Forensic Engineers and Consultants

Tag Archive: forensic engineering

  1. Machine Guarding Resources

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    So, you find yourself with a machine hazard that you need to guard.  Where do your turn for guidance regarding guards?  Several resources are available for the person who is tasked with providing machine guarding.

    The United States government provides resources in the Code of Federal Regulations (CFR).  These can be found at www.ecfr.gov.  Title 29 of the CFR, section 1910 covers “General Industry” regulations.  1910 Subpart O, covers Machinery and Machine Guarding.  Definitions are covered in 1910.211 and it is wise to understand how terms are defined. For instance, in 1910.211(a)(1), Point of operations is defined by the regulation as “that point at which cutting, shaping, boring, or forming is accomplished on the stock.”

    Example of a point of operation

    29CFR 1910.212 is titled “General requirements for all machines” and 1910.212(a)(1) Types of guarding, states that “one or more methods of machine guarding shall be provided to protect the operator and other employees in the machine area from hazards such as those created by point of operation, ingoing nip points, rotating parts, flying chips and sparks. Examples of guarding methods are – barrier guards, two-hand tripping devices, electronic safety devices, etc.”

    29 CFR 1910.212 “General requirements” is not the only federal regulation out there.  There are also regulations for specific equipment such as 1910.213, Woodworking machinery requirements, 1910.215 Abrasive wheel machinery, 1910.216 Mills and calendars in the rubber and plastics industries, 1910.217 Mechanical power presses, 1910.218 Forging machines, and 1910.219 Mechanical power-transmission apparatus.

    CFR 1910 Subpart R – Special Industries includes, but are not limited to 1910.262 Textiles, 1910.263 Bakery equipment and 1910.268 Telecommunications.  Specific industries are also covered, including Maritime (29 CFR 1915, 1917, 1918), Construction Industry (29 CFR 1926) and Agriculture Industry (29 CFR 1928).

    But what about the details of the design for a guard?  29 CFR 1910 (a)(2) General requirements for machine guards reads as follows, “Guards shall be affixed to the machine where possible and secured elsewhere if for any reason attachment to the machine is not possible.  The guard shall be such that it does not offer an accident hazard in itself.”

    Here we see that per OSHA the guard should protect the operator from hazards such as those created by point of operation, ingoing nip points, rotating parts, flying chips and sparks.  Also the guard needs to be affixed to the machine where possible.  What other resources are available for the person tasked with designing a guard?

    Fixed Guard on a Rotating Shaft

    Here consensus standards are available to assist with the task.   The American National Standards Institute (ANSI) publishes B11.0 – Safety of Machinery.  The standard states in 7.9 Safeguarding, 7.9.1 General, that the guards, safeguarding devices, awareness devices, and safeguarding methods on machinery shall conform to the applicable ANSI B11 machine-specific (Type-C) standard and/or ANSI B11.19.  ANSI provides standards for specific equipment including mechanical power presses as an example.  If there is no machine specific standard available, then ANSI B11.19, Performance Requirements for Risk Reduction Measures: Safeguarding and other Means of Reducing Risk is available.

    ANSI B11.19-2019 (R2024) contains a specific section on guards, including fixed guards, movable guards, interlocked guards, adjustable guards, self-adjusting guards, partial guards, perimeter guards, nip guards, and shields. This standard can be used to assist the individual tasked with designing a guard.

    Fixed Guard on Belts

    International Standard ISO 14120 Safety of machinery – Guards – General requirements for the design and construction of fixed and movable guards is also available to assist in the design of guards for machinery.  Some sections included in this standard are “Principles for the design and construction of guards” and “Selection of types of guards.”

    The individual tasked with designing a guard has several resources available to assist in the design.  Proper application can lead to a safer piece of equipment.

    Chad Jones, PE, CFEI, CVFI, CMSE has a Bachelor of Science in Mechanical Engineering from Clemson University. Chad has over 25 years of engineering experience including mechanical, process, and manufacturing engineering. This work has included equipment design, machine safeguarding, cost estimating and safety compliance. Chad also has over 15 years of commercial, industrial, and residential HVAC and plumbing design experience. A lifelong auto and motorcycle enthusiast, Chad is accomplished in the maintenance, repair, and modification of vehicles and engines. Chad is a Certified Fire and Explosion Investigator, Certified Vehicle Fire Investigator, and IFSAC certified Firefighter II in Greenwood County, South Carolina.

  2. Water Removal In Windows and Doors – Part 2: Weatherstripping

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    Welcome back to my multi-part series about water resistance in windows and doors. Last time we discussed weep holes. Today, I’d like to talk about weatherstripping (also known as weathersealing).

