Fire safety engineering
ID:
Abstract
The primary purpose of this research is to illustrate the best practices which need to be followed in order to minimize the risks of leakages and mishaps resulting from the leakages. As the demand of LNG is on constant rise, the need of the hour is to prevent the leakages which may result either from the technical glitch or lack of adherence to the standard processes to be followed as recommended by the best practices through industrial standard. It is known that the Liquefied Natural Gas (LNG) is not as harmful as the Liquefied Petroleum Gas (LPG) and the effect of the leakages of the latter are more hazardous, but, still heavy precaution is recommended as incidents have occurred which has caused severe harm and even resulted in the building explosion. In this research paper, extensive review of the literature with respect to the best practices has been conducted. The aim was to search those sources which can show the directions with an object to prevent the leakage and the risks thereof. An exploratory research is also conducted in this direction by exploring the procedures which are followed by the best in industry. Based on the research, a set of recommendations are also proposed at the end. A direction and future road map is suggested for the enhancement to the next level.
Acknowledgements
I wish to thank University Of Central Lancashire that gave me this opportunity to conduct the research in the interesting topic of LNG. There has been a continuous source of knowledge and encouragement which I found from my guide, tutors and professor, without which this research could not have been possible. A special thanks to my supervisor Mr. Weiming Liu, who helped me to reach the end of this research with his continuous guidance and support in all aspects. Many thanks to my friends and colleagues who helped me to identify and find the primary and the secondary sources required for this search. They also provided me with help and encouragement throughout this research. I also want to thank my family for providing me the adequate support.
Chapter 1: General Introduction
Proper upkeep of the storage tanks where LNG is stored at the plants, the efficient and recommended method of gas transmission to the outlets in the building, timely testing and following the standards are the key to safety and security. The key to the safe operations of the LNG gas are safe storage, safe transmission and routine testing. (Foss, 2006). By operating the LNG gas with safe operations, all the incidences and possibilities of leakages cannot be avoided, but the risks can be minimized by following the best practices. (API, 2003) .The object of the research is to find the best practices in LNG Operations which must be followed so as to minimize the risks of leakages and catastrophes caused by such leakages. The Liquefied Natural Gas (LNG) is not as harmful as the Liquefied Petroleum Gas (LPG) and the effect of the leakages of the latter are more hazardous, but, still heavy precaution is recommended as incidents have occurred which has caused severe harm and even resulted in the building explosion. (ABS Consulting, 2004).
However, in domestic supplies, LNG is preferable as it is lighter than LPG, provided the best practices in safe operations are followed. The rest of the paper is organized as --- the introduction about the research is given in the first chapter. Next chapter concentrates on the extensive Literature Review from different sources and note the findings on the recommended best practices for safe operations which must be followed to avoid the Gas Leaks. The following chapter provides the details of the research, including some methodology and the data collection. Last chapter pertains to the conclusion and recommendations. (Foss, 2006).
Introduction
Energy for domestic purposes is used for three core societal needs - heating and cooling, mobility, and electric power. The majority of energy use in (50%) is actually for heating – both space heating and process heat for industry. This is followed by energy for mobility (30%) and finally electricity (20%). Today, natural gas has a central place in domestic or industrial energy mix meeting over 30 per cent of the energy needs. The majority of the customers are the homes, flats and buildings. But the greater volumes of natural gas are delivered to non-residential customers – businesses, institutions, and large industry.
Customers use natural gas for:
• Heat – in industrial uses and for space and water heating in homes;
• To generate electricity; and
• A very small amount – less than 1% - is used as a transportation fuel.
Already hundreds of thousands of kilometres of underground pipeline infrastructure and storage facilities have been built out to bring natural gas across the countries to customers and the natural gas utility franchise areas are in and near urban centres. Since 2005, the natural gas distribution sector has invested over billions of dollars in this extensive network to ensure the safe, secure, and reliable operation and maintenance of this system. Special care has been taken to find innovative ways of storing the LNG gas in the overhead tanks. The storage tanks have been subjected to innovative designs so as to prevent the disasters like leakages and explosions. Moreover it is ensured that the storage of the LNG gas is away from the densely located areas. This is so because even if the mishap takes place, it does not cause much harm to the public. Similarly, due care is taken to maintain the storage takes as pre the recommended best practices. Proper maintenance routines are scheduled and the checks are conducted to ensure the safe storage operations. (Foss, 2006).
LNG Popularity
The primary reason as to why the LNG is gaining more popularity than LPG is that as compared to only 50 times for LPG, LNG compresses 600 times and occupies a very less volume when liquefied. This is a very big difference, due to which the transportation of LNG is more economical than LPG. Another advantage is that if LNG leaks or spills, it gets easily vaporized and creates very less flammable air/gas mix. For instance, if the LPG leaks in a kitchen, it can get easily ignited by a spark produced by, say, switching on an electricity button or any other equipment. The concentration of LPG is also very high and can easily create an explosion. This is not the case with LNG. Since LNG can be compressed 600 times, so if it leaks it creates less risky mix with air, and certainly cannot create an explosion. Hence the chances are almost 6 times less likely to create a fire as compared to LPG gas. (Moon et.al., 2009).
