In this Issue:

EXPLOSIONS & PRE-EXISTING CONDITIONS

CORROSION: ARE YOU SUFFICIENTLY INFORMED TO MAKE DECISIONS?

ROOFING FAILURES, CAUSES AND PREVENTION

Explosions & Pre-Existing Conditions

EXPLOSIONS & PRE-EXISTING CONDITIONS

BY: STEPHEN TERNULLO, P.E. & FRANK STREHL, P.E.

The recent house explosion in Royal Oak is raising insurance claims from the owners of the structures surrounding the explosion. Many of these neighboring structures have experienced distress as a result of this event. Documenting the distress to these structures is a critical task which insurance companies must perform in a timely fashion. An important facet of this documentation process is knowledge of the condition of the structure prior to the explosion. Not all distress to a structure may be the result of this event and may have been in existence for some time prior to the event.

Many times an insured will examine their property following a catastrophic event, and observe distresses that they had not observed previously but were in existence. Because they have not observed these distresses before, they will usually attribute them to the event.

Types of distress most likely to be reported by insured property owners include:

  • Fractures observed in the brick veneer
  • Fractures in the basement walls or foundation
  • Fractures in the interior wall finishes
  • Broken windows or double pane window seals
  • Impacts to the exterior of the structure
  • Structural damage to the house framing

Stephen Ternullo & Associates has the experience to determine if distresses to a structure are the result of a sudden event, such as this explosion, or if they have been in existence prior to the event. Our Licensed Professional Engineers will look for evidence of pre-existing conditions that may indicate the timing of the distresses in relation to the event, and for the cause of distress to determine if the distress is a result of a recent event or of some other cause.

Some of the considerations and methods utilized to age distress include:

  • Wear and weathering of fractures in concrete and wood structural components
  • Location and nature of distresses in relation to the event
  • Interviews with the insured to determine the circumstances surrounding the observed distress
  • Determination of structural displacement using electronic surveying equipment

If you have a claim resulting from this recent explosion in Royal Oak, or if you have a claim concerning foundation or structural issues, Stephen Ternullo & Associates has the expertise to determine the existence, extent of, and the cause and origin of the structural distress. We also have the expertise to prepare plans for repair of this distress in a manner that employs sound engineering principles and economic considerations.

CORROSION: ARE YOU SUFFICIENTLY INFORMED TO MAKE DECISIONS?

CORROSION: ARE YOU SUFFICIENTLY INFORMED TO MAKE DECISIONS?

BY: HERBERT H. DEFRIEZ, P.E.

Corrosion, everybody knows what it looks like, just like the bolt shown on the right; it looks in really bad shape and if the corrosion was caused by a leak that your company insured against, this could be costly.

But what about things that don’t look like corrosion. Take the photo to the lower right for example. You find this piece lying on the ground after a plant accident. Looks like a mechanical failure of a brittle section of perhaps a torque tube – was this where the problem started? You take a good look, note the crystalline nature of the fractures, note the many fissures in the metal, note that the metal is mostly shinny and shows no signs of “rust”. If you concluded that this was a mechanical failure due to overstressing, you would be completely wrong. This is a section of Type 316 Stainless Steel tubing carrying smoke stack gases to an analyzer. The fractures are actually chloride-induced stress corrosion cracking and the disruption was caused when a pipe fitting was being removed by hand. Not your culprit at all.

And these revelations about corrosion can go on and on. To give you the most basic insight into the potential problems in assessing corrosion, let’s start by just listing the nine general forms of corrosion, (probably many more than you thought and way more than you wanted to know). Corrosion comes in the following forms:

  • Uniform (like bolt shown)
  • Localized (pitting)
  • Galvanic (connecting brass to steel)
  • Velocity Induced (erosion corrosion)
  • Intergranular
  • De-Alloying
  • Cracking
  • High Temperature
  • Microbial

The items not followed by an example are the more difficult types to evaluate and often require sophisticated analysis to determine. If your company has corrosion exclusions in its property policies, could you recognize if corrosion were involved and recommend a cause and origin investigation?

