butt-welding equal-diameter and reducing-diamater bend standard:GB,ISO,ANSI ,JIS,DIN butt-welding equal-diameter and reducing-diamater bend 45/90/180 degree seamless an welding standard:GB,ISO,ANSI ,JIS,DIN1 size:1/2"-72"2 type : Long-radius or short-radius3 shape: equal-diameter or reducing diameter4 thechnics: seamless or welding5 standard:GB,HGJ,SHJ,SY,DL,ISO,ANSI ,JIS,and DIN6 wall: STD , ...