Need to CYA , who is going to issue the confined space permit . Who is going to provide or even operate the equipment to see is the air is safe . Most water has chlorine ,that may be a problem
There's a difference between reading and comprehension.
Reading means just that you read it and when you answer it'll probably make no sense.
Comprehension means you actually understood what it said and when you answer it'll probably be on subject.
Yair . . . 95zIV. Those two reasons you mentioned are the only ones that I could bring to mind . . . there are probably other factors at play here but on a normal installation neither of them are legitimate concerns.
I would suggest that filling into the bottom of the tank with a check (oneway) valve is normally a better design option . . . and a LOT simpler in this case.
With top fill there are factors of splash and oxygenation and what all but we won't go there
I have seen a case where a "professionaly" designed system utilised two 90 mill poly pipes to a one hundred thousand gallon installation on top of an escarpment . . . one came out the bottom for delivery and one went in the top to fill???
We are talking an extra half a mile of 90 mill. pipe for no advantage.
Yair . . . oops! Tiny was quicker on the trigger, I was typing while he posted.
I'll get back about the pump thing later unless some one beats me to it.
the scaffolding could be built from the top down on the inside. just give the dimensions of the tank to a scaffold company. they will design a system to meet your needs.
I used to build scaffolding about 30 years ago. the tube lock scaffolding can be built into about any shape you want..
Tube lock pipe starts a 4 feet in length.
as mentioned you will need to ventilate and monitor the air
No good deed goes unpunished....
Things have been going great since we redefined success as slowing the rate of failure.
Education's expensive no matter how you get it.
You can get it right or you can get it now, but you can't get it right now.
You can get any two of good, fast, and cheap.
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So I finally got a chance yesterday to look at the tank. Thanks for all the responses guys, I really appreciate it. I'm not the contractor, I'm just providing the crane to lift the pipe up, but the welder doing the pipe work, just calls me and says "hey, how we gonna do this?" I just charge by the hour while I'm there with the crane.
The tank is actually closer to 80' tall (by my rusty trusty eyeball), and the pipe we're replacing is actually the overflow pipe. If they are pumping into the tank, and the shut offs don't work, this releases the water back out of the tank onto the ground. The tanks get inspected as public water systems, and if the pipe is rusty, it needs to go. The bad part is the inside inspection and painting of the tank. I'm sure they scaffolded it when they built it years ago, but they're gonna have a fit on what it will cost now.
The ladder starts about 30' up the side-no cage- no rest platforms-so I didn't climb it to look for roof hatches, but from a distance I can see no hatches directly above the overflow pipe. The one picture shows the bottom access hole, thats my 2AA mag lite setting on it for a reference of size. I don't think my 11year old boy could fit through it. In the third picture, the pipe we're replacing is on the right, the ladder is on the left.
Its also kind of handy having the power lines close for working. Thanks for the confined space comments too Tiny- that had slipped my mind also.
I think the best option right now is welding/installing a new 3'x3' roof access hatch right above the overflow. Weld it in first, replace pipe, manbasket through hatch to inspect welds and paint, and paint underside of new hatch from on the roof.
Tiny, that's a great observation about the confined space. Not the best place to use can of krylon.
"You can't have 'no' in your heart." - Joe Dirt
google the tanks address, you will get an overhead view of the tank. no need to climb the ladder
Call the inspector and ask how He intends to inspect the weld and paint.
How about an arborist saddle? Osha just approved the use of a crane to hoist a tree climber, I would think if you followed the standards you'd be okay.
If you're interested send me an email and I send you a copy of the standards.
Red Seal Crane Operator
ISA Certified Arborist