Patent ID: 6851727

Claim:
A threaded joint for pipes defining an axis ( 21 ), comprising a coaxial male member ( 1 ) consisting of a pipe provided with a threading on a portion of its outer surface in proximity of at least one of its ends ( 13 ) and a female coaxial member ( 2 ), consisting of a pipe or sleeve provided with threading on a portion of its inner surface in proximity of at least one of its ends ( 14 ), wherein the male member ( 1 ) is provided with a cylindrical portion, intermediate between its ends having walls of a constant thickness and wherein the male member is provided at said at least one of its ends ( 14 ) with an annular abutment surface ( 9 ) and wherein a corresponding annular abutment surface ( 10 ) is formed on the inside of the female member ( 2 ), said threadings being adapted to screw on reciprocally and reversibly to produce a contact between said annular abutment surfaces ( 9 , 10 ), said threadings being complementary and wherein the thread profile, in a section along a plane containing the axis ( 21 ), defines a load flank ( 4 , 3 ) forming a first angle (α) with respect to a plane perpendicular to the axis ( 21 ) and defines a lead-in flank ( 6 , 5 ) forming a second angle (β) with respect to a plane perpendicular to the axis ( 21 ), characterized in that said second angle (β) has a value between 10 and 25°, and in that when the joint is assembled and the contact between said annular abutment surfaces ( 9 , 10 ) is achieved, in absence of axial loads, there is provided, between the lead-in flank ( 6 ) of the threading formed on the male member and that ( 5 ) of the thread made on the female member, a gap of a size between 0.01 and 0.12 mm, measured along a direction parallel to the axis ( 21 ) of the joint, and in that the internal diameter (D 3 ) and external diameter (D 4 ) of the cylindrical length of said male member ( 1 ), the internal diameter (D 1 ) and external diameter (D 2 ) of the abutment surface of the female member being linked in the relationship (D 2 2 −D 1 2 )/(D 4 2 −D 3 2 )≧0.5.