List of Previous Work - O'Donnell Consulting Engineers

Coke Oven Battery Analysis

A comprehensive engineering analysis was performed on a coke oven battery roof and heating walls. Premature grouting of the roof was a major consideration in evaluating the structural integrity and projected life expectancy of the battery. O'Donnell Consulting (OCE) made extensive use of finite element engineering analysis to calculate temperatures, deflections, strains, and stresses using time-dependent creep analysis methods to evaluate the long term integrity of the roof and heating walls. When in operation, coke oven batteries normally undergo time-dependent deformations, and creep, due to static and cyclic thermo-mechanical loads. Using finite element analysis methods, evaluations were carried out for a 25-year operating period. OCE performed analyses of the refractory material properties to determine input for engineering analysis. The boundary conditions are used to model the type and direction of constraints on the battery. Three dimensional, non-linear models were developed to quantify the stability of the heating walls and evaluate the wall stresses. These models were subjected to cyclic pressure and thermal loading conditions, due to charging. The effects of operating conditions on the as-built battery with construction imperfections were evaluated to determine the battery displacements and stresses vs. time. The finite element results showed that the battery oven walls would not deflect enough to induce instability. The construction imperfections had no meaningful effect on the structural integrity, robustness, or longevity of the battery. Such studies are quite useful in planning battery maintenance efforts.

Pollution Control Equipment

The growing need for efficient electric power generation led to the use of pulverized coal as a basic fuel for large steam generating units in the United States around 1920. The combustion of coal that has been pulverized to tiny particles results in the creation of even smaller ash particles, known as flyash particles. About 80 percent of these flyash particles are swept up by by the moving stream of combustion gas and carried out of the boiler. Such particles would be discharged from the chimney and create a major air pollution problem in the atmosphere, unless they are removed from the flue gas. Thus, an electronic precipitator was used to remove particulate matter (flyash) from the boiler flue gas prior to emission from the chimney. Electronic precipitators immediately achieved wide acceptance for the efficiency removal of flyash. For hot-side precipitator designs, ductwork designs included temperatures exceeding 700 F, which had to allow for "thermal breathing". When these movements are restrained, large forces are created, which can cause tearing, cracking and buckling of the steel. Sliding supports, expansion joints, and appropriate elevated temperature structural design practices are therefore used to avoid restraining thermal movements. O'Donnell Consulting performed structural and design life analyses of an electronic fly-ash precipitator system, determining errors in the design of the ductwork system.

Cracked Ductwork

When reinforced ductwork failed shortly after being placed in service, O'Donnell Consulting performed an extensive failure analysis. The results determined that that the ductwork was overly-constrained. Thermal breathing and bending due to a thermal gradient that existed between the top and bottom surfaces were constrained, creating high thermal stresses. Finite element analyses (FEA) were used to quantify the fracture conditions. During expert testimony, O'Donnell used the finite element analysis results to explain how the ductwork failed - pioneering the application of FEA technology in litigation.

Ore Unloader

During the delivery of a shipment of resin, damage occurred to a storage tank at a production facility in Southwestern Pennsylvania. Damage to the tank was apparently the result of tank overpressurization. O'Donnell Consulting performed a failure analysis of the tank, and determined that overpressurization was due to a "blow-down" following the transfer of resin from transport tanks to the storage tank. O'Donnell also inspected the tank and made recommendations on how best to repair the vessel.

Propane Pump

A propane pump explosion killed one worker and injured three others at a central Ohio factory. The pump was being used to charge aerosol cans with propane propellant at high pressure. The accident occurred when gas leaked past the pistons in the pump. Originally, the pump was built with metal pistons that wore rapidly against the seals. They were replaced with ceramic seals. Designed to pump mud, the ceramic components eventually cracked and loose pieces fell away, causing a massive leak. After examining the crack pattern and characterizing the ceramic material, O'Donnell engineers theorized that the cracking was due to the sudden chilling of the outer ceramic surface. Finite element stress analysis and testing confirmed the opinion. O'Donnell performed an investigation at the request of attorneys, who represented the workers. Based on the O'Donnell findings, four separate cases were settled out-of-court. The plaintiffs received a substantial payment in each case.

