weld neck reducing flange 1.size: 3/8''~160''. 2.material: ... ,20II,20Mn,304,316L,321 3.standard:HG20592, ASME16.5B, weld neck reducing flange 1.size: 3/8''~160''. 2.material ... , weld neck flanges, socket weld flanges, lap joint flanges, spectacles flanges, ring joint flanges, orifice flanges, long weld neck flanges etc. Weld Neck Flange fitting