Pick out the wrong statement

• In a flanged and standard dished head, the crown radius is ≤ shell outside diameter.
• In a flanged and shallow dished head, the crown radius is > shell outside diameter.
• Flat head covers are most suitable for larger vessels operating at very high pressure.
• Flanged only head is a type of flat head in which gradual change in the shape at the centre results in reduced local stresses.