Is Small Bore Tubing Systems an Achilles’ Heel of Asset Integrity? An In-Depth Analysis Through Case Studies

Abstract

Small bore connecting (SBC) systems, including small bore piping (SBP), Small bore tubing (SBT) and Flexible Hose Assemblies (FHA) with size below DN 2″, are significant contributor to the incidences of Loss of Primary Containment (LOPC) and are a major source of failures in piping systems. Modern hydrocarbon installations feature large numbers of control and monitoring instruments, which require a considerable application of SBT assemblies, along with enormous number of threaded fittings and joints. However, the basic expectations from these SBTs will remain to provide the integrity over the entire life cycle of the installation. One of the estimates from standard database (Courtesy: Energy Institute Guidelines, year 2013) indicate that 20.4 % of all hydrocarbon leaks recorded in the Hydrocarbon Release (HCR) data were related to SBTs. Of these events, over half were classified as major or significant HCRs events (notionally an amount greater than 1 kg) linked to SBT assemblies. With complexity and extensive applications, SBT assemblies are vulnerable to failure due to incorrect design, selection, installation, operation, modification, inspection & maintenance and could result into events of LOPC and Major Accident Hazards (MAH). Despite availability of guidelines for design and installation, failures in SBT assemblies continue to occur in operational phase. Lack of formal procedures, inconsistent controls to manage the biggest contributors to HCR on assets, signifies the requirement of a structured approach to achieve Asset Integrity. Then there arise a question “is small bore connection systems an Achilles heel of Asset integrity? This paper covers, an in-depth analysis of few LOPC events, of geographically different installations, related to SBTs with an aim to achieve overall Asset Integrity through a. Verification of availability of sufficient barriers, between safe operation & incident. b. Effective management of threaded connections in existing SBT assemblies with respect to relevant ASME standards. c. Practical guidelines for providing preventive and recovery controls barriers for an effective management of SBTs.