Schedule 40 Malleable Iron fittings for fuel oil piping? 3

[USAeng]

I look in b31.1 for guidance to if I can use schedule 40 malleable iron pipe fittings for fuel oil piping... all I can find is for fuel system "joints" they say to use extra strong no matter what the material... which would be shedule 80... then they say its ok to use malleable iron up to 350psi or 400degrees F...

The fuel oil will be at about a max of 70 psi which falls well below the schedule 40 fittings 150 max psi called out in the mcmaster catelog, but if a "joint" is considered any place there is a fitting then maybe I need the schedule 80 according to b31.1?

In this case it is where the oil leaves the regular oil piping and enters a 5 foot flexible steel hose which is made for fuel oil and then goes through a quick disconnect into these fittings which is a 90 degree elbow, then through a tee, and then into a nipple...

I know these are very cheap components, but we need a LOT of them, so the price difference between schedule 40 and 80 is actually quite a bit more... and malleable iron is also the cheapest... so trying to save as much money here as possible but still stay legit

Thanks for any guidance

 

[GenB]

for the pressure antd temp of oil no2/diesel S40 pipe/150# fittings are good.
pay attention to the sealing compound used if not the right one, you will ahve leaks everywhere.
ask McMaster what's good for oil/diesel application.
genblr

 

[USAeng]

Is there any place I can go to confirm that? I was hoping there would be some kind of reference in NFPA or ASME.... Thank you

 

[Duwe6]

ASME B31.3 covers it. [B31.1 is for boiler external steam piping]. Rectorseal - Soft is an excellent pipe dope for oil. However, why not use socket-welded fittings with your Sch 40 pipe? Screwed fittings come unscrewed with very little torsional loading, and the threaded area is greatly thinned, with a sharp stress-riser at the root of the threads. Industry standard - driven by bad experiences - it to not thread anything below Sch 80, and socket-weld anything that leakage would be a big problem.

 

[rmw]

B31.1 is for power piping and is invoked on much more than piping related to boilers. Some plants that have B31.1 power piping don't even have boilers on site.

rmw

 

[pipesnpumps]

What CODE applies, and which STANDARDS does it reference?

If you are an engineer being paid by a client to perform a complete design package, then you need to figure out which codes apply.. Is it NFPA 85 (boiler), or just NFPA 30; Find out if NFPA 85 references NFPA 30. do the ICC codes apply? are there any clients standards that are more stringent than the code?

If you are only concerned with designing for pressure, then the sch.40 would not fail. Look up in ASME B16.3 for its rating or trust the MAWP listed in McMaster Carr.

In the commercial/manuf. world, schedule 40 piping and MI fittings are the fine for something like 70 psig at low temps..particularly since there is no corrosion concern.

Alot of the posters here are into heavy process where all threaded end piping is sch.80, and the threaded fittings spec'd out are also correspondingly thicker... But spec a 3000# fitting in the commercial/manuf. world and you will look like a fool. So your answer all depends on what you are doing..

 

[littletoes]

PipesandPumps is all over it.

Sch 40 is plenty for fuel oil as are threaded fittings/pipe. Socket weld is too excessive for such an application. Costs of Labor and material would kill the job. The installing pipe fitters would think you were crazy.