Atmospheric Galvanized Steel Tank

[JHernandez]

Team,
I have an Atmospheric Galvanized Steel Tank,
3/16" thickness and in good conditions, which I'd like to use, but I don't know the design temperature nor design pressure other than it's atmospheric. This tank has an internal heater system, but I don't know what steam pressure was used or designed for.

1)Could I use it for a design pressure of 302 degress F?

2)Being an atmospheric galvanized steel tank, can I install a rupture disc say 8 psig (has to be <15 psig for atmospheric)?

3) What "vacuum pressure" would this type of tank be designed for, ~ 10"WC??

Thanks,

JHernandez

 

[JHernandez]

Team, item 1) should say design temperature of 302 degrees F.

JHernandez

 

[JStephen]

What size and configuration is this tank?

You seem to assume that "atmospheric" means less than 15 PSI gauge pressure. Less than 15 PSI gauge pressure will exempt it from the ASME PV code, but doesn't mean it's atmospheric, either. Larger tanks designed for atmospheric service are only adequate for very small pressures. If this is a small tank, it might be adequate for much more. Ditto on the allowable vacuum- very low on large tanks, more on smaller tanks.

Regardless of the size, I wouldn't won't to be in the vicinity when a 300-degree tank popped a rupture disk.

At 302 degrees, there should be some reduction in the strength. You could check the design versus ASME B&PV for that temperature.

I'm thinking zinc melts at around 800 degrees, so you won't just melt the zinc off of it. I don't know if corrosion resistance drops off at the elevated temperature, though.

 

[JHernandez]

Team, The tank is 8' diameter, 13' T-T, bottom cone shape with 1 1/2' distance from bottom tangent to cone bottom.
JHernandez

 

[JHernandez]

Team, I have another tank same but D= 11'
H=11" T-T

JHernandez

 

[JStephen]

1)Could I use it for a design pressure of 302 degress F?
I don't know of any reason why not.

2)Being an atmospheric galvanized steel tank, can I install a rupture disc say 8 psig (has to be <15 psig for atmospheric)?

The maximum allowable pressure is likely to be less than 8 psi. You can evaluate per ASME B&PV code or API-620. API-620 is easier to use, but actually only covers up to 250 degrees. Pressure rating will depend on details of the cone-shell junction among other things. The tank should preferably be vented with a pressure-vacuum type vent.

3) What "vacuum pressure" would this type of tank be designed for, ~ 10"WC?? As a rough guess, 1-3 PSI, so the 10" WC probably wouldn't be too bad. You can evaluate it for vacuum per ASME B&PV Code, API-650, or stability formulas in Roark's Formulas For Stress and Strain.

 

[panduru]

"... in good conditions ..." does not sound very technical. Have the joints been RT'ed? Have any other checks been done on the vessel? Does your area require ASME BPV/ API/ other regulatory compliance?

If a certain code is applicable in your area, you will have to evaluate the equipment and get certification, don't you?

Just being conservative, especially since steam at >300 deg F is what you have in mind.

 

[BigInch]

Hope you have a very good way to keep this tank from developing very high pressure when you partially load it with 300º fluid and it starts heating up the air or blanket gas in the tank. Just a thought.

 

[panduru]

Of course, it seems the idea is to heat the contents after loading, since there is an internal heater. All the same, partial vapor contents building up pressure is a very plausible hazard.

 

[BigInch]

Much more than plausible. Heating of the tank contents is probably worse than loading hot. At least if you're loading, your probably displacing some hot gas as you do it. Not partial pressure, the summation of all partial pressures. With vol a constant, tank closed and then heating from 60F to 300F, its pretty easy to get 15 psig and into ASME territory.

 

[IFRs]

Watch for collapse due to vacuum if the heater fails.

 

[BigInch]

IFR... Now that's good thinking.

You could install a vacuum breaker.

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