Angular tolerance of tank nozzles

[Ahmed Habashy]

Hi
I would like to ask about angular tolerance for nozzles on plan view is there any code define a value like .25 deg or 0.5 deg

 

[Geoff13]

What Code are you asking about? Customer specifications may also give tolerances.

In API 650 nozzle tolerances are listed in 7.5.6.

 

[Ahmed Habashy]

Thanks for your reply i mean api650 or ASME
API650 states tolerance for radial deviation and elevation of 6 mm but not angular

 

[LittleInch]

I think you mean that if you want a nozzle at 35 degrees based on plant or tank North, then what accuracy is prescribed?

In my experience this is down to what your specification and drawing says.

In practice anything less than 1 degree will be really quite hard I think. But specify what you want and let the tank vendor respond.

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

 

[Ahmed Habashy]

Thanks alot i think you mean any thing more than 1 deg will be difficult to accept

 

[Geoff13]

Your tolerance for location should be a dimension, not an angle.

For a 30mØ API tank, a ±1 deg tolerance would be ±260 mm! I'm quite certain you don't want that high a variance.

As you've no doubt already discovered, ASME does not have any nozzle tolerances. You'll have to specify what you want. Using API's would be a good start.

 

[IFRs]

If the piping is there, install nozzle to match the piping.
If the piping is not there, install piping to match the nozzle.
In either case you might want to leave the outside nozzle flange and last pipe flange to be field instlalled as there is some flexibility there that can make up final minor angular differences.

 

[JStephen]

"Flange tilt in any plane" is one of the tolerances listed in API-650, and sounds like that would fit your application, not limited to vertical angles.