*2.1.7 Influence of inspectability (IN)*

The IN indicator mainly considers whether the object can be monitored, the number of monitoring parameters, the monitoring cost, and the technical level of the monitoring personnel. The maintenance of the mechanical equipment in petrochemical enterprise cannot be separated from the monitoring of its important subsystems and components. A comprehensive analysis of the existing monitoring technology of mechanical equipment in petroleum and petrochemical enterprises has determined the difficulty of monitoring the object, that is, the IN index is divided into four levels, and the specific scoring standards are shown in **Table 8**.

### *2.1.8 Influence of downtime (DT)*

The outage time includes the time required for the outage, maintenance, and start-up of mechanical equipment, so the DT index is related to factors such as the structure type, power, temperature, and pressure of the object. According to the distribution of outage time caused by object failure in offshore oil and gas production, the DT index is divided into four levels according to the working hours. The scoring standards are shown in **Table 9**.

#### *2.1.9 Influence of maintenance difficulties (MDs)*

From the perspective of object maintenance, MD is an important indicator that affects the level of object risk, which is related to the difficulty of the object (including height and surrounding environment), the complexity of the object, and the supply of spare parts. Based on a comprehensive consideration of on-site maintenance of mechanical equipment in petroleum and petrochemical enterprises, the MD index is divided into four levels, and its scoring standards are shown in **Table 10**.

*2.1.10 Influence of service length (SL)*

*Maintenance Decision Method Based on Risk Level DOI: http://dx.doi.org/10.5772/intechopen.91913*

**Table 10.**

**Table 11.**

*Scoring criteria of SL.*

*Scoring criteria of MD.*

can be expressed as

**337**

From the perspective of mechanical equipment maintenance management, object service age (or operating time) and frequency of use are also indicators that affect its risk level. The SL index is related to the service life of the mechanical equipment, the operating environment and working conditions, the frequency of use (continuous operation, interval operation, and temporary use), the past failures, and the maintenance of the mechanical equipment. Therefore, through discussions with field operations and maintenance personnel, it was determined that the SL index of mechanical equipment in petroleum and petrochemical enterprises

**Serial number Ease of maintenance Score** Easily 0–2 General 3–5 More difficult 6–8 Difficult 9–10

**Serial number Length of service (year) Score** 1 <3 0–2 2 3–8 3–5 3 8–12 6–8 4 >12 9–10

is divided into four levels, and its scoring standards are shown in **Table 11**.

comprehensively consider the rating vector *V* of its evaluation index and its corresponding weight value vector *W* [12]. The object's risk level evaluation index

After completing the scoring according to each evaluation index, it is necessary to comprehensively evaluate the risk level of the object. Therefore, it is necessary to

Among them, *F*½ �� is a comprehensive evaluation function that reflects the degree of influence of each evaluation index on the object risk level and can be a function of various forms. Using a simpler linear weighted model, the formula for calculating

*i*¼1

*Index* <sup>¼</sup> <sup>X</sup>*<sup>n</sup>*

*Index V*ð Þ¼ ,*W F v*½ � <sup>1</sup>*w*1, *v*2*w*2, … , *vnwn :* (1)

*viwi* (2)

**2.2 Research on risk assessment methods of mechanical equipment**

*2.2.1 Establishment of risk assessment model for mechanical equipment*

the object risk level evaluation index, namely, *Index*, is as follows:


**Table 8.** *Scoring criteria of IN.*


**Table 9.** *Scoring criteria of DT.*

### *Maintenance Decision Method Based on Risk Level DOI: http://dx.doi.org/10.5772/intechopen.91913*


#### **Table 10.**

*2.1.7 Influence of inspectability (IN)*

*Operations Management - Emerging Trend in the Digital Era*

*2.1.8 Influence of downtime (DT)*

**Table 10**.

**Table 8.**

**Table 9.**

**336**

*Scoring criteria of DT.*

*Scoring criteria of IN.*

scoring standards are shown in **Table 9**.

*2.1.9 Influence of maintenance difficulties (MDs)*

The IN indicator mainly considers whether the object can be monitored, the number of monitoring parameters, the monitoring cost, and the technical level of the monitoring personnel. The maintenance of the mechanical equipment in petrochemical enterprise cannot be separated from the monitoring of its important subsystems and components. A comprehensive analysis of the existing monitoring technology of mechanical equipment in petroleum and petrochemical enterprises has determined the difficulty of monitoring the object, that is, the IN index is divided into four levels, and the specific scoring standards are shown in **Table 8**.

The outage time includes the time required for the outage, maintenance, and start-up of mechanical equipment, so the DT index is related to factors such as the structure type, power, temperature, and pressure of the object. According to the distribution of outage time caused by object failure in offshore oil and gas production, the DT index is divided into four levels according to the working hours. The

From the perspective of object maintenance, MD is an important indicator that

(including height and surrounding environment), the complexity of the object, and the supply of spare parts. Based on a comprehensive consideration of on-site maintenance of mechanical equipment in petroleum and petrochemical enterprises, the MD index is divided into four levels, and its scoring standards are shown in

**Serial number Ease of monitoring Score** 1 Low 0–2 2 Medium 3–5 3 High 6–8 4 Very high 9–10

**Serial number Working hours (h) Score** 1 <2 0–2 2 2–8 3–5 3 8–12 6–8 4 >12 9–10

affects the level of object risk, which is related to the difficulty of the object

*Scoring criteria of MD.*


**Table 11.** *Scoring criteria of SL.*
