Uses of lighter, stronger, reliable and cheaper welded steel structures are constant trends. There is a various industrial application where structural steels with higher strength replace conventional low strength structural steels. This paper will outline basic comparison of three type of structural steel selection influence on total welding fabrication costs of atmospheric oil storage steel tanks (design and fabrication according to API 650). However, there are a number of parameters which may influence welding fabrication costs, as well as different company’s experiences, and therefore provided calculation assumptions in this paper do not have any intention to underestimate them. While considering typical types of structural steels, i.e. S235, S275 and S355 (acc. to EN 10025) the basic parameters which influence its selection on total welding fabrication costs are described. In particular, paper will outline selection influence related to size of oil storage tank. In addition, only one particular type of tank shall be evaluated, i.e. oil storage tank with fixed roof within its size limits applicable for oil industry. While considering minimum required thickness of shell structure as defined in API 650 according to selected structural steel, and almost non-affected thickness of roof and bottom, the main influencing parameter, i.e. sizes of tank shell butt weld joints shall be evaluated. In all cases, the same possibly applied welding technology shall be considered, while considering appropriate filler material strength class. Finally, range of total welding fabrication costs savings due to the use of stronger structural steel shall be outlined in relation to oil storage steel tank size, as well as used spreadsheet calculation.

Under the influence of temperature and stresses, the heat resistant materials react by creeping. Boiler components subjected to creep have a limited lifetime. Creep and material structure evolution are tightly related and according to this rule a number of studies have been performed in order to relate micro structural investigation and service exposure or residual life. The determination of the structural conditions and the materials exhaustion of creep exposed power plant boiler components is increasingly carried out by field of metallography. For assessment of damage and of the risk associated with failure it is necessary to know the potential mechanisms of degradation and the rate of accumulation of damage. VGB-TW 507 represents guideline for the assessment of microstructure and damage development of creep exposed materials for pipes and boiler components.

This paper describes influences of heat input on leg size of pulsed GMAW fillet welds of unalloyed steel with thicknesses of 4 mm, in horizontal and overhead position. Varied parameters were welding current and speed, while voltage and current profile were predefined by welding equipment manufacturer. Influence is described through models based on linear regression analysis. Comparison is made between developed models, as well as with those available in literature.