The transportation of LNG is more economical as more volume of LNG can be transported. However, there are some concerns, which lead to designing specific propulsion systems and cargo handling systems for porting LNG. The most important concern in handling LNG gas is to maintain the structural integrity. As the liquefied LNG stored in the tanks are comparatively heavy, so the structural integrity of the carriers will ensure that there is low risk of accidents in transportation. For instance, LNG ships are provided with the double hull. This ensures that maximum protection is available even if a remote incident of ship collision or grounding occurs. The LNG is still protected due to the provision of the double hull. LNG ships are also fitted with the safety equipments, specific to the LNG. These ships also carry sophisticated radar and positioning system for an early warning, help and support system, in case of an accident. (Moon et.al., 2009).
The key to safety of LNG is proper storage, proper transmission and proper upkeep. If these three functions are followed with due care then the mishaps related to leaks can be avoided. Although not all the accidents can be prevented, but the risk involved with the LNG can be minimized. The transmission of LNG gas by ships is a major operations having very high risk. The leakages, if any, can lead to terrible explosions and considerable loss. Therefore, innovative designs of the ships or vessels which carry the LNG are designed. The ships have double hulls and have remarkable stability. There is sufficient buffer and cushion as shock absorber which can withstand a collision. The leaks are avoided at all costs as the leakage may mean lot of chances of collision as LNG gas has very high compression rate.
Another aspect is that, due to the excellent properties of LNG which are conducive to the transportation and storage, there is remarkable record of safety in LNG operations. This helps in constructing the storage tanks at very high altitude. LNG gas is lighter as compared to LPG gas, due to which the LNG gas, if stored at high overhead tanks, cannot come down to the ground. The inflammable mix is therefore at higher levels, much higher than the residential buildings or commercial complexes. It is possible to build very high capacity, for instance, 7000 cubic meters (1,000,000 barrel) capacity over the ground tanks. The higher the location of the tank, its better and with the help of improvement in the building technology, like pre-stressed concrete design, even higher capacity tanks, to the tune of 200, 000 cubic meters are being built. This is remarkably high capacity, capable of supplying to large areas for domestic and commercial usage, through the pipelines. Incidentally, it is not advisable to construct storage tanks near densely populated regions, so it is better to store at the outskirts or sub-urban areas and supply to the densely located regions through a mesh of pipelines. (Foss, M., 2006)
The below table shows a brief comparison between LNG, LPG, Gasoline and Fuel Gas:
Comparison of Properties of Liquid fuels (Foss, M., 2006) Clearly, both LNG and LPG are better, however, LNG scores still better, when it comes to storage and porting as described above.
Aims and Objectives
The primary aim of this research is to establish the hypothesis that following the recommended standards (key to safety) in installation, transmission and maintenance of the LNG system can reduce the risks of leakage and fire. (California Energy Commission, 2003).
The objectives of the research are to highlight the best practices in storing the LNG gas and the recommended procedures to test the equipments which will help in preventing the leaks and fires (API, 2003). Also, the transmission is another crucial factor in avoiding LNG related mishaps. To recommend the best and innovative means of transmission is another object in this study. Another object of this research is to suggest the future trends and enhancements in the techniques of store and transmission of the LNG in the cost effective, safe and secured manner.
Research Methodology
This research is more of exploratory in nature. So lot of resources and contemporary literature have been studied. Some primary and secondary sources have also been considered for instance the scope documents of actual plants and the recommended best practices being followed by several agencies dealing with the store and supply of the LNG Gas. Based on the recommended best practices by the Agencies and the results obtained by following the standards have produced deep insights to conduct this research. The research process has been followed as discussed in the relevant section, starting with conducting the proper literature review from as many as 20 academic as well as industrial resources. Primary as well as secondary sources have been considered for the research. The analysis of the resources and the relevant data and information obtained thereof has been the main body of the research.
Chapter 2: Literature Review
In this section the focus will be to study the different sources extensively concentrating on the Objects of this research. The focus will be on the key factors for LNG safety and avoid leakages. (Foss, 2006). The California Energy Commission safety standards for natural gas and liquefied natural gas (LNG) facility operators provide the standards for Safety and security of the Gas pipelines and upkeep (California Energy Commission, 2003). The standards also mandate the safety and security of the installation by specifically mentioning that: (Aspen Environmental Group, 2005). As part of its Damage Prevention Program, it is recommended that each natural gas utility needs to maintain well documented procedures for protecting existing underground facilities during directional drilling and other trenchless technology installation techniques. These documented procedures shall utilize the guidance material provided by the Gas Piping Technology Committee (GPTC) detailed in Guidance Material Appendix G-192-6, or other recognized industry standard.