    During the life of typical exterior fenestration products, every driven rain is a test of the product’s water weathersealing system. Most windows and doors handle water without much homeowner input, but racked or misaligned windows, poor weatherstripping corner joints, and torn piles all contribute to reduced water infiltration resistance. They can allow moisture into the structure, where damage to flooring, walls, and (more…)

  3. Don’t Get Burned With Your Gas Grill!

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    If there is one thing Americans can agree upon, it is the enjoyment that comes from an outdoor barbeque.  Whether a summertime cookout or a fall BBQ to watch a football game, we all love the fun and fellowship that comes from sharing a meal that was prepared outdoors on a grill or smoker.  In fact, 64% of Americans own a grill or smoker.  The great majority of these are LP fueled gas grills with comparatively few natural gas fired grills.  These products can be enjoyed safely when designed, installed, and used in a proper manner.  However, given the grill’s use of flammable fuel gas and high temperatures, the potential exists for things to go wrong and result in burn injuries or uncontained fires that spread to the surroundings. (more…)

  4. Water Removal In Windows and Doors – Part 1: Weep Holes

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    In architecture, the word fenestration is used to encompass the windows and doors in a building. During my twelve-year career as a design engineer in the fenestration industry, water infiltration resistance (I.E., stopping leaks) consumed almost as much time in the test lab as pressure or impact testing. During the life of typical exterior fenestration products, every driven rain is a test of the product’s water evacuation system. Most windows and doors handle water without much homeowner input, but poor, clogged or covered water drainage systems can allow moisture into the structure, where damage to flooring, walls, and molding may occur. Poor water infiltration resistance also increases the humidity in a living space.

    PVC Sliding Door w/screen and track weep holes. Note how the weep hole in the lower slot is filled with clay.  A weep hole cover should be installed in the slot to prevent more dirt or insects from blocking the slot. Without the slot, the sliding door tracks would collect water and overflow.

     

     

     

     

     

     

     

    There are a handful of ways manufacturers address water infiltration resistance. Ideally, the glazing (adhesive, extrusions or other methods employed to hold glass into a window or door frame) blocks water. Low pressure water and mist intrusion can be mitigated with weatherstripping seals around sashes and doors. But many PVC and aluminum windows manufactured in the last 30-40 years also take advantage of the hollow nature of sills (bottoms of windows/doors) to utilize weep systems.

    Today I’d like to discuss the benefits, drawbacks, and failure modes of weep hole systems in fenestration products.

    Inswing casement window cross-section showing weep hole. Note how the hollow cavities must create positive drainage pressure on the weep hole to “pull” water out of the shallow passage. Without a weep hole, water would quickly spill into the home.

    Benefits

        Weep holes offer the following benefits:

    • They are relatively unobtrusive. A weep hole size as defined by the International Code Council (ICC), R703.8.6 is a minimum 3/16-inch diameter hole for brick construction. For windows and doors, industry standard weep holes are 3/16-inch X 5/8-inch or larger slots.
    • The hollow extrusions used for energy efficient PVC or aluminum frame windows can have weep holes integral to the window product. This makes for easier retrofit where product needs to be replaced. With modern welded PVC frames, weep holes make sense because they allow the manufacturer to use a similar extrusion for the frame sill, header and jambs (thus allowing for full 4 corner welding).
    • The height differential of frame holes allows excellent drainage for hollow framed windows. A 2-3 inch rise typical to hollow frames means the positive water pressure can empty out the sill beneath a sash or the ledge where a fixed window sits.

    • Weep hole cover. These readily available parts prevent dirt and insects from blocking weep holes.

      When used in conjunction with weep hole covers and weather seals, weep holes can provide excellent water infiltration resistance against flooding events. Weep hole covers offer simple mechanical flaps that close under negative pressure, preventing water, bugs or dirt from moving up into the window.

    Drawbacks

    Unfortunately, weep holes face special challenges:

    • They require a hollow beneath the frame. Swinging doors typically have “solid” sills that sit directly on flooring substrate. Casements and awnings sometimes use angled sills.
    • Weep holes are easily obstructed by insects or dirt. Particularly in the south, hornets are known to build their nests in uncovered weep hole slots.
    • Sometimes, windows are misinstalled or homeowners place exterior substrates on top of weep holes, inadvertently covering up the drainage holes. I have seen and heard of homeowners who seal weep holes with caulk in an attempt to stop water intrusion!
    • For doors, weep holes only work when the sill is stepped up from the outside, which is generally not ADA compliant.
    • Poor machining of weep holes leads to poor fit of weep hole covers, and installers typically do not inspect weep hole cover fit.

    Possible Damages

    Wall/Floor damage from overflowing window sill

    When weep holes become blocked or inoperable, they can cause water to infiltrate the window or door.

    Water damage from weep hole failures usually starts small. Water builds below the sash or glass when there is light precipitation or water is sprayed on a window. It stagnates below the sash or glazed unit with nowhere to go. In fixed units, the life of insulated glass can be decreased substantially by the presence of standing water on sealant. This can cause insulated glass to “fog,” which is considered a failure of insulated glass.

