit-required confined spaces. 2011.

[8]       NFPA, “NFPA 70E Standard for Electrical Safety in the Workplace.” NFPA, Quincy, Massachusetts, 2024.

[9]       OSHA, 29 CFR §1910.333 Electrical – Selection and use of work practices. 1994.

[10]     OSHA, 29 CFR 1910.252 Welding, Cutting and Brazing – General Requirements. 2012.

[11]     F. Straub, “High risk, lone worker – The Unacceptable Risk,” Professional Safety Journal, Jul-2018.

[12]     OSHA, 29 CFR §1910.145 Specifications for Accident Prevention Signs and Tags. 2013.

About the Author:

Martin Timm, PE is a forensic mechanical engineer affiliated with Forcon International in Atlanta.  He is a B11 Licensed Machinery Safety Specialist (LMSS), Certified Safety Professional (CSP), and a licensed professional engineer (PE) registered in 12 states including Georgia.  Over his 40+ year professional career, Mr. Timm has been active in codes and standards development; he is also skilled in consequence modeling, process hazards analysis, and incident investigation.  He has participated in standards writing activities at B11 Standards, the Compressed Gas Association (CGA), The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), and the International Institute of Ammonia Refrigeration (IIAR).