environmental management

ENS5161 Environmental and Process Risk Management LEC 11 Process Safety Management (Part 2)

ENS 5161:

Environmental and Process Risk Management

Process Safety Management (Part 2)

Dr Lei Shi

Office: JO 5.227

Phone: 6304 2879

Email: [email protected]

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PSM Case Study

Recall: In 2010, Gulf of Mexico

Causes to disaster

 Dodgy cement (not sealing properly for oil & gas) Design

 Valve failure (fail to stop oil penetrating the sealing) Mechanical failure

 Pressure test misinterpreted Operation

 Leak not spotted soon enough Operation

 Valve failure no. 2 Design & Mechanical

 Overwhelmed separator (Mud-gas separator could not handle large volume) Design

 No gas alarm Design

 No battery for Blow-out Preventer (isolation could be performed) Design

Conclusion: It is evident that a series of complex events, rather than a single mistake or failure, led to the tragedy.

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Oil and Gas Operational safety: Inherent Hazards

Hazards inherent: extraction, storage and processing of raw materials and products

1 Meaning and relevance of various phrases associated with hazards inherent in oil and gas

 Flash point: lowest temp to form ignitable mixture

 Vapour density

 Vapour pressure

 Flammability

 Fire triangle

 Flammable range

 Carcinogenic properties

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Oil and Gas Operational safety: Inherent Hazards

2 Properties and hazards of various gases associated with the oil and gas industry

 Hydrogen

 Hydrogen sulphide (H2S) Time Weighted Average (TWA) of 8 hours at 5 ppm, or 15 minutes at 10 ppm

 Methane

 Liquefied Petroleum Gas (LPG)

 Liquefied Natural Gas (LNG)

 Nitrogen

 Oxygen

in 1966 at Feyzin in France. The resulting Boiling Liquid Expanding Vapour Explosion (BLEVE) killed 15 people and injured a further 81.

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Oil and Gas Operational safety: Inherent Hazards

3 Properties and hazards of associated products and their control measures

 Anti-foaming agents and anti-wetting agents

 Micro-biocides

 Corrosion preventative (MSDS should always be available)

 Refrigerant (regular safety checks/MSDS)

 Steam

 Mercaptan (Gas detector /serivice/MSDS)

 Drilling Mud (safe working procedures/gas detectors/flammable proof)

 Low Specific Activity (LSA) sludges are also naturally Occurring Radioactive

Note: Always take MSDSs seriously

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Risk management techniques used in the oil and gas industries

Within the oil and gas industry there are inherent risks of accidents occurring at any stage of the process, from exploration through to the extraction, refining and final delivery of the product. These risks include fire, explosion, environmental contamination and injury to personnel.

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Five Steps to risk assessment

 Hazards identification

 Risks analysis and decide on precautions

Setting control: As Low As Reasonably Practicable (ALARP), the Hierarchy of Control should be used

 Decide who might be harmed and how (Consequence analysis)

 Implementation

 Review

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Risk management tools

A Hazard Identification Study (HAZID) Hazard Checklist

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Risk management tools

A Hazard Identification Study (HAZOP)

Left Right

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Risk management

Industry related process safety standards, inherent safe and risk based design concepts, engineering codes and good practice

Standards

Inherent safe design

 Minimizing the amount of hazardous material present at any one time

 Replacing hazardous materials with less hazardous materials

 Moderating the effect a material or process might have (reduce temperature or pressure)

 Simplifying the design by designing out problems rather than adding features to deal with problems

 Allowing for human error by designing in failsafe features such as valves which fail to a SHUT position

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Risk management

Barrier Models

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Oil and Gas Operational Safety

Note: The oil and gas industries use PSM extensively, particularly where they are processing volatile products or have large inventories of flammable or toxic materials.

Permit-to-work system

Type of permits

 Hot work permits

 Cold work permits

 Equipment Disjoining Certificate

 Breaking Containment Permit

 Electrical work permit

 Confined spaces entry certificate

 Radiation certificate

 Diving certificate

Lock out, tag out and isolation

 Lock out device

 Tag out device

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Oil and Gas Operational Safety: Safe Shift Handover

In the 1970s, shift patterns in the oil and gas industry gradually changed from 8-hour to 12-

hour shifts. The view at the time was that inter-shift communications improved because the

number of handovers was reduced, which in essence meant the number of occasions when

critical information might not have been passed over was effectively reduced.

