2 flange can base of custmers request to according state criterion of hg gb jb ansi jis bs din to smithing also can confirm by pact , because of machining craft of airproof - side , so advice to choose flat weld flange of board form neck form . airproof - sides are all planar airproof form , in order to install pipeline , we can afford volitant flange of flat welding 2法兰可根据用户需要按hg gb jb ansi jis bs din等国家标准，可以是锻造，也可由合同确定，因密封面加工工艺建议选用板式平焊法兰带颈平焊法兰。
