1949 Code Allowables 1

[jharris3]

Is anyone aware of the reasons why the 1949 ASME Code dropped the stress allowables?

1943 and 1952 had an allowable stress of 13,750 for SA-285 C for example but in 1949 the allowable was dropped to 11,000.

 

[JEB66]

Just to guess, someone died.

 

[Bobfromoh]

When you multiply 11,000 x 1.25, you get 13,750. There is probably a paragraph in that code that allows you to use the multiplier depending on your requirements. So in the end you still get to use the same alowable stress.

 

[jharris3]

There was not a paragraph that allows the use of 1.25 to increase the allowable for any situation regarding shell thickness.

 

[jte]

Pre World War II factor against ultimate = 5

During the war factor dropped to 4 to save steel.

Post-war the factor raised back to pre-war level.

1950 edition of Section VIII is back to a factor of 4. Presumably not too many war era vessels were experiencing problems and the committee decided that the factor of 4 was sufficient. Until the late 1990's...

jt

 

[jharris3]

Thank You jte!

 

[nuche1973]

jst: Nice response. It is always cool to get the back story on the how and why of the codes we work with.

There are days when I wake up feeling like the dumbest man on the planet, then there are days when I confirm it.

 

[boilerone]

Thanks, Jte.

Just want to add that the current safety factor is 3.5 but not every state of the US nor every other country is accepting it.