Purpose and scope iii OCIMF: [email protected] [email protected] Purpose and scope This publication makes recommendations on the safety of cargo handling and associated operations on board Floating (Production) Storage and Offloading facilities (F(P)SOs). It supplements guidance in OCIMF’s International Safety Guide for Oil Tankers and Terminals (ISGOTT) by addressing activities and procedures that are either outside the scope of ISGOTT or are conducted differently on F(P)SOs. The guidance is for F(P)SO operators, but will also be of interest to anyone involved in the design and management of F(P)SOs. Fundamental differences exist between the operation of an F(P)SO and a tanker. An F(P) SO may remain on station for several years and may be required to concurrently undertake oil and gas processing, loading, water management, discharging and in-tank maintenance activities. Existing industry guidance for conventional tankers, e.g. ISGOTT, is not always suitable for F(P)SOs because it does not address the safe management of these concurrent activities. The purpose of this publication is to provide guidance, recommendations and best practice on management. Full attention is given to the need for robust planning and work scope development, supported by appropriate risk analysis and Permit to Work (PTW) systems. This publication also takes into account the operational issues associated with the potential presence of contaminants in oil and gas streams, which may include, for example, mercury and hydrogen sulphide (H2S). Sediments in storage tanks may include harmful substances such as oilfield scales and Naturally Occurring Radioactive Materials (NORMs), which can pose potential health risks to personnel. Many storage tank maintenance activities on an F(P)SO have to be undertaken while the unit is on station and handling oil and gas production streams. This publication provides recommendations on the safe isolation of tanks from the active systems and procedures for safe tank entry. Specific guidance is provided for hot and cold work in tanks, tank inspections and safe practices for the routine removal of sediments from cargo spaces. Where differences exist between the recommendations in this publication for activities undertaken on F(P)SOs, and those in ISGOTT for oil tankers, the procedures detailed in this publication should be followed by F(P)SO personnel, with the aim of achieving equivalent or higher levels of safety. Although the recommendations in this publication primarily relate to F(P)SOs that have a conventional hull form, much of the guidance can be equally applicable to other designs, e.g. those based on a cylindrical hull, as there are no fundamental differences in cargo management procedures. Operators of such units are encouraged to review the relevance of the guidance on a case-by-case basis. Routine cargo transfer operations to offtake tankers are outside the scope of this publication and are addressed in OCIMF’s Guidelines for Offshore Tanker Operations. It is recommended that personnel competence assessment activities follow the guidance in OCIMF’s Competence Assurance Guidelines for F(P)SOs. Always refer to the current edition of any publication referenced in this book. Glossary vii Glossary Within this publication, the terms below have the following meanings: Adsorption The adhesion of a thin film of molecules (of a gas, liquid or solid) to the surface of a liquid or solid that it is in contact with. As Low As Reasonably Practicable (ALARP) Each company should develop their own definition of ALARP. OCIMF uses the UK Health and Safety Executive (UK HSE) definition in this publication: Making sure a risk has been reduced to ALARP is about weighing the risk against the sacrifice needed to further reduce it. The decision is weighted in favour of health and safety and against commercial interest because the presumption is that the duty-holder (e.g. the ship operator) should implement the risk reduction measure. To avoid having to make this sacrifice, the duty-holder must be able to show that it would be grossly disproportionate to the benefits of risk reduction that would be achieved. Thus, the process is not one of balancing the costs and benefits of measures but, rather, of adopting measures except where they can be ignored because they involve grossly disproportionate sacrifices. Basic Sediment and Water (BS&W) The amount of suspended solids and water in crude oil, expressed as a percentage of the overall volume. Best practice OCIMF views this as a method of working or procedure to aspire to as part of continuous improvement. Bottom slamming The impact of the bottom structure of an F(P)SO onto the sea surface. In rough seas, the F(P)SO’s bow and stern may occasionally emerge from a wave and re-enter the wave with a heavy impact or slam, as the hull structure comes in contact with the water. Bullheading system Used to displace the contents of the subsea lines with stabilised (processed) crude and/or diesel oil into a well to prevent hydrate or wax formation during periods the well is not flowing. Bursting disc A sacrificial, one-time-use membrane that fails at a pre-determined differential pressure. Cause and Effect strategy A Cause and Effect strategy is used for defining how and when actions are executed in a safety system. It shows the relationship of all factors (causes) that lead to a given situation (effect). Closed drains system A completely closed piped system designed to collect liquid drains, from F(P)SO systems (vessels, piping, pumps, etc.) that may