Kubota Corporation

Masahiro Inui

Junichi Sugitani

Kenji Otsubo

Teruo Yoshimoto

Koji Tsuchida

Kaoru Hamada

A cracking tube () for use in thermal cracking furnaces for producing ethylene or the like has fins () formed on an inner surface thereof and inclined with respect to an axis of the tube for stirring a fluid inside the tube. The fins are arranged discretely on one or a plurality of helical loci, and the tube inner surface has regions (Z) wherein no fins are present over the entire axial length of the tube from one axial end of the tube to the other axial end thereof.

Cracking tube having helical fins

A heat-resistant alloy having a high creep rupture strength under high-temperature low-stress conditions and excellent resistance to carburization even when used at a high temperature exceeding 1100.degree. C. The alloy comprises, in % by weight, more than 0.1% to less than 1.5% of C, more than 2% to less than 3% of Si, more than 0% to less than 2% of Mn, more than 20% to less than 30% of Cr, more than 25% to less than 40% of Ni, more than 0.6% to less than 2% of Al, and the balance Fe and inevitable impurities. When required, the alloy contains at least one component selected from the group consisting of 0.01 to 0.5% of Zr, up to 0.2% of N, 0.2 to 2.0% of Nb, 0.2 to 2.0% of W and 0.01 to 03% of Ti.

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Takarazuka, Japan

Masahiro Inui