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 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 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.