    More water defeats the sash or glazed barrier in the window or door. Water then spills over the edge of the inside and runs along and/or down the window frame.  This type of damage manifests as fungal growth or soft spots in drywall, followed by separation and expansion of the walls. Long term water infiltration leads to wall damage. Larger flows of water will make their way along the floor, where localized delamination of flooring and even substrate damage along the wall/floor interface will occur.

    Water damage from blocked or otherwise non-functioning weep holes normally manifests as a “halo” effect of discoloration or fungal growth around the sill of a window. I have seen similar patterns from amateur installers who install picture windows with weep holes on the tops instead of the bottom, where water has nowhere to go. Overzealous pressure washers are also culprits in weep hole failures when water evacuation rate cannot match the water sprayed on lower DP (design pressure) residential windows typical to non-coastal installations. Water overcomes the drainage capacity of weep holes and bubbles up inside a home or business.

    Weep holes provide drainage for fenestration products that take advantage of modern hollow-framed window and door technology. While failure can usually be prevented by routine inspections and cleaning, damage includes wall and floor deterioration, as well as fungal growth. Skilled forensic engineers with fenestration certification from FGIA are ideally suited for identifying whether weep hole failures originated with the manufacturer, installer or somewhere else. Give us a call at The Warren Group if you would like to discuss fenestration-related leakage issues.

    Brian Tenace is a Licensed Professional Engineer and holds a FenestrationMaster® Professional Certification. He has over 15 years of manufacturing and machine design experience in production and quality-driven environments. Brian earned a Master of Science in Mechanical Engineering from the University of Florida. Over his engineering career, Brian worked in fenestration design in addition to designing hardware, above/below ground spill containment vessels, extrusions, dies and molds. He conducted root cause analyses for fatigue, weld, and corrosion failures in steel, springs, pressure vents and sheet metals. He developed tests according to standards and custom specifications as needed, along with modifying manufacturing processes. His failure analysis experience includes impact testing, design for ballistic protection, water infiltration resistance and corrosion. Brian has an in-depth knowledge of many standards with emphasis on fenestration standards and impact standards. Brian regularly investigates property damage claims involving machinery and equipment in a variety of environments, as well as personal injury, wrongful death, and product liability claims for both insurance adjusters and attorneys. 

  5. Hidden Dangers at Home 3 Surprising Household Hazards You Shouldn’t Ignore

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    Most folks think that chemical hazards are strictly limited to manufacturing or other industrial sites.  The fact that there are potential chemical hazards in the safe confines of their homes often comes as a surprise.

    A surprising number of residential fires are caused by the spontaneous combustion of stain application materials.  When an oil-based stain is applied to furniture or flooring, the oils react with the oxygen in the air to form very large polymer chains.  The process of the liquid stain turning to solid barrier is called curing (it is not drying via evaporation) and the reaction is oxidation.  This reaction generates heat.  On the floor or chair, the heat dissipates into the room without an issue.  That same oxidation reaction is occurring on the brush, towel, sponge, or rag that was used to apply the stain.  If those materials are piled in a corner or in a trash can, the heat cannot dissipate.  If there is enough product present, enough heat can be generated to (more…)

  6. Safety Hazards in Waterjet Cutting

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    Waterjet cutting machines (often simply called ‘waterjets’ in the industry) are essentially platforms that use ultra-high pressure water to manufacture cut parts with accuracy as high as .001 inch. They can cut materials ranging from glass and stone to steel and even plastics. Such machines can cost under $1.00 per minute to run, even including labor. Waterjets are some of the most versatile cutting tools available today. They produce virtually no heat-affected zone. They also use CNC (computer numerically controlled) programs, which allow continuously variable speeds for different edge conditions and cut quality. The waterjet dissipates heat, and the jet stream minimizes harmful chemical vaporization from cut materials. Small and mid-sized companies throughout the U.S. depend on these powerful tools to manage all sorts of custom two-dimensional cuts.

    But waterjets present unique hazards to the manufacturing environment. The following challenges require special attention: (more…)

  7. WARREN Welcomes Mechanical Engineer Brian Tenace, M.S.M.E., P.E.

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    Brian’s Areas of Expertise Include:

    (more…)

  9. More HVAC Equipment Changes on the Way

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    The United States Department of Energy (DOE) finalized energy efficiency standards for residential gas furnaces in late 2023.  These new standards are slated for implementation in late 2028.  The last time the DOE raised the efficiency rating of gas furnaces was in 2007, when the minimum efficiency for gas fired furnaces was raised from 78% to 80% efficient.

    Let’s look at what efficiency means in this context.  In simple terms, (more…)

  10. New Year, New HVAC Refrigerant

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    As we ring in the new year 2025, a significant change is coming for several heating, ventilation, air conditioning and refrigeration (HVACR) systems that are currently used in both residential and commercial applications.  The 2020 American Innovation & Manufacturing (AIM) Act is bipartisan legislation that was signed into law.  The AIM legislation empowers the Environmental Protection Agency (EPA) to reduce the production and consumption of hydroflourocarbons HFCs by 85 percent by the year 2035. (more…)

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