Loose flange type flare tube fittings, steel pipe for loose flange type flare tube fittings, manufacturing methods and steel pipe joining method of steel pipe for loose flange type flare tube fittings

摘要

PROBLEM TO BE SOLVED: To improve sealing performance when stress is apllied to a loose flange type flared pipe coupling, repeatedly in particular.;SOLUTION: This loose flange type flared pipe coupling makes loose flanges 4 engaged with flare parts 2 formed by flange-processing the end of a steel pipe 1, causing the end surfaces of the flare parts 2 to abut on each other by interposing a gasket 3, and also causing an abutment part to be sandwiched between the loose flanges 4 to be mechanically fastened, wherein a flare part end surface angle θ[°] between the end surface of the flare part 2 and the axis of the steel pipe 1, and a corner curvature radius R [mm] between the flare part 2 and steel pipe 1, satisfy the expression: 87≤θ≤0.88ln(R)+89.3. The excellent sealing performance is thus provided.;COPYRIGHT: (C)2010,JPO&INPIT