SMS_S2016_07

Now to clean the room by the time they're a teenager, they're not going to start doing it in college. I mean, you know, this is something your parents were supposed to do when before five, okay. Let's teach you how to behave. So I'm sort of, I think we should treat students like adults and they will behave like adults. It's sort of great expectations. If you expect students to respond, I find they do respond, okay, as far as that goes.

And I — have I mentioned this, I had a father who basically expected, he was a perfectionist and he expected perfection from his children, and he figured if you were five years old you were an adult, you should be able to take care of yourself. And so the joke around the family is when I was five years old I used to fix Sunday morning breakfast for my family. I've always gotten up early, and I'd get up early and I would fix — at five years old I'd fix a full breakfast of hot cereal and bacon and eggs, and we're in the south, maybe grits or, and stuff. And I had to pull a chair up to the stove to stay up on top of the chair to be able to reach the burners and stuff when I was five years old. But, you know, my father treated me like an adult, and that's how I think we all treat students.

I see more and more, we have, we have the dean for student affairs office. When I was a student, you know, just fifty years ago, now almost fifty years ago, had like four people in it. There's a professor of mechanical engineering, Cad Wadley, was the dean for student affairs. Well, last time I counted, or I didn't count, but I looked it up about twenty-five years ago, we had thirty-seven people in the dean for student affairs. It's not dean for student affairs, dean of student affairs — this was a major change they made, okay, because they didn't want the students having affairs. I mean, there's the people who get paid to do these things, you know, to think of these things.

So I have sort of a negative attitude about this whole evaluating students and treating students like they're their kids. They used to have, well, in orientation week for freshman, they used to, when I was freshman, they basically put us in Kresge Auditorium and scared us to death. And then in the 1980s they hired people and they would have these games out on the fields, okay, and it was supposed to be a team building exercise for the freshman class, right. And they'd play tug of war, which I think was fine. But they had these other little games with balloons and things like that, which I felt we were coming right out of kindergarten and treating them like kindergartners.

So people have criticized me, faculty have criticized me, for this course for not doing enough to make sure the students do the work. And I've told you a couple of times now, maybe just at least once, then I don't care if you do the work. If you want to pay this kind of tuition and not get anything out of it, go ahead, you know. I mean, not my problem. But anyway, and I actually have a tremendous faith in MIT students. You wouldn't have gotten here if you weren't overachievers anyway. So anyway, enough of that.

I guess we are — so I talked about magnetic materials. We talked about hard magnetic materials briefly, and how tremendous increase in strength and different types of magnets, and I'll pass this around. This, I passed the others around, but now we have some ceramic magnets, and we also have on here some neodymium iron boron magnets, and you can feel the difference in the strength of these as they stack up. Slightly easier to pull the ceramic magnets apart than it is the iron boron magnets, so far as that goes.

[Tom holds up another sample.] This is a piece of soft magnetic material. I talked about it. It's an amorphous metal foil, getting kind of old as rusty. This was made down in South Carolina and they can make this about six inches wide, maybe they're up to a foot wide. But it's rapidly solidified. They basically squirt the metal out on a high-speed wheel, copper wheel, and if you squirt it properly you'll make a foil that's as thick as they can make it, and it solidifies at about a million degrees per second, or million degrees Kelvin per second. And it is the world's softest magnetic material. You can't really tell by doing this, but it has low, lowest, lower magnetic losses than any other material.

And it turns out the company that invented this, which used to be called Allied Signal and now it's part of Honeywell, and they're the ones who built this fifty million dollar plant. The plant was commissioned by someone — as a graduate of this department, happened to be my house tutor when I was a freshman, but he was a material scientist. Turns out Honeywell or Allied Signal didn't get the patent on the most important property for this material. They were studying rapidly solidified metals back in the 1970s and they made some metal and they sent it to a guy named Professor Chad Graham, University of Pennsylvania, and said, because he was studying magnetic materials, he said can you measure the magnetic permeability of this. They just were trying to dot the i's and cross their t's. He measured it, showed it was five times better, lower, softer magnetic material than anything else ever discovered. And since they didn't have a nondisclosure agreement with him, he owned the patent rights — and the University of Pennsylvania owned the patent rights to that material. So they had to buy him back, and it was a big fight and things, so far as that goes.

