Mechanical Integrity GuidebookComplex processes such as industrial refrigeration involve a number of potential failure points that include: rotating mechanical equipment, actuators, pressure containing components (piping & vessels), controls, and sensors. The impact of one or more of these components failing can range from degraded system performance to leakage of refrigerant and its associated health risks to plant personnel, off-site public, and/or the environment.
Historically, many industrial refrigeration systems were operated continuously until components failed after which their replacement would be sought. This operating strategy is sometimes referred to as run-till failure (RTF) maintenance. Increasingly, end-users of industrial refrigeration systems are realizing that RTF maintenance is not consistent with their operational needs and goals. Apart from safety risks, unplanned outages create process interruptions with the potential of significant direct and indirect impacts to the business. Direct impacts include the loss of product manufacturing capacity for an unspecified time period. Indirect impacts may include increased product waste, increased repair costs, and regulatory non-compliance. As such, many industrial refrigeration end-users have recognized there is a significant business case associated with managing the mechanical integrity of their systems.
Mechanical Integrity:
Those activities undertaken to provide assurance that mechanical equipment is designed, fabricated, procured, installed, operated, protected and maintained in a manner appropriate for its intended application.
Other organizations view and define this activity as a reliability program in order to emphasize the collateral benefits realized by improved equipment reliability and reduced unscheduled downtime.
Our goal in preparing this guidebook is to provide you with information that will facilitate your development and implementation of an effective mechanical integrity program for your systems and plants. Specifically in this guidebook, we will explore methods that the ammonia refrigeration industry can utilize to meet the requirements of the Inspection and testing portion of Mechanical Integrity in the PSM Standard [1910.119(j)(4)] The bulk of the content in this guidebook is aimed at vessels and piping systems. This focus grew out of the gap that currently exists in the industry. At present, there is no industry-recognized consensus method for inspection and testing of in-service refrigerant piping, vessels or related components to insure their on-going integrity or fitness for continued use. In this guidebook, will discuss the need for inspection and testing of piping and vessels, we will consider the common causes of mechanical integrity problems for piping and vessels, we will explore the inspection methods available, we will present relevant portions of guidelines originally developed for the ammonia refrigeration industry, we will review inspection standards developed for the broader kindred industries, and conclude with recommended inspection practices based on both current published information and the current practices of industry leaders.
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