contain hydrocarbons, for further processing. Competent person A person who has acquired through training, qualification and experience the knowledge and skills necessary to undertake the tasks that they are required to perform within their job description. See OCIMF’s Competence Assurance Guidelines for F(P)SOs. Crash tank A slack storage tank designated to receive crude oil in the event of an operational disruption. Crude oil rundown Processed crude oil stream flowing from the production plant to the storage tanks in the hull. De-mucking The removal of a build-up of sediments from storage tanks. Double block and bleed valve A single valve with two seating surfaces that, in the closed position, provides a seal against pressure from both ends of the valve, with a means of venting/bleeding the cavity between the seating surfaces. A B C D Cargo Guidelines for F(P)SOs viii Enclosed space A space that has the following characteristics: • Limited openings for entry and exit. • Unfavourable natural ventilation. • Is not designed for continuous worker occupancy. This includes, but is not limited to, cargo spaces, double bottoms, fuel tanks, ballast tanks, pumprooms, compressor rooms, cofferdams, void spaces, duct keels, interbarrier spaces, engine crankcases and sewage tanks. Also known as a confined space. Enclosed space entry Entry of personnel into a space meeting the enclosed space criteria. Ex Register A list of all intrinsically safe equipment and components on board, including glands and penetrations, which require periodical inspection in accordance with regulations. Executive action An action taken by the person in charge of the facility at a defined time to avoid an unsafe situation. Front End Engineering and Design (FEED) An engineering design study used to thoroughly plan a project and control project cost. Green water A large quantity of water rolling onto an F(P)SO’s deck as a result of high waves and vessel motions during bad weather. Grit blasting Use of high velocity air, that is carrying sand or other abrasive particles, to clean metal surfaces. This is also known as abrasive blasting. Guidance Provision of advice or information by OCIMF. Hazard and Operability study (HAZOP) A structured, team-based approach to investigate how a system or plant in operation deviates from the design intent and creates risk for personnel and equipment and results in operability issues. Hazard Identification study (HAZID) A structured, team-based approach to identify hazards, their potential consequences, and requirements for risk reduction. Hazardous area An area on an F(P)SO which, for the purposes of the installation and use of electrical equipment, is regarded as dangerous. Hazardous areas are graded depending on the probability of the presence of a flammable gas mixture, e.g. zones 0, 1 and 2 as categorised in section 3.1. Hot work Work involving sources of ignition, or temperatures high enough to cause the ignition of a flammable gas mixture. This includes any work requiring the use of welding, burning or soldering equipment, blow torches, some power-driven tools, portable electrical equipment that is not intrinsically safe or contained within an approved explosion-proof housing and internal combustion engines. In the offshore industry different categories of hot work may be used, e.g. activities may be classed as having low energy (spark potential) or high energy (open flame). Integrity management system A formal management philosophy and program designed to identify critical equipment and systems, describe the required level of equipment inspections and identify the tests and procedures for managing performance. Lifting equipment Includes lifting appliances (equipment performing the lifting), lifting accessories (devices that connect the load to the lifting appliance) and lifted equipment (containers, baskets, etc.). Live crude oil Processed crude oil with a flashpoint less than 60°C. Management of change The process of bringing controlled and planned change to an operation, procedure, vessel equipment or personnel to meet a defined goal. Often to ensure that safety and/or environmental standards are not compromised under changed operating conditions. E F G H I L M Glossary ix Marine systems Cargo loading, discharge, cleaning, heating and vapour systems, which includes associated components such as valves, seals, gauging and custody transfer systems. Open drain system A system designed to collect drained liquids from containment systems (drip trays, spill bunding, tundishes, etc.) to prevent the release of oil-contaminated rain/wash-down water or oil leaks/spills to overboard and to prevent extensive on-deck liquid accumulations within the facility. The open drain system is typically segregated into hazardous (that may contain hydrocarbons) and non-hazardous (not containing hydrocarbons) open drain systems. Permit to Work (PTW) system A system for controlling activities that expose the F(P)SO, personnel or the environment to hazard. The system will provide risk assessment techniques and apply them to the varying levels of risk that may be experienced. The system should conform to a recognised industry guideline. Positive isolation The physical disconnection and/or blinding to positively segregate the energy, substances and materials from the proposed activity, without relying on valves or control systems. Pyrophoric iron sulphide Deposits that form when the H2S in crude oil reacts with the rust in tanks, creating a material that can spontaneously ignite in air. Recommendations