Cement Lining for Steel Water Tanks

I recently purchased a 65' steel ketch built in 1968. She has two large water tanks which have been thoroughly neglected during the past 40 years. We are currently in the process of cutting out and replacing rusted sections of the tanks. Within a couple of days, we hope to sandblast the inside of the tanks, clean thoroughly, and then coat with cement (apparently the lime in cement makes for sweet water?).

Does anyone have any experience with this? Our primary question is what type of cement should we use? Is it just a standard Home Depot style cement? Are we supposed to use any additives to make the cement sanitary? Is there anything we should do to promote adhesion to steel or inhibit corrosion? Should we leave the access ports as simple uncoated steel?

 

I'm not the most knowledgable person when it comes to tanks, but I have NEVER heard of cement-lining. You might like to consider a sprayed epoxy finish if you want to prevent further rusting.

Tim B.

 

Cement coating tanks is common and very effective. There is another fairly long thread on this forum on the subject, including the formula for mixing it. Do a search...I am too lazy right now.

 

OK I got off my *** and found it for you.

http://boatdesign.net/forums/showthread.php?t=6371&highlight=cement tanks

 

I do know that trowels and wheelbarrow will not rust if coated with a thin later of cement. Must be standard portland cement mixed thin and "roto-molded". Probably works great.
Something so cheap to be so effective, I like the idea though I hadn't heard of it til just now.

Alan

 

Had a word with our local water tank 'installer' - he also digs septic pits.
He says that cement lining for steel tanks is a 'regular go'. But first he paints the inside with lanolin (oil from sheep wool). It gives a protective barrier against cement acids and moisture without affecting the cement 'sticking' power. He allows up to a couple of weeks for the cement to 'cure', then flushes out with a hose. He recommends standard cement mix - but favouring the cement ratio rather than fine sand.
From experience I know that the 'rainwater' collected tastes far sweeter than that obtained via the town mains. It makes one hell of a mug of tea - and on their (thankfully) infrequent visits my in-laws from Sydney return home carrying poly-containers of 'my' water - for just that purpose. A local 'home-brew' fanatic also swaps samples of his 'beer' for samples from my tank.

 

I remeber we had bad water.

The boat was in Vietnam for 5years and during this time nothing was done to it. We opened up the thanks and it was all naked steel. We coated them with cement.

The sement used has litle relation to the one used for construction.
It has a high content of calsium.

I was on a newbuildt boat and there we had painted thanks and I don't think the water there was that good.

The cement is aplied with a brush just like painting, I think you can find somewhere to buy some if you go to one off the larger ports. The seller would be able to advice you on how to use it.

 

Thanks for the feedback, and for looking up that old thread. I also posted a reply on the old thread, but I think it's pretty much dead, so I'll continue to post here.

I've started trying some sample cement on painted/unpainted/rusted/fresh steel surfaces, just as a test for adhesion. The thing that I won't be able to test quickly is whether or not rust will form on the steel underneath the cement. Here's what I'm currently doing; let me know if you have any recommended modification for this:

Cement mix, from Home Depot:

• 1 part Portland Cement
• 1/2 part Lime
• 3 parts fine sand (#30 grit)
• Sufficient water to create a smooth, pancake batter-like consistency

In terms of how to apply it, I see three options, and wanted to get advice:

1. Paint the cement on over the old, yellowed epoxy which is currently in the tanks
2. Sandblast the tanks, and paint the cement on over the fresh steel
3. Sandblast the tanks, coat the fresh steel with epoxy (or lanolin?), and then paint on the cement.

I'm planning on a thin layer of cement, perhaps a quarter inch. (Basically, as thin as I can get a non-porous layer of cement).

I look forward to your advice. The procedure laid out above is only a guess by a complete novice in the field of cement-lined water tanks.

 

I had a masonary water cistern that I had to periodically put a wash coat of cement on the inside. All I used was Portland Cement mixed with water to a slurry and then would slop it on with a broom. Sam

 

Steel water tank has been around for over a decade now and has become the most popular water tank of its type in Australia. Their popularity is due to several key factors with the main ones being competitive pricing, corrosion resistance and durability as well as the large range of shapes and sizes.

water tank