max speed of external floating roof

[gelsi]

There are any limits to the speed of an external floating roof (API650 hydrocarbons) during operations?
Somewhere I read ~3.5 m/h, that's correct? There are useful technical references?

The objective is to carry out safe loading/unloading operations.
Thanks

 

[LittleInch]

Gelsi.

I asked the same question a while back and came to the conclusion there isn't one.

3.5 m/hr sound like 1ft every 5 minutes converted to metric.

I think anything up to 5m/hr sounds ok.

See

http://www.eng-tips.com/viewthread.cfm?qid=415297

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[IFRs]

For any reasonable size tank, the liquid inlet and outlet rates will translate into a very slow upward velocity. What are your numbers for flow rate and tank diameter? One foot in 5 minutes is certainly well within reason. It works out to one inch in 25 seconds which is pretty slow, try moving your finger on a table at that rate.

 

[gelsi]

I agree ~1 mm/s sounds enought low, but I think that there are some safety topics that justify a standard, would like your opinions about follows:
1 - when the roof leans on the supports happens a dynamic load that could be higher than verified/designed,
2 - high speed of roof could give wall more wetted with more emissions of VOC and risk of fire,
3 - electro-static charges.

 

[LittleInch]

If by 1 you mean the floating roof is sitting on it's legs, this is, or should be, a rare case and special conditions apply relating to the venting and vacuum capacity. Usually fill and drain rates when the roof is on legs are much reduced as the tank is then acting like a fixed roof tank and all ion and out breathing is happening through the roof vents which are often pretty small. You can get a hazardous atmosphere in the tank at that point.

2 & 3 are part of normal operation. I can't see either being an issue.

floating roof tanks tend to be a decent size normally and fill rates are just not that high in terms of roof speed.

SO unless someone finds some company guidelines, I don't believe there is any recognized or written standard which addresses this specifically.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[gelsi]

ref. 1
i m talking about an anomalous run:
wrong indication of level and operator distracted
so the speed of the roof is still the normal, until reaching the support quota and below.

I understand that the case is very rare and can be easily avoided with more safeties.

ref. 2
i don't know if there is a speed of the roof beyond which the wall becomes too wetted.
If i understand, you said there is not a limit, a little more liquid over the seal doesn't grow up the risk of fire.