I should have looked at, for bliss, on the web — here's, I did this morning, and the web's getting better and better. This is a nice graphic of a turbine disk that is not a bliss [blisk]. And here's your root where the vane has to attach to the big heavy flange, and the root itself is whereas over here, and something where you can make the whole thing integral, which they do for thirty thousand — m250 engines of Rolls-Royce. This thing is a lot lighter than this great big mass right here, as you can see, okay. So you'd like to do that because there's collateral weight savings.

I'll pass around, as we also talked about, single crystal blades. I probably pass this around, I usually find some excuse to pass this around several times. [Tom hands a single-crystal blade sample around.] This is a time to remember. This comes from an old Pratt & Whitney engine from like 1980s. It's a disc from either the engine, goes on a 757 or 767 engine, but hot section single crystal blade. You'll see it has cooling ports on here, if I can't see them there, that's why I pass around. But it has cooling ports. It's been filleted, they took a wire EDM and sliced — it was a single crystal, but it has an internal structure. They cast these turbulent ear, and so this is your getting cooling of the hot gases coming through. Hot gases being a thousand degrees F, but this thing operating in an environment of 3,000 degrees Fahrenheit gas with the melting temperature of 2400 degrees Fahrenheit, okay.

And it has, they, these holes in here are drilled at certain angles because they want the gas come out to create this boundary layer effective cooling on these blades. Today this is a thirty, forty year old blade design, but blades today are even fancier. They'd like to make them thinner and thinner. They're down to about seven to ten thousandths wall, and the problem is if your core that you're casting — you have a ceramic core inside this thing that you grow the single crystal very slowly — if it shifts by one or two thousandth of an inch, you've got junk. Because you can't afford to thousandths of an inch out of seven thousandths, okay. So you really can't get them any thinner than they're already making them. So they've gone about as far as they can with cooling. So that's blisk technology.

Zine [Does anyone] know why they want to keep going to higher and higher temperatures? Have any idea what the economics are of a fifty degree centigrade increase in operating temperature of the gas and the engine? Means about two billion dollars a year fuel savings for the airlines around the world, okay. So there's a lot of money to be made by getting higher temperatures. Maybe fifty degrees doesn't seem like that much, but people would kill for it.

So anyway, so we talked about there's collateral weight savings on the structure through use of lightweight materials. I talked about the blisk and how you could save twenty pounds on a disc that could be 200 pounds on the engine, because you got ten discs. And there, the engines are out there hanging off these wings, and the wings can be lighter and whatnot. That's a general principle. I can remember going to Chrysler twenty-five years ago and they were working on some new smaller vehicle and they were going to make an all aluminum version of this vehicle, and they had the same, or they had a 1.6 liter engine. And it turns out when they went to the lightweight aluminum, they didn't really get as good a bang for the buck on the fuel savings because they were using an engine, there was one point six liters. If they actually had a 1.2 liter engine for this small car, they could have gotten even more fuel savings. But you can't just go out and design a whole new engine just because you switch materials to get the best advantage of the material that they were using. They're using aluminum for the sheet metal of the body, they were saving weight. They could have saved a lot more weight on the engine too. They actually, to get the full advantage of the material, you really have to design the whole thing from scratch and optimize the whole part.

Another example of that, as we've got some lowing [Boeing] people here, see them, but, you know, what the first part of a major aircraft is, first part you design if you're starting your design? You design the landing gear first, because the landing gear has to take the weight of the structure when it lands, and the whole rest of the structure has to be built around that to be able to transfer those loads from the rest of the structure to the landing gear when it lands. So if you talk to a designer at Boeing, they project, okay we're going to build a replacement for the 747, it's going to weigh a half a million pounds, so we got to have a landing gear that's going to support a half million pounds. And we're going to have to design structures like the keel beam. Everybody knows there's a keel beam in an aircraft, just a great big I-beam goes front to back, and it's called a keel beam because it's a ship, just like the ships we float in the water that have a keel beam, okay. The aircraft has a keel beam and you build everything off that, and that keel beam has to support the loads that come from the landing gear when it lands.

