Abstract: A heat exchange tube useful as a reactor tube for producing ethylene and highly improved in heat transfer efficiency has fins formed on the inner surface of wall of the tube in one or a plurality of regions or all regions arranged from an inlet end of the tube to an outlet end thereof axially of the tube. The fins are positioned in a direction intersecting the axis of the tube and have a suitable pitch. The fins are formed by a projection helically extending on the tube wall inner surface around the axis or are each in the form of an annular projection circumferentially extending on the inner surface in a direction intersecting the axis at right angles therewith. The pitch of the fins, the angle of intersection of the fins with the axis and the height of the fins are suitably determined in conformity with the inside diameter of the tube.

Abstract: 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.

Abstract: A method of ultrasonic flaw detection of a pipe comprises comparing ultrasonic waves passing through a test piece portion with the arithmetic means of ultrasonic waves passing through portions adjacent each side of the test portion. The comparison is made around the entire periphery of a pipe, for example, an austenic heat resisting cast steel pipe used as a hydrogen manufacturing reformer tube. This method is free from adverse influence of macrostructures unevenly distributed in the peripheral direction of the pipe, and enables a quantitative grasp of flaws in a base material and a weld of the pipe.

Abstract: A reactor tube for thermally cracking or reforming hydrocarbons comprising a tube member made of Fe-Cr-Ni heat resisting material and a covering layer of self-fluxing alloy fusing to the inner surface of the tube member, the covering layer made of heat resisting material free from Ni or with a low Ni content. The tube member is manufactured by centrifugal casting, and the covering layer is formed by applying the self-fluxing alloy powder by scattering with or without thermit agent or spraying the alloy to the inner surface of the tube member.

Abstract: A method of ultrasonic flaw detection of a pipe, worth particularly for instance for a heater pipe as is used for catalytic gas reforming with steam. A transmitter probe and a receiver probe are disposed on the pipe outer surface with suitable spacing one from the other both in axial or longitudinal direction and in peripheral direction of the pipe. The transmitter probe launches ultrasonic radiation under proper angle of incidence upon the pipe outer surface at the point of entering material of the pipe, to be refracted under a particular angle of refraction so that it may then pass through the material of the pipe straight to another point upon the pipe outer surface. The receiver probe receives the ultrasonic radiation transmission echo. Flaw in the material of the pipe is detected from fluctuation of the echo, as seen upon scanning the pipe surface by moving the transmitter and receiver probes.

Abstract: A heat resistant cast iron-nickel-chromium alloy outstanding in creep fracture strength at high temperatures and resistance to thermal shock and to carburizing and containing the following components in the following proportions in terms of % by weight:C:0.3-0.6,O<Si.ltoreq.2.0,O<Mn.ltoreq.2.0,Cr:20-30,Ni:30-40,Nb+Ta:0.3-1.5,N:0.04-0.15,B:0.0002-0.004,Ti:0.04-0.50 and0.07<Al.ltoreq.0.50the balance being substantially Fe.

Abstract: A reactor tube for thermally cracking or reforming of hydrocarbons wherein a reacting layer contacting hydrocarbons is made of heat resisting steel comprising, in terms of % by weight, 0.3 to 1.5% C, up to 3% Si, 6 to 15% Mn, 20 to 30% Cr, up to 3% Nb, up to 0.15% N, the balance being substantially Fe and a covering layer which covers the said reacting layer is made of Fe-Cr-Ni heat resisting steel and is fused to the reacting layer at their boundary.

Abstract: A heat resistant alloy excellent in bending property and ductility after aging, comprising 0.12 to 0.33% (by weight, the same as hereinafter) of C, less than 1.2% of Si, less than 1.5% of Mn, 23 to 25% of Cr, 37 to 40% of Ni, 0.5 to 1.8% of Nb and 0.04 to 0.15% of N, the balance being substantially Fe and unavoidable impurities, with the mutual relationship of C and Si contents represented by the range indicated by hatching in FIG. 1, which may be manufactured into tubes by centrifugal casting, to be used as deformed tubes after bending.

