Bowtie ; sterilizer at palm oil mill

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🌴 Bowtie: Sterilizer Overpressure / Explosion

🔷 Visual Concept

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🔶 1. 🎯 Top Event (Center)

💥 Sterilizer Overpressure / Door Failure / Explosion

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🔶 2. ⚠️ Threats (Left Side – Causes)

Typical real issues in mills:

• Steam inlet valve stuck open

• Pressure control valve failure

• Blocked condensate / drain line

• Faulty pressure gauge (wrong reading)

• Door not properly locked

• Interlock system bypassed

• Operator error (wrong steaming sequence)

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🔶 3. 🛡️ Preventive Barriers (Left Controls)

To prevent the top event:

• Pressure relief valve (PRV) – tested regularly

• Interlock system (door cannot open under pressure)

• Routine calibration of pressure gauges

• Steam control valve maintenance

• SOP for sterilization cycle (charging, steaming, venting)

• Operator training & competency certification

• Drain/condensate line inspection

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🔶 4. 💣 Consequences (Right Side)

If failure occurs:

• Fatal injury (door burst / steam release)

• Severe burns to workers

• Equipment destruction

• Production downtime

• Legal & regulatory action

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🔶 5. 🚨 Mitigation Barriers (Right Controls)

To reduce impact:

• Emergency steam isolation valve

• Pressure venting system

• Safety distance / barricade around sterilizer

• Emergency response plan

• PPE (heat-resistant gear)

• First aid & medical readiness

• Incident investigation system

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🔷 Simple Bowtie Layout (Sterilizer)

Threats                       Prevention                TOP EVENT                     Mitigation                   Consequences
--------                      ----------                ---------                     ----------                   ------------
Valve failure          →   Valve maintenance     →   Sterilizer Explosion     →   Emergency isolation     →   Fatality
Blocked drain          →   Line inspection       →                             →   Pressure venting       →   Severe burns
Gauge faulty           →   Calibration           →                             →   PPE                    →   Injury
Door unlocked          →   Interlock system      →                             →   Barricade              →   Equipment damage
Human error            →   SOP & training        →                             →   ERP                    →   Shutdown

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🔥 Critical Real-Life Lesson (Palm Oil Mill)

Most sterilizer accidents happen due to:

• Interlock bypassed

• Operator rushing cycle

• Poor maintenance of PRV

👉 The danger is not visible — pressure builds silently.

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✅ Practical Tip for Your Mill

Turn this bowtie into:

• Control checklist for operators

• Audit checklist for management

• Training poster in control room