So a complex structure is an interaction between the materials and the design, and you can't just go substituting one for another. I gave you, or I pointed out, an article that I wrote for Technology Review back in 1995, for twenty years ago now, on bringing new materials to market. And in there I talked about something I had learned through buying refrigerators, okay. When I was your age, the outside panel of a refrigerator was steel and the inside panel was steel, and the shelves on the inside of the door were screwed into the sheet metal of the steel, and they work just fine.

And then in the mid-80s I bought a new refrigerator and the outside was steel and the inside was a panel of plastic. And plastic is a much better material for the inside of a refrigerator because you're going to spill foods on it, you know, it doesn't, it's got a low inner surface energy, much lower than metals, and so things don't stick to it as easily. But within five years I had to replace the refrigerator because they use screws to attach the shelves to the plastic, and plastic is a lousy material for threaded joints. You just shouldn't use threaded joints in plastics, maybe for, maybe if you're talking Hasbro or Fisher-Price or something, some toy, okay. And your child is going to come to you and say daddy or mommy, you know, my toy broke, can you glue it together. And you say, of course not, I took Professor Eagar's course on adhesives and we know that plastics have low surface energy and there is no good glue to make this, to fix your cheap little toy, child. Well maybe you won't say it exactly that way to them, but that's in fact the case. Most of these things you just throw away. Well I had to throw away the refrigerator because the shelves were broken.

By that time, by 1990, I bought a KitchenAid, which I think I still have. At least I think I — I know it, who has it, still in use. They designed the plastic sheet metal, not cheap metal but cheap plastic, so that the shelves basically slid into a slot like a drawer. Well that's exactly the way you should join a shelf to a plastic wall, right. You designed the wall so it has something that slips in and you don't have these sharp stress concentrations of threaded joints. So the point was you can't just substitute one material for another. Plastic is a better internal material for a refrigerator, but you can't just design it the same way you designed your steel one, okay. And I was sort of irritated cause I had to buy the refrigerator after five years, but by the time I'd done that, people had learned, and those refrigerators are lasting longer than I want to have them.

The outside is still steel for most refrigerators. Why? Because your children are going to run their tricycle into it, they're going to dent it, and steel is stiffer, it will take the tricycles much better than plastics, which would likely crack, okay. And you'd be irritated when you have a cracked refrigerator and whatnot. So you have to optimize your structural design with your material, and when you get a better material you can't just willy-nilly say substitute. Competition among materials — and we talked about food packaging, you got glass, you got composite, you got plastic, paper, you got metal, you name it — and as one of them gets better, the people refine the design of the other, and there's still a healthy competition, I guess it's healthy, among different materials, okay. Any questions on that? In large industries, in small industries, most people don't care that much.

The schedule, by the way, I checked with Dr. Belmar and I went all the way up to March first. If I do twelve lectures and he does eight, we will finish lectures on March first, and probably give you a week break in between or something, and then we'll try to schedule the presentations. How many people have a presentation already sort of in the can or close to it? So, I mean, I don't want to start scheduling things, start putting too much pressure on you to get something done. But I mean, is that going to be a problem? You got ten to three weeks, that's, I mean, not everyone's going to go that first week, okay. In fact, unless I can — I'm still trying to see if I get this room for multiple hours, just eight nine to ten, but nine to eleven, and that way I could do six a day. Since there's forty-eight students, that would still be a couple weeks of presentations for me. And again I'm going to ask you to keep track of the twenty presentations — you include your own that you attended, your own, okay, but you're going to have nineteen others, and on top of that, okay. And if you have any questions or if you want to talk about it again, don't —

Student: [asks question]

Has described how to solve world hunger. I just got a question about what was your question, what was your proposed thing you were thinking about just now? I can't remember. Okay, so natural fiber reinforced concrete. Lots of good issues there. Natural fiber tends to decompose, organic fibers to rot. But we've been using them to make bricks since the days of Moses and before. Make, you know, can't make bricks without straw. But what are the issues if we want to use it for concrete, okay. And talking about the issue of Roman concrete and why Roman concrete is better than any other concrete. I was pointing out there's articles on that.