The resource (CEE, 2003) also recommends that when the gas utility is installing natural gas facilities with these techniques, the procedures shall require mandatory exposure of existing underground facilities when alternate methods of protecting these facilities are impractical or not available. Any new findings should be augmented to update the documented procedure records.
Research further notes that whenever conducted by third party excavators, the procedures shall require mandatory monitoring of these excavations when the utility is notified and the utility determines that the proximity of the proposed excavation could affect the integrity of the gas facility. The utility shall train its operating personnel, including locators and others who monitor trenchless excavation activities, in the specific requirements and hazards associated with those activities (Kidnay & Parrish, 2006). The training shall follow the recommended and documented training procedures. These researchers provide that these ocedures shall be reviewed annually and modified as necessary to be consistent with industry best practices (API, 2003).
The buildings must also be equipped with the Facilities on System Maps Using GPS Coordinates. The research explains that each natural gas utility shall provide global positioning system (GPS) coordinate identifiers, referenced to the North American Datum of 1983, for the location of all facilities installed after January 1, 2012 (Kidnay & Parrish, 2006). The location points for existing facilities shall be recorded whenever an underground facility is exposed, but coordinates for all existing critical valves shall be obtained by January 1, 2013, whether or not they have been exposed or accessed for other reasons. The GPS location data for new facilities shall be obtained for critical valves, at intersections with service lines, main or other gas facilities, at any point of directional change and at intervals along a pipeline sufficient to achieve geospatial accuracy.
The Emergency procedures have been laid down, if there is incident of the leakages so that the natural gas utility staff shall notify the Gas Safety Staff by telephone in accordance with the Standard Contact Protocol promptly, without jeopardizing the response to the emergency, but no more than one hour following the discovery of the emergency. The emergency records shall also be maintained as per the standards (European Union, nd). The installation of the protection meters and safety of the meters and the pipelines, especially those which are exposed to the vehicular traffic have been put as mandatory. Gas meters, regulators, and aboveground pipeline facilities located in areas subject to vehicular damage shall be provided adequate protective barriers on each side exposed to vehicular traffic. Operators that have above-ground piping and appurtenances at commercial and industrial premises shall consider the potential for damage to the gas facilities from equipment used in the operation and maintenance of that facility and provide adequate protection (CEE, 2003).
The research literature from the contemporary sources also recommends about the safety staff visits to the sites, buildings or the customer places to check the safety and security of the installation (Aspen Environmental Group, 2005). This goes a long way to ensure the avoidance of the leakages. It is mentioned that when visiting a customer’s premises for any technical service, such as atmospheric corrosion inspections of utility facilities or connecting or reconnecting a customer service, operators shall also observe visible customer piping for atmospheric corrosion or other potential safety issues. The operators shall implement standard Procedures that include a “Red Tag” hazardous equipment procedure for suspending service to a customer when a hazardous condition is noted that makes the continued delivery of gas unsafe.
They would put a red tag if the conditions are found hazardous. The utility operators shall modify their Public Awareness Plans to include notification to customers that their piping must be in compliance with standards and maintained to prevent atmospheric corrosion. Customer notifications shall also describe the procedures of as given in the Operation Manuals (European Union, nd).
In the research literature (Kidnay & Parrish, 2006) available for the safety and prevention of the leakages in buildings, provide the set of installation procedures which must be followed to ensure that the safety measures are observed from the start itself during the Installations including the installation of Plastic Pipe, Warning Tape, and Tracer Wire. To facilitate location of buried plastic pipe, when plastic pipe is installed or replaced the various location methods shall be used. An electrically conductive tracer wire must be installed with new or replaced plastic pipe, including plastic pipe that is inserted into existing buried cast iron pipe as a means of pipe replacement. Tracer wire may not be wrapped around the pipe and contact with the pipe shall be minimized but is not prohibited when trenchless technology, including pipe insertion, is used. Continuous gas pipeline warning tape shall be installed approximately one (1) foot below finish grade. The warning tape shall be yellow, indicate the presence of a gas line, and at least six (6) inches wide. No warning tape is required when pipe is installed by trenchless technology, including pipe insertion. Plastic Pipe Joining and Design recommendations have been provided. Each person that joins plastic pipe shall be qualified to do so for each joining method at intervals not exceeding 15 months, but at least once each calendar year. Each completed plastic joint must be inspected by a person qualified to perform the joining method to be inspected. This person cannot be the person that performed the joining method that is subject to inspection. Design of plastic pipe shall be in accordance with the given standards as per the operations manual.
