Innovative Adequacy Assessments for Brownfield Civil Structures: A Case Study from Harweel

Abstract This paper meticulously investigates the multifaceted challenges and the innovative solutions implemented during the structural adequacy checks on a multi-tier Piperack involved in extensive brownfield modifications at the Harweel Production Station. It delves into the advanced engineering practices employed to effectively resolve these challenges, with a critical focus on maintaining stringent safety standards and meeting precise operational objectives, ensuring the structural integrity and functionality of the existing infrastructure is not compromised. The primary structure of interest, the main Piperack at Harweel Main Production Station, erected in 2007, has undergone numerous modifications to support a series of new process and utility lines. The new project scope additions included the installation of additional platforms, a 20-inch Non-Return Valve (NRV), and a substantial extension of 150 meters of piping to enhance the facility's operational capacity. Our evaluative approach involved conducting detailed site inspections coupled with thorough analyses of the existing as-built drawings and structural analysis reports. These efforts were pivotal in accurately assessing whether the Piperack could withstand the increased load demands introduced by these modifications, ensuring a comprehensive evaluation of the structure's capacity. The initial phase of our adequacy assessment unearthed considerable discrepancies between the physical structure, its documented as-builts, and prior structural analysis reports. With the original Finite Element Method (FEM) model files missing, traditional evaluation methods were rendered obsolete. Addressing this challenge, we innovatively extracted FEM codes from a scanned PDF of the 2007 structural report and integrated them into contemporary FEM software. This adaptation required precise adjustments to reflect actual site conditions accurately. Our refined models initially indicated potential failures under existing load conditions, raising immediate concerns about the structure's ability to support additional modifications. A thorough investigation followed, employing advanced analytical techniques such as fishbone diagrams and the 5 Whys methodology to delve into the root causes of these discrepancies. This exhaustive analysis pinpointed critical miscalculations in the original assumptions regarding piping forces, structural geometries, and the manual code extraction process. After correcting these foundational errors, we developed a rigorously validated model that confirmed the structural integrity of the Piperack, ensuring it met all required safety and functional standards. This research looks into the most appropriate method of reviving and repurposing outdated FEM codes from archived documents, substantially streamlining the engineering evaluation process and avoiding new Piperack construction. This methodological way of solving the lack of data and conducting analysis not only reduced the time and resources typically required for comprehensive structural assessments but also enhanced the accuracy of our evaluations. Additionally, by integrating some key principles such as systematic root cause analysis, we fostered a collaborative and insightful problem-solving environment, setting new benchmarks for project execution in civil engineering, and establishing a model for future projects.