Study of subsea xmas tree remote operated vehicle (ROV) tree cap assembly, function testing and machanism loading

• Main Author: Cheong, Chin Long.
• Other Authors: Ang Hock Eng
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Mechanical engineering::Robots
• Online Access: http://hdl.handle.net/10356/17115
• Institution: Nanyang Technological University

This Final Year Report (FYP) aims to propose an enhancement on the design of the ROV Tree Cap to eliminate the risk of the latter dislodging during high pressure testing. Although no catastrophic consequences have been witnessed, few occurrences of the tree cap being rejected after pressure test warrants a serious study to review some aspects of the design. The format of the FYP is such that it progressively narrows down the scope of information provided to readers. In the first part of the report, readers are first exposed to the macro overview of a typical offshore operation followed by an introduction to the subsea systems manufactured by FMC Technologies and lastly to zoom into the detailed functions and features of the tree cap so that the readers can better appreciate how the tree cap fits into the subsea completion system which forms part of the justification for its design. The next section of the FYP provides a background of the failed pressure test which forms the motivation of engineering a possible solution to the problem. Detailed mechanical analysis such as Singularity functions and the Superposition method is carried out to throw light on the possible root cause of the problem. The last section consists of technical justifications of the author’s proposal to enhance the structural integrity of the Tree cap by increasing the seal plate thickness to increase its second moment of area or increasing the contact area of the internal locking dog.