The contemporary literature (European Union, nd) also provides Minimum Cover and Separation Standards for Mains and Service Lines so as to ensure proper safety with an ultimate aim to reduce the occurrence of the leakages. Mains in Public Right-of-Ways to be used. New or replaced mains located in public rights-of-way shall be installed with at least thirty-six (36) inches of cover, except where an obstruction prevents that installation depth or when pipe is inserted into existing pipe. It is recommended for the Separation from Subsurface Structures.
Kidnay and Parrish suggest that where there is interference with other subsurface structures, including other utilities, the pipe shall be laid at a clearance distance of not less than twelve (12) inches away from such structures unless adequate shielding is provided to protect the gas pipeline and the other utility. (Kidnay & Parrish, 2006). Any interfering structure which provides a space in which an explosive atmosphere might accumulate in the event of a leak shall be avoided where possible and preference shall be given to crossing over rather than under such structures. When the installed pipe has less than 24 inches of cover, it shall be protected with shielding that conforms with gas industry standards both in respect to material and manner of installation (European Union, nd).
For the Service Lines the recommendation are provided in the literature to prevent the mishaps. (Aspen Environmental Group, 2005). Each buried service line shall be installed with at least 24 inches of cover in private property and at least 30 inches of cover within street and road right-of-ways. Cover may be reduced to a minimum of 18 inches for the connection to a prefabricated riser. Natural gas utility operators shall be responsible for the maintenance, leak testing and repair of system service lines. The Accessibility and Operability of Pipeline System Valves is also essential. The research literature (Aspen Environmental Group, 2005) provides that for each pipeline valve installed on a main shall be in an accessible location and its Global Positioning System (GPS) coordinates and triangulation ties shall be marked and maintained on a pipeline system drawing. Current maps should be easily accessible to operating personnel. Each valve installed on a main for emergency purposes, shall be maintained to be readily accessible to facilitate its operation in an emergency. (Aspen Environmental Group, 2005). Each distribution valve designated as an emergency, or critical, valve shall be inspected and partially operated at least once each calendar year at intervals not to exceed fifteen (15) months. Each operator must take prompt remedial action to correct any valve found inoperable, unless the operator designates an alternative valve. Each distribution valve, not designated for emergency purposes, shall be inspected and partially operated at least once every five (5) calendar years at intervals not to exceed 66 months. Each operator must take remedial action to correct any valve found inoperable, or document on valve records and maps that the valve is inoperable. (Aspen Environmental Group, 2005). Utilities that do not have a Commission-approved isolation zone plan shall install sufficient distribution valves on mains to isolate looped portions of a pipeline system and minimize outages to no more than 500 customers but no more than the number that the gas system operator has sufficient technical resources, including mutual aid, to relight within 8 hours. The relight interval shall begin immediately upon restoration of sufficient system function to support reconnection of service load. (Aspen Environmental Group, 2005).
The same literature (Aspen Environmental Group, 2005) further provides that if the valve is installed in a buried box or enclosure, the box or enclosure shall be installed to avoid transmitting external loads to the main and service line(s). The valve box or enclosure shall be maintained to be readily accessible. Operators shall maintain all valve boxes that are necessary to system operation or emergency response so as to avoid being paved over or filled with debris that prevents access to the valve or degrades valve operability. The Quality adherence is also important and critical to ensure that the leakage is prevented in the building. All the procedures, installations, maintenance, upkeep, replacement and security measure must adhere to the quality standards. Furthermore, it is also recommended in the literature that the quality assurance is provided with every installation (Aspen Environmental Group, 2005).The researches in this area recommend that a quality control program must also be in place so as to ensure the safety and security of the buildings.
The research literature for Quality Assurance/Quality Control Program is also given in various resources. It is provided that (Aspen Environmental Group, 2005) each natural gas utility must, as part of its compliance with the Procedural manual for operations, maintenance, and emergencies, include procedures for evaluating the work performed by utility personnel to determine the effectiveness and adequacy of the procedures used during normal operation and maintenance tasks and to modify the procedures when deficiencies are found. Such procedures shall be set out in a written Quality Assurance and Quality Control Program (QA/QC) that promotes gas system and related employee and contractor safety through monitoring of field work activities performed during the construction, installation, operation and maintenance of gas facilities. The utility shall also develop a construction inspection program for new construction and facility repair work done by utility employees and by contractors as part of the QA/QC Program. A mandatory component of the natural gas utility’s QA/QC Program shall be on-going audits of tasks performed with a goal to ensure compliance with written company policies, practices, procedures and specifications; and with applicable codes. Record keeping accuracy and completeness verification audits are also included in this component of the QA/QC Program.