An actual example involves a sail boat mast failure in high winds. Clearly the cause was the wind but the policy had a corrosion exclusion. The broken section was sent for evaluation. Dismantling the stainless steel sail retainer and its stainless rivets from the aluminum mast exposed exterior corrosion at each rivet hole. Micro sectioning also reveled cracking around each hole; these cracks were the probable initiation point for a massive tension failure. Perhaps without the corrosion induced cracks, the mast would not have failed? The insurance company did not pay.

Fortunately, your I-ENG-A family of investigators has a Registered Corrosion Engineer - myself. I can work through your local investigator to provide evaluations of simple-to-complex corrosion problems. Once engaged, I would prepare inspection, photograph and interview criteria for the local investigative engineer to perform on-site. Over 80 percent of the time, the origin and cause can be determined over the Internet using this locally collected data. Should the problem exceed this approach, I can also travel to photograph and retrieve samples for sophisticated chemical and physical analysis. Should subrogation become an issue, I am also a court-tested expert witness. Contact your local I-ENG-A member for details.

By the way, about the bolt. You would most likely have been wrong about it as well. This bolt was submerged in water for nearly two years in a newly poured concrete footing sump. The water’s alkalinity prevented most of the uniform corrosion that would have occurred under other circumstances. After drying out, the bulk of the “corrosion” appeared to be silt and hydrated lime, easily removed with a wire brush. The cleaned bolts would easily accept new nuts. To verify that the bolts were still suitable for their originally intended purpose, in-place pull tests were performed; these tests indicated the bolt’s strength was still in excess of design specifications. After only cleaning, the bolts were returned to service. These results would have saved you a lot of money.

ROOFING FAILURES, CAUSES AND PREVENTION

ROOFING FAILURES, CAUSES AND PREVENTION

BY: OWEN SWEITZER

In using the scientific method, an investigative engineer is constantly comparing “cause” and “effect.” In many cases one can study cause and predict effect, and from effect one can determine cause. However, in roof failure analyses one must be aware of hundreds of variables that are not only affected by climate and weather conditions, but start with the manufacturer, leading through design, installation, and ending with building maintenance.

The task of the roofing system designer is to consider and to determine the effects of many factors and conditions that the roofing system will encounter. The designer must then select system components and integrate all components into a complete system that will withstand these factors. Designers often fall into the trap of not integrating all components into a complete system. The primary factor is to properly consider the design factors in relation to the components. Components unsuitable for the task, or combination of incompatible components, seem to be frequently selected for the system.

Even properly designed and specified roofing systems may be subject to failure when poorly executed. Site labor, (i.e. workmanship), is crucial for the efficacy of the initial roof application and its subsequent care and maintenance. Successful refurbishment and repairs, as well as in new work requires key elements, such as: proper weather conditions, correct materials, properly trained and equipped labor force, and the formal inspection of all work, commissioned upon completion. In the labor force, it cannot be assumed that a roofer experienced in one material can transfer to another without training. Plastics, rubbers and bitumens all require different skill sets to properly install a roof to meet its life expectancy.

Once the roofing project has traveled from conception to completion, it will require proper care. The roof has been called the most vulnerable part of the building exposed to the elements. Even the best designed and applied roofing systems cannot reach a full-life expectancy without proper inspection and maintenance. A roofing system is subject to damage from foot traffic, extreme weather, stress concentration, abuse and even vandalism. It is critical that minor repairs be made immediately to prevent further deterioration of the roofing system. According to the National Roofing Contractor Association (NRCA), a roof should be inspected at least twice yearly, in the spring and in the fall, and after any severe storm. Any repairs should be performed by a qualified roofing contractor and all documentation, including job records, plans and specifications should be kept current . Failure of a roof to perform as expected over a reasonable length of time is likely to be attributable to inadequacies of use, of design, and of workmanship (or a combination of these factors). As an investigative engineering project manager, I have found roof failure investigations are most effective when the roof is approached as an entire system by an investigator experiencedwith numerous waterproofing systems. Many I-ENG-A member firms have both the experience and holistic views of projects to provide useful forensic investigations of damaged roof systems.