Pipe Nozzle Loads for Water Tank 1

[sdz]

I have been asked to design /check a range of nozzle connections to water tanks, similar to the picture. This is a bolted corrugated water tank with ~2m head at the nozzle. Ideally the pipework is meant to be independently supported so the nozzle connection should not have to support significant pipe weight. Size is 150mm NB.
I think possible sources of loads could be static water pressure, flow loads, water hammer, someone standing on a fitting, ground movements (expansive soils).
So far I haven’t been able to find any recommendations appropriate to this sort of tank.

What we have here is a 150mm NB flanged fitting. A flat plate ~2mm thick is bolted to the inside of the tank with a loose flange on the inside. The tank has a liner so gaps between the flat plate and the corrugated wall don't matter.

 

[JStephen]

I'm not aware of any standards governing a corrugated tank like this.
Generally, in the municipal waterworks industry, neither piping nor nozzles are evaluated for mechanical loads (ie, bending moment, etc), unlike certain industrial applications.
There are recommendations in the tank standards (and I think in ASCE 7) for recommended amounts of flexibility in attached piping to allow for seismic movement of tanks.
In the tank standards, there are requirements for reinforcing nozzles for the hoop stress occurring in the shell. However, for a small tank, this is quite often fulfilled entirely by excess plate thickness already available in the shell, and doesn't imply a separate reinforcement.
Slip-on or mechanical joints, or flexible couplings, may not include thrust restraint for the fitting. On an inlet riser on a tank, it is fairly common to omit the thrust restraint, assuming the weight of the tank furnishes adequate thrust restraint. This will normally be true for actual operating pressure, but may be hard to justify for the rated pressure of the line.

 

[1503-44]

Nozzle loads are typically addressed in tank, pressure vessel and piping specs.
Do you have a tank design specification?

https://communities.bentley.com/pro...pressure-thrust-on-nozzles-in-autopipe-nozzle

http://www.api620steel.com/products/api-650-storage-tank/

https://www.fs.fed.us/eng/pubs/html/02511318/02511318.htm

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[LittleInch]

If you don't have a value, the most tank nozzles can only just about carry their own weight, never mind any other connected loads or moments.

Assume virtually zero for all thos Fx, Fy, Fz and Mx,y,z and you'll be good.

Providing a high level of flexibility of the connecting pipework ( flexible hose come in very handy) is a must.

Tanks just really don't like nozzle loads.

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

 

[HTURKAK]

Bolted corrugated tank wall bending and axia load stiffness is negligible.. The piping should be self standing ..( provide necessary pipe supports to avoid moment transfer to the tank shell..).

 

[sdz]

@1503-44, I have API650, AS2304, and AWWA D103. API 650 has reinforcement requirements for nozzles but those are not applicable for a corrugated water tank.

 

[sdz]

Thanks for your comments. It seems that the reason I couldn't find any design loads is because there aren't any. The tank manufacturer has not supplied any loads.
Probably the worst likely load is someone standing on a nozzle, 'cause I just need to that little bit higher. This would be a 1.1kN load load at say 2xNB cantilever, or 300mm, giving a moment of 0.33kNm=330Nm, which is a pretty small load. I'll put this to the manufacturer and see what they say.

 

[LittleInch]

To be honest I wouldn't even let a 110kg person stand on one of those nozzles....

50kg maybe.

It's probably worse if the tank is empty as the water pressure will try and keep the tank circular.

Maybe it's the photo but it doesn't even look like those bolts are in the flat spot of the corrugation? so there is some local deformation as they've tightened it up.

I suspect the tank mfr is not going to accept any loads. At least not in writing.

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