If it is under scope of ASME Sec VIII-Div 1 see 'Table UG-45 Nozzle Minimum Thickness Requirements'

Engineers, think what we have done to the environment !https://www.linkedin.com/in/goutam-das-59743b30/

You need to see what standard the tanks were made. See API 620 and API 650 for advice

How big is this tank and what is the "code of record" for the tank ?

Was there a "corrosion allowance" specified for the tank ?

Generally speaking, for ASME-VIII pressure vessels and boiler components, common practice is to have nozzles constructed with a wall thickness MUCH GREATER THAN the adjoining vessel/boiler wall...... In other words, just the pressure developed stresses do not determine wall thickness.

The reason for this is to allow the adjoining piping system to impose reasonable reaction loads on the vessel without making the nozzle to shell joint itself the weakest part of the system.

Furthermore, on larger nozzles, pressure vessel codes require an evaluation of "pressure reinforcement area" which governs the design.

https://www.eng-tips.com/viewthread.cfm?qid=352733

I have worked for consulting firms where policy was no nozzle neck on new construction shall be less than Schedule 80 piping thickness ..

Theoretically, you may get by with your ultra thin nozzle neck ........ but only if there is zero corrosion allowance, atmospheric design pressure and there are zero reactions from adjoining piping systems.

More information = better answers ....

MJCronin
Sr. Process Engineer

For pressure vessels, see the pressure vessel code in question (ASME, etc.)
For atmospheric storage tanks built to a specific code, see the code in question (API 650/620, UL-142, etc).
There are a lot of small non-code tanks also built, and there are no specific requirements on them.

DEAR Asif Khan (Mechanical),
Just curious and not sure what is special for your thread .. If the tanks are atmospheric ,you may look API 650 Table 5-6a , You will see the dimensions for Shell Nozzles.

Moreover , if you write nozzle and search the forum, there are 6,194 records …
Or write nozzle thickness ; there are 229 records..
Or write self reinforcing nozzles ; there are 50 records..

I am sure one of threads will be answer to your question..