Sample HAZOP Study Worksheet (P&ID 100-002)

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Process Description Vapor product from R-100 is partially condensed at E-100 using cooling water. The two-phase product goes to D-100, where the condensed liquid is separated from the uncondensed vapor. The liquid product is sent to R-200 via P-100, and its flowrate is controlled by D-100 level. On the other hand, the vapor product is sent to T-100 for further processing.

Deviation Causes Consequences Safeguards Remarks

1. No/Less Flow The manual valve on P-100 suction line is inadvertently closed.

Immediate cavitation on P-100. Manual valve on P-100 suction line is Locked Open.

(FYI: Clogging of temporary strainer on P-100 suction line during startup and check valve failure are also considered on actual HAZOP, but not considered for this course).

2. More Flow

3. Low Pressure

4. High Pressure

The manual valve on the cooling water supply line is inadvertently closed.

Cooling water to E-100 stops, resulting to loss of condensation and overpressure at D-100 due to higher vapor input.

PI-10206 on D-100 vapor line with high pressure alarm (PAH-10206).

PI-10206 on D-100 vapor line with high pressure interlock (PAHH-10206) closes XV-10204 on D-100 feed line when activated.

PSV-10213 on D-100 vapor line protects the system from overpressure.

The manual valve on the cooling water return line is inadvertently closed.

Cooling water to E-100 stops, resulting to loss of condensation and overpressure at D-100 due

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to higher vapor input.

Stagnant cooling water on E-100 tube side expands due to continuous flow of hot R-100 vapor on E-100 shell side, resulting in overpressure.

Manual valve on cooling water return line is Locked Open.

External fire on the vicinity of D-100.

Overpressure at D-100 due to vapor generation.

5. Low Temperature

6. High Temperature

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7. Low Level LIC-10204 on D-100 malfunctions and causes FV-10209 on D-100 liquid product line to fully open.

D-100 level drops, resulting in cavitation on P-100.

LAL-10216 on P-100 suction line shuts down P-100 when activated.

FIC-10209 on P-100 discharge line malfunctions and causes FV-10209 to fully open.

LIC-10204 on D-100 with low level alarm (LAL-10204).

(1) LIC-10204 on D-100 with low level interlock (LALL-10204) and (2) LAL-10216 on P-100 suction line shut down P-100 when activated.

FV-10209 on P-100 discharge line malfunctions and fully opens.

LIC-10204 on D-100 with low level alarm (LAL-10204).

(1) LIC-10204 on D-100 with low level interlock (LALL-10204) and (2) LAL-10216 on P-100 suction line shut down P-100 when activated.

8. High Level E-100 tube ruptures. Cooling water from E-100 tube side flows to D-100, resulting in liquid overfilling.

LIC-10204 on D-100 with high level alarm (LAH-10204).

(1) LIC-10204 on D-100 with high level interlock (LAHH-10204) and (2) LAH-10215 on D-100 vapor line close XV-10204 on D-100 feed line when activated.

This scenario assumes that E-100 tube side pressure is higher than the shell side.

When the liquid level reaches the installation point of PI-10206, then the high pressure protection will be activated. See High Pressure.

(FYI: Verify if cooling water will flash upon contact with the hot R-100 vapor. This consequence

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is called steam explosion and it is very difficult to protect any system against it. The rate of vaporization is much faster than the response time of any interlocks and the opening time of any PSV.)

LIC-10204 on D-100 malfunctions and causes FV-10209 on D-100 liquid product line to fully close.

The liquid product line is blocked, resulting in liquid overfilling.

LAH-10215 on D-100 vapor line close XV-10204 on D-100 feed line when activated.

P-100 shuts down due to operator error or partial power failure.

The manual valve on P-100 discharge line is inadvertently closed.

FIC-10209 on P-100 discharge line malfunctions and causes FV-10209 to fully close.

(1) LIC-10204 on D-100 with

When the liquid level reaches the installation point of PI-10206, then the high pressure protection will be activated. See High

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high level interlock (LAHH-10204) and (2) LAH-10215 on D-100 vapor line close XV-10204 on D-100 feed line when activated.

Pressure.

FV-10209 on P-100 discharge line malfunctions and fully closes.