I mean I don't want you to come in and talk about all the different variations of concrete. It's a 2.2 billion ton a year industry. There's actually a lot of technology there and you can't cover it in ten slides. But if you wanted to talk about Roman concrete, there's something — you're interested in Roman architecture or something — Roman concrete has lasted for two thousand years, and there's some good scientific articles why it's so much better than the concrete we make today. So something more specific that gets down where you can be critical and learn something about the details of the material, then leave it to me to talk about the generalities.

So I was going to kind of use part of today as a little bit of a recitation on competition among materials. And say, okay, take something fairly simple and fairly basic that we've been doing for thousands of years, like how do you convey water? What was the first material that was probably used to convey water that you could think of? [Tom takes a hand from the class.] Yeah?

Student: [suggests answer]

Okay, they conveyed it up. That's good, that's probably earlier than I was thinking of. I was thinking of dirt, okay. So you have a stream over here, and you have a little hill coming down from the side of the stream, and you dig a ditch and you let the water run down the ditch. You tend to lose a lot through the soil, but if you got a whole stream, who cares, okay. So if you, or you want to irrigate your, you're filled with water, you just kind of take a stick and you hold the ground and make a ditch, and you, see, use soil. What might have been the next thing, because you're eroding away your ditch? What would you do to line your ditch? Right, rocks. Is someone say rocks? Yeah. Leaves? Yeah, use leaves. That tends to be somewhat temporary because the leaves only last a season or two, but that's, that would work, leaves would, okay. In fact, people have made wooden pipes or wooden troughs, so far as that goes.

And then they use stone, but then they invented mortar, okay, so far as that goes. And mortar in general, you take limestone, which is found everywhere in the world because it basically is formed from the little sea animals that made, took the calcium in the water and turn it into calcium carbonate and then it precipitates out. You make limestone or — Matt or — dolomite, which is calcium carbonate and magnesium carbonate mixture. And most of the calcium and magnesium is in the ocean anyway, and oceans have covered most of the world over the last six billion years or whatever. So you can find a lobster — limestone — virtually anywhere except in a place like — why not? — not a lot of limestone on something that just was built up out of the ocean floor with a volcanic ash. So if they use cement in Hawaii, they have to import the cement from somewhere else that has limestone.

But anyway, concrete aqueducts. The Romans used concrete, and then they started using something — as soon as been in the paper recently in the past week — they started using a metal that has excellent corrosion resistance. So you might know what it is and why it's in the papers now. It's in the paper yesterday in the Boston Globe. You don't read the Globe? Okay, well, you know, as on your political persuasion, but I don't particularly like the Globe's political persuasion. It's called lead, okay. Lead has excellent atmospheric corrosion resistance, and it's easy to form into a pipe. It's relatively abundant, and it wasn't too expensive. And so in the 1920s to the 1930s when they were doing plumbing in houses, they had lead pipe.

In fact, when I bought my house, which was built — finished in 1938, was built during the Depression — for cooking about five or six years to build it — but there was a piece of lead pipe over the laundry sink and I took it out, okay. Not that piece, most of the rest of lead pipe have been replaced, and it's typically copper pipe now. But apparently in Medford, Massachusetts, forty-seven percent of the homes have lead pipe for their service water, for the town piping. It won't corrode for hundreds of years, okay. But now we won't even let people use lead tin solder on the copper pipes, because the EPA, every town will send you with your water bill an annual statement of how much lead and how much arsenic is in your water that you drink. And as we get more and more precise in our ability to measure the amount of lead, the EPA requirements become lower and lower, because parents think that their children are stupid because they're drinking the local water. And I say that's not the reason, it's genetic, okay. It has nothing to do with the amount of lead in the water, okay.

But in some places such as Trail, British Columbia, or Flint, Michigan, some of the children do have developmental cognitive problems because of drinking too much lead. Trail, British Columbia, it's been a zinc smelting community for over a hundred years, and there's lots of lead oxide in the air. And so children in Trail, British Columbia, have been growing up breathing lead, and they've done studies and show that they've had got developmental disabilities because of it.

