Abstract: An electric resistance welded steel pipe for an automotive part, the pipe comprising a base metal portion and an electric resistance welded portion, wherein the base metal portion has a chemical composition comprising, in terms of % by mass: from 0.42 to 0.48% of C, from 0.01 to 0.20% of Si, from 0.10 to 0.70% of Mn, from 0 to 0.030% of P, from 0 to 0.030% of S, from 0.005 to 0.050% of Al, from 0.005 to 0.040% of Ti, from 0.0005 to 0.0050% of B, and a balance comprising Fe and impurities, wherein a steel structure of the base metal portion is a ferrite-pearlite mixed structure, and wherein the base metal portion has a hardness of from 110 to 150 Hv.

Abstract: To facilitate a preheating operation in a vacuum degassing apparatus having a flow path of a glass melt in an uprising pipe, a vacuum degassing vessel and a downfalling pipe constituted by a refractory material. Flow of a glass melt G between a melting vessel 100 and an upstream pit 210 of a first conducting pipe structure connected to a vacuum degassing vessel 320 is shut off, and in a state where the flow of the glass melt G in a by-pass 500 for the glass melt G is shut off by a first closing means 220, a combustion gas from preheating burners 530, 540 is introduced to the by-pass 500 to preheat the flow path of the glass melt G in an uprising pipe 330, the vacuum degassing vessel 320 and a downfalling pipe 340.