Gas Well Pipe

O'Donnell evaluated a pipe rupture resulting from a gas well accident in which a worker lost a leg at a plant, north of Pittsburgh. The injured well tender, whose leg was severed below the knee, was initiating a "post-fracking" procedure-blowback operation to release pressure in the capped well-at the time of the mishap. When the main valve was opened, the pipe ruptured due to water hammer. The pipe, set off center, broke loose and whipped around, striking the well tender. O'Donnell engineers, conducting the evaluation on behalf of the worker, found that the pipe did not fail because of faulty material or construction. Our engineers also learned that the fracking subcontractor, after finishing his work at the site failed to issue sufficient instructions to the well tender concerning the potentially dangerous procedure. An out-of-court settlement was negotiated in favor of the worker.

Steel Tube Chair
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O'Donnell Consulting Engineers was requested to perform a failure analysis on a chair that had failed when a 180 pound individual sat down. The evaluation was accomplished using generally accepted engineering design calculations and modern finite-element elastic-plastic large-deflection three-dimensional computer analyses. The failure was due to gross plastic deformation of the material in the bend, which had been deformed during fabrication. The failure occurred when the bending moment applied to the tube exceeded its plastic moment capacity. A three-dimensional finite element analysis was performed to evaluate the structural integrity. The results were compared to the relevant American National Standard, requiring that dynamic loads be included in the structural adequacy of such chairs. The results showed that the chair did not meet these requirement in the �as-built� condition, and was structurally defective per this American Standard.

Air Tank

O'Donnell engineers performed extensive testing and analysis that led to an out-of-court settlement after a ruptured air tank caused a workman to lose a leg in Corpus Christi, Texas. The tank, with a maximum allowable working pressure of 150 psi, was intended to energize an air starter for diesel-powered oil well test equipment. After thoroughly examining the tank and reviewing the circumstances surrounding the accident, O'Donnell engineers became convinced the tank exploded while a 2,000 psi nitrogen bottle was being used to pressurize it. According to the evidence, the safety relief valve was isolated while the tank was being energized. O'Donnell, after performing destructive testing of more than twenty tanks, demonstrated that failure likely occurred at more than three times the maximum allowable working pressure. A modest out-of-court settlement was reached between the tank manufacturer and the injured workman.

Compressor Valve Cover

An employee was killed and another suffered serious injuries at an Alabama chemical plant when a valve cover failed on the 1350 psi stage of an Ammonia Compressor. Under a law existing only in Alabama, the injured worker filed suit against his co-employees alleging improper maintenance of the equipment. O'Donnell engineers conducted an examination that showed threads had been stripped from several nuts. As a result, the valve cover lifted and the remaining sound studs and nuts bent and broke. Transient temperature analysis of the valve body and the water-cooled compressor case showed the valve body reached operating temperature significantly faster than the casing. Consequently, the valve body expanded to a greater length during heat-up, applying an additional, unanticipated load to the studs and nuts. The additional load was insufficient to cause the nuts to fail, but caused failure in the weaker nuts. The results of the analysis were presented by an O'Donnell engineer in a deposition. The defendants later contributed a small portion to an out-of-court settlement, the larger portion of which was paid by the compressor manufacturer.

Tank Welds

O'Donnell Consulting Engineers performed structural analysis on imperfect welds in an accumulator tank. Metallurgical evaluations were performed in addition to finite element analysis. OCE determined that the welds met Code Safety Margins, and were able to withstand the anticipated environmental and vibratory loading conditions.

Threaded Closure Failure

O'Donnell Consulting Engineers investigated the cause of an accident due to a failed threaded closure on a wellhead. Through metallurgical evaluations, material testing, and engineering analysis, it was determined that the cast iron nut had failed due to fatigue.

Coolant Injection Plate

Failure of panelcoil components in a large sterilizer was investigated. A failure specimen was examined, and it was determined that the cracking was due to fatigue. This observation led to an investigation of the possibility of the failure being caused by vibration due to the rotating agitator. Bounding calculations indicated that the panels possessed natural frequencies between 8 and 100 Hz. The forcing frequency of the six-bladed agitator was 15 Hz and vibration was therefore identified as the most likely culprit. Concurrently, finite element dynamic methods were used to established a natural frequency to account for the immersion of the panel in water, the frequency was close to 15 Hz. The two independent analyses both demonstrated the failure was induced by fatigue. Locations were provided for panelcoils supports to eliminate the lower modes of vibration. O'Donnell personnel provided further guidance to assure the adequacy of welding processes and welding materials to achieve modifications that subsequently performed reliably in service.