So lead pipe — anybody, we have a whole building covered with lead here at MIT, anybody know what it's called? Lead sheet, by the way. It's called Kresge Auditorium. Kresge Auditorium has got a surface of lead for corrosion resistance. Copper's too pricey, they used lead. Kresge's a very — it's one of the architectural marvels of MIT, along with Building 13 and the Stratton Student Center. But Kresge Auditorium has a roof that has a thickness that is thinner than an eggshell in terms of the radius of curvature, okay. It is incredible structure from an architectural mechanical standpoint, because it has this very thin roof for the curvature of the roof. And they put lead sheeting on it for corrosion resistance, and it will last for a very long time.

If I know what's unique about the Stratton Student Center — it's floating, okay. All of this was filled land, okay, this was — the reason why they call it the Back Bay, okay. And there's a stone down there, down in Boston, says the sixteen miles to Harvard. Everybody knows that's sixteen miles to Harvard. It was, when they put the stone there, because you had to go around the back bay. And Beacon Street — you might know why it's called Beacon Street in Boston. You know, right on the other side is — Boston Common, everyone had a right to graze their cow, and you still do. You bring your cow out of the Boston Common and you can graze your cow on the Boston Common and the police can't stop you, okay. It's in the law, that's where you graze your cow. As where you got your milk, they didn't have refrigerators back in those days.

And Beacon Street was a causeway across the back bay. Boston was a bay, and they didn't start filling it in until the 1850s. And before that, Beacon Street was a one lane causeway, and you had to carry a beacon on your cow when you went home at night or coming over in the morning, so that you wouldn't push somewhere else off into the bay, okay. It was called Beacon Street or Beacon Causeway or whatever. But in any case, we're cycling with that. Oh, MIT is built on filled land, okay. It was just a little island here, okay. And MIT wanted to move from Boston, where they were over in the back bay on the filled land over there, and they wanted to move over here, and they purchased a lot of the filled land that was over here.

But there was one little island that had been owned by an alumnus of MIT, one of the first alumni — and this was around 1900, he had passed away — and his widow would not sell the land to MIT. And they had all the other land they wanted when they needed, right in the center of this was this little island that he had owned, that she owned. And finally one day she saw a beaver on that island, and she decided that was a sign that said she should sell it, sell the island, MIT, so they could move over here to Cambridge. And she sold it, but on the condition that the main entrance on Mass Ave be 77 Mass Ave, because her husband graduated in the class of 1877. So now you know. And when you have dinner tonight with one of your classmates, you can say, and why is it 77 Mass Ave, and I'll bet you they don't. Okay, I don't remember the guy's name but anyway, needed — neither does the beaver, okay.

In any case, we had lots of ways to convey water. Pipe, lead pipe before World War Two. And in some parts of the Midwest today, we use galvanized steel pipe to convey water, and you can do that in certain parts of the country, particularly where the water is hard, means it has a lot of calcium in it, because the galvanized zinc coated steel has reasonably good corrosion resistance. In acidic waters like we have on the East Coast, galvanized pipe will last for a couple of years before it starts rusting and everything, so we don't use it. And second half of the twentieth century, after World War Two, we started using, not lead pipe on the East Coast, we started using copper pipe, and we use copper pipe for many years.

And now, what do we use, anybody know? What most new homes are they're putting in? Polyethylene, cross-linked polyethylene, okay. PEX. This is PEX-A, cross-linked with an electron beam to crosslink it. There's PEX-B, which is chemically cross-linked. But we basically use plastic pipe that's pretty stiff. [Tom holds up a piece of PVC for comparison.] This is a piece of PVC pipe, which is not anywhere near, stiff, not same diameter, but nonetheless you can feel the difference in the stiffness. But PEX tubing is very quick to install, takes about half the labor as copper pipe.

But even more importantly, nowadays — ten years ago this was no problem, but the offices over here that were redone for the student lounge and Course Three, and my office got moved for that — they basically used a crimp on connector, a mechanical crimp on with a rubber gasket. So it's copper to copper with a rubber gasket. And each one of those fittings costs like thirty or forty bucks, okay. I need to buy one sometime. But you can't get them at most hardware stores, these are plumbing supply houses that you got to go buy one of these. I need to steal one from some construction site I guess, but they're not cheap, okay.