OCIMF supports and endorses a particular method of working or procedure. Risk Based Assessment (RBA) Overall process of risk analysis and risk evaluation to support Risk Based Inspection (RBI). Risk Based Inspection (RBI) A risk assessment and management process that is focussed on hull structural integrity and loss of containment of pressurised equipment in marine and process systems due to material deterioration. These risks are managed primarily through inspection. Routine Simultaneous Operations (SIMOPS) Concurrent activities identified in the SIMOPS matrix and covered by existing, approved written instructions or procedures. Safety case A structured argument, supported by a body of evidence that provides a compelling, comprehensible and valid case that a system is safe for a given application in a given operating environment. Formal safety cases may be a locally legislated requirement. Safety helmet Any helmet designed to protect the head from accidental injury. The type of helmet will depend on the specific nature of the physical risks that have been identified in the risk assessment undertaken for the activity. Typical examples of safety helmets found on board an F(P)SO are the hard hat or construction worker’s helmet and the fireman’s outfit helmet. Simultaneous Operations (SIMOPS) Activities that take place at the same time and are either in the same area, and/or could directly or indirectly affect the safe performance of any other activity on the facility. Skim pile caisson A large diameter pipe, fitted with baffle plates and suspended from the F(P)SO to a point well below the sea surface, with means to skim any oil carryover back to the facility’s hazardous drain or slop system. Slack tank A storage tank that is only partially full. Snuffing system A fire suppression system that may be fitted on vent masts to extinguish ignited vapours. Sparging The introduction of small gas bubbles into a fluid. Storage tanks Cargo oil tanks, slop tanks, off-spec reception tanks, settling tanks and produced water treatment tanks in the F(P)SO hull. O P R S Cargo Guidelines for F(P)SOs x Total Acid Number (TAN) A measurement of acidity that is determined by the amount of potassium hydroxide in milligrams that is needed to neutralise the acids in one gram of oil. It is an important quality measurement of crude oil. Weathered crude oil Crude petroleum that, owing to evaporation and other natural causes during storage and handling, has lost a significant amount of its more volatile components. Weathering A process to raise a crude oil’s flash point to above 60°C by encouraging the release of lighter ends, thereby enabling the crude oil to be used as a fuel source. Work management system Set of work instructions for the tasks to be performed in accordance with the safety management system. It uses the PTW form as a basis to plan the task and to identify what will be required to execute the task. T W Section two: Hazardous materials associated with F(P)SO operations 13 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + AluminiumLead Alpha Beta Gamma Figure 2.1: Relative penetration of alpha, beta and gamma particles 2.2.3 Mitigating measures Personal exposure limits should be established in accordance with regulatory or F(P)SO operator requirements, whichever are more stringent. Respirators may be necessary in dry processes to protect against inhalation in case NORM scales and dust become airborne. Personnel should use PPE to protect them from physical contact with NORMs. PPE should typically comprise rubber boots, rubber gloves and appropriate chemical suits. It is recommended that any handling of NORMs is undertaken or supervised by specialist contractors, who should also be responsible for the transport and subsequent disposal of any contaminated residues. Personnel handling NORM residues should not eat, chew or drink anything during the activity. After the activity they should wash their hands and face with soap and water before handling any food. 2.3 - Mercury 2.3.1 General Mercury is a silver-white liquid metal. It is the only metal that is liquid at room temperature and atmospheric pressure. It solidifies at -39°C (melting point) and has a very low boiling point (357ºC). Mercury is a volatile element with a high vapour pressure at room temperature. It forms alloys (amalgams) with many metals, which weakens the parent metal. Various mercury compounds have been reported in natural gas, gas condensates and crude oil streams. Insoluble particulate mercury can contribute to more than 50% of the total mercury content found in storage tanks. It can also concentrate in produced water streams. 2.3.2 Hazards associated with mercury Both high-level/short-term and low-level/long-term exposures to mercury can cause serious health problems, including damage to the central nervous system, kidneys and liver. The risk Cargo Guidelines for F(P)SOs 14 varies depending on the quantity, duration and frequency of exposure, i.e. the cumulative effect. Exposure to mercury may cause paralysis and even death. High-level, short-term exposure can cause skin rashes, diarrhoea and respiratory distress. Repeated low-level exposure, or low-level, long-term exposure, can cause muscle tremors, irritability, personality changes or rashes. Mercury can adsorb on to the surfaces of process equipment and process vessels of different material construction and desorb at a later time. Separators, storage tanks and other vessels that have been cleaned and freed from mercury vapour have tested positive for mercury some