Vessel thickness

[steamir]

I'm calculating a nozzle addition and trying to replicate the original vessel thickness for a Section VIII Div 1 vessel built in 1961.

Using the 4.0 safety factor and formula from UG-27 I'm getting a result just short of being acceptable. Vessel was fully radiographed so I'm using an efficiency of 1.0.

Question? Are there any other variables that were different back then that are not used now?

 

[Duwe6]

Are you using the pre-1999 Sect II-D tables, or the Sect VIII 1961 table for material allowable stress?

 

[steamir]

I thought that I clearly answered that by saying that I used the 4.0 safety factor.

I figured out what I was doing wrong. I had added head pressure. This is a propane tank and most likely designed without it. I took it off, now it works.