Funny Engineering Pictures

[MetroRAFB]

I work for a truss company now, but while in college I co-oped with a large electrical contracting company and spent some time working in the field. That's where I gained my PVC experience, roughing electrical work in the concrete slabs before they poured them. Lots of times heating and bending the PVC is easier than cutting and glueing on factory fittings. Cheaper too. But you've got to be careful, too much bend will cause the pipe to collapse. A trick some of the field guys use sometimes is to fill the pipe with sand while you bend it. That provides some stability and support while you're bending it. Once you're finished with the bend you can flush the sand out of the pipe with water before you connect it to your pipe run.

 

[Mike1144]

When they built my inlaws pool, they used torches. I guess their procedure was to heat it till it turns brown, then bend. Granted this was only 2" PVC.

I managed to catch one major boo-boo. When the electrical guys did their PVC bending, they got a little too close to the flexible PVC water line with their torches. It was under pressure for a leak test and ballooned out to almost twice its diameter. They were all set to bury it in concrete.

 

[Art]

re: blowers

why not 'amp' them to see where on the curve they are operating, ie, HP

you know the speed, I'm assuming it was a 'rootes' type postive displacement...

take a pressure at the discharge (usually a gauge is provided)

and one at the diffuser header (you may have to tap the pipe and plug) 15 min job

then you could tell exactly what was going on...

these machines typically don't overload, as HP is a function of displacement/speed/delta P all fixed...most have a weighted blow off to prevent the DP from going too high...ie, start up with water in the pipe...

all have circuit breakers and motor overloads that should trip at 115% of rated current, and since motors are generally rated for 1.15 duty factor, they should never be damaged...

 

[MA_PE]

I don't see any fittings and I can't see someone melting an 8 in. pipe to make the connection. Instead you cut it and put on a coupling.

Also that looks like pretty heavy wall stuff. We all know that plastic creeps with time. I suspect that the pipe was restrained at both ends and had sufficient compression to buckle the wall. Once is buckled it continued to creep to relieve the compressiona nd eventually closed up like you found it. DLeg aren't you in a tropical paardise somewhere. what was the burial depth. Aren't ambient temperature often 100+ degrees. The sand gets too hot to walk on? correct?

What was the process temp of the flue gas? Elevated temp flue gas would also make the pipe elongate creating more compression for restrained ends.

 

[MetroRAFB]

I doubt a coupling would have worked, the two segments have to align perfectly in order to get the coupling on and once you get much above 1" PVC there's no room to "bend" it manually to make them line up. That's why you don't start at both ends and work towards the middle, ever ever ever. Of course the railroads did it in the 1800's but I bet they had some serious coordination as the two railroads came closer to meeting.

I don't think that could have happened once the pipe was buried. Even if the surface temps of the sand were 100+ degrees, below the surface it cools off quickly. Also, what would cause the pipe to deform so badly in that one specific area? The picture looks exactly like what PVC does once you've heated it locally to a couple of hundred degrees F.

Any volcanic activity directly underneath that pipe when it was dug up?



:beerchug

 

[MA_PE]

I doubt a coupling would have worked, the two segments have to align perfectly in order to get the coupling

Not for anything but after they cut out this bad section, they must have installed a coupling to get the line back into service. I doubt they just abandoned the line or excavated all the way to back to one end to start over. This was an air line so slope wasn't exactly critical and you can get twice the production by starting at either end and meeting in the middle. Check out the boot in the picture for reference, you'll see this is a pretty good sized line and the buckle looks pretty uniform around the perimeter. Uniform heat from somewhere. Would be tough to get with a torch.

Another thought might be chemical softening from whatever the flue gas was. Also interesting that it occurred in the middle of the line. If both ends are restrained, expansion/contraction may be concentrated near the center.

Details! We need details! B)

 

[Art]

if the pipe was used to convey blower air it gets hot, sometimes as high as 200F...

if the pipe was blocked at each end, where it went down & came up...when it expanded it it would have buckled...at the weakest spot...and highest force, equi-distance from the 2 ends/blocking, ie, ~ the middle...

I guess that's why ductile iron or SS is usually used...

