Mechanical Interference Fit Connection (MIFC) for Offshore Pipeline Application: A Case Study of Dynamic On-Bottom Stability Analysis

Abstract

Abstract The offshore oil and gas industry requires pipelines to transport hydrocarbons from wells to processing facilities. Application of Mechanical Interference Fit Connection (MIFC) has been considered one of the optimization solutions in jointing of line pipes for pipeline installation, especially for offshore application. This method allows faster or less duration in pipe joining, which subsequently contributed to significant cost reduction in offshore pipeline installation. These pipelines are often subjected to harsh environmental conditions, including strong currents, waves, and seabed scouring. To ensure stability of pipeline on seabed, normally concrete coating is applied to provide sufficient weight for the pipeline. However, with concrete coated pipe, the faster joining rate by MIFC may be offset by longer duration to perform field joint coating due to longer field joint length required for MIFC to cater for clamping equipment to joint both-end of the pipes. This paper presents a case study of the dynamic on-bottom stability analysis of an offshore MIFC pipeline. The pipeline is a 12-inch diameter pipeline with a total length of 60 km. The pipeline is located in an offshore field with a water depth of ninety meters and 150 km away from shore. The dynamic on-bottom stability analysis is carried out to investigate the pipeline's response to environmental loads, including waves and currents. The dynamic on-bottom stability analysis is performed using a finite element analysis software package. The analysis considers the pipeline's structural behavior, seabed soil properties, and environmental loads. The results show that the MIFC joined pipeline is stable on seabed within the design envelope of the environmental loads without requirement of concrete weight coating. The maximum displacement and stress in the pipeline are well within the allowable limits, indicating that the pipeline's integrity is maintained. In addition, the study evaluates the effects of different parameters, such as seabed soil properties, current velocities, and wave heights, on the pipeline's dynamic response. In conclusion, this case study demonstrates that MIFC supported by dynamic on bottom stability analysis can be an effective solution for offshore pipeline jointing, providing stability and integrity on the seabed under the environmental design limit. The dynamic on-bottom stability analysis is an essential tool to investigate the pipeline's response to environmental loads and optimize the design and operation. Based on the findings of this study, we recommend that offshore pipeline engineers and designers may consider MIFC as a viable option for pipeline jointing. In overall, this case study contributes to the industry's knowledge and understanding of MIFC jointing for offshore pipelines, improving safety and efficiency in the offshore oil and gas industry.