Forensic Engineers and Consultants

Archive: Liability Claim

Unguarded Shear Point on Force Tester Amputates Worker’s Finger

A worker was injured while testing gas springs similar to the type that hold the hatchback of an SUV open. The hazard that injured the worker was an unguarded shear point. The tester contained a mounting plate that was raised and lowered by a pneumatic cylinder.

The pneumatic cylinder lowered the mounting plate while the worker’s fingers were in the hazardous, unguarded shear point. The force testing machine violated applicable safety standards including ASME B15.1-2000 Safety Standard for Mechanical Power Transmission Apparatus sections 1.3 and 3.1.

Unguarded Shear point 1 white

The force tester. 

It was technologically and economically feasible for the manufacturer to have guarded the hazardous shear point at the time they designed and built the force testing machine by installing a fixed guard to prevent a worker from getting too close to the hazard. The hazardous, unguarded shear point on the force testing machine was capable of producing serious injury, including amputating fingers.

The risk of injury associated with the hazardous shear point was high because the hazard was unguarded, workers were exposed to the hazard every time the force testing machine cycled, and serious injury would occur every time a worker’s body part became trapped in the rapidly closing shear point. The high risk of injury associated with the hazardous, unguarded shear point was not tolerable because it was feasible to control the hazard using a fixed guard with no effect on the utility of the force tester.

It was or should have been foreseeable to the manufacturer at the time they designed and manufactured the force testing machine that the hazardous, unguarded pinch point would cause serious harm any time an operator got too close to the hazard.

Unguarded Shear Point Img 2

A shear point was created between the fixed frame and the movable mounting plate when the pneumatic cylinder lowered the mounting plate.

The force testing machine was unreasonably dangerous and defective.  It contained an uncontrolled hazard with a high, foreseeable and intolerable risk of serious injury with a certain probability of occurrence any time a worker’s body part is caught in the shear point.  There were technologically and economically feasible means that existed to control the hazard at the time of the machine’s design and manufacture. The unreasonably dangerous and defective condition of the force tester was a cause of the worker’s injury.

Unguarded Shear Point IMG 3 whiteA simple Lexan guard was all that was required to protect a worker from the hazardous shear point.

If you have a case involving personal injury involving a worker injured on a machine in an industrial setting, please give us a call. We are happy to consult with you.

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Jeff_Warren_WEB
Electric Hazard Guardrail photo

Hazards Can Lurk Anywhere … Watch Your Step …

Author

While on a lunch stop during a recent vacation trip through Tennessee, I happened across a safety hazard that required immediate attention.  The establishment had a raised concrete patio at the front with a steel railing around the perimeter.  At one edge of the patio was a set of stairs with a continuation of the steel railing used as a handrail.  The top edge of the patio had light strings wrapping the top metal bar as accent lighting for the perimeter.  The light string continued down the stair handrail wrapped in the same manner as the rest of the patio.

Electric Hazard Guardrail photo

FIGURE 1 – A view of the subject patio

While walking down the stairs, it was noted that two bulbs were missing from the sockets on the portion of the light string that wrapped the handrail.  The sockets, a common Edison-style base, were open to the weather.  More significantly, the open sockets were in the path of a person’s hand (adult or child) sliding down the handrail while traversing the stairs.  The damaged condition of the light strings due to the missing bulbs presented an electrocution hazard.  While the risk of electrocution may be mitigated if the light strings are supplied by the required National Electric Code (NEC) Article 527.5, Ground Fault Circuit Interrupter (GFCI) protected circuit, the condition of the light string presented a hazard.

Closeup photo of one of the open lamp sockets

FIGURE 2 – Closeup photo of one of the two open lamp sockets

Further, the wrapping of the light string around the handrail violates the International Building Code (IBC) requirements.  Section 1012.4 Continuity states that “Handrail gripping surfaces shall be continuous, without interruption by newel posts or other obstructions.”  The random placement of the cable from the light string randomly interferes with the continuous profile of the handrail.

View of the cord wrapping the handrail interfering with usability

FIGURE 3 – View of the cord wrapping the handrail interfering with usability

While there was likely good intent with the placement of the light string to add light to the stairs, the method that was used impeded the use of the handrail.   Further, lack of maintenance by not replacing the missing bulbs crated a shock or electrocution hazard.   Beware of these lurking hazards, if things don’t look right, they probably aren’t.

Tom Kelly has a Bachelor of Science in Electrical Engineering and a Master of Science in Electrical Engineering from Florida Atlantic University, Boca Raton, Florida, along with a Master of Business Administration with emphasis in strategic leadership from Winthrop University, Rock Hill, South Carolina. Tom’s 25-year career in electrical engineering includes forensic engineering investigations involving industrial electrical accidents, electrical equipment failure analysis, control system failures, robotics and automation components, and scope of damage assessments.  He has conducted investigations for fires, arc flash incidents, electrocution and electric shock accidents and lightning strike evaluations.