Abstract: A reactor tube for thermally cracking or reforming hydrocarbons comprising an outer tube member made of Ni-containing heat resisting material and having enhanced mechanical strength with a large wall thickness, and an inner tube member of small wall thickness fitted in the outer tube member and made of heat resisting material free from Ni or with a low Ni content. The inner and outer tube members have been subjected to a diffusion treatment with a thin coating of Ni-P solid solution provided at the junction therebetween and thereby bonded together.

Abstract: A heat resistant cast iron-nickel-chromium alloy outstanding in creep fracture strength at high temperatures and resistance to thermal shock and to carburizing and containing the following components in the following proportions in terms of % by weight:C: 0.3-0.6,O<Si.ltoreq.2.0,O<Mn.ltoreq.2.0,Cr: 20-30,Ni: 30-40,W: 0.5-5.0,N: 0.04-0.15,B: 0.0002-0.004,Ti: 0.04-0.50 and0.07<Al.ltoreq.0.50the balance being substantially Fe.

Abstract: An iron-based heat-resistant cast alloy for high-temperature, high-pressure pipe, consisting essentially of, by weight %,______________________________________ C 0.10 to 0.16 1.0 .gtoreq. Si > 0 1.5 .gtoreq. Mn > 0 Cr 17 to 23 Ni 28 to 35 Nb 0.3 to 2.0 0.1 .gtoreq. Mo .gtoreq. 0 0.08 .gtoreq. N .gtoreq. 0 ______________________________________One or two or more kinds of: ______________________________________ B 0.001 to 0.080 Ti 0.011 to 0.02 Ca 0.001 to 0.01 Ce and/or La 0.001 to 0.01 Zr 0.01 to 0.10 Fe balance.

Abstract: A heat resistant cast iron-nickel-chromium alloy outstanding in creep fracture strength at high temperatures and resistance to thermal shock and to carburizing and containing the following components in the following proportions in terms of % by weight:______________________________________ C 0.3-0.6, O < Si .ltoreq. 2.0, O < Mn .ltoreq. 2.0, Cr 20-30, Ni 30-40, Nb + Ta 0.3-1.5, N 0.04-0.15, B 0.0002-0.004, Ti 0.04-0.50 and Al 0.02-0.50, ______________________________________the balance being substantially Fe.

Abstract: A heat resistant cast iron-nickel-chromium alloy outstanding in creep fracture strength at high temperatures and resistance to thermal shock and to carburizing and containing the following components in the following proportions in terms of % by weight:C--0.3-0.6,O<Si.ltoreq.2.0,O<Mn.ltoreq.2.0,Cr--20-30,Ni--30-40,Nb+Ta 0.3-1.5,W--0.5-3.0,N--0.04-0.15,B--0.0002-0.004,Ti--0.04-0.50 andAl--0.02-0.50,the steel further containing 0.2 to 0.8% by weight of Mo when so desired, the balance being substantially Fe.

Abstract: A heat resistant cast iron-nickel-chromium alloy outstanding in creep fracture strength at high temperatures and resistance to thermal shock and to carburizing and containing the following components in the following proportions in terms of % by weight:C--0.3-0.6,O<Si.ltoreq.2.0,O<Mn.ltoreq.2.0,Cr--20-30,Ni--30-40,W--0.5-5.0N--0.04-0.15,B--0.0002-0.004,Ti--0.04-0.50 andAl--0.02-0.50,the balance being substantially Fe.

Abstract: A heat resistant cast alloy for uses in as high a temperature range as around 1,100.degree. C., having high resistances to oxidation and cementation and high creep-rupture strength, which alloy consists of following components, as represented on weight basis: C, 0.35.about.0.6%; Si, 1.58.about.2.5%; Mn, 0.3.about.0.9%; Cr, 24.about.28%; Ni, 30.about.38%; W, 2.about.6%; N, 0.07.about.0.3%; P<0.04% and S<0.04%; and balance, substantially Fe.