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How do you add hinges and latches to a metal lid on a concrete water tank?

Steve5
Having an Impact

How do you add hinges and latches to a metal lid on a concrete water tank?

 

I replaced the heavy concrete lid on my in-ground water tank with a metal plate.

 

It is screwed down into wall plugs in holes drilled in the concrete top.

 

After numerous times unscrewing to check water levels, I want to add hinges and latches to make access easier.

 

Since the top of the concrete water tank is curved like a dome, the metal plate edges don’t contact concrete near the edge when it’s not screwed down. (See yellow lines on the photo)

 

With 3 hinges on one side and 3 latches on the other side placed near the screw holes, the latches would need to pull the metal lid down like the screws.

 

I like these strap hinges since they spread out the concrete drill holes.

https://www.bunnings.com.au/pinnacle-100mm-stainless-steel-heavy-duty-strap-hinge_p4150030

 

A toggle latch seems like the best approach to pull down the metal lid but there’s no give on the concrete lid like a box trailer cage.

https://www.bunnings.com.au/pinnacle-60mm-stainless-steel-adjustable-toggle-latch_p3962537

 

The existing seal is a 3mm felt strip but I might use a thicker foam or D shape weather strip.

The biggest gap is on the corner closest to the concrete top edge.

Thicker foam or D shape strips would compress so latching does not need as much pressure to bend the metal plate to mate with the dome concrete top.

But then I need to address the additional height difference between the metal lid and the concrete which will depend on how much compression of the D shape weather strip.

The adjustable toggle latch will allow easy adjustment so I’ll probably put these on the side of the metal plate closest to the edge of the concrete top.

The metal lid is about 3mm thick.

 

The toggle latch and strap hinges come with screws so I can use wall plugs in the concrete but need to use bolts/nuts/washers on the metal lid. 

Stainless rivets might be better since they won’t stick out as much on the bottom of the metal lid.

Stainless steel flat washers can be used to adjust the contact heights on the concrete.

Is there a way to find out what size bolts/nuts/washers would fit the latch and hinges? 

Same question for rivets for latch and hinges.

 

Now the big question, have I been so focused on hinges and latches that I’ve missed out on a better approach?

 

Any ideas/thoughts greatly appreciated! 

 

 

Water Tank Hatch Hinges and Latch GIF.gif

MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: How do you add hinges and latches to a metal lid on a concrete water tank

Hi @Steve5,

 

I think the best approach to determine the size of the bolts/nuts/washers and rivets would be to have a helpful team member assist with their selection in-store. I could speculate on what might fit, but due to the application, I think it's best to try a few different options to find the best solution. 

 

Regarding a better approach, have you considered installing an access port in the lid to check water levels? If you were to cut a 100mm hole in the lid and use Sikaflex 11FC to glue a Holman 100mm PVC DWV Threaded Access Coupling into the hole, a Holman 100mm PVC DWV Threaded Access Cap could be screwed onto it. A couple of rotations of the cap would be all that is needed to secure it, and it could be taken off and put back on far quicker than having to undo all those latches. It would also save the work needed to implement your method above. Combine the access port with a timber depth measuring stick, and you can check water levels conveniently.

 

Following a similar theme, other smaller inspection outlets would likely work, too, like this Kinetic 100mm Square Clear Out Floor Grate.

 

Please let me know if you have any questions.

 

Mitchell

 

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Re: How do you add hinges and latches to a metal lid on a concrete water tank

Hi Mitchel,

 

Yeah, I enjoy wandering around Bunnings brainstorming with the staff but I've been too busy lately so I've been ordering online for delivery.

 

Access port with a wooden dip stick is an idea, similar to petrol station tank checks when I was young.  I'll give it a think.

What's the best way to cut a hole in the 3mm thick diamond stainless steel lid?

 

I could probably use the screws included with the hinges and latch to screw directly into the metal lid, then cut/grind off he tips if they contact concrete.

 

Instead of using stainless steel washers to add about 3mm on the concrete side for the hinges/latch, do you sell any 1-3mm plastic sheeting I could make a spacer with?  Something I can cut to fit?

 

Thanks

 

 

MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: How do you add hinges and latches to a metal lid on a concrete water tank

Hi @Steve5,

 

The best way to cut the hole in the lid would be with a jigsaw and a metal cutting blade

 

We've got clear PVC sheeting in 3mm. That can be a little tricky to cut, so perhaps 3mm packing shims would work better. We also have other thickness shims.

 

Mitchell

 

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Steve5
Having an Impact

Re: How do you add hinges and latches to a metal lid on a concrete water tank

Hi,

 

The dip stick with access port is a great solution except it would be trip hazard so I'll stick with hinges.

 

Found this hinge which will move the screw holes farther farther from the edge of the metal so less chance of hitting concrete below.

https://www.bunnings.com.au/austyle-100-x-125-x-3mm-304-grade-stainless-steel-broad-butt-fixed-pin-h...

 

I don't think the toggle latch will give a good seal as it will pull to the side instead of down.

Seems a screw down on one side might be the only option.

Do you have any ideas on how to pull down without tools something like this:

https://www.boltandnut.com.au/machine-screws/wing-head/m6-x-1-00p-coarse-stainless-a2-70-g304-wing-m...

Do you think machine threads will grab onto the wall plug insert or do I need a different type of insert?

 

Thanks

Dave-1
Home Improvement Guru

Re: How do you add hinges and latches to a metal lid on a concrete water tank?

Good Morning @Steve5 

I was thinking outside the square (Hate drilling concrete and always worried it will crack/splinter) How about a lever instead? No hinges needed.

Water Tank Hatch Hinges and Latchd.jpg

So the lever is at a 30 deg angle. It would be easy to control the lifting of the sheet just by tilting it. You could have a chain fastened to a spike in the ground to loop the handle in so it wont fall on you. No hinges as its just rotating through that pivot point. The rubber strips would still be sealing it as well.

 

I like the idea of the inspection cut out that @MitchellMc suggested. That would really add to not having to open the lid.

 

Dave

Steve5
Having an Impact

Re: How do you add hinges and latches to a metal lid on a concrete water tank?

Hey Dave,

 

Very creative, great you added the photo markup!

Would probably be an option if the concrete top was flat.

Unfortunately, the metal lid doesn't lay flat and needs screws to draw it down on one side.

Need to keep the snakes, toads, rats, and mice out..

 

Cheers

EricL
Bunnings Team Member
Bunnings Team Member

Re: How do you add hinges and latches to a metal lid on a concrete water tank?

Hi @Steve5 

 

Have you thought about forgoing the hinges and just using the Pinnacle 60mm Stainless Steel Adjustable Toggle Latch on both sides? This will guarantee that the edges will be pulled down tight if the toggles are installed at the corner ends. This also allows you to lift and remove the cover out of the way.  

 

If you need further assistance, please let us know.

 

Eric

 

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Steve5
Having an Impact

Re: How do you add hinges and latches to a metal lid on a concrete water tank?

Hi Eric,  I like the toggle latch but realized it pulls to the side, instead of down since everything is on the same basic level/plane.  Cheers

 

Steve5
Having an Impact

Re: How do you add hinges and latches to a metal lid on a concrete water tank

I experimented with metal screws and wall inserts where I could make them work but they don't have enough grip

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