Gas Appliance testing lab

Testing As Part of Gas Appliance Incident Investigation

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Equipment and appliances supplied with fuel gases like natural gas, propane and butane are a common and convenient part of most of our lives.  Such devices as gas grills and ranges, ovens, furnaces, space heaters and water heaters usually perform without incident.  However, when they malfunction the potential for incidents such as fires and explosions, carbon monoxide (CO) poisoning and burn injuries may occur. These incidents may be due to design and manufacturing defects in the product, or improper installation or operation of the device.

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Hot Tub Hazards

Danger Lurking in the Hot Tub

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Several dangers involving the use of a hot tub (spa) may readily come to mind, such as the risk of shock or electrocution, or the risk of drowning for unsupervised young children.  Not so readily apparent is the effect of overheating the human body, or “hyperthermia”.

Some individuals are more susceptible to the effects of hyperthermia, including the elderly, young children, and those in poor health.  The effects of hyperthermia, or overheating of the human body, cause direct responses such as headache, nausea, heat exhaustion, increased cardiac output, lethargy, confusion, heat stroke and unconsciousness.  The onset of hyperthermia is defined as being at 99.5° F; if the body temperature reaches 104° F, a life-threatening medical emergency exists.  Read More

Figure 1: A view of a playground with impact absorbing surfacing. The brightly colored surfacing beneath the play equipment is a poured-in-place rubber and polyurethane material.

Children Will Fall At Playgrounds. What Shall We Do To Protect Them? A Multipart Blog Series – Part III: An Overview of Selected Playground Safety Technologies

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Co-Authored with Aron Olson, PE

Welcome to the third and final post in our multipart series of blog posts about a young boy’s fall and serious injury at a public playground. In our first post we gave a brief overview of the incident and our investigation. In the second post we discussed some of the safety standards applicable to public playgrounds. In this post, we will examine some of the impact-absorbing playground surfaces available to protect children at playgrounds from injury. If you would like to read the first two posts, they are available here and here.
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Figure 1: A view from a vendor's website of a material known as engineered wood fiber that is designed for use as a playground surface.

Children Will Fall At Playgrounds. What Shall We Do To Protect Them? A Multipart Blog Series – Part II: A Brief Summary of Playground Safety Standards

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Co-Authored with Aron Olson, PE   

Welcome to the second part in our multipart blog series examining a young boy’s fall and injury at a public playground. If you missed the first part in this series, click www.warrenforensics.com/2017/10/11/children-will-fall-at-playgrounds-what-shall-we-do-to-protect-them-a-multipart-blog-series-part-i/ to read it. In this post, we will highlight some resources that designers of public playgrounds can use to help ensure their designs are reasonably safe. Read More

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Children Will Fall At Playgrounds. What Shall We Do To Protect Them? A Multipart Blog Series – Part I

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Co-Authored with Aron Olson, PE   

In 2011, a 5-year old boy was severely injured at a public playground when he fell through a second floor opening around a fireman’s pole in a playhouse. He fell more than seven feet and struck a bare concrete floor. We are thankful that he eventually recovered from his injuries. The person who designed and built the playground was accused of negligence. A lawsuit ensued, and eventually settled in favor of the boy. Read More

Figure 1: A view of the blower machinery.

Improper Design Leads to Fatigue Failure In Blower Shaft

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A blower used to exhaust air from an industrial process stopped functioning when the blower wheel drive shaft fractured.  The process, and thereby most of the plant, had to operate at a reduced volume until the blower wheel could be replaced.  The blower wheel had been installed during a shutdown a week before the incident.  The blower wheel was a spare installed when the existing blower wheel was sent for scheduled remanufacturing. Read More

A clevis pin with the spring clip attached.

Defective Clevis Pin Culprit in Runaway Trailer

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A large agricultural trailer had been connected to a truck using a clevis pin with a spring locking clip.  The trailer became disconnected from the truck and collided with an oncoming vehicle.  The trailer was in poor condition, did not have safety chains, and had substantial recent modifications by the owner. Read More

Figure 2. A view looking into the mixer. The grate and ribbon are visible. The grate openings are large enough to admit a worker's leg.

Case Study of an Injury Involving a Soil Mixer

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Co-Authored with Aron Olson, P.E.

In May, 2014, a plant farm worker was seriously injured when he fell into the hopper of an electrically powered soil mixer.  The mixer in question used a rotating steel ribbon powered by a 7-1/2 hp electric motor to mix batches of materials such as sand, mulch, wood shavings, fertilizers and other landscaping materials to create potting soil. At the top of the hopper sidewalls, within 6 inches of the ribbon, was a steel grate. Read More

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