The Bureau of Land Management is planning a truly boneheaded move, angering some conservationists over the affects to herd populations and migration routes. From Field & Stream.
The Bureau of Land Management (BLM) recently released a draft plan outlining potential solar energy development in the West. The proposal is an update of the BLM’s 2012 Western Solar Plan. It adds five new states—Idaho, Montana, Oregon, Washington, and Wyoming—to a list of 11 western states already earmarked…… [read more]
The title of this article is rather broad and audacious, so let’s do what all good engineers would do and set the boundary conditions for the analysis.
All calculations will be approximate given the time invested in this analysis and the purpose thereto. Some assumptions and engineering judgments will be made due to the lack of independently verified information and data. This analysis is meant to be brief and the intended audience is both engineers and non-engineers (for educational purposes). Why am I writing this – out of some sort of ghoulish focus on death? Well, engineers study the ghoulish consequences of the failures of other engineers as part of our profession. Consider the fact that most engineers can explain the cause of the Hyatt Regency walkway collapse (if you can’t, you shouldn’t be an engineer), the Tacoma Narrows bridge failure, the Union Carbide Bhopal disaster, and the space shuttle Challenger disaster (where Morton Thiokol was told to take off their engineer hats and put on their manager hats when considering O-ring temperature certification). This is part of what we do to become better.
Moreover, the public needs to be more aware of things like this. Every time an individual walks into a building or drives on a bridge, they are entrusting their very lives to engineers. Let’s say all you do downtown on a given day is walk into a building to use the restroom. How do you know that the HVAC system won’t kill you? At the Bellevue-Stratford hotel, the engineers designed the intake air to be in the proximity of the condensation pooling, thus concentrating what is otherwise a fairly innocuous bacteria called Legionella to a finally fatal concentration to the occupants.
We’ll go in a sort of flow of consciousness fashion under headings for purposes of clarity, and rather than clutter the analysis with links, a series of source URLs will be posted at the end. I will use information from those sources. Understand that this puts us at the disadvantage of trusting what may be later learned to be erroneous information.
Final Pressure
Computation of the final pressure upon destruction of the vessel is fairly easy, but then fairly complicated, depending upon how precise you want to make it. Under normal conditions, many mechanical engineers use a simple rule for conversion, i.e., 0.433 psi/ft. This comes from the STP (standard temperature and pressure) value of 62.4 lbm/ft³ / 144 in²/ft² = 0.433 psi/ft. So assuming that the vessel imploded at 4000 meters, this converts to 3.28084 ft/m ⋅ 4000 m = 13,123 ft, but we’ll use 13,000 feet. The pressure at that depth is 13,000 ft ⋅ 0.433 psi/ft = 5629 psi. This will be seen to be important later.
True enough, this is a simplification. The assumption of 62.4 lbm/ft³ is at STP, and water becomes more dense down to 39.2 ºF (also, there is a compressibility factor for water to be incorporated). So as the temperature of the water decreases and the pressure increases, the water will become more dense. If asked to solve this more precisely, I would use the ASME steam table data and enter it into TableCurve-2D, then use the fit and coefficients it gave me to enter into MathCAD or JupyterLab for integration. Another option might be just to solve the equations of state. But the resultant value wouldn’t be much different than the one above.
Hull Fabrication
OceanGate apparently used a mixed composite of carbon and Titanium fibers wound with adhesive to construct the hull. Whether this is a good design notwithstanding, the vessel had been to approximately this depth before. Apparently, the assumption was that if it was safely done once, it can be safely done again. But that doesn’t account for deformation where the crystalline structures slip, discontinuities form along grain boundaries, and you go beyond mere elastic deformation to loss of material strength. The operations manager wanted NDE (non-destructive examination) to be performed on the hull and viewport (we’ll get to the viewport shortly). The CEO responded that there was no NDE that could possibly be successful on this design, an assertion I flatly deny. The chief of operations was fired because of his concerns.
Viewport
From all available sources, it is apparent that the viewport was designed and certified down to a depth of 1300 meters, not 4000 meters. I have found no information to contradict this. This was perhaps the largest concern that the operations manager had. The viewport material is essentially Plexiglas. He wanted the viewport to be redesigned by the same company to be worthy and certified down to the same depth as the hull, of course, assuming the hull hadn’t sustained plastic deformation. As the analyst says in the video I embed at the end, this is the most egregious failure of all. I agree. I would assess that it’s mostly likely that the catastrophic failure the Titan sustained was caused by the viewport. It was previously stated by the CEO that each time he descended to that depth, the viewport deformed several inches inward. Whether that was plastic deformation or not is unknown, but that’s what NDE might have determined.
Construction & Vessel Closure
Videos I have seen showed no concern for FME (foreign material exclusion) during either fabrication of the vessel or closure of the aft end (done externally, I’m assuming, with torquing passes on the bolts). Foreign material in any of these design materials or in the closure head would of course completely negate any engineering analysis done on the vessel.
