(a) 
         A wrinkle bend may not be made on steel pipe to be operated at a pressure that produces a hoop stress of 30 percent, or more, of SMYS.
     
    
        
        (b) 
         Each wrinkle bend on steel pipe must comply with the following:
     
    
        
        (1) 
         The bend must not have any sharp kinks.
     
    
        
        (2) 
         When measured along the crotch of the bend, the wrinkles must be a distance of at least one pipe diameter.
     
    
        
        (3) 
         On pipe 16 inches (406 millimeters) or larger in diameter, the bend may not have a deflection of more than 1 1/2 ° for each wrinkle.
     
    
        
        (4) 
         On pipe containing a longitudinal weld the longitudinal seam must be as near as practicable to the neutral axis of the bend.
     
    [35 FR 13257, Aug. 19, 1970, as amended by Amdt. 192-85, 63 FR 37503, July 13, 1998]