How to calculate required wall thickness for square duct

[CobusvanJ]

Can anyone point me in the right direction on how to calculate the thickness required due to pressure for a square duct. Pressure is extremely low, 5kPa/-2kPa. We need to add nozzles to it so I just have to make sure that the reinforcement calcs are done correctly.

 

[DriveMeNuts]

Putting a nozzle in the flat side of a square duct isn't something which is covered by any code rules.
I think it would be possible to develop a hand calc from fundamental principles. Otherwise a more in-depth analysis is required.

 

[LittleInch]

Any thickness calc at that pressure (50 mbar) will give you fractions of a mm. Structural issues will predominate.

Most "ducts" are very thin sheet steel, but people make connections for them surely.

If you add as much steel as you're removing from the hole immeadaitely around the hole you cut out you're half way there.

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

 

[r6155]

See:
1)International Mechanical Code Chapter 5
2)NFPA National Fuel Gas Code
3)UL 1738 Standard for Safety Venting Systems...

Regards

 

[FacEngrPE]

This sounds like it might be within the range of pressures covered by "Rectangular Industrial Duct Construction Standards" By SMACNA

https://www.smacna.org/store/product/rectangular-industrial-duct-construction-standards

 

[SnTMan]

And how not to: ASME Sec VIII Div 1, Apx 13

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[goutam_freelance]

More important here will be support loads on ducts and related buckling, insulation loads, if any etc.

Engineers, think what we have done to the environment !

https://www.linkedin.com/in/goutam-das-59743b30/

 

[HTURKAK]

You did not mention the size of the duct.. But the low pressure implies better to go with
ASCE Structural Design of Air and Gas Ducts for Power Stations and Industrial Boiler Applications

https://sp360.asce.org/PersonifyEbusiness/Merchandise/Product-Details/productId/268268603