Risk-Based Inspection: Keeping Industry, Commerce and Society Safe and Prosperous
Most people take the safe operation of power plants for granted. Inside them are major components — including vessels, valves and piping — that operate under extreme pressure for years at a time. Yet the plant and others like it around the world run reliably and raise no alarm.
It’s probable that not one person knows just how many pressure vessels and miles of pipeline are currently in use. Every day they give us the electricity, fuel and steam that light and shape the modern world. But news photos from Manhattan in July 2007 show a gaping hole in Lexington Avenue which reminds us of what can happen when a steam pipe fails under pressure.
A steam pipe explosion beneath a street near Grand Central Terminal propelled a giant scalding jet of brownish steam toward the sky, sending commuters stampeding to safety. Officials said that one person died and more than 30 were hurt. Photo: New York Times
A steam pipe installed in 1924 ruptured in a thunderous explosion, sending steam, water and debris shooting outward through Midtown Manhattan. The authorities ruled out any criminal activity, saying the explosion was apparently caused by a failure of antiquated infrastructure. Photo: New York Times
The management of many power plants and their counterparts in the petroleum industry have methods for keeping operations safe and reliable. They know the risks posed by different parts of their work sites — the likelihood and consequences of failure of every major piece of equipment. They keep a close eye on the big-risk areas and react to early signs of impending failure.
The practice is called risk-based inspection. It lets companies weigh the risks posed by their equipment so they know how often they should inspect each key component and how to deal with the unexpected. It makes more effective use of resources and usually requires fewer shutdowns. Plants operate safely and companies save money.
The practice of risk-based inspection is less common outside petroleum and power generation businesses. That is the reason for a new American Society of Mechanical Engineers (ASME) standard, which is designed to introduce risk-based inspection practices and planning to a wider range of industries.
In the normal course of events, inspectors responsible for the safety and reliability of plants have a seemingly endless list of hazard areas to review, and all of these areas are given equal weight. Large parts of a plant or refinery are shut down so that the inspectors can do their jobs. Product flow and services diminish, and the company loses large amounts of capital.
The new ASME standard, PCC-3-2007 Inspection Planning Using Risk-Based Methods, was specifically developed for planning and executing risk-based inspection of fixed pressure-containing equipment and components. Equipment covered ranges from piping and boilers to pumps and compressors, from heat exchangers and furnaces to storage tanks and valves. Risk-based inspection planning takes the concepts of RBI and applies them to such issues as frequency of inspection.
Author: Phillip Smeall, Process Improvement Specialist
