The integrity management, changes, repairs, upgrades and modification of offshore infrastructure to meet the functionality and operational availability requirements presents a constant and growing challenge for operators. A bolted connection arrangement can form a constructible and cost effective solution for the modification of existing platforms with minimum impact on platform operations. Historically, bolted connections have been avoided due to concerns about integrity management and degradation mechanism uncertainties and corrosion in particular. However, where structures are not in direct contact with sea spray, and given appropriate safety and integrity procedures, bolted connections can be used successfully on live production platforms to mitigate risks without the exposure to hot work.
The use of bolted connections covers a wide range of applications. This implies that the requirements for a bolted connection must be specified in relation to the given application and its criticality. As the requirements for fastener material, specification/design and installation are defined based on the given application, the present guideline does not provide specific requirements (minimum requirements) that can be used universally. In addition the installation procedure assurance, integrity management and corrosion protection of bolted connections require an appropriate degree of attention.
This paper gives an overview of the challenges and discusses various aspects of bolted connections related to brownfield modification of offshore structures. The discussion aims to represent potential risks to the integrity and the required mitigation actions and overall requirements for design, installation, maintenance, re assessment and repair to maintain the structural integrity of the bolted connection and attached structures. The paper also provides an overall view on the documentation and calibration/validation of the bolted connections required to ensure an adequate safety level is maintained by means of maintenance and inspection programs.