Leak Detection Equipment Calibration and Maintenance is also required. Each natural gas utility shall maintain written procedures for the calibration and maintenance of leak detection equipment. These procedures shall consider the type of equipment, frequency of use, manufacturer’s calibration recommendations, historical performance, age of equipment, required maintenance intervals and equipment failure protocols. These procedures shall be reviewed annually and modified to the degree necessary to ensure that leak detection equipment used in the field has been properly calibrated and maintained.
Each natural gas utility shall institute and maintain on a continuing basis a leak progression mapping system of its service area in a format that conforms with the specifications of the manual. Map attributes to be included for each leak shall be: pipe or appurtenance material, location of leak, cause of leak, and type of joint, if joint leak. All leaks that have occurred shall be entered and recorded into the system. Historical Leak information should be entered if the accuracy of the information can be verified.
The literature also mentions that the proper records be maintained for the purpose of documentation and reporting. These should be maintained as per the prescribed standards and specifications. It is suggested as the best practice to ensure the participation in the Plastic Pipe Data Collection and Sharing Initiative. Each natural gas utility shall participate in the Plastic Pipe Data Collection and Sharing Initiative and report each discovered incident of plastic pipe failure as prescribed in the Initiative.
California Energy Commission and some other Public Utility Commissions adopt an Annual Submission of Operation Plans to be done. Each natural gas utility shall annually file electronically with the Maine Public Utility Commission Gas Safety Manager current copies of the following written plans for each pipeline system operated within the State of Maine:
a. Pipeline Operating & Maintenance Plan (O & M Plan)
b. Construction Standards
c. Pipeline Emergency Plan (may be combined with O & M Plan)
d. Pipeline Operator Qualification Plan
e. Damage Prevention Plan
f. Public Awareness Plan
g. Integrity Management Program (when required by 49 CFR Part 192)
h. Quality Assurance / Quality Control Plan
California Energy Commission. 2003 also provides the most recent revisions to each plan submitted shall be underlined. The annual filings shall be made no later than the 1st day of May or no later than two weeks prior to the start of pipeline operations by a pipeline operator of a new or newly acquired pipeline system. Acceptable electronic formats for the plans may have the following file name extensions: .doc or .pdf, or other formats that are approved in advance of the filing deadline by the Commission’s Gas Safety Program Manager. Each utility shall designate person responsible for coordination of the plans listed in (a) above, and who will be responsible for on-going evaluation of the effectiveness of each plan and identifying changes needed due to changes in technology, code requirements, or improved procedures. Coordination of Written Operation & Maintenance (O & M), Emergency, and Operator Qualification (OQ) Plans. Each natural gas utility shall Annually review its O&M Plan to verify that it meets the requirements of the standard manual, and that its Emergency Plan meets the requirements thereof; Identify the company specifications, procedures and/or any applicable manufacturer instructions that apply to the operations described in the pipeline O& M and Emergency Plan(s) and to the identified covered tasks listed in its OQ Plan; Clearly indicate within each plan the natural gas utility specification, procedure and/or manufacturer instructions that persons performing the operation or task must apply or follow by tabbing, footnoting, end-noting, indexing, linking or by other method(s) that will provide all required information to personnel in the field, as well as to operator managers and supervisors, and to the Maine Public Utilities Commission Gas Safety Engineer. Logging and Analysis of Responses to Gas Door and Leak Reports that each utility operator shall record each gas leak or odour report it receives. A log shall be kept and maintained on file recording the receipt and handling of each such report and shall contain the following information:
a. Incoming date
b. Incoming time
c. Address, town and state
d. Work order number
e. Dispatcher name or employee identification number
f. Technician name or employee identification number
g. Time assigned to technician
h. Time accepted by technician
i. Time en route
j. Time arrived on site
k. Total time work order held in dispatch
California Energy Commission. 2003, also recommends to report of Performance Measures also needs to be made to help maintain the system efficiently. The annual system performance measures shall be reported to the each year. Leaks per mile by pipe material, where leaks are defined in accordance with the standard templates. Leaks per mile for steel pipe shall be reported for each of the following categories of installed pipe, as specified in c – e below:
1) bare steel,
2) coated steel, and
3) cathodically protected steel.
c. Tickets per mile shall be derived as follows:
# current year tickets / # system miles
d. Damages per mile, calculated as follows:
(# current year damages / # current year system miles)
e. Damage per 1000 tickets, calculated as follows:
(annual # current year damages / # current year tickets) x 1000
As per the contemporary literature, care needs to be taken to follow the above standards to avoid the effects of radiations on the people. Several research papers are available which reveal the effects of the LNG radiations on human beings. From the review of literature which reveals this effect, it is clear that these effects are directly proportional to incident heat flux and the time of the exposure. The data which was estimated in evaluating the effect was by conducting the appropriate experiments. The experiments were conducted on:
a. humans, obviously with low level of radiations
b. with animals, with the appropriate levels and time of exposure
c. review of actual available records from the places where the incidents did occur, involving the LNG leakages and fire. The data came mostly from the clinical data recorded. (ABS consulting, 2004).The researchers have used primarily 2 models to conduct this research – first is the tabulated radiation levels model and other is the probability model or the probit model.
