US 4,373,754 AGranted

Threaded connector

AssigneeHydril Company

InventorsCharles A. Bollfrass, Leonard S. Landriault, Patrick E. McDonald

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Abstract

A new and improved threaded connector having one or more non-tapered threads on separate diametral steps with at least one flank "hooked" so as to achieve a tensile strength approximately that of the tubular body, is disclosed. The wall thickness of the female member is controlled to improve thread loading and enable inwardly radial movement with the male member to prevent "pulling out" under axial tensile loading. The outer thread step on the male member may only partially engage the threads on the female member such that the critical reduction of the tube wall thickness at the thread roots is a minimum. The resulting threaded connection formed on tubular members has a tensile efficiency in excess of the tube body yield strength and approaching that of the tube body ultimate tensile strength.

Claims20

Dependent claims

A high tensile strength threaded connection for releasably securing separate members by rotational make-up of a threaded male member with a threaded female member along a common longitudinal axis to form the connection, including:

a male member having an external helical thread means formed thereon, said external thread means having a negative angled loading flank relative to the longitudinal axis of the threaded connection;
a female member forming a longitudinal axis and having an internal helical thread means formed thereon, said
a female member having an internal helical thread means formed thereon, said internal thread means also having a negative angled loading flank for engaging said negative angled loading flank of said external thread means formed on said male member;
a first make-up limiting means formed on said male member;
a second make-up limiting means formed on said female member for engagement with said first make-up limiting means formed on said male member for limiting rotational make-up of said helical thread means;
a portion of external thread means having a loading flank of a smaller loading area than the remainder of said external thread means loading flank to minimize the critical reduction of thickness of said male member;
and
said female member having at least a portion thereof of reduced strength relative to the remainder of said female member located adjacent said smaller loading area loading flank of said female member to insure a more uniform distribution of the loading on the negative angled smaller area loading flanks wherein the tensile loading on the thread loading flank is distributed on said male and female members to enhance tensile strength of the threaded connection.

5 more elements

A threaded male member adapted to be rotationally made up with a threaded female member to form a high tensile strength threaded connection, including:

a male member forming a longitudinal axis and having an external helical thread means formed thereon, said external thread means having a negative angled loading flank relative to the longitudinal axis of the threaded male member for engaging a loading flank of a complementary internal helical thread means formed on the female member;
a first make-up limiting means formed on said male member for engagement with a second make-up limiting means formed on the female member for limiting rotational make-up of said helical thread means formed on said male member;
a portion of said external thread means having a loading flank of a smaller loading area than the remainder of said external thread means loading flank for engaging a smaller loading flank portion of the female member thread means and to minimize the critical reduction of thickness of said male member;
and
said smaller loading area flanks adapted for mating with a reduced strength portion of the female member to enable elastic strain of the female member of said portion relative to the remainder of said female member to insure uniform distribution of the tensile loading on the negative angled smaller area loading flanks of the male member wherein the tensile loading on the thread loading flanks of the male member is more uniformly distributed on the female member to enhance tensile strength of the formed threaded connection.

2 more elements

A threaded female member adapted to be rotationally made up with a threaded male member to form a high tensile strength threaded connection, including:

a female member forming a longitudinal axis and having an internal helical thread means formed thereon, said internal thread means having a negative angled loading flank relative to the longitudinal axis of the threaded female member for engaging complementary loading flanks of a small and a large loading flank area on a complementary external helical thread means formed on the male member;
a first make-up limiting means formed on said female member for engagement with a second make-up limiting means formed on the male member for limiting rotational make-up of said helical thread means formed on said female member;
and
said female member having a reduced strength portion relative to the remainder of said female member to enable longitudinal elastic strain of the female member to insure a more uniform distribution of the tensile loading on the negative angled smaller loading area flanks of the male member to minimize the critical reduction of thickness of the male member adjacent said external helical thread means wherein the tensile loading flanks of said female member is more uniformly distributed to enhance tensile strength of the formed threaded connection.

1 more element

Dependencies are inferred from the claim text.