P/V Valves on Drain Tank Vents 1

[302Hugo]

It was brought up to our department that we should be looking in to see if flame arrestors (or pressure/vacuum valves) are required on our drain sump tank vents. These tanks would be about 5 cubes and used for seal leaks, piping drain down, and in some cases pop tanks. The fluids being captured are crude and/or diluent. I beleive both are considered Class I fluids. Once the fluids hit the high level the fluids are removed. The tanks are typically empty.

I reviewed API 2028, API 2210 and they basically seem to say that tank vent lines shall be installed with a flame arrestor or P/V valve. I read NFPA 30 and an OSHA document and they state:

"Vent pipes from underground tanks storing Class I liquids shall be located so that the discharge point is outside of buildings, higher than the fill pipe opening, and not less than 12 ft. above the adjacent ground level. Vent pipe outlets shall be located and directed so that vapors will not accumulate or travel to an unsafe location, enter building openings, or be trapped under eaves, and shall be at least 5 ft. from building openings and at least 15 ft. from powered ventilation or intake devices."

I contacted the ERCB to see if they have any directives on it but they don't. I beleive all of our underground drain tanks just have normal vents that rise about 5ft above the tank.

I'm hoping someone else here has these in their facilities and can give me an idea of what they have, or if someone knows the exact industry standard.

Thanks.

 

[EthanolBlending83]

Hi 302Hugo

I think you have to evaluate posible ingition sourses. API suggest the flame arrestors for above ground storage tanks because usually tank farms are located in open spaces with no high structures around. So, the tank roof is close to be a shortcut for lighting to strike to ground. Even if the tank farm has the proper lighting protection rods, the posibility of ingnition is very high.

So they recomend to install flame arrestors or P/V valves. If you see NFPA doesn't adress the issue in that aproach. Only gives directions about how to locate your vent.

In that line of thought, underground tanks have vents that doesn't rise to much above ground. Look around and see what else could become a ingnition source to evalute the need for the flame arrestors or P/V's.