Non-metallic hole plug 1

[illini8181]

I have a 1.5 inch through hole (not tapped) in a 1.5 inch thick painted steel plate that I need to plug. The plug must be able to be installed under water. The plug must cover the hole from both sides, but does not have to be water tight. It is preferred that the plug be a non-metallic material. The plug also must not sit proud on the plate. I am trying to brainstorm a simple solution here, but am not coming up with anything. Any ideas are welcome!

 

[btrueblood]

You've perused the plastic plugs available from, for example, caplugs.com? Can you explain what the purpose of the plugs is, if not water tight nor protruding? Would a vinyl cap, installed inverted then trimmed flush with a razor knife work?

 

[ornerynorsk]

Is the hole true enough to turn a plastic plug with an o-ring groove, with said o-ring to create enough friction to hold the plug in place?

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[illini8181]

btrueblood - the hole is in a rotating part, so the plugs are intended to prevent cavitation erosion. I have looked through the plugs on sites similar to caplugs.com. I cannot picture what you mean by installing a vinyl cap inverted. What keeps it in place? Just friction?

ornerynorsk - since the hole is in a rotating part, I would be worried that friction would not be enough to hold the plug in place.

 

[illini8181]

ornerynorsk - similar to what you suggested, I am considering machining shallow grooves in the hole to hold a plug with an O-ring in place. I would rather not have to do any machining, but this would allow a simple plug to be used and would make underwater installation very easy.

 

[Tmoose]

What are Rpm, radius, min and max operating temperature and pressure difference on both sides of the hole?
Are there any features on the hole? chamfer, slight counterbore, extraordinarily rough finished bore, etc
Could there be?

http://www.yankeemarinediving.com/MyImages/underwater-welder_4344.jpg

http://www.loctite.sg/sea/content_data/168612_FIXUREEN.pdf

http://www.mbca.org/sites/default/files/7009016_FreezePlug.JPG

http://outdoorpowerinfo.com/repairs/images/kohler_walbro_lmk/_welch_plug.JPG

To secure the Plug drill and tap a hole for a set screw axially into the joint between plug and plate. Sometimes called a dutchman, although Google was unable to dredge up a picture of one. I did find a reference to installing a pin that way.

http://www.roton.com/eng_bul_964.aspx

 

[77JQX]

Old school:

http://www.brownwoodinc.com/industrial/pipe-plugs.asp

et al.

 

[1gibson]

Does it need to be removed? Use underwater epoxy?

 

[MikeHalloran]

77JQX is on the right track.
A straight cylindrical wooden plug with low moisture content, driven in, should expand nicely once it gets wet, and stay in for a long time, unless it's then allowed to dry out.





Mike Halloran
Pembroke Pines, FL, USA

 

[btrueblood]

And you can use a wood chisel to smooth the profile to match your shaft o.d.