Tabulated models include the tables as shown below to indicate the burn injury criteria:
Thermal Radiation Burn Injury Criteria (ABS consulting, 2004)
The above table shows the intensity and time of the exposure which can produce the severe pain or second degree burns. The same sources also reveal the amount of permissible radiation intensity levels:
Permissible Thermal Radiation Exposure for Flares (ABS consulting, 2004)
This data is quite important as it show that what levels of protections are necessary to avoid the risky levels of radiations and intensity. Perhaps an exposure of low intensity of 500 can still be tolerable, as some times it happens at homes or handling while operations, but higher levels are certainly injurious. This data drives the innovation in storages, handling and porting of the LNG Gas.
Chapter 3: Research
Introduction
Following the best practices in building the additional capacity to store LNG helps to prevent the leaks which may eventually lead to explosions. So the design characteristics of the tanks to store LNG are as follows: Design pressure of these tanks should be 150 mbar (gauge) and the maximum working pressure should be 125 mbar (gauge) and this pressure should be controlled by the automatic pressure control valve connected to the flare. Furthermore, there are four safety valves, whose diameters are 12”/16” each, set pressures are 135 mbar (gauge) with 32” pipe line opening directly to the flare and there are three safety valves, whose diameters are 12”/16” each, set pressures are 150 mbar (gauge) opening to the atmosphere directly in each tank. In addition, there are 9 pieces of 12” vacuum breaker valves, which take the air into the tank being opened with -1,8 mbar(gauge). Each tank has 4 pieces of pump sump, in which there are pumps with 300 m3 LNG discharge capacity and 12,8 bar(gauge) exit pressure being equivalent with each other.
Total discharge capacity of pumps in each tank should be 1200 m3 LNG with 12,8 bar(gauge) (with four pumps). If a new tank is to be installed, it should have an equivalent area with the existing tanks needs to be prepared for this purpose. Ring roads need to be built. LNG flow channels, impounding pool, and underground fire water lines have to be installed and be in service. (MARMARA EREĞLİSİ LNG TERMINAL, nd)
Methodology
A proper control system needs to be in place for the LNG system as per the recommended practice. Without the proper control system, there are chances of leaks, fires as well as explosion. Since this is an exploratory research so the existing resources were examined and it was observed that the best practices for the control system is as given hereunder (NFPA, 2006)
Research methodology used was as per the recommended practice for exploratory research methods as recommended by Saunders et. al., 2007. It is an iterative research process, where the search is started from the extensive search of parks and the related incidents. At each step, the attempt is made to analyze from the studies iteratively. The sources are filtered so as to focus into the selected and relevant sources and augment the findings through this process. The research process itself is illustrated in the below figure:
Research Methodology . Saunders et. al. ( 2007 )
It is in the form of a research onion where each layer is peeled and the findings augmented an enriched as we go deeper into the study. This method also helps to be stayed focus on the research topic and assists in getting the accurate findings, most relevant to the context of the research.
DCS system, (MARMARA EREĞLİSİ LNG TERMINAL, nd) through which all equipments in the terminal are controlled and commanded, is Honeywell Experion PKS 211 version. There are three pieces of C200 CPM module, each of them has back ups, in the system. There is Honeywell FSC (Fail Safe) system as the Emergency Stopping System, which stops the terminal safely in case of inadmissible process conditions and works independent of DCS system. There are two pieces of Servers, which work as a redundant of each other, and three pieces of operator station, two of which have double screen. (MARMARA EREĞLİSİ LNG TERMINAL, nd).
There are sufficient empty spaces in the system room for additional DCS and FSC system panel board to be installed in the scope of this investment and for the transfer cabins to which inputs/outputs coming from the field shall be connected. However, it is going to be analyzed whether the existing modules and I/O cards in question systems are sufficient for the equipment to be added in the scope of this project and the list of the required equipments and their technical characteristics shall be determined, and project design and engineering studies shall be carried out.
Existing Central Fire Warning, Alarm And Protection System (Fire And Gas Detection & Extinguish System ): There is a comprehensive protection, warning and alarm system to be protected from the LNG and gas leakage and fire that might occur in the terminal.
Protection from the fire is carried out through the following items existing in the field
- Fire water spraying/ejection systems,
- 3 pieces of fire water pumps, two are diesel and one is electrical
- Deluge system and valves,
- Monitoring apparatus on the port and fire monitor,
- Dry Chemical powder system in LNG Storage tanks,
- Foam generator and pools next to the LNG Storage tanks,
- Hydrates and hose boxes,
- Dry chemical and foamed fire fighting equipments
And also provided with Halon and HVAC systems existing in buildings.
