242 Insulation bore size (mm) COPPER PIPE STEEL PIPE PLASTIC PIPE OD (mm) OD (inch) Nominal Ø (DN) OD (mm) OD (inch) OD (mm) 6 6 1/4 6 10 10 3/8 6 10.2 1/8 10 12 12 1/2 12 15 15 5/8 8 13.5 1/4 18 18 3/4 10 17.2 3/8 16 20 19 3/4 20 22 22 7/8 15 21.3 1/2 28 28 1 1/8 20 26.9 3/4 25 35 35 1 3/8 25 33.7 1 42 42 1 5/8 32 42.4 1 1/4 40 48 48 1 7/8 40 48.3 1 1/2 54 54 2 1/8 50 60 60 2 5/8 50 60.3 2 67 67 2 5/8 63 76 76 3 65 76.1 2 1/2 75 80 80 3 1/8 89 89 3 1/2 80 88.9 3 93 92 3 5/8 90 108 108 4 1/4 114 114 4 1/2 100 114.3 4 110 Sheet required 125 133 125 139.7 5 140 159 160 150 168.3 6 180 219 200 219.1 8 225 250 267 250 273 10 280 315 300 329.9 12 350 355.6 14 355 400 406.4 16 400 450 457 18 500 508 20 600 610 24