Panel Coil

Failure of panelcoil components in a large sterilizer was investigated. A failure specimen was examined, and it was determined that the cracking was due to fatigue. This observation led to an investigation of the possibility of the failure being caused by vibration due to the rotating agitator. Bounding calculations indicated that the panels possessed natural frequencies between 8 and 100 Hz. The forcing frequency of the six-bladed agitator was 15 Hz and vibration was therefore identified as the most likely culprit. Concurrently, finite element dynamic methods were used to established a natural frequency to account for the immersion of the panel in water, the frequency was close to 15 Hz. The two independent analyses both demonstrated the failure was induced by fatigue. Locations were provided for panelcoils supports to eliminate the lower modes of vibration. O'Donnell personnel provided further guidance to assure the adequacy of welding processes and welding materials to achieve modifications that subsequently performed reliably in service.

Coolant Injection Plate

During a shutdown of the Kuosheng 1 plant, Taiwan, operation of the LPCI system for normal shutdown caused failure of an LPRM. Testing by G.E. in their (HF)2 facility duplicated the failure, which has been attributed to flow-induced vibration of the LPRM. G.E. devised a flow-deflector to prevent cross-flow from the LPCI across core components. This deflector had to be installed in Grand Gulf very quickly to avoid delay in fuel loading. In order to increase assurance that the design, construction, and installation of the deflector plate were proper, Mississippi Power & Light Company asked O'Donnell to review the problem and the proposed solution. O'Donnell analytically determined that the fatigue usage factor, pump-induced vibration, low-pressure injection system head loss, fluence at welds, and the diaphragm connection of the LPCI line to the shroud were adequate. Subsequent testing confirmed the adequacy.

Sprinkler Analysis

O'Donnell Consulting performed a failure analysis of a sprinkler pipe system. The investigation included structural analysis, metallurgy, and material testing. Although material thickness was suspect, it was concluded that the failure of the pipe was due to tensile overload.

Space Telescope

O'Donnell Consulting Engineers evaluated the nature of vibratory conditions in the framework supporting the Hubble Space Telescope. Combined analyses and tests showed that conditions were due to second order shortening of the transverse bracing members not found by conventional computer analysis. The vibration problems were then solved using lateral restraints on the transverse members.

NASA Space Shuttle Main Engines

O'Donnell developed an analytical procedure for predicting thrust chamber life limited by the small number of firings. In an operating rocket thrust chamber the hot-gas-wall ligaments separating the coolant and combustion gas are subjected to pressure loading and severe thermal cycling. The resulting stresses cause plastic straining resulting in incremental bulging of the ligaments during each firing cycle. This mechanism of creep ratcheting was analyzed considering combined bending and membrane loading. The incremental permanent deflection and progressive thinning near the center of the ligaments was evaluated. Creep and tensile instability were identified as the limiting mode of failure. Results of these analyses compared favorably with available experimental data and allowed design changes which extended the design life.

Heat Exchanger Analysis

O'Donnell Consulting performed an extensive engineering analyses of a high-temperature heat exchanger for NASA. The results showed that the cracks were caused by excessive cyclic thermal stresses, and a repair redesign was developed.

Pressure Vessel Recertification

O'Donnell completed a seven-year program to create the equipment safety program for pressure vessels and pressure systems at the NASA-Lewis Research Center. Some of the vessels and systems at Lewis are over forty years old and were a part of the original NACA installation. O'Donnell: (1) obtained design documentation and service records; (2) performed stress, fatigue and fracture analyses to establish regions to be subjected to nondestructive examination; (3) performed nondestructive examination of selected regions and features; (4) performed repairs or analysis to demonstrate the permanent or temporary acceptability of defects; (5) defined the conditions and lifetime for system recertification, and the cyclic interval at which the next inspection is necessary and (6) established areas requiring repair and recommending repair and or replacement based on cost effective analysis. This process costs approximately 15% of the cost of replacement, and the necessary down-time is minor; so there is a major economic incentive for recertification rather than replacement of systems and components. O'Donnell has extensive experience in the recertification process. This evaluation of vessels and piping systems included radiographic, dye penetrant, ultrasonic, magnetic particle and visual inspections to establish soundness of base material and of weldments. Where indications were found, they were characterized and analyzed as appropriate to establish whether the defect is growing or is arrested. O'Donnell also defined the remaining useful life of the item or established specific methods of repair that could be accomplished with minimum impact on operations and at minimum cost. O'Donnell Consulting has performed these services at other major industrial plants.

Maritime Mooring

O'Donnell Consulting performed structural analyses of a barge mooring that had failed during a flood condition on the Monongehela River in Pittsburgh, PA. Engineering and finite element analyses showed that the bow and stern mooring lines were subjected to excessive loads as the river water levels increased, causing failure of the u-bolts and other structural elements of the mooring.

