Welding issues in fuel industrial boiler tubes
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Let’s first provide a brief overview of the boilers we have purchased: Design parameters: two sets of 45t/h fuel-fired industrial boilers, with dual boiler drums; combustion takes place at slightly positive pressure. The feedwater temperature is 110 degrees, the rated steam pressure is 6.4 Mpa, and the rated steam temperature is 280 degrees； Fuel: Heavy oil, rated at 2930 kg/h ； Materials: The inner diameter of the upper drum is Ф1200 with a wall thickness of δ=65mm; the inner diameter of the lower drum is Ф900 with a wall thickness of δ=48mm. The distance between the centerlines of the two drums is 3000mm. The straight section length of the upper drum’s body is 9000mm, and that of the lower drum’s body is also 9000mm. The material used in both drums is SA515.Gr.70 ； Convection tubes: Made of tubes with a diameter of f51´4.5; they are arranged between the upper and lower drum, the water-cooled walls on the partition, and the membrane-type water-cooled wall on the right side. Their upper and lower ends are joined by expansion joints to the upper and lower drums, with a total number of tubes exceeding 3,000 ； The issue now is that, according to several engineers in our company, the reliability of the expansion jointing process for convective tubes is lower than that of processes involving expansion followed by welding or direct welding. However, the manufacturer insists on using welding. According to **relevant standards, boiler expansion joints can meet the required performance standards, but certain requirements exist regarding the equipment and processes used for expansion jointing. The construction contractor also stated that it would be difficult to ensure the construction quality if the expansion jointing equipment could not be guaranteed. I hope everyone can offer some suggestions and advice regarding the expansion bonding or welding of furnace tubes. Thank you all in advance!
In our company, we first perform expansion welding and then welding. Although the expansion joining process is feasible and simpler than welding, its reliability is somewhat lower; it is difficult to ensure quality, and it requires high precision in drilling. In my opinion, welding is still the better choice. Looking forward to expert explanations. . I’ve also wanted to ask this question for a while; it’s a good question. By the way, if copper pipes and stainless steel sheets are to be welded, what are the requirements in terms of welding techniques? Is brazing or TIG welding feasible, and what are the specific procedures? Does electrochemical corrosion occur when copper and stainless steel are first placed in boiler water? How severe is this corrosion, and how can it be prevented? This post was last edited by tomkan00 on 2009-2-26 09:07.]