Single-walled per EN 12285-1 
or DIN 6608-1 and
DIN 6616

Double-walled per
EN 12285-1 or DIN 6608-2
and DIN 6616

CR = D_o
KR ≥ ~ 1/30 D_o

Technical explanations

D₀ = external head diameter
D_i = internal head diameter
CR = crown radius
KR = knuckle radius
SF = straight flange height
DH = depth of dishing
TH_i = total internal head height
t = wall thickness