Models View all Flange ___-__-01-1-B-St.20-IV GOST R 54432-2011 1 73 0 Concentric transition GOST 17378-2001 3 50 0 T-piece GOST 17376-2001 0 97 0 withdrawal GOST 17375-2001 1 30 0 Ventilation elbow 9 265 0 Ventilation duct 9 317 0