Licensed Professional Engineers



A newsletter dedicated to keeping attorneys informed of the technical side of product liability cases.

Issue 71: Fall 2018

Hazard Assessments of Machinery

By John L. Ryan, P.E.

© 2018 M.A.S.E. LLC

It is rare to have one tool that can be applied to a variety of product liability cases involving industrial machinery accidents. Hazard assessment is such a tool. ANSI B11.0 2015 Safety of Machinery contains criteria that any machine falling under the B11 series of standards, which covers a very wide range of machines, must adhere to. This standard is the foundation of all B11 standards. This standard details the risk analysis process in detail, and requires that machinery be brought to have an acceptable level of risk associated with it. While voluntary, failure to comply with this standard shows a failure to meet industry standard practices and can result in settlements or judgments in favor of the plaintiff. Most machinery accidents could have been prevented if the manufacturer had done a hazard assessment and taken appropriate action to reduce risk.

The American National Standards Institute (ANSI) publishes standards for a wide variety of products. Their machine guarding standard series has long been an industry benchmark for risk assessment and guarding requirements. While many of the standards list specific guarding requirements for a variety of machines, the standard series also calls for a hazard analysis to be performed as part of the design process, and corrective action to be taken until a product is deemed to have acceptable risk. ANSI machine guarding standards put the primary burden of responsibility on the machine manufacturer, but also hold entities involved in the chain of commerce responsible including distributors, suppliers, and end users. ANSI B11.0 2015 is currently the most recent standard that details the ANSI risk assessment and mitigation process. On the next page you will find an overview of the B11.0 risk analysis procedure.





Step 1: Identify tasks and hazards

The true challenge here involves identifying ALL possible tasks and hazards associated with the tasks. Often hazards are overlooked due to a lack of understanding, or assuming perfect human functioning without any errors. Human error is a fundamental fact of our existence, and must be considered at this stage of a risk assessment.

Step 2: Assess initial risk with risk scoring system

Assessing initial risk involves identifying the severity of harm that can occur from a given hazard, and the probability of occurrence of the harm or contact with the hazard. There are a variety of methods for this, and the ANSI standard does not require a specific method of scoring risk, although it must involve the basic elements of severity and probability of occurrence. The ANSI standard provides detailed explanations of how to do this.

Step 3: Reduce risk using the hazard control hierarchy

Once the overall risk is assessed based on the analysis involving frequency of potential occurrence and level of harm, a decision must be made as to what acceptable risk really is. This will depend on many variables which can be specific to a particular product or machine, or where the machine is located. Generally, designers should work to get the level of risk to at least a “low” level. The other part of this decision making process is compliance with other safety standards.

Step 4: Assess residual risk using the risk scoring system

After redesign, the remaining risk should be assessed using the same risk scoring system that was used initially.

Step 5: Determine if residual risk is acceptable .

If the risk level is acceptable, the engineer can continue the hazard assessment process by moving to the validation phase. If not, the engineer should return to the step of identifying tasks and hazards, and/or reducing risk.

Validate Solutions

Validation of solutions involves essentially checking to determine that the proposed solution is truly effective in controlling the hazard. This could involve a review of overall operation to determine if any additional hazards have not been considered, reviewing how other machinery interacts with the specific machine, and how that machinery may cause additional hazards.


Documenting the hazard assessment, redesign, and re-analysis is important in the event of an accident or other problem with a machine. Often, companies and designers claim that a verbal form of risk assessment was performed, but they have no substantiating


How We Can Help

At MASE, we can perform a risk analysis to show compliance or lack thereof to ANSI B11.0. We offer full service mechanical engineering expert witness services. Call us at (855) 627-6273 / email

We offer full service mechanical engineering expert witness services from inspection to trial testimony. Call us at (855) 627-6273 or email us at


What We Can Do For You

Provide mechanical engineering expertise for your product liability case

Help you decide on whether to take a case—we’ll give you a free, no obligation case assessment just call us at (855) 627-6273

Perform detailed and thorough engineering analysis of products involved in accidents

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Design solutions to product hazards that are left unguarded

Please call us to discuss any questions you have about unsafe products. (855) 627-6273

© 2018 Mechanical and Safety Engineering