I have a 1 million USG drinking wat

[ashtree]

I have a 1 million USG drinking water reservoir constructed of Glass Fused Lined steel panels with mastic sealant along all the bottled joints. The tank is only a couple of years old and the mastic has failed twice due to the chlorine levels in the water which can be as high as 9mg/l near the inlet.

We are not going to use this product again as it is only rated to about 4mg/l of free chlorine. Unfortunately in another tank that has lower chlorine levels (2-3mg/l) the mastic has failed as well, just not as rapidly. The current product is SIKA and is recommended by the tank manufacturer but is obviously not a suitable selection for the high chlorine levels.

Does anybody have a product they can recommend in this circumstance?

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[ScottyUK]

Does the joint have to be movement-tolerant? An epoxy sealant would meet the chlorine resistant requirement, but likely be less tolerant of movement than a mastic - these materials are typically used in swimming pool environments where chlorine is present as a disinfecting agent.

 

[ashtree]

Scotty thanks for the reply.
Its hard to say but the tank design is intended to bulge about 20-25 mm at the base when full. Although there is no obvious movement in the joints something must move a little to get that much expansion. Most likely it would crack the epoxy.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[ScottyUK]

Both have some movement tolerance, both have considerably greater tolerance in compression. One from Sika, funnily enough.

https://www.sealantsonline.co.uk/Pr...iffe-arbokol-1025-swimming-pool-epoxy-sealant

https://gbr.sika.com/sealantsandadh...pools/sika--everbuild-tecnic-stayseal-75.html

 

[epoxybot]

You might want to look into a Polysulfide Epoxy Sealant.

 

[blakmax]

I suggest that you look at the failure surfaces. If the failure is at the interface, then an alternate adhesive may not solve the problem, because most adhesion failures are3 driven by hydration of the surface oxides on the metal, and that is a surface preparation issue, not a materials selection issue. Certainly if you select an epoxy then you must treat the surface with some chemical process that prevents hydration.

Regards


Blackmax

 

[ashtree]

The problem is not at the interface , but the fact that the existing mastic breaks down in the chlorinated water.
Scotty,
The products you list might be a good alternative and are worth investigating. The data sheets do not list potable water approvals though.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"