NDE
I am not an NDE engineer, but I know a bit about it. There are many kinds of NDE: visual examination, eddy current testing, acoustic testing, dye penetrant testing, radiograph, ultrasonic testing. Of these, I would surmise that UST would be effective, and I know for certain that radiograph would be a successful test of the hull, and I assume the viewport (I am less certain on the viewport, but the viewport may be an easier test by other means anyway). Cobalt-60 is a commonly used radionuclide for radiography. Grabbing David Kocher, ORNL/NUREG/TM-102, Co-60 emits two photons at 100% yield, 1.173 Mev and 1.332 MeV. For simplification (so I don’t have to interpolate), we’ll use 1 MeV for our calculations.
Using ANSI/ANS-6.4.3, the mass attenuation coefficient for carbon at 1 MeV is 6.352E-2 cm²/g. After doing research in which I found that most carbon fibers are being sold at around 1.5 g/cm³ density, I decided to conservatively use 2 g/cm³ to prove my point. (6.352E-2 cm²/g) ⋅ (2 g/cm³) = μ = Linear Attenuation Coefficient = 0.127 cm(-1). The hull is approximately 5″ thick ≈ 12.7 cm. EXP(-0.127 ⋅ 12.7) = 0.1993. Thus, 20% of the emitted photons would have completely penetrated the hull, and this doesn’t include buildup (in other words, these simple attenuation calculations assume death of the particle at first collision, but there are always follow-on particles). Yes, there is a better way to do this calculation, i.e., with Monte Carlo transport analysis. But doing so wouldn’t change the basic point.
Radiography would most certainly have been a successful means of NDE for the vessel. After all, we perform radiography of pressure vessel nozzle welds in nuclear power plants. I assess the claim made by OceanGate to be completely false, perhaps due to ignorance, perhaps because they didn’t have any safety culture to speak of.
Thoughts on What Engineering Is and Is Not
It is the solemn duty and responsibility of engineers to protect the safety and health of the public. There are dishonest and corrupt actors in every profession, of course, but they are to be called out, shunned, and their license revoked.
Designing a vessel that can go to a shipwreck and view the remains may be fun, challenging, and motivating. Doing it, whether successfully or not, is not engineering. It’s clear from the words of the CEO himself that he held a low view of both safety and highly experienced analysts. But it’s precisely those people he needed to hold him and the project accountable to proper engineering principles.
It’s also not engineering if you solve an ODE (ordinary differential equation). Second year calculus students do this all day, every day, all across the globe. That’s called mathematics. Engineers use math a lot, but doing math doesn’t make you an engineer, and certainly not a good one.
If you want to understand the life of an engineer, consider that ODE in a different context. A client asks you to solve an ODE for him to model a chemical or nuclear system. To begin with, all equations need input. Solving symbolically does him no good. That input might be correct, or it might not be, and might be based on instrumentation that doesn’t have the range it needs, or left in the field in harsh conditions or not inspected and calibrated on regular intervals. A simple field walkdown of the instrumentation the client is trusting indicates that workers are using impulse lines as ladders to get to valves above the instrument. The impulse lines are bent or broken. Thus, the engineer cannot trust that instrument.
The engineer must correct this with the client. He must ensure that there is a calibration done on regular intervals, and he must also understand whether the inputs he has been given are normal operating conditions or transient conditions, and what happens when the system is not operating as intended. The system is out of specification. How does that effect his calculations? What are the consequences of those out-of-normal operating conditions?
You see, he is responsible for every possible use of the system he’s modeling. He must make that clear to the client, must document each and every assumption and engineering judgment in his file, and then write a document that, in today’s expectations, looks more like a book with footnotes, references, reference page numbers, and possible use of alternative methods to arrive at his results (if he used forward differencing in EXCEL, what does JupyterLab tell him and how well does it benchmark?). Did he find errors in his work? Did he find any computational instability due to numerical stiffness of the equations? How did he document and display his results? Can the client use it without confusion, or worse, mistakes and errors that may lead to personnel or equipment safety problems?
Next, on to the PowerPoint presentation of results to the client, along with recommendations for corrective actions, field notes and observations, and statements of liability. After all, the Hyatt Regency walkway collapse occurred due to deviations the construction company made from the drawings and specifications. But our engineer knows that the engineering firm was held responsible for not knowing that, and their errors and omissions insurance had to come to the rescue.
Unless there is complete and total traceability of inputs, references, communications, instrument calibrations, SSC (structure, system and component) qualifications and environmental conditions throughout the entire SSC train, no engineering has been done. I repeat. Unless these things obtain, engineering has not been done. Someone is pretending to be an engineer, but he’s not doing engineering.
These are lessons every engineering student learns in their classes all the way through school. But incorporation of these principles takes time and experience, and rarely if ever have I seen a student fresh out of any school, regardless of pedigree or extent of education, display these attributes. This approach has to be trained into people. That’s the value of age and experience.
