B. mm tube diameter; and for > 15 mm tube diameter, tube sheet thickness is smaller than

C. O.D. of the tube is 6 to 40 mm while the tube lengths used are 0.5, 2.5, 3.0, 4.0, 5.0, 6 metres

D. Minimum tube sheet thickness (in which tubes are fixed) is equal to the O.D. of the tube upto

E. Minimum cleaning lane of 6.5 mm is provided, when tubes are on a square pitch

F. e diameter