But does anyone know why we've gone from soldering pipe to using this crimp-on connector, mechanical connector? Because too many plumbers burn down too many houses soldering pipes. And the law now says, in the last ten years, you must have a fire watch, okay, in Boston, to — these are what, this one of the externalities of material selection. They got rid of the lead tin solder in 1978 by legislation. And so they went to 95-5, which is ninety-five — ten — five percent antimony, or is it, some of it's got a little couple percent silver in it for strength.

And the plumbers hated it. When the plumbers would solder up something like a furnace in the basement with lead tin, they'd check it and they might have one leak out of a hundred joints they've just soldered. They do it with 95-5 and they'll have ten leaks, and they got to go back and repair them. And if you repair ten of them, you're going to have another leak out of one of the ones that leaked, or a couple more, so you got to fill up the system. It takes forever to get rid of all the leaks. You can do it obviously. But now the real reason that they use these compression fittings in most things is because you have to have a fire watch. You got to pay a Boston policeman like sixty bucks an hour to stand there and watch you not burn down the house in the city of Boston. And in city of Boston it must be a Boston firefighter off duty, okay. So he's making money, he's making better money than he makes as a fireman, to watch you screw up the job plumbing and not burning down the house. And if you do burn out here, everybody, copper and brass.

We switched to PEX-A and B. We use cast iron, but cast iron pipe that we put in, in the old days in water has been switched to, we concrete line it, because the concrete has better lifetime than the cast iron. After about a hundred years, will start to decarbonize, or graphitize they call it, and it will lose its strength. And so turns out about five percent of all the water going through the streets of Boston is lost through leaks, okay. There's leaks all over, and they got old concrete pipe, and every now and then a concrete pipe main will break, burst, and do ten million dollars worth of damage downtown and tie up traffic and everything. We got aging infrastructure. We used to use cast iron.

What would be the best material if costs were no object? Probably gold, okay. Very corrosion resistant in water. But in fact that's not what we use on critical applications. What the Navy is starting to use on nuclear submarines, where cost is no object, is, they tend to start, they used to use vigorous [rigorous?] steel pipe, which would corrode away after about twenty-five years. The ship had a thirty-year life. And you just — I remember one officer, I was a lieutenant junior, and Inson, when she graduated from the Academy, her job on the ship was to fix the leaks on the thirty-year-old ship full of leaks, okay. They put in carbon steel, but now they have to build fifty year ships, and they use titanium, okay. Very expensive, very lightweight. You can use almost no thickness of the titanium and you can have excellent corrosion resistance forever.

Boeing's aircraft — I remember when the 747-400 came out, this is like probably thirty years ago, twenty-five or thirty years ago. I got a call from — I'd been over in the Far East for a couple weeks and I got came back, and I got an emergency call from Englehard Metals. And they were making the platinum catalyst for the 747. And if I know why you have a catalyst in a 747 for the air you breathe, okay. Up there there's lots of ozone, and if you breathed that much ozone for a trip all the way across the Pacific, you would have a very bad headache, okay. Ozone will give you headache. So all the air coming into the cabin has to go through one of two catalysts, just like the type of catalyst that's on your car to get rid of the carbon monoxide. This gets rid of the ozone and converts it back to oxygen, so you don't get a headache on your flight. Plus those zones not good for your heart and other things, supposedly, medically.

And the 747-400 was an extended-range — each one of these different series of aircraft is try to go further — and they were light weighting it. And they had made stainless steel ducting pipe to carry the oxygen through the cabin, and they would switch to titanium just to get rid of the weight, okay. Pretty expensive, but hey, you're talking on aircraft and you're talking about extended range, probably valued at more than two hundred dollars a pound, okay, to switch from stainless steel titanium.

