tank linings 4

[The Glen]

thread338-365989
best all round lining for a 30,000 litre waste tanker, waste includes ferric chloride, HCL <28%, mixed acids hydrofluoric, nitric, sulphuric, plating acids, generally all < 10 % ambient temperature. And best substrate Carbon steel or 316 Stainless. Last tanker was Carbon Steel with a Corrocoat Polyglass VEF lining, a glass flake vinyl ester acrylic co-polymer. I have always understood the lining bonds to carbon steel better than S/S. Any good advise would be welcome

 

[TugboatEng]

Consider that CS would typically be sand blaster prior to coating while SS may not be. Specify abrasive blasting of your SS tank IMMEDIATELY before coating and expect similar bond strength to CS.

With that said, there isn't much benefit to a SS tank if coated. Even in areas of damage SS will corrode similarly to CS due to crevice corrosion.

 

[EdStainless]

Stick with CS. Some coating systems even use a reactive primer that will chemically react with the steel for better bonding.
How long did the pervious coating last?


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P.E. Metallurgy, consulting work welcomed

 

[The Glen]

On its 5th year now doing well, although ordering a new tanker and undecided weather or not to go for rubber lining instead of the Glass more interested in the pro's & cons of rubber to Glass flake think I'll stick with CS, biggest problem with waste is customers that forget to tell you the exact composition of their waste streams, always fearful of a rouge load destroying the lining, suppose this applies to rubber or glass. Tankers are vacuum loaded impact damage being a concern and grit content of the load, galvanisers acid always have a % of grit and odd nuts & bolts mainly affecting valves. My thoughts are rubber would cope better although people have said that vacuum can affect the rubber bonding. Do I stick with Glass or has anyone any good reasons to try rubber.

 

[The Glen]

Whilst I'm at it, what's the best practice for welding pits in 316 S/S, always used tig although have been advised to use stick welder 2.5 mm rods, reason being better build up less thinning of steel. Would of thought this depends on the man welding it any thoughts.

 

[EdStainless]

No reason that couldn't weld 316L with rod.
I am presuming that fully grind the pits out leaving a nice open groove to weld into.
The real problem is that the welds will always have significantly lower corrosion resistance than the base metal.
316 and 317 have significant segregation on solidification.

As for the coating it isn't the glass that I am worried about (unless you get a load of HF) it is the resin that seals everything. There are a lot of resin systems out there.
If it were me I would go with the same as you have.
But I would get coupons coated with various other system and put them into a line for long term exposure.
That way down the road you would have a basis for selection.

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P.E. Metallurgy, consulting work welcomed

 

[Dhurjati Sen]

Perform a visual inspection of the existing lining. Look for any physical damage.

Also, carry out holiday testing of the lining.

If both above results are satisfactory, apply the same to the new tanker.

If not, explore repair procedures for the same.

Since you have strong solid data regarding your existing lining, going for any change is unnecessary.

DHURJATI SEN
Kolkata, India