s Shasfand - T abriz petrochemical company, T abriz, Iran
Seyed Mohammad Seyed Hosseini - Iran university ofscieince and technology, Tehran, Iran
Kamran Shahanaghi

Optimum maintenance of hundreds of thousands of equipment used by each company is one of the main challenges of maintenance, operation and procurement managers. Continuous production and competition in the business environment as well as resource constraints require that the vital equipment of each company be controlled and monitored.To do this, it is necessary to identify sensitive and critical items of equipment. A formula for determining the equipment sensitivity index was defined in thispaper, 1- by field surveys and the use of preferences from the 75 oil industry experts. Ten effective features in determining the sensitivity of the equipment were extracted by expert opinion and the weighting coefficient of each one was obtained by using the group decision making method (AHP).2- Introducing the formula of resistance maintenance index represents the capability to use strengths and opportunities, as well as sustainability and resistance to weaknesses and threats. The original formula has 5 sub- indicators consisting of the overall equipment effectiveness (OEE), overall labor effectiveness (OLE), overall cost efficiency (OCE),degree of endogeneity ,extraversion and exogeneity (EEE), the rate of health requirements, safety and Environmental events (HSE) and all are non-dimensional proportions. The perspective of 64 specialists, group decision making method and Paired Comparison Matrix of AHP were used in order to determine their weight coefficient. It can be propelled toward the enlighteningresistive maintenance by employing the two formulas mentioned above.

Criticality index; vital equipment; resistance index; expert preferences; group decision making