And I get this call, Boeing had a ridiculous spec. They said that the pipe that — Boeing has a lot of general specs, most companies do, big companies do, and the general spec basically said you had to make a — you had to make a weld, let's say that, to make two welds. Oh yeah, they had to make two welds. How — you got this, if you think of an anaconda that's just ate, okay, this is your catalytic converter in here, and you got to make a weld here and you got to make a weld over here, so you got to make two welds, put the catalyst in here. That's what Englehard was doing. They have to make a weld here, three hundred and sixty degrees around, they have to make a weld over here, so they have to make two welds. And the welds on the general spec for welding of titanium, Boeing had a spec that had to be x-ray inspected and could not have a flaw larger than ten thousandths of an inch in diameter, about four human hairs in size, okay.

You were not going to get Boeing to change the spec, because Boeing has, how many employees, 200,000. And who is the person at Boeing that could change that spec? There is no such person, okay. It would be a committee and it would take three years. So Englehard was having to weld these out on titanium, and they hadn't done a lot of titanium welding before. And they were getting a failure on twenty-five percent — half their welds — on the x-ray, they would find some little pore in there, okay, and it was larger than ten thousandth of an inch. They had to cut it out and reweld it, and they only got one chance to reweld it. You couldn't do two rewelds, okay. So the odds were, you're going to have one failure, and then when you cut it out, the whole thing out, and try to weld again, the odds are you're going to have another failure. So they had not been able to produce any of these units for Boeing, and it was going to hold up the whole roll out of the aircraft, and people are getting very upset and very concerned.

And so I said, well how are you cleaning your titanium? Because titanium is very sensitive any source of hydrocarbon like your fingerprints. You should, when you're welding titanium, you should wear white gloves, just like a clean room. And of course they've been welding stainless steel, it's just like a welding shop, you know, the guy's hands are all greasy, his gloves are all greasy, everything's greasy. And I said, get some reagent grade acetone and degrease everything, and — because I didn't have time to go down to New Jersey — and degrease it and then weld it and you won't get the porosity, because the porosity comes from small amounts of hydrogen in titanium, and I knew that anyway.

So I get a call again a week later, well, we tried what you said and we still can't get it, no, can you come down? Well, it's going to have to be — I'm in New Jersey two days later for something else — I said, okay, when I finish I'll come by, may not be till six o'clock that evening, that someone wait for me. So I go by, and I walked through their shop and I look at everything, I said, did you get some reagent grade acetone? No. Oh. So I explained to him how to clean the titanium and get rid — I said, you got to get reagent grade acetone, because regular acetone is got oils in it, and when the acetone evaporates away it leaves oil. You thought you cleaned it but that leaves oil on there. And so they did what I said. They called up a week later, said, we're passing a hundred percent now. Nothing oh great. So I sent in my little bill.

And then they call me up two weeks later, said we're failing twenty-five percent of again. I said, have you changed your cleaning? Whoa, no, we're doing the same thing. I said, go get some more reagent grade acetone and do a better job of cleaning, and make sure everybody wears white gloves. And I eventually got him out of the problem. Exact same thing happened up here, GE Lynn, with electron beam welds and titanium. If you take my welding course I'll probably tell that story in there. But so we even used titanium in some cases that was conveying air. But in ships now, we're using titanium to convey water. Gold would be the best, but it's a little pricey, okay.

And I think I probably spent enough — well, no, I might as well kill the whole day on alternatives. Conveying gas, okay. You talked about conveying water, what about conveying gas? What have we traditionally — what — well, we didn't originally have gas, because it's too difficult to transport. You can get gas coming, you get swamp gas coming out of the swamps, and you can see flames come — sometimes some swamps where the gas is coming up out of the ground. And the first gas they had, they used to make coal gas. You might know what coal gas is. You take hot coals, you drip water on the hot coals, and the water reacts with the hot carbon. And carbon plus H2O gives you carbon monoxide plus hydrogen plus some CO2. When I was an undergraduate, my thermo class, we had to calculate the coal gas reaction all the time, because it was a nice algebra example. It's a waste of time but it's nice algebra example to get the, what's called the water gas, or coal gas, or sometimes called the water gas reaction. So you can take water and hot carbon and you can make carbon monoxide and hydrogen gas.

