1 Practical Reliability Tools For Refineries And Chemical Plants H. Paul Barringer, , Barringer & Associates, Inc., Box 3985, Humble, TX 77347, Phone: 713-852-6810, FAX: 713-852-3749. Abstract Reliability is the probability of equipment or processes to function without failure, when operated correctly, for a given interval of time, under stated conditions. Reliability numbers, by themselves, lack meaning for making improvements. For business, the financial issue of Reliability is controlling the cost of unreliability from equipment and process failures which waste money. Reliability issues are understandable when converted into monetary values by using actual plant data. Several Reliability engineering Tools are discussed. Reliability Definitions Reliability , reduce unreliability costs, generate more Reliability has many definitions (Omdahl 1988). If profit, and get more business. repairs are not possible, Reliability is the duration or probability of failure-free performance under stated We talk about Reliability (a good word), but we conditions.
2 If repairs are possible, Reliability is the measure failures (a bad word). Failures demonstrate probability that an item can perform its intended evidence of unreliability with unfavorable cost function for a specified interval under stated consequences for businesses. Failures in most conditions. A single word definition for Reliability is: continuous process industries are measured in dependability. process downtime. Cutbacks/slow-downs in output are also failures. Failures require a clear definition Reliability definitions include probabilities with values for organizations making Reliability improvements. between zero (absence of Reliability ) and one Failures are loss of function when the function is (perfect Reliability ). Reliability is difficult because needed particularly for meeting financial goals. probabilities change with time. Quantifying Reliability sets the stage for quantifying risks when monetary Everyone knows downtime stopping the production values are included.
3 Process measures unreliability and defines a failure. Fewer people know that cutbacks/slow-downs in Measuring the Reliability of plants and equipment by output are demonstrated failures. Define your quantifying the annual cost of unreliability incurred by failures to understand the need for Reliability the facility puts Reliability into a business context. improvements. Failure definitions (when attached to Measurement, planning, and improvement are things dollars) galvanize organizations into action for making businesses do well, but only when efforts are improvements. focused on important problems. Make Reliability improvements pay their way by reducing the flow of funds into costs of unreliability. Reliability Improvement Find affordable business solutions. Avoid searches Motivation for perfection as business Reliability solutions must Higher plant Reliability reduces equipment failure result in profit improvements.
4 Costs. Failures decrease production and limit gross profits. Boosting Reliability , by reducing the cost of Can your plant afford a Reliability improvement unreliability, improves business performance. The program? Answer these questions for your plant: clear reason for reducing unreliability is spelled: What is the annual cost of unreliability? money. The motivation for improving Reliability is Where are losses occurring inside the plant? straight forward for a business plan: Improve Do you know the root cause for the losses? What are the alternatives for reducing costs? Page 1 of 8. Are top ten Pareto items identified? productive maintenance programs. Use root --What are the specific items for correction? cause analysis to efficiently solve problems. --Who is responsible for corrective actions? Learn and use a host of straight forward --What is the budget (time and cost) for change?
5 Reliability engineering Tools to solve problems. Spur improvement programs by using statistics to Answering these questions requires identifying the quantify and understand scatter in the results. expected annual failures occurrences (both obvious Build Monte Carlo computer models to simulate failures and cutback/slow-down failures) and then plant availability, Reliability , maintainability, calculating the losses. These facts help motivate capability, and life cycle costs for deciding Reliability improvement programs. Reliability strategies. Reliability requirements for businesses change with Keep all Reliability scores measured in dollars. competitive conditions and business risks the playing field is always tilting. Unreliability values The Reliability improvement hierarchy shown in change with business conditions. You don't need the Figure 1 depends on having lower level programs best Reliability in the world for your business you operational as precedents to accomplish higher level just need a cost advantage over your fiercest objectives.
6 Competitor. Even low cost industry providers need Reliability improvement programs Reliability does not stand still. Unreliability costs usually increase. R. Motivations for Reliability improvements are driven by E. the cost of unreliability this tells the magnitude of P. the pain. Where the pain occurs within the plant is important. Why the pain occurs gets to the root Root cause of the problem for corrective improvement Cause programs. Don't rely on a magic bullet to fix Analysis Reliability problems because seldom will correcting one item make a big change in overall Reliability . Total Reliability Tools Productive Reliability Tools showed their real value in the 1930s, Maintenance 40s, and 50s when used on exotic military programs. Fortunately many Reliability Tools do not need a rocket scientist to use them cost effectively. Some Good Maintenance simple Reliability Tools provide big gains quickly and Practices defer the use of higher powered Tools for squeezing out the remaining improvements.
7 In all cases, score Figure 1: Reliability Hierarchy cards for Reliability improvements in business need measurements in dollars. The Reliability improvement hierarchy uses a host of Use of Reliability Tools is evolutionary: new Tools to reduce both failures and the effects of Start Reliability improvement programs with failures. This work-process initiative is to gain a simple arithmetic and spreadsheets. Quantify beachhead and expand territory by improvements. important cost and failure numbers. Few lasting improvements are maintained without Gain momentum with good maintenance improving Reliability as a work-process using four practices. Improve teamwork using total important programs: Page 2 of 8. Good maintenance practices (GMP) uses the Generally, Reliability work-process programs are best-of-class practices for doing activities. driven by the need for improved profitability.
8 They This requires having trained people at various begin by determining the cost of unreliability. This levels with a commitment to on-going training. exercise requires plant failure data and cost data. Use good procedures and practices to avoid calamities. Teach new techniques and verify the Age-to-failure data- Acquiring good data for workforce has accepted them as requirements equipment sounds easy. In many ways, it is a for correct performance such as precision difficult task. The data acquisition task is as difficult alignment of rotating equipment along with as taking beautiful and salable photos with a camera. precision alignment of all piping and equipment. Photos are advertised as easy to acquire. However, Start teamwork between maintenance and few candid photos are sold and used in professional production departments. literature. Taking a beautiful photo requires: Total productive maintenance (TPM) is a 1.
9 Good data logging equipment , camera, way of life for involvement of production 2. Knowledge of art and science of photography, personnel into appropriate maintenance tasks for 3. Careful illumination of the subject, tender loving care of both equipment and 4. Clear understanding of the photo's purpose, and processes. Aim TPM for effective use of 5. Photo appreciation for either art or commerce. equipment and loss prevention by a preventive maintenance effort with involvement of all Failure of just one element results in a useless photo. people from top to bottom in the organization. Not all photos made by the experts are salable . Promote preventive maintenance through the most are junk. Trying to take a beautiful photo by TPM program by use of self-directed small work simply walking down the street taking snapshots groups. won't produce good results. Similarly, acquiring Root cause analysis (RCA) works on defining photos rapidly is equally unproductive.
10 In short, problems into categories such as people, taking a good photo requires a carefully constructed procedures, or hardware. Demonstrate RCA plan it doesn't just happen! solutions to problems will prevent recurrence, meet the organizations goal, and be within an Abernethy (1996) says acquiring equipment failure individuals control for preventing recurrence. data has three basic requirements (items 1-3); and Reliability engineering principles (REP) uses for commercial businesses, add two other elements new Tools to solve old nagging problems. The (items 4-5): program is interested in solving the vital few 1) Define an unambiguous time origin, problems that save/make the most money to 2) Define a scale measuring the passage of time, reduce overall cost of unreliability. Many Tools 3) The meaning of failure must be entirely clear, use bathtub concepts to match correct Tools to 4) Measure cost consequences for failure, and cost effective strategies by applying science and 5) Gain data analysis expertise for using data.