Critical information

 Work permits – the status of existing permits and the status of work in progress

 The updating of work permits

 Preparations for upcoming maintenance

 New personnel to the shift

 Any plant overrides – existing and planned

 Information about any abnormal events

 Any existing or planned shutdowns

 Inhibits to the Fire and Gas (F & G) and Emergency Shutdown (ESD) systems

 Any completed work and equipment which has returned to service

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Oil and Gas Operational Safety: Plant operation & maintenance

1 Asset Integrity

 Inspection

 Testing

 Maintenance

 Corrosion prevention

 Monitoring

 Competency

 Training

2 Safety Critical Elements (SCEs)

 Blowout preventers

 Fire deluge protection systems

 Emergency shutdown valves

 Fire and gas detection systems

3 Control of ignition

 Direct fire heater

 Hot oil systems

 Processes operating above auto-ignition temperatures

 Lightning

 Engines

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Oil and Gas Operational Safety: Start-up Operation Procedures

Example: Gas production train on a gas producing installation

 The lining out procedure is a joint operation carried out by both the control room operators (CROs) in the control room and the operators on the platform.

 Throughout the whole start-up operation, it is essential that close communications are maintained between the control room and the plant operators, usually by radio.

 All Safety Critical Elements (SCEs) are checked to ensure they are operational.

 All pipes and drains opened during maintenance activities are closed off as required, all instrumentation has been replaced, calibrated and in good working order, and all spades, blinds or spectacle blinds have been removed or turned to their correct operational position.

 Once all preliminary procedures are satisfactorily completed, the production train is walked and lined out as per the pre-start-up procedure set out in the operating procedure document.

 In this case, each valve is fitted with a unique, specially designed key. Only when the correct valve is put into the correct position can the key be removed to open the next valve in the sequence.

 This process is repeated until all the valves are put into their correct position and in the correct sequence, resulting in a foolproof procedure for a highly critical operation.

 Once all the valves are set and the isolator valve is opened, gas from the well is introduced into the system.

 At this stage, the gas pressure is set to a low level and only increased gradually as per the start-up procedure document.

 Constant checks will be made to the system to ensure nothing is amiss. This will include monitoring readings in the control room as well as watching and listening for leaks by the operators at the plant.

 In this stage hydrates (ice plugs) might form, and as a counter measure, methanol may be injected upstream.

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Oil and Gas Operational Safety: Critical equipment controls

Emergency Shutdown (ESD) equipment and systems:

The petrochemical industry, both onshore and offshore, processes large quantities of hazardous material within a contained environment. Consequently, it needs to have in place systems which will either prevent loss of containment from happening or mitigate the consequences of such an event if it does happen.

ESD Functionality:

 Various sensors to detect any fire or escape of gas or vapour

 Valves and trip relays to isolate sections of the process

 A system logic for processing any incoming signals

 An alarm system to warn operators and control room staff of a potential adverse occurrence

ESD Typical Actions:

 Shutdown of part systems and equipment

 Isolate hydrocarbon inventories

 Isolate electrical equipment

 Stop hydrocarbon flow

 Depressurize/blow down

 Activate fire-fighting controls (water deluge, inert gas, foam system, water mist)

 Activate emergency ventilation control

 Close watertight doors and fi re doors

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Oil and Gas Operational Safety: Critical equipment controls

Safety Integrity Levels (SILs):

 SIL 1: Where the acceptable probability of failure is between 1 in 10 occasions and 1 in 100 occasions. It is required where the potential for relatively minor incidents is involved with limited consequential outcomes.

 SIL 2 - Where the acceptable probability of failure is between 1 in 100 occasions and 1 in 1,000 occasions. It is required where the potential for more serious, but limited incidents is involved and where the consequences may result in serious injury or death to one or more persons.

 SIL 3- Where the acceptable probability of failure is between 1 in 1,000 occasions and 1 in 10,000 occasions. It is required where the potential for serious incidents is involved and where the consequences may involve a number of fatalities and/or serious injuries.

 SIL 4- Where the acceptable probability of failure is between 1 in 10,000 occasions and 1 in 100,000 occasions. It is required where the potential for a catastrophic incident exists.

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Oil and Gas Operational Safety: Critical equipment controls

Procedures to by-pass ESD:

 ESD needs to be tested and maintained on regular basis.

 ‘Override or inhibit’ time should be minimized.

 Inhibits should only be applied as part of an established procedure and risk assessment must be conducted.

 The control room operator should be aware at all times of the application and location of all inhibits.

 A password or key should be entered before an inhibit can be applied in visual display unit.

 Inhibits should only be applicable to protective functions which are graded to Safety Integrity Levels 1 (SIL1) and Safety Integrity Levels 2 (SIL2).

 Protective functions which are graded Safety Integrity Levels 3 (SIL3) and Safety Integrity Levels 4 (SIL4) should not normally be capable of being inhibited.

