Pipe elbow

　　Pipe elbow is divided into straight and non-straight section, it is recommended to use a straight section of the structure. The basic size of the elbow is to ensure that the product must ensure that the parameters, including straight length, angle, inside and outside the wall thickness, roundness and the radius of curvature of the arc, the size of the deviation and the interface position tolerance. The minimum internal diameter of the elbow shall be such that the flow area is equal to that of the pipe and shall not be less than 90% of the area of the pipe. The length of the straight section of the elbow shall be greater than the sum of the axial length of the end face groove and the size of the transition area. The angle deviation of elbow shall not be more than 0.5. , The roundness of the bent part should be less than 506. DN400 above the low pressure elbow roundness can be less than 7%.