WHEN SHOULD THERMAL IMAGING BE UTILIZED?
By: Stephen Ternullo, P.E., I-ENG-A of Southeastern MI by Stephen R. Ternullo & Associates, Inc.
Thermal imaging is a non-destructive method of inspection useful for locating building, electrical, and mechanical problems where temperature changes occur. This includes locating water leaks behind wall coverings, air infiltration resulting from poor insulation, electrical connections in need of repair, worn bearings used in mechanical equipment, and much more. A thermographic camera measures the heat emitted in the infrared spectrum, and can operate in complete darkness. Timing a thermal imaging investigation must be considered and coordinated so that the thermal evidence can be best captured. For example, when inspecting a flat roof for signs of water intrusions, it is best to perform the inspection shortly after sundown because the moisture trapped beneath the roofing membrane will cool down at a much slower rate than roofing surface, rendering problem areas as hot spots on thermographs. A Certified Infrared Thermographer will be able to interpret temperature gradients and take into account atmospheric temperature, humidity, winds, reflections, and other factors that affect accurate thermal imaging.
Recently we were asked to determine if hail impacts had damaged a flat roof. The insured’s contractor had prepared an estimate for a complete roofing material removal and replacement. Upon visiting the structure, it was apparent that hail had indeed impacted the roof and that the roof membrane was damaged. One of the contributing factors of the damage was the age of the roof and that it had become brittle and more susceptible to damage from impacts. Although we had confirmed damage to the roof membrane, we were suspect of the amount of water damage to the interior of the building. We suggested to the adjuster that Infrared Thermal Imaging of the roof may provide additional information regarding the cause or the source of the water damage to the building. The infrared thermal imaging information would also provide the extent of wet and damaged roof insulation.
The insurance adjuster approved us to return to the subject site with our staff Certified Infrared Thermographer and a Licensed Professional Engineer to conduct a thermographic inspection of the roof. Both video and still images of the entire roof were recorded. With the additional data available, we were able to map out suspected wet areas of the roof insulation and documented that they were concentrated in the area of skylights and also corresponded to the areas of the majority of water damage to the building. The areas totaled less than 20% of the total roof area. The other areas of the roof were documented to not be suspected of being wet.
As a result of using thermal imaging, we were able to develop a repair recommendation that required the removal and replacement of only the wet insulation, significantly reducing the cost of repairs. Of the area of the wet insulation, we were also able to determine that poor flashing construction of the skylights were contributing to the water damage and that the hail damage was not the only source of water wetting the insulation and damaging the interior of the building.
As Investigative Engineers, we were able to consider all aspects concerning the subject roof, including determining the age of the roof, manufacture approved methods of repairs and replacement, sources of water intrusions, and provide a recommendation of repair. The results of our investigation were then provided to the client in a single, comprehensive yet easy to understand report that included photos, thermal images and sketches.
Stephen Ternullo & Associates, located in southeastern Michigan, is a Member Firm of the Investigative Engineers Association and provides Investigative Engineering services to the insurance industry, building owners, contractors and the legal profession. You can contact Stephen Ternullo, PE at (586) 868-0220 or by visiting their website www.STAengineering.us
FIRE SPRINKLER SYSTEM FAILURE INVESTIGATIONS
By: Babar Khan, P.E., I-ENG-A of New Hampshire by Concord Engineering Group, PLLC
During the 2013 I-ENG-A Convention, held October 27—30, 2013 in San Antonio, TX, Babar Khan, PE, presented the topic, ‘Investigation of Failures of Fire Sprinkler Systems’. As a follow-up to that presentation, Babar offers the following article.
Every year, around this time, falling leaves, shorter daylight time and falling temperatures announce arrival of winter. At the same time, we also start to get more assignments for investigation of failures in fire sprinkler systems primarily due to freeze-up conditions.
Fire sprinkler systems are required to be installed on multifamily and commercial building by various building codes. These systems offer protection for life and property during fire events. Water is discharged onto fire resulting in elimination or reduction in damage. The systems consist of pipes, sprinkler heads and fittings installed at locations where water discharge will cover all areas vulnerable to start or propagation of fire.