 All inhibits or overrides should be logged and a record should be kept.

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Oil and Gas Operational Safety: Critical equipment controls

Flare types:

 Steam assisted flares

 Air assisted flares

 Unassisted flares

 Multi-point pressure assisted flares

Drainage:

With any process or production facility there will always be a residual amount of liquid that finds its way to ground, or there will be a requirement for vessels to be occasionally drained of liquids of some sort so they can be maintained.

Drainage systems:

 Open system

 Close system

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Oil and Gas Operational Safety: Safe containment of hydrocarbons

1 Hazards and risk control for storage tanks:

Note: Tanks may be quite small (e.g., 1,000 m3) or very large (e.g., 50,000 m3).

Evolving damage mechanisms:

 Corrosion

 Erosion

 Creep associated with non-metallic thermoplastic tanks

 Fatigue

 Chemical attack

 Brittle fracture

 Mechanical damage

Safety Control: include regular inspection and maintenance of valves and vents together with any sensors associated with them.

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Oil and Gas Operational Safety: Safe containment of hydrocarbons

2 Hazards and risk control for tank with fix and floating roof:

 External floating roof tank (reduce evaporation amount )

 Internal floating roof tank (Internal floating roof tanks tend to be used for storing material with a low flash point, such as gasoline)

Safety Control:

 Double seal

 Detection system for leak

 Earthed

 Lighting conductor

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Oil and Gas Operational Safety: Safe containment of hydrocarbons

2 Hazards and risk control for tank with fix and floating roof:

 Supported fixed roof tank

 Self-supported fixed roof tank

Safety Control:

 Depressurization during loading to avoid rupture

 Avoid vacuum formation due to faulty air inlet valve

 Pressure and Vacuum (P&V) relief valve fitted on or near the top of the tank

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Oil and Gas Operational Safety: Safe containment of hydrocarbons

3 Bunding of tanks:

 Bunds are designed to contain any spillages and stop them escaping (includes seeping into the ground). Consequently, bunds should be built on an impervious base and the material the bund is constructed from should also be impervious.

 A bund needs to contain any amount of spillage from the tank(s) it surrounds. Hence, the capacity of the bund must be equal to the total maximum content of the tank(s) within the bund plus an extra 10 per cent.

 The bund itself must be complete, that is to say it must not be breached.

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Oil and Gas Operational Safety: Safe containment of hydrocarbons

4 Filling of tanks, overfilling/alarms/tanker connections:

Safety Control:

 Charging line with non-conductive hose

 Dip pipe design

 Guardrails

5 Pressurized and refrigerated vessel (e.g., LPG vessels, CO2 and LNG vessels):

Safety Control:

 Wall thicknesses of up to 15 cm

 Pressure relief

 Fire water deluge system

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Oil and Gas Operational Safety: Safe containment of hydrocarbons

6 Pipeline Inspection Gauges:

 Internal inspections and surveys

https://www.youtube.com/watch?v=vb_iyAwu0K4

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Oil and Gas Operational Safety: Furnace and Boiler Operations

1 Boiler and furnace:

Boilers are devices which heat large quantities of water in order provide a constant supply of hot water, or to turn it into steam. Where steam is generated, this is captured and kept in a pressurized state.

Furnaces, or process heaters, are devices which are used to provide a large source of heat to various process streams and are used extensively in the oil and gas industry

2 Boiler and furnace safety components:

 Safety relief valve which allows excessive steam pressure to be released to prevent overpressure or explosion.

 Drain which allows sediments and contaminates to be drained from the water.

 Safety controls of automatic and continuous monitoring of pressure and temperature high and low gas or oil pressure, high and low water.

 Flame safeguard controls.

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Oil and Gas Operational Safety: Furnace and Boiler Operations

3 Boiler types:

Fire tube boiler: Advantage

 Fire tube boilers are relatively inexpensive and are easy to clean

 They are usually smaller than water tube boilers

 easy to re-tube

Disadvantage

 Not suitable for high pressure application above 1.7 Mpa

 Unable to generate high capacity steam

Water tube boiler: Advantage

 Extremely high temperature steam (superheat)

 Recover faster

 High pressure steam up to 34.5 Mpa

Disadvantage

 Expensive capital outlay

 Difficult to clean

 Large in size

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Oil and Gas Operational Safety: Furnace and Boiler Operations

3 Furnace types:

Natural draught furnace:  Use natural draught to move the air and combustion

gases through the combustion chamber.

