13. Other Risk Mitigation Activities

Question 1

13 Other Risk Mitigation Activities

13.1 General

Highlights

Answer 1

1. Inspection may not always provide sufficient risk mitigation or may not be the most cost-effective method.
2. These risk mitigation activities fall into one or more of the following:
   a) reduce the magnitude of consequence;
   b) reduce the POF;
   c) enhance the survivability of the facility and people to the consequence;
   d) mitigate the primary source of consequence.

Question 2

13 Other Risk Mitigation Activities

13.2 Equipment Replacement and Repair

Highlights

Answer 2

When equipment deterioration has reached a point that the risk of failure cannot be managed to an acceptable level, replacement/repair is often the only way to mitigate the risk.

Question 3

13 Other Risk Mitigation Activities

13.3 Evaluating Flaws for Fitness-For-Service

Highlights

Answer 3

1. A Fitness-For-Service assessment (e.g. API 579-1/ASME FFS-1) may be performed to determine if the equipment may continue to be safely operated, under what conditions, and for what time period.
2. A Fitness-For-Service analysis can also be performed to determine what size flaws, if found in future inspections, would require repair or equipment replacement.

Question 4

13 Other Risk Mitigation Activities

13.4 Equipment Modification, Redesign, and Rerating

Highlights

Answer 4

1. Modification and redesign of equipment, utilizing a rigorous MOC process, can provide mitigation of POF. Examples include the following:
   a) change of metallurgy;
   b) addition of protective linings and coatings;
   c) removal of deadlegs;
   d) increased corrosion allowance;
   e) physical changes that will help to control/minimize deterioration;
   f) insulation improvements;
   g) injection point design changes;
   h) resizing of the relief device.
2. Rerating the equipment may result in a reduction of the POF assessed for that item.

Question 5

13 Other Risk Mitigation Activities

13.5 Emergency Isolation

Highlights

Answer 5

1. Proper location of the isolation valves is key to successful risk mitigation.
2. Remote operation is usually required to provide significant risk reduction.
3. Operators need to be able to detect the release and actuate the isolation valves quickly.
4. Longer response times may still mitigate effects of ongoing fires or toxic releases.

Question 6

13 Other Risk Mitigation Activities

13.6 Emergency Depressurizing/Deinventorying

Highlights

Answer 6

1. This method reduces the amount and rate of release.
2. Like emergency isolation Emergency Depressurizing /Deinventorying should be achieved within a few minutes to reduce the risk from an explosion/fire.

Question 7

13 Other Risk Mitigation Activities

13.7 Modify Process

Highlights

Answer 7

1. Any process changes should be conducted only after a MOC.
2. Mitigation of the primary source of consequence may be achieved by changing the process toward less hazardous conditions. Examples:
   a) Reduce temperature to below atmospheric pressure boiling point to reduce size of cloud.
   b) Substitute a less hazardous material (e.g. high flash solvent for a low flash solvent).
   c) Use a continuous process instead of a batch operation, where applicable.
   d) Dilute or eliminate hazardous substances.
3. Mitigation of the sources of corrosion can be achieved by changing the process toward less corrosive conditions. Examples:
   a) process water washing to remove corrosive materials (e.g. salts);
   b) addition of neutralizing or inhibitor chemicals;
   c) removal of contaminants with process equipment (e.g. absorbers, filters);
   d) protection of downtime corrosion (e.g. PASCC protection).

Question 8

13 Other Risk Mitigation Activities

13.8 Establish Integrity Operating Windows

Highlights

Answer 8

1. IOWs should be established for process parameters (both physical and chemical) that could impact equipment integrity if not properly controlled.
2. Key process parameters for IOWs should be identified and implemented, upper and lower limits established, as needed, and
3. Deviations from the IOWs limits should be brought to the attention of inspection/engineering personnel.
4. Particular attention to monitoring IOWs should also be provided during start-ups, shutdowns, and significant process upsets (reference API 584).

Question 9

13 Other Risk Mitigation Activities

13.9 Reduce Inventory

Highlights

Answer 9

1. This method reduces the magnitude of consequence. Examples:
   a) Reduce/eliminate storage of hazardous feedstocks or intermediate products.
   b) Modify process control to permit a reduction in inventory contained in surge drums, reflux drums, or other inprocess inventories.
   c) Modify process operations to require less inventory/hold-up.
   d) Substitute gas phase technology for liquid phase.

Question 10

13 Other Risk Mitigation Activities

13.10 Water Spray/Deluge

Highlights

Answer 10

1. This method can reduce fire damage and minimize or prevent escalation.
2. A properly designed and operating system can greatly reduce the probability that a vessel exposed to fire will BLEVE.

Question 11

13 Other Risk Mitigation Activities

13.11 Water Curtain

Highlights

Answer 11

1. Water sprays entrap large amounts of air into a cloud.
2. Early activation is required in order to achieve significant risk reduction.
3. The curtain should preferably be between the release location and ignition sources (e.g. furnaces) or locations where people are likely to be present.

Question 12

13 Other Risk Mitigation Activities

13.12 Blast-resistant Construction

Highlights

Answer 12

1. Provides mitigation of the damage caused by explosions and may prevent
   escalation of the incident.
2. Used for buildings (see API 752), it may provide personnel protection from the effects of an explosion.
3. This may also be useful for equipment critical to emergency response, critical instrument/control
   lines, etc.

Question 13

13 Other Risk Mitigation Activities

13.13 Others

Highlights

Answer 13

1. Other risk mitigation includes:
   a) spill detector;
   b) steam or air curtains;
   c) fireproofing;
   d) instrumentation (interlocks, shutdown systems, alarms, etc.);
   e) inerting/gas blanketing;
   f) ventilation of buildings and enclosed structures;
   g) piping redesign;
   h) mechanical flow restriction;
   i) ignition source control;
   j) improved design, assembly, and installation standards;
   k) improvement in PSM program;
   l) emergency evacuation;
   m) shelters (safe havens);
   n) toxic scrubbers on building vents;
   o) spill detectors and containment;
   p) facility siting and/or layout;
   q) condition monitoring;
   r) improved training and procedures;
   s) emergency feed stops;
   t) improved fire suppression systems.