Welding of steel with propane-oxygen flame became possible, when both the enriched oxygen flame and the welding rod containing sufficient deoxydizing elements were used.
The objects of this investigation are to find out the proper ratio of volumetric flow rate of oxygen to propane in propane-oxygen flame for the greatest flame intensity to melt steel plate, and to find out another way to increase the intensity of the propane-oxygen flame. The intensity of flame was experimentally evaluated with the time to start meltintg in the same way described in the previous report.
Three kinds of improved flames were examined as below.
i) Thermal cracked propane-oxygen flame : propane begins to convert into hydrogen, methane, ethylene and propylen by thermal cracking at 600°C and is cracked completely at 900°C,
ii) preheated propane-oxygen flame: the burning velocity of propan oxygen gas mixture becomes high by preheating under 550°C, and iii) propane-acetylene-oxygen flame: in place of a part of propane is added acetylen having higher burning velocity than propane.
The results were shown as follows;
1) The effect of preheating on an increment of intensity of flame is the greatest of those of any other flames. The effect is obtained at lower preheating temperature than thermal cracking temperature.
2) Each minimum time to start melting of the propane-oxygen flame and three improved flames with various flow rate of oxygen is obtained at the location inside the inner cone with a stoichiometrical oxygen mixture for complete combustion.
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