 

[Dleg]

Damn, I'm having trouble with my browser - I replied to this last week, and it never showed up after my browser gave the "not found" error message.

MA-PE: I think most of the details are given in the earlier messages, the pipe is only about 100 feet long. I am tempted to lean more toward the expansion/buckling theory, except that the plant operators had originally told me that it was the contractors who had melted the pipe to make it fit. Although I am sure they are only guessing, it really is a common practice around here. I think the contractors think that just because they can do it with electrical conduit, they can do it with any other type of plastic pipe. At $3.05 an hour ($2.75 an hour at the time the plant was built) for the foreign workers used on most construction jobs out here, we unfortunately get exactly what we pay for.

PS - and that's not a boot. (Shhhh! don't tell!)

 

[MA_PE]

At $3.05 an hour ($2.75 an hour at the time the plant was built) for the foreign workers used on most construction jobs out here, we unfortunately get exactly what we pay for.

I understand the cheap labor, but you figure the plant owner would pay a "task master"/overseer to make sure the job got done correctly.

If that was truly installed like that, then the supervisor should be shot.

 

[Dleg]

Actually, there was a A&E firm hired to do construction management, and I know who it was. The excuse is that the melted fitting was "obviously done in the middle of the night" to hide it from the CM. But I say, no CM should ever accept buried work that he/she did not personally see. So I agree with the shooting verdict. I have sent this picture out as an e-mail to several engineering friends, titled "the importance of CM". So in that respect, I'd be embarassed to find out that the pipe buckled due to creep & expansion. Since I know the CM and he's not a bad guy, I think I'll jsut stop sending the e-mail around. But the picture still hangs on my wall at work!

 

[Road Guy]

alright, this might not be a funny pic, but maybe the story. my first "engineering related" job, co-op , Georgia DOT, They were building a bypass around the town of Thomasville,GA. The area, while rural, has many a"really really rich"land owners (such as former President Jimmy Carter) so the only land they could purchase was an old landfill.

yes, they built a road over a landfill, using something called dynamic compaction (see pic) what they would do is drop an 8-ton weight on a grid (10' X 10' spacing) 8 times. Then they would come back with a 6-ton flat "stamp" and clean it up. It would compact the fill area (or at least reduce the height) by at least 10 feet)

well what I found funny was they they paid for this construction, not lump sum, but they paid the contractor by the drop, so guess who counted all those damn drops, and this bypass was about 6 miles in length...

if you look far in the distance in this pic, you can see the height differnce where the crane is sitting...

it was also my job to lay out the grid for the crane operator each morning :brick:

 

[FusionWhite]

Ahh, the glorious world of cooping. Whats funny about that RG is that the city of Louisville is building an interchange right through a land fill and guess who got to do the environmental sampling out there? Yeah it smelled like we were drilling into a port-a-pot crap tank.

 

[Hill William]

That dynamic compaction stuff is pretty cool. Counting the drop sucks. While in construction, did you ever have to take care of a pile driving operation?? That sucks ***. You have to count each blow and watch to see when it takes 12 blows per inch. Mind you the diesel pile hammers are usually pieces of **** and spew soot and oil all over you. When I was in construction, I had special cover alls in the truck that were only used for pile driving.

 

[Road Guy]

ah yes I am familiar with a kobe diesel pile driving hammer

on the dynamic compaction about every 10 blow they would hit a huge pocket of trash and it would spew up in the air like a damn aerial bomb, you didnt get to close.

my first week on the job, they just dropped me off and left me (not even a truck )

 

[RIP - VTEnviro]

he area, while rural, has many efluent land owners

Effluent land owners?

Do they own the discharge pipe from the local treatment plant? :dunno:

 

[Road Guy]

you know what I meant...."really really rich"

 

[Guest]

Cool stuff RG !! :thumbsup:

I would kill for more field time - even if it meant working next to a diesel or having oil (or other media) spewed at/on me. Seriously. I hate riding a desk. :brick: :hung:

JR

 

[MA_PE]

I've heard those effluent guys are usually incontinent, too.

 

[McEngr]

I've heard those effluent guys are usually incontinent, too.

:lmao:

 

[Hill William]

Its a video

http://www.break.com/index/crane_drops_steam_roller.html