Welding and butt welding flange are backing ring with two ring lining. When the equipment is made of stainless steel, the carbon steel flange 7 and stainless steel lining ring can save the stainless steel.
When flange size is determined by flange standard, the nominal diameter and nominal pressure of flange must be known. The nominal diameter of the pressure vessel flange is the same number as the nominal diameter of the pressure vessel. For example, the DN 1000mm pressure vessel shall be fitted with the DN 1000mm pressure vessel flange.
The nominal pressure of the flange is determined by the maximum operating pressure of the flange, the operating temperature, and the flange material. Because the flange size series and flange thickness are calculated, the mechanical performance of 16MnR at 200 DEG C is based on the standard. Therefore, the flange size determined by this benchmark shall be considered as the nominal pressure of the dimension flange at the maximum allowable operating pressure at 200 degrees c.. For example, the flange, which is called nominal pressure PNO.6MPa, refers to a flange having such a specific dimension, which is made of 16MnR, and its maximum allowable operating pressure at 200 DEG C is 0.6MPa. If the flange of this PN0.6MPa is applied to a condition higher than 200 DEG C, its maximum operating pressure will be below its nominal pressure 0.6MPa. On the other hand, if it is used under the condition of less than 200 DEG C, the maximum working pressure is still determined at 200 DEG C. If the flange material is changed to Q235-A, then the mechanical properties of Q235 steel A is worse than 16MnR, the nominal pressure PN0.6MPa of the flange, even if it is operating at 200 DEG C, the maximum allowable operating pressure it will be lower than its nominal pressure. On the contrary, if the flange material changed from 16MnR to 15MnVR, then, because of the mechanical properties of 15MnVR is better than 16MnR, the nominal pressure PN0.6MPa of the flange, 200 degrees in the operation, the maximum allowable operating pressure will be higher than its nominal pressure.
In short, as long as the flange nominal diameter, nominal pressure is determined, the size of the flange will be determined. As for the maximum operating pressure allowed by this flange, it depends on the operating temperature of the flange and what material it is made of. The flange material specified in the pressure vessel flange standard is low carbon steel (Q235-A, 20g, etc.) and general low steel (16Mn, 16MnR and 15MnVR etc.)