GB/T 32857-2016 in English

GB/T 32857-2016, as an important standard for process industry safety risk assessment, proposes a semi-quantitative protection layer analysis methodology. Its core value lies in:

• Establish a complete scenario chain from initial events to consequences
• Quantitatively evaluate the effectiveness of existing protection measures
• Provide technical basis for SIL classification

Appendix A of the standard provides the PFD benchmark values widely recognized by the industry:

• Basic process control loop (BPCS): 10^-2~10^-1
• Operator intervention (10 minute response): 10^-1~10⁰
• SIL1 safety instrumented function: 10^-2~10^-1
• Mechanical safety valve: 10^-5~10^-1

Note: The actual value needs to be adjusted in combination with the service conditions and maintenance level of the equipment

1. Preferentially adopt intrinsically safe design to eliminate hazards
2. For residual risks, at least two layers of independent protection
3. Regularly verify the effectiveness of IPL (such as SIS functional testing)
4. Use the LOPA record sheet provided by the standard to standardize the analysis process

A typical case shows that in the scenario of temperature runaway of the polymerization reactor, the risk frequency can be reduced from 10^-2/year to 10^-5/year by adding a SIL2 interlock system.