Installing Inspection Ports in Water Tank

I decided to write a short how to blog instead of a film strip. People can take their time to read and look at the photo's at their own speed. In the spring of 2013 I started working on the water system in "The Queen". The fresh water tank was just gross. The price for a new one was a little steep. So I figured if I screw it up I'll buy a new one. If I can make it work I'll save myself a couple hundred $$. So why not give it a whirl. My question to myself was how can I clean the scum out of the tank. I started exploring the internet and came across an interesting article that this one fellow did. Ingenious I thought. How can I improve this idea to fit my application. Here is a link to his how to article.

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/14222886/print/true.cfm

I detached all the fittings and hookups and removed the tank out of the dinette compartment. Rinsed it, sloshed it around with some bleach and let it drain. 

This is the tank with the scum in it.

Items that you will need to purchase:

1 or 2 - Beckson Screw Type smooth 6 inch clear center - white deck inspection ports

I purchased mine from Defender (P/N DP60-W-C) @ $17.00 each.

6 - stainless steel pan head sheet metal screws for each port from your local hardware store

(I think they were #12 x 1/2" that came with each port) Check the size before purchase

1 or 2 - small poly cutting boards. They are 1/4" thick. I bought mine at Wally World for $1.50 ea.

1 - tube of marine grade or 100% white or clear silicone caulk $6.00 from hardware store

Required tools:

Jig saw, scribe, drill with 3 different size drill bits, black marker, file, heat source, utility knife & alot of guts

Unscrew the clear center plate and place it on the tank where you would like it. Be sure to give yourself plenty of clearance from any fittings and as far away from the edges as possible. Think about how not to compromise the structural integrity of the tank. You want as much meat (structure) from the edges of the tank as possible. Mark the inside diameter of the inpection port. Find the center of the diameter and scribe a  4 1/2" diameter circle. Check again.

Take a deep breath. Use a jig saw with a fine tooth blade and slowly cut the hole or holes out. Leave the line. Marker will come off later. Check your fit. Use a file clean up the roundness of the hole then a utility knife to get the majority of the fuzzies off. I used a cigarette lighter and quickly melt the fuzzies from the edge then burnish the edges smooth with a spoon or something metal. Check your fit of the hole to your top port ring.

These aren't the clearest shots. That is all that I have. It gives ya a good idea. That thick black line on the inside of the tank is the nasty scum.  Now I was able to scrap and scrubthe crap out of it. Whoohoo!!

The next step is to fabricate the lower inside mounting ring. This ring really stiffened everything up and is used as a backplate that the screws go into. Take the inpection port and place it on one of the cutting boards. Mark the interior diameter ( 4 1/2") and outside diameter ( 6 1/8") of the ring. Add 1/8" to the outside diameter and inside diameter with a scribe. This will componsate for the blade thickness when cutting the ring in half it will fit inside of the tank hole. Mark a the center line to cut in half.  Check your measurements. Take a deep breath. Cut the piece out using a jig saw. Leave the lines. Clean up the edges with a file and heat source. I used the flame from a gas stove. Worked great! Not to much heat.

Cut the outside diameter first.

Then the inside Diameter

Yes I use the kitchen table for my winter projects. Thank God my better half is use to this.

Shot of the finished inside mounting ring. Checking the fit up on both pieces inside the tank. With the top ring in the hole. Make sure the the center seam is nice and snug to eachother.

Now we are ready to start adding the additional holes in both the top port ring and bottom ring. First clamp everything together. The ports come with 6 holes that are predrilled. I marked from center to center the of the original holes and added 6 more in the outer plate. I wanted more stiffness and no leaks. First counter bore with a brad tip drill or fostener bit for the head of the screw then a smaller hole almost through the inside mounting plate. Use the original hole to gauge what size holes are needed to be drilled.

Mark the pieces so they can be put back exactly how they were when you where drilling the holes. Wipe all the surfaces clean that will have caulk on them with rubbing alcohol. Let them dry. Put a nice bead of caulk along the inside ring of the top port plate. Be sure to get some in the mating surface of the screw holes. Place the port ring back in the tank hole. Now it is time to get messy! Put a generous amount of caulk on the mating surfaces of the lower interior ring. Do one side at a time. Line up the holes and clamp together. This is a little tricky. I used toothpicks to align the holes to one another. Attach the plate together with stainless steel screws. Do one screw first check to see if it protruding through the interior ring. If it is grind the screw down or use a shorter screw. All the screws will have to be modified alittle if that is the case. I had to grind mine about two threads.

Voila!!! One done one more to go.

Screw in the clear center plates and tighten. There is a gasket that seals it water tight.

The gasket can be replaced when it gets old and tired.

After I installed the tank back in the compartment; I found that when filling it up with water it became easier. We could see what was going on. We can get a quick visual of how much water we have left before we need to fill it up. Winterizing has become easier. I can use a little hand pump to get that last inch of water out with no problems. Wipe it dry with a towel. Clean out any nastys that want to hitch hike with us. If I every have to buy a new tank in the future I will install these ports in it. I hope this is helpful. Proceed at your own risk and with caution.