oilfield flange 1)size:1/2" - 48" 2)service:OEM 3)certificate:ISO9001:2000,API 4)standard:DIN, API 6A etc oilfield flangeTechnical specification1)size:1/2" - 48"2)service:OEM3)certificate:ISO9001:2000,API4)standard:DIN, API 6A etc 5)used on wellhead6)producing method: forged