And people wanted that, particularly as they got bigger cities in the 1800s, because they could use it for streetlights, wow, okay. Except you had to pump the — you had to pipe the gas to the streetlights. And the first material they used for the pipes to get the gas from the coal gas generator to the lights down the street was — anybody know? It was wood. They would take logs and they would gun drill them out. What's a gun drill, anybody know what a gun drill is? A gun drill is something where ordinarily, if you had a lathe, you have a — you have the drill, you have the piece of wood that would spin and the drill would be stationary, okay. But in a gun drill you basically spin the drill opposite to the direction you're spinning the wood or the metal. They call it a gun drill because that way you can get very straight holes. If you try to drill a piece of — if you try to drill a long hole with a metal drill and a piece of metal like a gun barrel, it will always walk to one side, okay, and you won't get a whole more than twelve inches deep. But if you have both of them counter-rotating — okay now this is an important trick here, can you counter-rotate? Most people will rotate in the same direction. I spent my senior year high school doing this in class, okay, cause I was bored, and I can do figure eights in opposite directions, but anyway, took me a year of practice. But if you gun drill, you can drill long holes.

They would gun drill logs and bury them in the ground, mud them up with some mud or other stuff, or oakum or something, which is just grease, and they would run the pipe through there. I can remember going down — I wish I'd taken a picture of the wooden one, but in Boston when they're digging in the city, they will sometimes uncover these old wooden pipes, okay, that they used to convey the gas. Then they got to cast iron because it lasted longer than the wood, didn't rot in the wet soil, and the cast iron can last for a hundred years. Then they went to steel. We still use steel, black iron pipe we call it, because it's got a magnetite Fe3O4 coating on the surface that's just as good as paint. Go down the basement of MIT, look and see the fire sprinkler system, it's all black iron pipe.

So we use steel and then we got to, in the 1980s, the gas researchers spent a lot of money developing plastic pipe. Turns out gas pipe is supposed to be yellow, so that when people are working on things they know not to cut through the yellow pipe — it could be an explosion, okay. So this is actually a piece of polyethylene pipe, it's distribution pipe, it's been welded together, and it's got yellow stripe on it to identify it as gas pipe. About the same time in Japan, they developed something called corrugated stainless steel tubing, and they put a plastic coating on it, but it's corrugated, okay. Ten thousandths of an inch thick stainless steel. This is great. You can — well, sort of great — you can plumb a house with this stuff in one day. If you're building a new home, you can put all the gas piping in all over with this stuff, where it would take you three days with black iron pipe, where you have to thread it, screw it together and everything. The labor savings are dramatic.

You buy this stuff in 150-foot coils, and it very easily, with the tubing cutter, put a special thirty dollar brass fitting on it to make the connections, and everything's wonderful, save a lot of money. Until you have a lightning storm. And the lightning storm, you'll have an arc, and the arc can perforate the polyethylene coating, which is good for 30,000 volts, not a problem for the household current, because it's insulated. And so if you had a copper wire come in contact, it would have to defeat the insulation on the copper wire and have to defeat the insulation on this. The probability that is very low. But in this case — and I'll pass this around tomorrow — this one, you can have a little holiday, there's a little teeny hole in the yellow coating. You won't conduct electricity, but 30,000 volts is nothing compared to the millions of volts of the lightning bolt. So lightning, just like the yellow tubing is not there. If the lightning strikes your structure, you'll blast a hole on the inside ten times the diameter of the little hole in the end of the stuff here, and you will get — actually this was probably done with 110 volts through a wire, but anyway, but you'll get it, and it burns down about a hundred homes a year, okay.

So the companies deny it. Actually they deny it and they admit it. The guy who first got all this stuff qualified, the father of corrugated stainless steel, he admits there's about a hundred homes a year that fires are starting cause the lightning, okay. But they still fight it, because for them it's probably half a billion dollars a year of profit, okay. They sell it for five bucks a foot, where as the black iron pipe you can buy for less than a dollar a foot, and it saves you sixty percent of labor, and in that sense it's a wonderful product. Until the rains come and the lightning storm, in your house burns down. Okay, I'll see you tomorrow and we'll actually get into —