Boiler Tube Failure

O'Donnell Consulting performed an extensive failure analysis of a boiler tube. The results showed that the tube failed due to a combination of deposit buildup in the return bend, and excessive cyclic thermal stresses.

Lift Truck

An accident involving a lift truck occurred as it was transferring equipment. Initial inspection of the vehicle determined that failure occurred in the threaded regions of the two tilt cylinder shafts with their corresponding end yokes. Mast restraint was lost, resulting in a forward tipping of the mast and dropping of the frame. O'Donnell Consulting performed an engineering investigation, and determined that the tilt cylinder was arranged too short of thread engagement between the cylinder end and yoke for the loads applied to the truck. Thus, fatigue in the threads caused a sudden failure under load.

Turbine Exhauster

O'Donnell Consulting investigated an accident involving a turbine exhauster, which is a high speed, three-stage centrifugal compressor, used to pump exhaust gases out of a coke oven battery. All three compressor stages are located on the same shaft and housed in the in a common casing. The third stage compressor suffered severe damage, and caused subsequent damage to the facility. O'Donnell performed finite element, engineering analysis, metallurgical, and material testing on the disk and blades. It was concluded that small flaws that had been detected earlier had not been correctly evaluated, and were growing to critical size during normal operating conditions. As the crack grew, the stresses in the disk increased - to the point of disk rupture.

Lift Hook

O'Donnell Consulting investigated the failure of a lift hook. A Three dimensional finite element model consisting of over 75,000 elements and 120,00 nodes was constructed to evaluate the failure mode. The results determined that the hook failed by metal fatigue.

Large Diameter Ductwork

During operation of a ferro-silicon furnace in Washington State, a nine foot diameter duct failed. This duct carried exhaust from furnace stacks to a baghouse. It was made of one-half inch thick low alloy steel. The failures were predominantly located at the duct supports. Stress analysis and material evaluations showed that the cause of these failures was low cycle thermal fatigue. O'Donnell redesigned the ductwork and support system to reduce the amount of constraint on the duct. The rebuilt system has been operating successfully for many years. O'Donnell later evaluated the work of the original designer and the depositions of witnesses, and provided legal testimony, resulting in a $7.4 million verdict on behalf of the claimant.

Conveyor System

A West African bauxite company was awarded $16 million in a U.S. District Court after a tippler building sustained severe structural damage. Bauxite was dropped twenty-two feet from rail cars onto the conveyor of a crusher system in the tippler building. The conveyor system and concrete support beams were most seriously affected. O'Donnell engineers determined that the impact loading of the bauxite boulders weighing up to ten tons had been grossly underestimated in the design of the building. They concluded that the structure had been under-designed for the anticipated and applied loads.

Bellows

An engineer was seriously burned when a thirty-nine inch expansion joint ruptured while workman were performing temporary repairs at a Texas refinery. The ruptured bellows spilled hot catalyst from a fluidizer catalytic cracking unit on the deck which the engineer had to cross to reach safety. The plaintiff alleged that the selection of Type 321 stainless steel by the process designer was unsound, and led to the rupture. O'Donnell was retained to establish why the bellows failed. We found that the stainless steel had not been heat-treated properly during the making of the steel itself and it was sensitized during fabrication and made susceptible to corrosive attack. The case settled out of court, with our client, the process designer, assessed a small portion of the settlement.

Process Vessel

For a major food processing company, O'Donnell engineers analyzed the failure of a horizontally mounted low pressure process vessel. The sequential failure of several of the nuts holding the closure head caused it to blow off, seriously injuring a worker. A review of the original design showed that the vessel had not been built with the number of nuts and swing bolts shown on the drawings or on the Manufacturer's Data Report. Metallurgical analysis of the nuts which had failed showed that they were fabricated of weaker material than that originally specified. Information provided by the operating personnel indicated that several of the nuts were generally not used because of inconvenient access. A finite element analysis of the closure head accounted for the maldistributed nuts. These errors taken together exactly used up the safety-factor of five required for pressure vessel bolting design.

Blower Fan

Failure analysis of a blower fan used to cool electronics was performed to determine root cause. The fan failed within the first two months or approximately 1400 hours of continuous operation. The investigation determined that defective bearings most likely caused unusual bearing loads, and subsequent fan failure.

