A48Y type are usedfor the equipment and pipeline of the with steam and air etc medium what the working temperature are less than 350 . A44Y type are used for the equi-pment and pipeline of the with air and petroleum gas medium what the working temperature are less than 300 , Take for extra pre-ssure protection devices. Flange connecting dimensions of comply with Standard series first of JB/T-94 when the pressure less than 6.4MPa, comply with Standard series two of JB/T-94 when more than 6.4MPa.