 Tall chimney to create temperature difference

Balance draught furnace:  fan or blower to increase and control the

flow of air and combustion

 Heat recovery system

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Oil and Gas Operational Safety: Furnace and Boiler Operations

4 Boiler/furnace hazards:

 Pilot lights (ignition source )

 Boiler over-firing (over manufacture’s recommended heat flux)

 Flame impingement (carbon deposition/ tube rupture)

 Firebox overpressure (fuel in fire chamber cause explosion)

 Low tube flow

 Control of Tube Material Temperature (TMT)- (poor quality of water cause scale-hardness of water is too high)

5 Maintenance:

 Close monitor Total Dissolved Solids (TDS), which are substances such as minerals, salts and even metals, which are held in a suspended form within water

 Logs

 Maintenance checklist

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Oil and Gas Operational Safety: Fire and explosion

1 Leak and fire detection systems:

The risk of fire and/or explosion on installations carries the highest level of consequence and, as such, needs to be addressed as robustly as possible.

 Spot systems

 Flame detection systems

 Heat detection systems

 Gas detection systems

 Smoke detection systems

 Leak detection systems

2 Active fire protection system:

 Water deluge systems

 Sprinkling system

 Chemical/foam

 Inert gas

Detectors

Active layer: water

deluge system

Passive layer

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Oil and Gas Operational Safety: Fire and explosion

3 Passive fire protection system:

 Spray-applied coatings

 Blanket/flexible jacket/wrap around systems

 Prefabricated sections such as walls

 Enclosures and casings

 Composites, Seals and Sealants

 Systems (e.g., cable transit blocks, inspection hatches, pipe penetration systems through bulkheads)

4 Specific examples:

 Floating roof tanks

 Spherical storage tanks

 Spherical storage tanks with fire fighting canon

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Oil and Gas Operational Safety: Fire and explosion

Good example of Emergency plan:

 Onsite emergency plan

 Content of emergency plan

 Fire and explosion strategy

Bad example of Emergency plan:

 Poor emergency planning and response leading to 167 casualties

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Oil and Gas Operational Safety: Fire and explosion

Medical Emergency:

 Triage: the assignment of degrees of urgency to wounds or illnesses to decide the order of treatment of a large number of patients or casualties

 On-shore emergency response

 Off-shore emergency response

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Oil and Gas Operational Safety: Fire and explosion

Escape, evacuation and rescue (Off-shore):

 Free fall life boat

 Life raft

 Helicopter

 Standby vessel

Training:

 Training specific to offshore installations (first aid/ basic fire fighting/ sea survive)

 Drills (evacuation procedures)

 Strategic command posts (commander determining best strategy)

 External support agencies (council, coastguard)

 Liaison with emergency services (emergency liaison officers)

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Oil and Gas Operational Safety: Marine transport

Case Example 1: Attendant/passing vessels hit the rigs

Mumbai High North Disaster: In 2005 the support vessel, MSV Samudra Suraksha, was in the process of transferring an injured worker to the Mumbai High North rig for medical attention when strong sea swells caused the vessel’s helideck to strike and sever one of the gas export risers. Escaping gas soon ignited and quickly developed into a fire which engulfed the whole installation. Twenty- two crew members were lost in the incident and the rig was completely destroyed by fire after two hours, with only the stumps of the jacket being left visible.

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Oil and Gas Operational Safety: Marine transport

Case Example 2: Loading and unloading operation

On 8 January 1979, the oil tanker Betelgeuse was discharging its cargo of oil via an offshore jetty at Widdy Island in Southern Ireland. At about 1am a rumbling or cracking noise was heard from the vessel. This was followed, a short time later, by a huge explosion. A further series of explosions followed which broke the vessel in half. Much of the oil cargo still on board ignited, and this fire continued for a further 12 hours, after which time the vessel sank at her moorings. Fifty people died in the incident. It was determined that a faulty unloading operation had unbalanced the vessel, causing it to break its back and thereby rupture several of its empty ballast tanks. Vapour from the ruptured tanks then escaped into the vessel and exploded in a fire ball when it found a source of ignition.

https://www.youtube.com/watch?v=k4zIufqkyLc

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Oil and Gas Operational Safety: Marine transport

Mooring:

 Avoid collision

Loading and Unloading:

Yokohama fender Single buoy mooring

Jetty loading Loading arms Unloading oil from a barge

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Oil and Gas Operational Safety: Marine transport

Personnel boarding:

Gangway boarding Accommodation ladder boarding Pilot ladder boarding

Billy Pugh transfer system Frog transfer system

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Oil and Gas Operational Safety: Land transport

Road tanker:

1 Explosive substances

2 Flammable gas

3 Flammable liquid

4 Flammable solid

5 Oxidizing agents

6 Toxic substances

7 Radioactive substances

8 Corrosive substances

9 Miscellaneous substances

Loading and Discharge: