CEE Oct-Dec 2002

,. j .... TECHNOLOGY TREND AND INNOVATION MANAGED CARE, NOT REPAIR Dol'e .-lhecunus, F?v!SC ClroUJJ. Inc.. US:·/ Today·s assets are not only more expensive. but also more complex to operate and maintain. I r managed properly, they will not only perform with kss failure, but also have a longer life cycle. This is achieved by not over-mai ntain ing them, but using a systematic approach to establishing guide l ines based on criticality and rroperly developed strateg ies. Strategies shou ld be based on history and techniques, such as railurc modes and effects analysis (f-'MEA). ori gi nal eq uipment manufacturer (OEM) information and experi ence. Using th is C1pproach will prov ide managed care for va luab le assets, whil e limi ting repair C1ctions. Today. proactivr maintenance (J>AM) organisations have devel oped a ba lanced mix of reactive (RM). preventive (PM) and predictive maintenance ( PdM). \\'ith th e usc of reliability cen tered maintenance (RCM) tec hniq ues. When using RCM , managed care is developed for a company's assets and this wil l result in reduced repatr. Reuclil'e maintenance is also referred to as 'fix whe n rail ' . Although common ly referred to as a 'bad thing· RM may be the desired approach tor some assets, such as lo\\ cost items thJt arc not cri tica l to operat ion and can be repaired or repIaced at mini 111 um cost. Pre\'C:nti1·e maintenance is no\v very common and utilised at almost every plant in eve ry industr y, worldwide. In most cases however. the extent o f PM or frequency of irs accomplishment may not always be justiliecl. An example of overkill in PM includes oil changes. Perhaps if it was poss ibl e to analyse the oil in.steacl or changi ng it based on a time interva l, it may not need to be changed. In fact, through the usc of oil analysis. more can be learned about the condition of eq uipment, ir i t were not changed except when really required. Lubrication analy sis is sometimes the first indicator of a p roblem within a machi ne . Lubricati on systems are notorious for acting li ke a d irt magnet, contaminati on be in g: th e biggest v ill ai n. By trending the analys is results. a problem can be diagnosed and pred icted to possibly occur arter a cert ain amount of tim e. T hese indicators arc normally earli er than ultraso und (UT) or vib ratio n ·w ill rick up . T he frequency of Iubricant changes can also be determined. based on the condition or the oi l and nor a ti me based li·equcncy. IIyclraulic systems also benefit from th is technol ogy. Predicfil'l.! nwintenonce is the newcomer to the different types ava il able . PdM follows th e philosophy of working smarter, not harde r and i ncludes v ibration analys is, infrared th ermograph y . airborne/structure borne ultrason ic te st ing. lubri cant ana l ysis and motor circu it analys is. Condi ti on monitoring is the term for utilising PdM, comparing data between the techno log ies and tre nding the results. Vibrati on analys is is used on rotating equi pment inc lud i ng pum ps, mill s, motors and compressors. Component fai Iures 27 that can be detected inc lucie misal ignment. imbalance. bearing and gear prob lems. electrica l malfunctions and other component problems. Un li ke some of the other tec hno logies. v ibration analysis i-; normally trended to more reliabl~ pred ict ra ilu rc modes and obta in the best results. Small problems can be monitored to prov ide a trend and an est imate of time to fail ure. This al lows an intervent ion to be sc heduled \\ell bel·ore the failure occu rs. The most desired programmes have plant level personnel that not on ly collec t the data . but accompli sh basic analysis as \\ell . T his allows the data to be trended at the pl ant level and provide a readi ly available history. Motor ci rcu i t analysis can be accompl ished i n the onl ine ~1ml oi'nine modes and. wi th the use ot' this t y pe or techno logy. the condition or motors of every t) pe can be tren ded and certa i n maintenance p lanned only when really needed. Using. this techno logy in conjunction with vibrati on analys is \Vi II cover almost any motor problem area and allcm earl y diagnosis. avo iding those unexpec ted shutdowns and major repa irs. I nfrared ( IR) thermography is often used o nl y in electri ca l inspect i ons including switc hboa rds . controllers and wi ring. ll o\\'ever, JR thermograph~ can be utilised for many mechanic<li inspections. For examp le. <bscmbly line and conveyor beari ngs can be monito red ro r te mperatu re variations. Airbo rne /stru c ture borne ul traso und (UT) is probab ly the