Nippon Steel Corporation

Kotaro Yoshida

Mikio Yamanaka

Satoshi Kado

Taketomo Yamazaki

Katsuhiko Yabe

Michio Kawai

Teruo Michishita

Tetsu Sakamoto

Makoto Kawakami

Yasuyuki Taniguchi

Yasuhira Takeshi

The tendons of a tension leg platform (TLP) used for producing petroleum offshore at a depth of 400-1000 m are protected against fatigue corrosion which mainly determines the life of the tendons. The straight steel pipes (1) have an insulative, corrosion-protection coating (8) having good damage resistance. The screw couplings (2) have a sprayed aluminum layer (9) having the ends contiguous to the ends of the insulative, corrosion-protection, and a galvanic current anode (5) is electrically connected to the screw coupling (2).

Tendon of TLP and electrical corrosion protecting method of the same

An austenitic heat-resistant steel which forms an oxide film mainly composed of Al.sub.2 O.sub.3 in a high-temperature oxidizing atmosphere, consisting essentially of not more than 0.2% of C, not more than 1.0% of Si, not more than 2.0% of Mn, 12 to 37% of Ni, 9 to 25% of Cr, more than 4.5 but not more than 6% of Al, and at least one member selected from the group consisting of Ti, Nb and Zr in a total amount of not more than 0.8%, with the balance being Fe; the .delta.-ferrite value of this steel, calculated from the formula set forth below, is from 0 to 7.9; this steel is removed of an internal oxide layer which has been formed just below the steel surface during hot working. ##EQU1## where Wi and Mi represent, respectively, the percent by weight and the atomic weight of Ti, Nb and Zr, and when the term ##EQU2## is negative this term is regarded as zero. This steel composition may contain one or more rare earth elements such as Y, Ce and La in a total amount of not more than 0.08%.

Austenitic heat-resistant steel which forms Al.sub.2 O.sub.3 film in

A ferritic stainless steel having high toughness both in the weld zone and the base metal comprising:

Ferritic stainless steel having excellent workability and high toughness

Growing community of inventors

Sagamihara, Japan

Kotaro Yoshida