ASSESSMENT OF IMPACT DAMAGE CAUSED BY DROPPED OBJECTS ON GLASS REINFORCED PLASTIC (GRP) COVERS

摘要

Glass reinforced plastic (GRP) subsea protection covers are used to protect offshore pipelines, umbilicals and structures from dropped objects released from offshore oil and gas and fishing activities. The aim of the present study is to perform assessment of impact damage caused by various dropped objects on GRP covers with different geometries. Impact energies carried by different selected offshore dropped objects are calculated by using the impact energy method given by NORSOK N-004 [1]. Computed results show a good agreement with the published dropped object impact energy results reported by DROPS [2]. The present study shows that the impact energies carried by dropped objects in oil and gas activities can range from 28 kJ for a small equipment to 2627 kJ for a typical subsea tree. Generally, the impact energies carried by the dropped objects in fishing activities range from 3 kJ to 14 kJ which is less significant than those in oil and gas activities. The impact absorption capacities of three different GRP cover geometries (i.e. square, triangular and semi-circular shapes) are computed based on finite element analysis (FEA). The results show that the triangular GRP cover geometry has the highest impact absorption capacity among the three investigated GRP cover geometries.