Pick out the wrong statement.

A. For a pressure vessel to be classified as 'thin vessel', the ratio of wall thickness to mean radius is less than 0.1

B. For calculating forces and efficiency of rivetted joint, either rivet diameter or rivet hole diameter is used in case of pressure vessel and in structural work

C. Longitudinal joint is normally made butt joint to maintain the circularity of the vessel

D. Maximum diameter of the opening provided in a pressure vessel, which does not require any compensation is 200 mm

Answer: Option B