How to adjust the leakage of pneumatic large diameter ventilation butterfly valve? CTOD fracture toughness test has been used by a large number of domestic welding workers to assess weld safety. During the construction of offshore oil platform, Offshore Oil Engineering Co., Ltd. applied CTOD fracture toughness test to evaluate the low temperature fracture toughness of welds. The test results showed that the fracture toughness values of most samples at low temperature are qualified for EH36 steel welding joints and heat affected zones with three welding techniques, namely, shielded metal arc welding, single wire submerged arc welding and double wire submerged arc welding without post weld heat treatment, The evaluation of welded joints can be used without post weld heat treatment to shorten the manufacturing cycle of offshore platform structures and reduce manufacturing costs. The whole test work has been well received by Philips Oil Company and DNV Det Norske Veritas.
5. Classification by operating temperature
(1) High temperature butterfly valve. Butterfly valve with t<450 ℃.
(2) Medium temperature butterfly valve. 120℃
(3) Normal temperature butterfly valve- 40℃
(4) Low temperature butterfly valve- 100℃
(5) Ultra low temperature butterfly valve. Butterfly valve with t ≤ - 100 ℃.