The CEO had a low view of that, apparently leading to confirmation bias. Because I’ve done it before, I can do it again. Chain of SSC qualifications (is the viewport qualified to the same depth as the hull), testing to detect plastic deformation, understanding material fatigue, spending a bit more money to ensure that proper engineering principles have been followed, obtaining fully independent review of his design – these are all things that were apparently not motivating or exciting or inspiring to him. The fact that this craft had a fairly new design schema doesn’t negate the need for review by experienced engineers – it increases it. The principles of physics, mathematics and engineering are timeless.
I am not saying that doing any or all of this would have prevented the implosion. I am saying that this vessel was not “engineered.” It was fabricated and set to voyage, but it was not engineered. The company also apparently marketed this vessel as having industry and academic involvement that it didn’t have.
I assess this failure to likely have been preventable, and the company negligent. Unfortunately, this will probably take its place as a case study alongside other engineering disasters like the Hyatt Regency walkway collapse, Union Carbide Bhopal disaster, the Texas A&M bonfire disaster, and the Tacoma Narrows bridge failure.
New evidence continues to strongly suggest that OceanGate’s submersible, which catastrophically imploded and killed all five passengers on its way to the wreck of the Titanic last week, unfit for the journey.
Arnie Weissman, editor-in-chief of Travel Weekly, initially agreed to join the June expedition, the Washington Post reports, but backed out at the last minute due to a scheduling conflict. A May dive he was supposed to go on also was canceled due to bad weather.
A conversation he had with OceanGate CEO Stockton Rush the night before the expedition, however, still haunts him to this day.
According to Weissman, Rush had bought the carbon fiber used to make the Titan “at a big discount from Boeing,” because “it was past its shelf life for use in airplanes.”
In other words, Rush knew that the carbon fiber — which is a very poor choice of material for a deepsea vessel, as many experts have pointed out — already potentially had flaws that could’ve played a role in the Titan’s tragic demise.
It’s yet another indication that Rush and OceanGate cut alarming corners in the development of the sub. In fact, experts had been warning them for years that building such a vessel while dismissing any efforts to have it qualified and tested by experts and regulators is a very bad idea.
Even after his death — Rush himself was on board during last week’s implosion — the CEO’s poor decision-making and rejections of prioritizing safety are starting to come to light.
“I responded right away, saying, ‘Don’t you have any concerns about that?'” Weissman told the WaPo, recalling his conversation about Rush’s decision to use expired carbon fiber for the hull of the Titan. “He was very dismissive and said: ‘No, it’s perfectly fine. Having all these certifications for airplanes is one thing, but the carbon fiber was perfectly sound.'”
Meaning what, exactly? Certifications for aircraft are fine, but not necessary for sea craft? Anyway, I don’t know how Boeing (or the manufacturer of the carbon fibers) ascertains a shelf life. But this exchange goes to show a cavalier and dismissive attitude towards SSC certification and traceability. I continue to believe the most likely failure point was the viewport, certified as we discussed above down to 1300 meters, or < 2000 psi. If I was the manufacturer of the viewport, at this point in the warranty I would get very, very precise with my calculations of depth, temperature/density assumptions, and pressure, as well as fold in margin of safety.
The U.S. Coast Guard has announced the launch of an investigation into the implosion of the Titan submersible that killed the five people on board.
The Deseret News reported that the Titan lost communications with the Canadian research ship Polar Prince about an hour and 45 minutes after the dive initially began and that the U.S. Navy heard a potential implosion of the submersible on June 18.
The Coast Guard’s Marine Board of Investigation is looking into the case and is set to include officials “from Canada, France and the United Kingdom as they look into what caused the deadly implosion,” according to CBS News.
[ … ]
The Guardian reported that some questions being asked following the incident included questions about “the craft’s experimental design, safety standards and lack of certification” for the submersible.
“My primary goal is to prevent a similar occurrence by making the necessary recommendations to advance the safety of the maritime domain worldwide,” chief investigator Capt. Jason Neubauer said, according to ABC News.
[ … ]
Axios reported that Neubauer said that officials investigating the incident “are taking all proper precautions on site if we are to encounter any human remains.”
No human remains will be found. Without trying to be ghoulish, the bodies have been incinerated and torn apart. This is what happens when engineers don’t do their job. However, this development does expand the potential scope of legal liability for the company, as well as cause pause to consider potential charges depending upon the outcome.
UPDATE #3:
A comment points to this photo.
NEW: photo reveals the monitor in the doomed Titanic sub was *screwed into* the carbon fiber hull… 😳 pic.twitter.com/0mrxf8gTCb
I would have to know more about how the interior inner lining was attached to the hull before I commented on it. If there is a compressible barrier (such as cork) and the hull doesn’t sustain a lot of deformation, it’s possible this modification to the lining makes no difference. However, if the lining becomes essentially an integral part of the hull and is compressed with it, then the screw holes become a “stress concentration point.” Every mechanical engineer knows about stress concentrations at keys on shafts, teeth on gears, etc., that cause localized stress to degrade the whole structure. It probably would have been better if the device was never mounted on anything attached to the hull.
