Dear Sirs,

For large opening calculation of 1-7 and 1-10,
The method of 1-10 have less thickness of nozzle neck and pad than 1-7 method, if applied.

So my question is What is based on those results for determining thickness.

And those have any definite difference of between 1-7 and 1-10 ?

Regards,
SEO

Dear SEO,

Large opening calculation as per 1-7 calculates Membrane stress & bending stress both, The maximum combined membrane stress & bending stress shall not exceed 1.5 times the design stress.

Whereas 1-10 is an alternative method for design of reinforcemnt for large openings in cylindrical vessels under internal pressure. Here it calculates membrane stress only.
But for using 1-10, there are some considerations given in 1-10 under para, "Caution to Designer", which states limit under which we can use 1-10, designer has to ensure that the opening is not falling outside the specified limit.

You can look in to this para.

So according to me this is the possible reason for less thickness in 1-10 compared to 1-7.