Drill Hole in Stainless Steel Pipe

[patrickbarbary]

Please give us a larger picture to see how the pressure applies.
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[Nic Homan]

One has to consider the thickness of the tube too. The hole looks large relative to the diameter. The loads will come from a variety of directions depending on the wind. I would strengthen the whole section by welding a brace above and below the hole so it can not collapse. In my mind it is better to be over engineered especially in foul weather,

[wbchinook]

Be careful welding on the pipe if there are wires inside. You don't want to fry the wiring.

[meirriba]

Different question: this hole will remain open? Or sealed against water ingress?
As to giving the structure back its strength, I think that you may weld S/S bar with two short legs across the opening (along the tube) it may not be the most elegant but it will counteract any bending force.

[smacksman]

Running the cables externally or in a dedicated conduit would have saved the agonising over strength and made maintenance easier. Too late now.

[GrowleyMonster]

Probably okay, but no way would I have cut such a big hole just to pass some wires.

You will of course need a grommet or something to prevent the pipe filling up with water, as well as chafing. Grommet or maybe an elbow pointing down to make a rain loop in the wires, AND a grommet. Welding an elbow there should be plenty of reinforcement for the 2" pipe, too. But please avoid putting such huge holes in stuff when a smaller one will do. It's just wrong.

[tdgaffney]

The problem, if and when it occurs, will be side deflection that places the cutout surround structure in compression, which will very easily cripple, followed by cracking and, in the extreme, loss of complete support. The most direct solution would be a 45 deg diagonal support pipe that constrains the joint from distortion. I would suggest the diagonal be 3/4 of the original pipe diameter, same gauge, weld attached leaving about two inches of main pipe material below the hole edge. Good luck.



(Free advice is worth what you pay for it. ))

[herbhunt]

All I can tell you is what I would do. First weld a tubular insert long enough to be welded all the way around protrude (same OD as the hole you drilled) into the hole that is say 1/4" wall thickness. Round the interior edge of the insert so as to stop chafing of the wires against the sharp edge BEFORE you weld it in place. Once in place grind the pipe where it protrudes to follow the curve of the upright and likewise curve the inside edges.

In MHO this insert will more than carry the loads in the pipe and make it stiffer than original around the hole.

Whether that is sufficient depends on what the davit was built to do.

If it was my boat I would likely also weld tubes triangulate where the horizontal and vertical bars meet in both planes (fore and aft and athwart) mount in place. I would likely make these tubes about 1 foot long to spread the load.

Hope this is of some assistance.

[nofacey]

It’s fine, biggest stress is at welded junction, then 1/2 way down unsupported length.

Next time use a smaller hole saw, absolutely no need for a hole that big - all you did was save an hour, and now you’ll worry about it in every storm.

[captain38]

My 2 cents worth: If the pipe truely holds the davit system and perbaps a few antennas and/sar panels, the 2" pipe was selected for aesthetics and not strength. The load of a few hundred pounds is insignificant to the unit even with that hole.

[captain38]

Originally Posted by captain38

My 2 cents worth: If the pipe truely holds the davit system and perbaps a few antennas and/sar panels, the 2" pipe was selected for aesthetics and not strength. The load of a few hundred pounds is insignificant to the unit even with that hole.

Oops. Typos. Meant Solar panel

[ejjawhite]

Geez... What the heck kind of wires requires that large a hole? I’d find some strong grommets to line the hole so the wires don’t chafe.

[Cadence]

Originally Posted by ejjawhite

Geez... What the heck kind of wires requires that large a hole? I’d find some strong grommets to line the hole so the wires don’t chafe.

What's done is done. I can only wish him the best and hoping to hear his outcome results in the best.

[Coltrek]

That shouldn't be a problem. Just clean it up, with sandpaper, not a file, or you will start rust. Think about some of the holes you have seen on spars around deck level, way worse than this. Especially how close it is to the end.

I have a SS fabricating shop, and am comfortable with this.

[capn_billl]

Why so big a hole? Planning on running 4 x 00 gauge wires down it?