关于安全仪表系统旁路的思考

Reflections on Safety Instrumented System in Bypass Mode

安全仪表系统(SIS)是保护工艺装置受控设备的常见且关键的安全措施。为了维护和测试SIS,通常需要采用精心设计且受控的旁路,一般包括报警记录、旁路授权和审核。然而,还存在将SIS组件置于旁路状态的其他途径,有一些甚至在无意识的情况下,且不受内操的监控。常见的起因包括电磁阀闩锁、关断阀手轮以及机泵和压缩机上的手动/自动切换开关(HOA)等。通过对某些设备如何被意外旁路的论述,探讨SIS旁路问题的验证方法。

Safety instrumented system(SIS) is a common and critical safeguard to protect equipment under control in process plant. For the purpose of maintaining and testing SIS, the SIS is usually implemented with well-engineered design and controlled bypasses, typically including alarm logging, bypass authorization, and auditing. Even so, there are myriad ways to place a SIS component into bypass, some even unconsciously and unmonitored by internal operations. Sometimes even without realizing it. Common causes include solenoid valve latches, shutoff valve handwheels, and hand-off-auto switches(HOA) on pumps and compressors.By discussing how some equipments are accidentally bypassed, the verification method of SIS bypassing problem is discussed.