time afterwards. The desorption rate will depend on the temperature and local air movement. Hot work on contaminated surfaces will increase the rate of desorption. Personnel should avoid all unprotected exposure to hydrocarbon vapours that may contain mercury, e.g. from the head space of storage tanks and associated piping, vent systems and machinery. Note the following: • The surface corrosion layer in uncoated steel, such as storage tank structure and piping, can retain amounts of mercury greater than 10 grams per square metre. • Equipment such as valves that have been cleaned of mercury may still have some adsorbed mercury on the metal. This may be released to the surface of the metal as vapour or small globules. • Enclosed spaces that have contained mercury may not be completely free of mercury vapour and should be treated with great caution. • Heating, welding and cleaning of contaminated equipment and storage tank structures may release small amounts of mercury vapour. 2.3.3 Mitigating measures Personnel who could be exposed to mercury in the course of their work should receive training before they start work. Training should address the following: • Health hazards associated with mercury exposure. • Potential sources of mercury exposure. • Air monitoring of mercury exposure. • Work procedures to reduce exposure. • Occupational health monitoring procedures. • The use of PPE including respiratory protection. • Hygiene procedures. • Dealing with accidental spills. The desorption of contaminated equipment will require the implementation of suitable health, safety and environmental precautions taking into account the following: • Implementation of a coating design plan that accounts for mercury in the cargo can help prevent or mitigate this issue. • When disposing of equipment that has been contaminated with mercury, possible adsorption of mercury should be considered. This may limit disposal options and mercury deposits may have to be mechanically removed, for example, by hydro-blasting. • Health and safety information should be given to third parties who may receive potentially contaminated equipment for refurbishment or disposal. It is recommended that equipment contaminated by mercury is handled by or under the supervision of specialist contractors, who should also be responsible for its transport and subsequent disposal. For more information see the OCIMF information paper Safety, Health, Environmental Issues and Recommendations for Shipboard Handling of Elevated Mercury Crude Cargoes. Section two: Hazardous materials associated with F(P)SO operations 15 2.3.3.1 Mercury detection methods There are a number of mercury detection techniques available that have excellent sensitivity for measuring mercury and can be used in instruments that are rugged enough for field applications. Common detector systems for mercury analysis include Cold Vapour Atomic Absorption (CVAA), Atomic Fluorescence (AF), resistance change to a gold leaf and reaction with various chemicals to produce a visible colour change. None of the detector systems will detect all of the potential compounds of mercury. F(P)SO operators are recommended to develop robust testing protocols to detect mercury compounds. 2.4 - Volatile Organic Compounds and BTEX 2.4.1 Volatile Organic Compounds The term Volatile Organic Compound (VOC) is generally applied to organic compounds that have a high vapour pressure at room temperature and a low boiling point. VOCs in crude oil evaporate from the surface of the oil and enter the vapour space in the storage tank. Benzene, Toluene, Ethylbenzene and Xylenes (collectively referred to as BTEX), found in crude oils, are all considered VOCs. Both acute and chronic exposure to VOCs can be harmful to health. Common symptoms of acute exposure are irritation of the respiratory tract, eye irritation, nausea and dizziness. Chronic exposure may increase the risk of cancer and liver or kidney damage. The main way VOCs enter the atmosphere is when an offtake tanker vents its vapour space to atmosphere during an offtake. Towards the end of the offtake the vapour can be rich in VOCs. The offtake tanker is responsible for the control of these emissions and guidance on how to control these emissions is contained within ISGOTT. Rundown rates to crude oil storage tanks on the F(P)SO are normally not sufficient to generate large quantities of VOCs during routine operations. The F(P)SO vent systems are designed to vent these vapours at a location that ensures safe dispersal to the atmosphere. If required, VOC conditioning systems can be installed to minimise the generation of VOCs or capture VOCs that have been generated. 2.4.2 BTEX ISGOTT contains more information on the toxicity and the toxic effects of benzene and other aromatic hydrocarbons. BTEX are aromatic hydrocarbons that are at the light end of the hydrocarbon family and are odorous and volatile. They occur naturally in fossil fuel reservoirs and can make up to 5% of the recovered oil and gas. • BTEX are harmful to health through both short and long-term exposure. • At low levels, effects include headaches and throat irritation. • If inhaled in high concentrations, BTEX can have a narcotic effect on the central nervous system. A lethal concentration may cause respiratory and cardiac failure. • Benzene is a known carcinogen (cancer causing substance) and chronic exposure may lead to cancers. BTEX can accumulate in coatings, scale and process equipment on F(P)SOs. F(P)SOs exposed to BTEX should have specialist detection equipment on board.