A query on EN 13121-3 (European code for FRP tanks and vessels).

[EdClymer]

Greetings

At 10.5.3 there is an equation (78) for critical buckling pressure.

p_cr = 0.242 x E_b x (t/R)² (Eq 78)

Can anyone help with which 't', is it, 't_b' or 't_k'?

Or, is it just another 'typo'?

EN 13121-3 is a 'newish' code (now on fifth edition): knowledge on
this code is in very short supply - hence question on this forum.

Regards


Ed

Ed Clymer
Resinfab & Associates
England

 

[dfoxy]

Hello Ed,

It seems this equation (78) is pretty familiar. I believe it dates back to 1939 in its original form. My notes have 't' as the shell thickness. 'tk' is the knuckle thickness whilst 'tb' seems to be shell thickness. I'd plumb for tb.

Hope this helps.
Dave

PS Not much interest in 13121 here.

 

[EdClymer]

dfoxy

Many thanks.

This equation has a relative in BS4994.

Given that t_b and t_k (dish and knuckle to shell) have different thicknesses;
I will run the equation at both thicknesses and take the worst case. I will use that
as critical buckling pressure p_cr.

Interestingly the word 'buckling' is used in the text; whereas in other parts of part 3, the expression
'fold forces' are used. I think fold forces are a poor translation of 'buckling' - do you have a view?

Regards

Ed



Ed Clymer
Resinfab & Associates
England