Life on an Oil Platform in the Gulf of Mexico

[BigJon@Work]

Schmeelkie, watch the horizon or something else far away for as long as you can on each circuit. Watching your shoes is making it worse becasue they are moving with the ride.

[analog]

What are the helical blades on outside diameter for?

Helical??? Too many syllables.....
. which one are you referring to?

I've been informed they are there to disrupt the flow of water, reducing the effect of currents on the platform's stability

that's bugged me for months now. I thought you meant to reduce "bobbing" up and down.

It finally clicked after that post on mechanical failures.... probably it's "vortex shedding"

a fluid flowing past a round cylinder kinda 'wobbles' from one side to the other.
You see it on a flagpole, the waving flag goes first one side then the other as airflow around the flagpole wobbles......

as a kid did you ever stick a fishing pole down in the water while boat is moving slowly? It'll vibrate... and that's why ski boat rudders and fast sailboat centerboards are flat on one side and curved on the other...

that huge 90 foot diameter cylinder projecting down from the platform would feel tremendous wobble forces, and woe if they were at its mechanical resonance.


at least that's my guess.

a.

[Haggis@wk]

at least that's my guess.

That would be my assumption as well, the underwater currents are pretty significant

[BigJon@Work]

Yes, that is what I assumed when I read that too. The fins may actually worsen boobing since they increase the surface area that the up and down swells can push on.

[Schmeelkie]

Schmeelkie, watch the horizon or something else far away for as long as you can on each circuit. Watching your shoes is making it worse becasue they are moving with the ride.

Thanks! Should have thought of that - it's like spotting in ballet - you hold your view on one spot as you spin until you have to turn your head. and whip it around until you're watching the same spot again. 13 years of ballet and I didn't think of that...OK, that was, like, 17 years ago....maybe I can be forgiven...

[Shapley]

Here's a smokestack with deflectors of similar construction.



Apparently, the use of the deflectors allows the stack to be constructed of lighter material than would be otherwise necessary.

This animation from wikipedia shows the effects of vortex shedding, as analog mentioned. The cyclical pattern can cause fatigue failure of the stacks.

[jamiebk]

A rather simple and elegant solution on that stack.

[analog]

well i learned something and that's a good day.

the spiral fin sure ugly-fies that stack.

industrial plants can, and IMHO should, be built with at least minimal sensitivity to aesthetics. The power station where i worked is four units two fossil and two nuclear. The reactor containment buildings are same height as fossil side boilers and viewed from a distance the plant approximates golden rectangles.



Hurricane Andrew cracked the stacks so badly the left one had to be replaced and the other one rebuilt.
But the cheapskates didn't paint them.

a.

[Shapley]

I don't find the spirals ugly at all. They remind of some of the minarets found in the Middle East and Africa.

Skimping on exterior painting isn't always a matter of money. EPA regulations have placed quite a burden on all painting done outdoors. Overspray, particularly near residential areas, can cost a bundle in insurance claims, as well.

[jamiebk]

Yeah...I kind of agree with Shap on the aesthetics of the stacks. I like the spirals. They look better than straight up columns.

[Shapley]

Whoa! Jamie agrees with me on something. I'll record this in the log...

[Shapley]

Haggis,

Had you been on the oil platform that suffered the explosion in the Gulf? Very sad situation, indeed.

My prayers are with the missing and the injured, and their families.

V/R
Shapley

[Haggis@wk]

Haggis,

Had you been on the oil platform that suffered the explosion in the Gulf? Very sad situation, indeed.

My prayers are with the missing and the injured, and their families.

V/R
Shapley

No, I missed that one, but one of the other guys working on the same project did. It's leased by BP. It's a dangerous job and mother nature always trumps mere mortals.

[jamiebk]

I hope that it doesn't end up on the bottom of the Gulf...of course, even this is eclipsed by the loss of life.

[Shapley]

...mother nature always trumps mere mortals.

I've always said that whenever you put up a structure, you have the four 'W's working against you: Weather, Wear, War, and the Will of God. One of them will eventually bring it down.

J.E. Gordon wrote an excellent book entitled [/i]Structures: Or Why Things Don't Fall Down[/i]. He sums it up nicely when he says, in essence, that any engineer worth his salt knows that a structure is only a time delay. What goes up will come down. The engineer's job is to design a delay that will allow the structure to hold up whatever it is supposed to hold up until the end of its useful life.

[Shapley]

Apparently, the rig has now slipped beneath the waves.

Oil Rig Hit By Blast Sinks

[jamiebk]

I guess the fire is out at least...here comes the ecological damage...oil strewn beaches and ocean impact for years to come. What a mess. And they want to put these off the CA coast..............

[Haggis@wk]

I guess the fire is out at least...here comes the ecological damage...oil strewn beaches and ocean impact for years to come. What a mess. And they want to put these off the CA coast..............

The shut off valves at the ocean floor shoud have shut off when the explosion happened. They're designed to. Most of the GOM wells have to inject salt into the oil and gas to get it to rise.

[Shapley]

I don't get excited over reports of long-term environmental damage, because they have been wrong on those accounts so many times before. When Saddam detonated the Kuwaiti oil wells, we were told it would be "years, if ever" before the fires could be stopped, and the cloud of smoke from the fields would encircle the Earth for years. It was months, not years, before the fires were all out, and the smoke cleared up pretty quickly.

There have been other environmental disasters that have offered similar wrongful predictions of calamity. I just take a wait-and-see attitude about it any more. The 'experts' don't know as much as they claim, but I guess they dont' get headlines by saying their won't be much damage.

[Shapley]

Coast Guard: No Oil Leak From Sunken Oil Rig