1939 Steel Tank Inspection Access Question

[SteveGregory]

I need to inspect a "Paint Ball" and its connection to the top of an industrial steel water tank. The ball is used to support a "painting platform". The tank is 124' tall and 22' in diameter. The ball is at the center of the conical steel roof with a pitch of 30 degrees. The ball is a 15" diameter hollow cast iron finial with a 6" diameter shaft and a flange that is bolted to the roof.

On the roof, there is a rotating ladder hooked to the shaft that rolls on 4 cast iron casters. Unfortunately the rotating ladder is not near the fixed ladder on the side of the tank.

How can I get safe access to the ball to make a good detailed inspection? I don't think that a crane basket would get me close enough to check it over.

Next, I have 3 more similar tanks with a ball to inspect that are only 30' tall on top of a 4-story building roof.

 

[MiketheEngineer]

Scaffold??

 

[SteveGregory]

The painting contractor proposed erecting scaffolding from the ground up 124' and it was expensive. So we get the call to inspect the ball to see if it can be used instead of scaffolding!

I asked them to find the painter who did it 20 years ago to find out how he got up there to the ball and they can't seem to locate him.

Here is a picture with a zoom.

 

[msquared48]

Why can't you hook a grappeling hook to the lower part of the rotating ladder and move it around to the fixed ladder for access.

The rotating ladder was probably originally moved away after the last painting for security and liability reasons to make access more difficult for those who should not be there in the first place.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[JedClampett]

I'd have your lawyer review this task before I even said yes to thinking about it. It sounds like a liability nightmare. You're never going to have enough information to absolutely say it's going to work. And if it fails, very likely someone is going to die. And even if it works, the painting contractor has to do everything perfect.
Maybe some steeplejacks can figure out how to get you up there, but even then, evaluating it is very scary. I'd bring along a change in shorts.

 

[MiketheEngineer]

A crane basket can get you to the rotating ladder and move it into position. Crane basket

But who is to say that the ladder is safe??

Scaffold is the safest method I know of. And of course that's what I do.

Depending on what part of the country you are in - I am guessing in the $30-60,000 range.

 

[JStephen]

http://www.ur.com/index.php/equipment/rental/browse/view/?category=Aerial+Lifts&id=1624

"Platform height...125'."

 

[SteveGregory]

I had an interesting talk with a painting contractor that I found on the internet. He said that he probably wouldn't use the ball, but that he would weld some of his own clips around the edge of the tank to support himself and his equipment.

I am a little relieved with this idea. Now all I need to do is inspect the fixed ladder on the side.