Forensic Engineers and Consultants

Category Archive: Safety and Design

The Concepts of Hazard, Risk, and Harm in Machine Safeguarding

Hazard, risk, and harm are terms that are used in the world of machine safeguarding.   How do these words shape the concept of machine safeguarding? Let’s look a little deeper….

Hazard, which Merriam-Webster defines as a noun, lists its first meaning as a source of danger.

1: a source of danger

2athe effect of unpredictable and unanalyzable forces in determining events CHANCERISK

  b:  a chance event ACCIDENT  Read More

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The Use of Taglines to Control Crane Loads

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The adequacy of a crane’s load line to support the weight of the object being lifted is an obvious concern when evaluating a crane lifting operation. Less obvious, but often equally important, is the presence and adequacy of taglines to provide control of the load orientation.

Taglines are simply ropes or lines that are Read More

How Long Before the Pipes Freeze?

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An unexpected severe winter freeze will remind many people and businesses that when water in a pipe freezes, the ice will expand and burst the pipe or pipe fitting.  Large losses will result from flooding when the temperatures rise.  Insulation will help, but not prevent freezing.  Insulation simply slows down the rate of heat loss.  The time of exposure to subfreezing temperature is an important factor.

The American Society of Refrigeration and Air Conditioning Engineers (ASHRAE) Handbook of Fundamentals has a short entry on the topic (Chapter 23, page 23.5-6), which gives an equation for estimating the time that it will take an insulated pipe to freeze, Read More

T is for Temporary – Issues with Extension Cords and Other Temporary Wiring Applications

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Temporary wiring is just that….temporary, and is typically used for repair and maintenance projects.  In this blog I am going to discuss guidance offered by Article 590 of the National Electric Code (NEC), as well as some points to consider when using temporary wiring, including extension cords and holiday lighting.

Before each use, extension cords need to be inspected for visual damage.  Cords with cuts or splits to the insulation need to be discarded.  Cords with damage to the connectors, including those that feel loose when connected, need to be taken out of service.   Failure to properly select and use extension cords can have a catastrophic result.  Read More

Conveyor Backstops: Sometimes One Isn’t Enough, Part 2

This is the second in a two-part blog series about conveying equipment that severely injured a worker at a mine. In case you missed it, click here to read Part 1 where I describe the incident and the mining equipment. In this part, I will discuss my engineering analysis of the incident and the machinery involved and share the conclusions I reached.

The injured miner was a front-end loader operator. He was not a maintenance worker. He simply responded to a radio request for help with the conveyor. Power to the electric conveyor motors was locked out, but none of the maintenance workers did anything to lock out or block the hazardous gravitational potential energy in the heavy load of stone on the belt. Read More

Conveyor Backstops: Sometimes One Isn’t Enough, Part 1

This is the first of a two-part blog series describing an incident involving conveying machinery that seriously injured a miner. Part 1 describes the machinery and the incident. In Part 2 I will summarize my engineering analysis of the incident and share the conclusions I reached.

A loaded, inclined conveyor belt may contain hazardous levels of energy due to gravity. To protect workers, anti-reverse devices called backstops are installed on inclined conveyors to prevent unexpected downhill movement. The Conveyor Equipment Manufacturer’s Association (CEMA) defines a backstop as: Read More

Lack of HVAC System Design and Poor Installation Lead to Extreme Conditions

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Construction defects can appear in many forms.  The building does not necessarily have to fall down. There are many types of construction defects, including roof leaks, water intrusion into walls, as well as Heating, Ventilation, and Air Conditioning (HVAC) defects.

One extreme example of this was an office complex I was called to for an investigation of the source of mold observed on the walls.  The occupants complained that they could not find a temperature setting on the thermostat where they could make the office comfortable. When I inspected the office, I couldn’t believe what I was seeing.  A band of black mold Read More

Industrial Equipment Failures and Construction Disputes

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At Warren, we frequently investigate losses involving industrial machinery.  Many of the losses involve workplace injuries, fires, or explosions; however, we also analyze industrial machinery and processes for other types of problems.  For example, we analyze failures of machinery or industrial processes to perform as expected or disputes that arise from the commercial supply and construction of such systems.  This can encompass a range of issues from failure to achieve required levels of product quality or production quantity, to matters concerning unclear specifications or contracts, Read More

Heavy Machinery Fires Caused by Hydraulic Hose Failures

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Heavy machinery fires are often caused by hydraulic hose failures.  Pressurized hydraulic fluid escaping from a failed hose assembly can be atomized into a fine spray that can be ignited by heated engine surfaces such as the engine exhaust or turbocharger.

Hydraulic hoses near the engine compartment of an excavator that burned.

 

Hydraulic hoses often fail due to age and wear, requiring regular inspection and replacement of hydraulic hoses to prevent failures. Hoses may also fail if they are misrouted.  Misrouting can lead to the hose being pinched or causing it to chafe against a sharp metal surface. Read More

TVSS or SPD … Can I Buy a Vowel? Understanding Surge Protection and the Changing Requirements

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Surge Protective Devices (SPD), formerly known as Transient Voltage Surge Suppressors (TVSS) have been around for a long time.   The most recognized version is integrated into outlet strips and used to protect sensitive electronics from surges, or higher than expected voltages on the power line.  Early versions of these surge strips were known to have problems where internal components could overheat and cause a fire.  Thermal protection was added to the designs to greatly reduce the potential for a fire hazard.  Such an implementation in an outlet strip is considered a Type 3 SPD. Read More

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