Highly corrosion resistant zirconium alloy pipe

The zirconium alloy pipes are used in BWR or PWR type reactor and further improved corrosion resistance by having alloy tissues different between inner and outer sides which has been attempted so far. From 5 to 30% of the thickness of the outer circumferential portion of the tube is constituted with recrystallized tissues or partially crystallized tissues, and the remaining inner portion is constituted with strain-removed tissues. Further, the tube is constituted with a first tube and a second tube disposed at the outer side of the first tube and having a wall thickness of from 5 to 25% of the first tube. The first tube comprises, on the weight bases, 1.20 to 1.70% of Sn, 0.10 to 0.50% of Fe, 0.05 to 0.30% of Cr, 0.090 to 0.16% of oxygen, 0.0080 to 0.0120% of Si, and substantial balance of Zr and impurities. The second tube comprises, on the weight bases, 0.30 to 1.00% of Sn, 0.10 to 0.30% of Fe, 0.05 to 0.20% of Cr, 0.05 to 1.0% of Nb, 0.003 to 0.1% of Ni, 0.0080 to 0.0180% of Si, 0.090 to 0.16% of oxygen and substantially balance of Zr and inevitable impurities. With such a constitution, a tube having improved with the corrosion resistance can be obtained. (T.M.)