Alarm signals coming to Fire Alarm and Warning System belonging to GENERAL MOTORS Firm in the control room via GD – gas, IV/IR – Flame, TD – Heat, HD – Heat detectors and SPB – Manuel control glass protected buttons and SD – fume detectors in the building, which can detect gas and LNG leakage next to and/or all equipment in the field are transmitted to both the DCS – Central Control System and FSC – Emergency Stopping System in the control room and also Fire Alarm and Warning State Panel mounted to the wall and they are displayed by LEDs in different colours and types.
Data
Metering station has 4 metering runs. One of them is 6” and three of them are 20”, and all of them are connected to a 20” headers (upstream and downstream sides). Metering station with its all mechanical and electrical equipments has an -/+ 1 % of overall uncertainty.
6” metering run is used for measuring the flows upto 40.000 Nm3/hour. Each piece of 3 pieces of 20” metering runs are identical and two of them are designed to measure 685.000 Nm3/hour, which is the design vaporization value of the the LNG terminal. One of them is stand-by.
PAY / CHECK measurement are done by the orifice meter. For the PAY; 3 pcs of Flow Transmitter, 1 pcs of Pressure Transmitter and 1 pcs Temperature Transmitter and for the CHECK; 1 pcs of Flow Transmitter, 1 pcs of Pressure Transmitter and 1 pcs of Temperature Transmitter are used on each run. All transmitters calibration periyods are different from others. Gas delivery from the terminal is calculated by PAY / CHECK redundant Flow Computers and Gas Chromatographs which is redundant to each other. There are manual valves on upstream side and MOV (Motor Operated Valve) valves on downstream side for each run.
Flow calculations are carried out according to ISO 5167-2003 and compressibility factors are calculated according to AGA 8. 14” Class: 900# 9R1J, Material: ASTM A 358 Gr304 CL1 F 304L, Test Pressure: 223,4 bar(g), longitudinally welded, wall thickness: 19,05 mm. (Marmara Ereğlisi Lng Terminal, n.d.).
Existing 14” pipe is designed to transfer the LNG of 3×228.300 Nm3/hour with high pressure from the HP field to the ORV field. . (Marmara Ereğlisi Lng Terminal, n.d.).
This 14” pipe coming out from HP header, goes to the East after passing through the pipe bridge in the HP and compressor field, following the pipe bridge in the east-west direction. Then it bends to the south through the pipe bridge passing in front of the tanks and going towards North-South direction. Afterwards it goes in the jetty direction following the pipe bridge going to the jetty in the West-East direction. When it comes in front of the ORV field it bends to the ORV field. Existing line: 20”, Material: API 5L Gr.B, Class: 900# 9P1, Test pressure: 229,7 bar(g), Wall thickness: 25,4mm, It passes in between welded 101FA and 101FB tanks and connects the ORV exit header to the metering station. It is laid as underground pipe. (Marmara Ereğlisi Lng Terminal, n.d.).
This existing pipe is designed to transfer the natural gas with a capacity of 228.300 Nm3/hour from ORVs to the metering unit. (Marmara Ereğlisi Lng Terminal, n.d.).
Analysis and Discussion
As a result of the feasibility study conducted, the volume of the tank to be installed shall be 140.000 m3 LNG which will be determined as the optimum storage capacity. Design pressure of the tank shall be approximately 250 mbar(gauge). According to the capacity of the tank to be installed, the number and power of the pumps shall be determined by the Employer. According to this number and the power, required design studies related with the pumps in the tank shall be carried out.
The height of the point in which the exit pressure of the pumps in the existing tanks is approximately 22 meters and the rating capacity of these tanks at this point 12,8 bar(gauge) of exit pressure is 300 m3 LNG/hour. Pumps to be installed in the 4th tank shall be designed to work in parallel with the pumps in the existing tanks.
While preparing the high capacity 4th LNG Storage tank project to be constructed, the infrastructure and the piping facilities made for the 85.000 m3 LNG storage capacity tank, which is planned to be built later, during the construction of the terminal, shall be used as much as possible and required additional investments shall be determined. The biggest, the most economic LNG storage tank shall be chosen having a minimum LNG storage capacity of 140.000 m3 in accordance with the soil survey, and seismic analysis values of the field to which the tank shall be installed and within the boundaries of possibility of the existing field to which the tank shall be installed.
