Chemical Processing-August 2008

tained. Equipment installed in ISS should be proven to provide required performance in similar operating environments. Equipment classification also must consider core attributes of protection layers, i.e., independence, functionality, integrity, reliability, auditability, MOC and access security. To counteract the unknown, owners/operators should rely on a defense-indepth strategy of multiple independent protection layers to lower operational risk [6] (also see www.ChemicalProcessing.com/ articles/2007/104.html). An independent and separate SIS is essential to ensure safe and reliable operation. Defense-in-depth also seeks to minimize common cause, common mode and systematic errors that cause multiple layers to fail [7, 8]. Detailed design should provide an ISS equipment list identifying equipment by unique designation (e.g., the tag number), required inspection and proof test interval. Validation activities should include an input-to-output test of each new or modified ISS to demonstrate and document that the equipment is installed according to specification and operates as intended for each operating mode. It’s crucial to satisfactorily complete validation prior to the initiation of any operating mode where a hazardous event could occur. Periodically conduct proof tests using a written procedure to demonstrate successful ISS operation and to identify and correct deviations from design and equipment specification. Train maintenance personnel on procedures and make sure they understand equipment pass/fail criteria. Choose the proof test interval based on relevant regulatory or insurance requirements, equipment history in a similar operating environment, manufacturer’s recommendations and risk reduction requirements. Operating plans should consider inspection and preventive maintenance necessary to keep equipment in “as good as new” condition. ISS proof tests should demonstrate that the mechanical integrity program maintains required equipment performance. (Feed records forward into the Check phase for trending and metrics.) Operating procedures should cover safe and approved ways for interacting with safety equipment, such as bypassing, manual initiation and reset. Train and test operations personnel on procedures as needed. Record and periodically assess operator actions in response to abnormal operation. CheCk A-T Controls, Inc. The answer for all your electric quarter-turn actuator needs TRIAC Electric Actuators from A-T Controls cover a broad range of applications • 500-26,000 in. lbs. on-off • Internal modulating controls 4-20ma, 0-10vdc, etc. • Single phase, 3-phase 220, 380, 440, 12 and 24vdc • Electric spring return (FSE series) • Battery fail-safe (BFS) • Complete controls • Floor mounted damper drives • CSA, CE, ATEX, AWWA • Suitable for nearly all quarter-turn applications A-T Controls, Inc. 11363 Deerfield Rd. Cincinnati, Ohio 45242 513 - 247- 5465 FAX 513 - 247- 5462 e-mail: sales@a-tcontrols.com www.a-tcontrols.com By what method? Only the method counts [4]. The Check phase applies metrics to assess performance against requirements. Sustainable operation is achieved by focusing on metrics providing real-time indication. Table 1 provides example metrics for the ISS. CCPS has suggested additional metrics [9]. Selecting appropriate metrics to track can seem overwhelming. Sometimes technical personnel want to measure everything just because they can. Carefully choose metrics so that just the right amount of meaningful data is collected. All systems involving humans and machines suffer some degree of variation in output quality. Good metrics drive personnel to do the right Client Contact: Design Contact: http://www.a-tcontrols.com http://www.ChemicalProcessing.com/articles/2007/104.html http://www.ChemicalProcessing.com/articles/2007/104.html http://www.a-tcontrols.com

Table of Contents Feed for the Digital Edition of Chemical Processing-August 2008

Chemical Processing- August 2008 Contents From the Editor ChemicalProcessing.com Field Notes In Process Energy Saver Compliance Advisor Protect your Plant What’s on Tap for Water? Keep Operations Safe Polystyrene Plant Gains Extra Output and More Process Puzzler Plant InSites Equipment & Services Adlits Product Spotlight/Classifieds Ad Index End Point

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