Accuracy of Steel Flange Measurements in Renovation and Construction Work for Offshore Industry

Abstract

Geometrical surveys are an important part of the renovation process in the oil and gas and shipbuilding industries. They enable improved safety and decreased costs of such types of processes. The crucial moment of such surveys is the determination of the position, deflections and dimensions of steel flanges in a local three-dimensional (3D) coordinate system. Companies that do such work declare submillimeter accuracy; however, no reliable publications have been found that could confirm this. This paper presents the main concept of such kinds of surveys and describes the two methods: standard and noncontact. The tests that were carried out allowed determination of the real measurement accuracy of flanges of different sizes for both methods. root mean square error (RMSE) was calculated for every parameter. The results show that for most of the flange parameters, the accuracy was better than 1 mm. The results indicate that the size of the flange and amount of measured points do not have a significant influence on the final accuracy; however, the distribution of the points is important.