Induction Furnaces

Induction heating is caused, as the name implies, by induced electric currents in a material. Just as electrical current can produce a magnetic field which ultimately can be used to power a motor, so can a magnetic field be used to produce secondary current in a material. The principle is exactly the same one used in constructing a voltage transformer whereby one AC voltage across the primary windings of a tranformer will induce a different AC voltage (higher or lower) across the secondary windings. The voltage ratio of the transformer is solely dependent on the ratio of coil windings due to electromagnetic principles, and the frequency is the same for both AC voltages. In an induction furnace, the metal to be heated becomes the "secondary" path. In a coreless induction furnace, shunts are used to cover a significant portion of the furnace coil which are used to focus the magnetic field back into the crucible/metal. These shunts contain layers, with insulating barriers. O'Donnell investigated the ongoing issues of such induction furnaces undergoing upgrades.

Quartz Tubes

O'Donnell performed an independent failure mode analysis to determine the cause of the failure of quartz tubes in a water purification system. The flow conditions around the quartz tube were evaluated using ANSYS computational fluid dynamics software. Natural vibration frequencies of the quartz tube and stresses for various loading conditions, such as shell distortion and impact damage, were evaluated using the ANSYS structural software. The natural frequencies of the hollow quartz tube were analyzed, in order to determine the flow rates at which shedding vortices would excite these frequencies. Mode shapes for each of these frequencies were obtained in order to determine whether the dynamic forces caused by shedding vortices would excite these mode shapes, causing the quartz tube to absorb energy from the flow.

Pressure Swing Absorption Vessel

For a major chemical producing client, one out of ten PSA vessels had developed a leak after 14 years of cyclic service. O'Donnell performed an independent analysis of the PSA vessels to quantify fatigue life and recommend either to continue in operation, repiar, or replace the vessels. It was determined that although imperfections in the fabrication were within ASME Code allowables, stress levels at the longitudinal weldments shortened their fatigue design life. It was recommended that the vessels be replaced.

Marine Air Compressor System

When an air compressed system used to control the engine and steering controls for a marine transport barge failed, O'Donnell Consulting Engineers performed an extensive analysis of the system. It was determined that the system contained a defective safety valve which was the primary root cause for the system failure, which caused a collision with another vessel. The valve had a latent defect exonerating the ship owner per Maritime Law.

Stress Analysis of Decanter

O'Donnell Consulting performed a stress and buckling analysis on a decanter, which is used to transfer microscopic materials from one vessel to another. The buckling analysis was performed in accordance with Section VIII, Division 1 of the ASME Boiler and Pressure Vessel Code. The stress analysis was performed using ANSYS finite element software, using ten-node structural tetrahedral solid (Solid 187) elements. For other features, such as the bolts, two-node beam elements were modelled. The model had approximately 99,000 nodes and 53,000 elements. Various loading conditions (bolt preload, deadweight, and vacuum pressure) were used to verify the structural integrity of the vessel.

Stress Analysis of a Vessel

O'Donnell Consulting performed a buckling analysis on a stainless steel vessel subjected to a vacuum loading at elevated temperature. Both instantaneous (linear and nonlinear) buckling and creep buckling were investigated. The analysis was performed using ANSYS finite element software, using linear shell elements (Shell 181) with creep capability. The analysis showed that the vessel maintained a significant safety margin against buckling under a vacuum load, at 1200 degrees F for short periods of time, with up to 1 percent out-of-roundness (measured after post weld heat treatment). The analysis also showed that the nozzle loads on the vessels had negligible effect on the governing buckling modes.

Stress Analysis of an Evaporator

O'Donnell Consulting performed an analysis to determine the impact of oversized holes in the tube support plates of a film evaporator in a water treatment plant. These support plates, which take up over 50 percent of the vessel cross-section, are designed to TEMA standards. During vessel fabrication, the holes for the tubes were found to be outside the recommended limits. Tube stresses, impact wear, sliding wear and fretting wear were investigated to address the concerns of the oversized holes.

Failure Analysis of a Hoist

O'Donnell Consulting investigated the failure of a 3 ton capacity hoist. It was concluded that improper installation of the intermediate nut had prevented the accomodation of off-center loads, inducing bending stresses and subsequent failure of the support studs.

O'Donnell Consulting Engineers performs a range of engineering design and analysis services-

Stress/ Structural Analysis
Thermal Transient Analysis
Fatigue & Vibration Analysis
Buckling/ Instability
Creep Analyses

as well as forensic engineering services-

Failure Analysis & Metallurgy
Engineering Expert Witness

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