A Study on Deformation due to Steel Constraint during Butt Welding and Line Heating of Thick-Plate in FLNG Topside Bearing Node

Abstract

Products manufactured in shipyards are predominantly steel structures, primarily fabricated through welding. There are various welding methods, all of which commonly use very high heat. Therefore, during the fabrication of steel structures, thermal deformation caused by welding occurs, resulting in dimensional deviations from the initial design. Methods to ensure dimensional accuracy include optimizing the welding sequence, predicting thermal deformation before welding and applying reverse-setting, and suppressing thermal deformation through constraints. However, the most commonly used method in the field is heat straightening. This study proposes a method to control thermal deformation caused by welding by using steel constraints during welding and line heating. Analytical verification confirmed both the effect of heat straightening and the variance in effects when steel constraints were applied. As a result, it was confirmed that line heating is effective in correcting thermal deformation, and steel constraints can maximize the effect of line heating.