*2.1.3 Influence of failure on system function (SF)*

The SF index mainly considers the impact of object failure on the entire production system or the function of mechanical equipment. In order to ensure continuous production operations, the important mechanical equipment in petrochemical companies generally has certain spare. During the production operation, once such mechanical equipment failure, you can immediately switch the standby equipment and quickly resume operations, which can effectively control downtime and avoid large economic losses. Therefore, the degree of impact of object failures with spare parts on system functions will be reduced accordingly. Therefore, in evaluating the object failures on the system, it needs to be divided into two cases: the object has standby and no standby. Based on the actual production process, the level of the SF index is determined, and its scoring standards are established, as shown in **Table 4**.

*2.1.5 Influence of failure on production loss (PL)*

**Table 5.**

**Table 6.**

**Table 7.**

**335**

*Scoring criteria of MC.*

*Scoring criteria of PL.*

*Scoring criteria of FF.*

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

*2.1.6 Influence of maintenance cost (MC)*

standards are shown in **Table 7**.

The PL indicator is due to the failure of components, subsystems, or systems, which will cause changes in product operation, cause standby products to be put into operation, and cause production problems such as drilling stoppages, which will cause economic losses in the enterprise. In combination with the production of offshore oil and gas, in the case of production loss caused by failure, the PL index is divided into six levels, and the specific scoring standards are shown in **Table 6**.

**Serial number MTBF (hours) Grading** >10,000 0 5000–10,000 1–2 3000–5000 3–4 1500–3000 5–6 500–1500 7–8 <500 9–10

**Serial number Outage loss Score** No loss 0 Little loss 1–2 3 Loss 3–4 Big loss 5–7 Great loss 8–10

**Serial number Maintenance cost (Yuan) Score** <10,000 0–2 10,000–50,000 3–5 50,000–150,000 6–8 >150,000 9–10

The MC index needs to consider the complexity of the maintenance object, the labor cost of maintenance, the cost of spare parts, and the inventory cost. Therefore, considering the above aspects of the mechanical equipment of petroleum and petrochemical enterprises, MC is divided into four levels, and the specific scoring
