Sumitomo Metal Industries, Inc.

Vallourec & Mannesmann Oil & Gas France

Takahiro Takano

Masaaki Sugino

Shigeo Nagasaku

Suguru Yamaguchi

Masaru Izawa

Takahiro Hamamoto

Noriko Ujita, Legal Representative

Mituo Watanabe

Kunio Godo

Yoshihisa Ujita

A threaded joint for steel pipes comprising a pinhaving a tapered male thread, a tapered sealing surface, and an end shoulder surfaceand a boxhaving correspondingly a tapered female thread, a tapered sealing surface, and a shoulder surfacewhich is capable of easy tightening and has improved air tightness by the sealing surfaces is arranged such that the pin and the box each have a noncontacting region B where the peripheral surfaces of the pin and the box do not contact each other between the sealing surfacesand the shoulder surfacesand. At least a portion of the noncontacting region of the pin adjoining the to end of the pin is a tapered surface portionhaving substantially the same angle of slope as the tapered sealing surface, and the noncontacting region of the box is a substantially cylindrical surface.

Threaded joint for steel pipes

By subjecting a threaded joint for OCTG (oil country tubular goods) to surface conditioning with an aqueous solution of potassium tetraborate or sodium tetraborate prior to manganese phosphate chemical conversion treatment, a manganese phosphate chemical conversion coating having coarse crystal grains with an average crystal grain diameter of 10-110 micrometers is formed on the surface of the steel member which may be any steel including a high Cr steel. This manganese phosphate chemical conversion coating can hold a large amount of a liquid lubricant, and it is effective at preventing the occurrence of galling at the time of makeup of a threaded joint for OCTG.

Surface conditioning prior to chemical conversion treatment of a steel member

A thread protector for protecting threads of a pipe includes a body having female or male threads shaped for threaded engagement with male or female threads formed on a pin or box end of a pipe. An elastically flexible annular sealing projection extends from the body to a location where it will be elastically flexed by and in line contact with an end surface of the pipe when the threads of the protector are engaged with the threads of the pipe. The thread protector can protect the threads of a pipe against deposition of dirt and against rusting without application of grease.

Thread protector for a pipe

A method and apparatus for surface treating metal pipes includes introducing a treatment liquid into a first distribution chamber having a flat bottom surface, and dropping the treatment liquid onto at least a portion of the outer peripheral surface of the metal pipe through a plurality of holes formed in the bottom surface of the first distribution chamber. Preferably, a distance between the bottom surface of the first distribution chamber and the metal pipe is maintained constant as the outer diameter of the pipe varies. The treatment liquid may be introduced into a second distribution chamber having a flat bottom surface, and the treatment liquid may then be introduced into the first distribution chamber through a plurality of holes formed in the bottom surface of the second distribution chamber. It is possible for the first distribution chamber to simultaneously drop the treatment liquid onto at least two metal pipes.

Method for surface treatment of metal pipes

Growing community of inventors

Wakayama, Japan

Takahiro Takano