Should schedule 40 ERW ASTM A53 piping be used for storm drainage? 1

[leathermanp]

I designed a hospital roof helipad drain system around fuel gas code considering life safety issues of patients. I specified ASTM A53 schedule 40 steel pipe with welded joints (Schedule 40 ERW with welded joints was installed). Will the corrosion characteristic of this pipe support the storm water requirements? What would be the life expectancy of this pipe in a storm water application?

 

[pennpiper]

Your system is way over designed and should have a life of well over 25 years.

 

[PEDARRIN2]

Where is this being installed?

You might check with the code/AHJ to even see if you can use ASTM A53 piping for storm.

 

[leathermanp]

The local AHJ is not accepting the ASTM A53, the only pipe the fuel code and plumbing code have in common is copper which has restrictions with the hydrogen sulfide level of the fuel.

 

[PEDARRIN2]

Once the fuel is "spilled" I am not sure the fuel code applies.

Look at the plumbing code for a material that would be compatible with the fuel components.

But if it is going to a storm system and has fuel in it, you will have problems.

You cannot discharge fuel laden water to the storm.

You could use an automated discharge basin that will only let the water be discharged. They use them to discharge rain water collected near above ground storage tanks for diesel fuel.

 

[cvg]

if there is chance of petroleum products or other contaminants, you could discharge this to a oil / water / grit separator or other type of treatment chamber which would be off the roof at ground level - prior to discharging to the storm drain system. StormCeptor is one type I have seen used.

stormceptor

http://www.stormceptor.com/en/

parallel plate Oil/Water Separators:

http://www.brentw.com/water/oilwater.html

 

[leathermanp]

The system is discharging into a packaged fuel separator/tank buried in the yard the separator then discharges to the storm sewer. A year or so ago a sister hospital campus in the same city had a helicopter crash and explosion on the roof involving fuel spill and leakage and building damage resulting in patient evacuation. This is why I'm not comfortable installing a simple storm system but feel compelled to install per the fuel code however, the fuel code and plumbing code do not come together for this situation.

 

[cvg]

I'm curious as to how the type of drainage pipe would have prevented the crash, fuel leak, explosion and building damage? Fuel code is for facilities designed to store and transfer fuel, not stormwater. You aren't storing fuel on the roof are you?

 

[leathermanp]

No, fuel is not stored on the roof, but in the case of a crash and fire on the roof the pipe would not prevent the crash, the pipe would safely convey the fuel saturated fluid to the fuel separator. Patient rooms are located directly below the helipad. In any building where fuel is being conveyed through the building, in a pipe larger than 4", threaded fittings are not allowed also cast iron fittings larger than 4" are not allowed indoors and brazing must have a melting pointin excess of 1,000 degrees F.

 

[stanier]

Have you consideredd GRP? This should be acceptable to both codes.

 

[BigInch]

You have a oily water hydrocarbon drain. Its not fuel piping. Perhaps you might consider B31.3. Carbon steel pipe may be used, if you want.


**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[Ron]

There's certainly no issue with conveyance, using A53. I agree with your approach considering the past issue. Non-threaded, mechanical connections (except bolted flanges) in steel pipe are likely insufficient to withstand a "blow-off" explosion at the top, thus the potential for leakage at joints would be greater in the event of an incident.

The AHJ might have an issue with corrosion; however, since you are using schedule 40, you have a good corrosion allowance. You might consider an internal coating if that's his issue.

 

[leathermanp]

I am looking into the coating approach now.
The problem I'm having with the installed piping is coming up with proof that it is superior to acceptable materials listed in the plumbing code. I have many telling me the schedule 40 welded will last longer than I will be alive (25+ years...hopefully) but the issue is proving it to the AHJ. Does anyone have a way of proving this?

 

[cvg]

I believe there is a corrosion engineering forum in here, you might pose the question there to get another perspective on this.

 

[PEDARRIN2]

In the IPC there is provision for "alternative engineered design" that relates to systems not specifically regulated by the code but performs in accordance with the intent of the code.

It would likely mean getting a variance from the code, but if you show the plumbing inspector that the A53 pipe is used to convey pure fuel - with no problems and that it will be more corrosion resistant than cast iron to the water and put your PE stamp on it - he will likely have to accept it.

 

[ccfowler]

I agree with BigInch that B31.3 would be the more suitable code to follow for guidance. I've found it most helpful in dealing with potentially messy or hazardous materials.

 

[Gator]

Tee-hee, let the arguments continue!

I'm inclined to listen to pennpiper and BigInch on this one.

Do storm water systems now have to be designed for every possible spill situation? What if a particularly nasty bodybag (could theoretically happen) ripped-open spilling unknown toxins onto the surface? Would the helipad have to be designed according to CDC design criteria with moon suited professionals ready to take charge of the situation?

Perhaps this is just a proposed justification to over-engineer something or someone over-analyzing potential scenarios.

I've been highly allergic all my life - do I, as a reasonable person, expect the world to change for me? No, I take the more reasonable approach.

At some point, reason has to take over, but the trend seems to be towards "well, if we can put a man on the moon, why can't we completely de-toxify the environment for everyone that could be ever possibly affected if only the tiniest way?".

Sheesh.

 

[unclesyd]

Instead of coating you might want to look at pipe liners such as the Perma-Liner.

http://www.perma-liner.com/perma_lateral.html

I just talked to a fellow who worked on the relocation of Helipad at a local hospital (Florida) who said that the drainage for the pad area was tied into an existing C.I. roof drain with C.I. pipe. He didn't know what code was used as that part of project was handled by the plumbing contract. All water and air piping was 31.3.

 

[BigInch]

I wouldn't even think you would have any real chance of hydrocarbons on a helideck, unless you also were considering having some refueling operations there.

Designing this for hydrocarbons does seem like overkill. Following the same logic, what would we have to do now with normal storm catchments along the street? Design them for tanker truck spills just because it might happen some day?

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[unclesyd]

All the local helicopters, except the dusters, are required to refuel at the airport. I think the only thing one might see is some water based concrete cleaners if there are oil drips.