There are four different types of fire sprinkler systems for buildings as follows:
Wet pipe system:
As the name indicates, water is present in pipes at all times. Sprinkler heads are activated or opened based on increased temperature due to fire. Water is then discharged on fire. This type of system has many advantages including low installation and maintenance costs due to systems simplicity. Water is also instantaneously delivered on fire resulting in reduction in response time.
Dry Pipe System:
After wet pipe system, this is the most common type of sprinkler system. It is used if the system is to be installed in areas subject to sub-freezing conditions defined as temperatures below 40 degrees F. These areas include unoccupied buildings, parking garages, attics and canopies. The pipes are filled with compressed air, nitrogen or anti-freeze instead of water. Once the system is triggered by high temperature, air, gas or anti-freeze escapes first and then water is delivered to area of fire. This type of system is substantially more costly and complex resulting in more failures primarily due to poor design, installation and maintenance.
This type of system is highly specialized and is used if instant response to fire is needed over a large area. The system is not triggered by high temperature but rather by smoke or fire alarm.
This is a combination of wet and dry pipe systems and is used at locations where accidental activation of the system could cause substantial loss.
Approximately 90 percent of the systems in use are wet or dry pipe systems. Failure rate of the dry pipe system is considerably higher than any other type of system.
National Fire Protection Association (NFPA) has developed standards for design installation and maintenance of fire sprinkler systems. NFPA 13 and NFPA 25 are two such standards.
Investigation of failures of fire protection systems includes a thorough records search including review of reports, design plans, calculations, specifications, permits, review of maintenance and inspection records, review of fire department and alarm company records indicating recorded incidents and interviews with maintenance personnel. A complete evaluation of the installed system is conducted to determine its compliance with NFPA standards. Materials engineers and metallurgists are consulted as needed to determine if material defects played a part in failure.
The forensic engineering report generated for the client will include an opinion regarding cause and origin of the failure as well as systems deviation from established NFPA standards.
THE INVESTIGATIVE ENGINEERS ASSOCIATION AND CRASH RECONSTRUCTION
By: Elvin Aycock, P.E., ACTAR, I-ENG-A Advisor - Atlanta Engineering Services, Inc.
At the 2013 I-ENG-A Convention, Elvin Aycock, PE, ACTAR, I-ENG-A Crash Reconstruction Advisor, conducted sessions on vehicular accident investigations and reconstructions, for the professional forensic engineer.
The association members learned that the majority of automobile collisions in which a reconstruction is requested tend to be much less complicated then one might suspect. A professional engineer has a background in physics which applies itself well to the field of automobile crash reconstruction. And, with some additional training, they can apply their skills in the field of accident reconstruction or more recently referred to as vehicular crash reconstruction.
Initial accident investigation reports may have conflicting witness statements, or physical damage inconsistent with the facts. Detailed measurements of automobile damage may be necessary to make an estimate of the speed of the vehicles, and/or trajectory of the cars, and this may not be possible to ascertain from the data available in the initial report or due to a loss of evidence.
It can be helpful to have a trained investigative engineer go to inspect the vehicle(s) to get accurate measurements of the damage. They then use this information in tandem with an understanding of the basic equations of motion, conservation of momentum, etc., to estimate the speed of the vehicle(s) at impact.
While there are many sophisticated programs and software packages available to the accident re-constructionist, a professional engineer has the educational background to perform the basic physics and motion calculations needed to reconstruct the majority of accidents. Additionally, the Investigative Engineers Association members have access to the latest technologies for vehicular black box / the event data recorder downloading.
Many elements of a vehicle accident can be verified by simple documentation of the accident scene and the involved vehicle(s). Investigation and documentation of these conditions, shortly after an accident can greatly assist with a subsequent formal and detailed accident reconstruction, if it should become necessary.
Stephen Ternullo & Associates, Inc.