The soil survey and seismic studies made during the construction of the terminal shall be submitted. A new soil survey and seismic study shall be done. Seismic design shall be done according to the latest version of NFPA 59A (NFPA, 2006). Equipment place selection shall be done accordingly also. Tank type, design pressure and production project shall be determined. The amount of heat that can enter to the tank and the amount of boil-off gas that shall occur due to this heat shall be determined. The effect of the diffusion around of the gas cloud which occurs due to the flow of the LNG leakage in LNG channels and accumulation of this leakage in impounding pool while LNG is filled to the tank from the ship or while transmitted from the tank via the tank pumps and the environmental effects of radiation heat occurring due to a fire shall be analyzed and reported. The effect of the intensity of the explosion that can occur in case of a collapse in the ceiling of the tank due to an explosion in the tank, the radiation heat due to the fire or environmental effects of the gas leakage cloud shall be analyzed. The utility consumption of the tank, such as IS, GNI, PA, and water shall be determined.
Necessary compressor capacity shall be determined. While determining the compressor capacity according to the need of the Employer related with the pipeline compressor to be procured, the Employer may intervene with the works of the Contractor and the compressor shall be determined with the approval of the Employer. Suction pressure 9,7 bar(gauge) and discharge pressure 80 bar(gauge) shall be applicable and the discharged gas shall be transmitted to the metering station via pipe with an appropriate diameter.
The newly installed compressor shall be able to function alone or may operate with the existing compressor in parallel. The compressors shall have pistons and shall be actuated with electrical engines. The place to which the compressor shall be installed will be chosen and the route through which pipes shall pass will be determined.
Two pieces of ORVs shall be installed and their capacity shall be calculated in accordance with the system needs (with the approval of the Employer). The design of the 5 pieces of ORVs in total including two pieces of additional ORVs to be added to the existing system shall be done for operating in 4+1 (4 in service, and 1 piece of backup) configuration.
The LNG to be used in vaporization is the LNG discharged by the high pressure (HP) pumps and it shall arrive to this unit with a pressure of 40 bar(gauge) and 115 bar (gauge).
The LNG gasified in ORV system, shall leave the unit with a pressure in between 35 bar(gauge) and 83 bar(gauge) a little bit higher than the BOTAŞ Main Pipe Line pressure. The temperature of the vaporized LNG leaving the ORV shall be minimum +0,5 oC.
The sea water that shall be used to vaporize the LNG in these units shall be provided from two sources. One of them is the normal sea water pumped to these units in its original temperature taken from the sea by the sea water pumps. And the other one is the sea water taken by sea water pumps from Trakya Elektrik Üretim A.Ş. and is 12 oC /13 oC degrees warmer than normal sea water. These units shall be equipped with piping systems that can take sea water from both sources.
The sea water completing its heating mission in ORV unit shall fall into the open channel and to the sea via a fall out. ORV units to be installed shall be equipped with piping system being able to take sea water from both sources. These ORVs shall be designed, according to the calculated capacity, so as to vaporize the LNG with both +8 oC sufficient amount of sea water and +17 oC hot sea water of the half amount of the normal sea water. Each ORV shall be designed to be able to realize same amount of the vaporization with the design capacity with both the +8 oC sufficient amount of sea water and half amount of the sea water which is heated to +17 oC. The ORVs to be constructed shall be designed in a manner that they shall be equipped with pipes, valves and instruments so as to work parallel with the existing ORVs.
The contractor shall prepare the project so as to add two pieces of additional ORVs to the existing ORVs in the open rack vaporization system.
The appropriate place for the installation of two pieces of ORVs shall be chosen. While choosing the appropriate place, the distance of these ORVs to the LNG incoming line, vaporized LNG exit line, normal and heated sea water lines that are used for vaporization, and the Fall-Out to which the sea water used for heating is poured shall be taken into account.
If it is determined that the existing station as a whole or some of the mechanical and electronically metering equipments are not conform standards, the Contractor shall prepare a report which includes engineering, feasibility and cost estimate works about all required technical revisions, renovations and/or construction of new metering station. After the approval of the report by the Employer, , the contractor shall done design, engineering and project works for whole metering station with new 20” line.
The characteristics of the new pump to be installed in the hot water intake pool shall be determined by the Employer. After the Employer determines the characteristics of the new pump to be installed in the hot water intake pool, the design studies related with the pump shall be carried out by the Contractor. This pump shall be designed so as to work with existing pumps in parallel. If it is decided to change the motors actuating the existing pumps in the hot water intake pool, which are mentioned in Article 2.8, with the more powerful motors, the project study of this works shall also be carried out by the Contractor.
If it is decided to change the engines of the existing pumps, the design shall be carried out to be able to put the newly procured pump or put the new engine.
Summary
The best practices in building the additional capacity to store LNG helps (API, 2003) to prevent the leaks which may eventually lead to explosions. So the design characteristics of the tanks to store LNG are given in this research. Certain design standards are necessary so as to build the high capacity LNG Storage Tank (CEE, 2003). Supplementary equipment investments are required to increase the LNG storage capacity and vaporized LNG delivery capacity,. This is in order to prevent the leakages or even explosions. Transmission of the stored LNG has to be done by the recommended set of pipes and must be subjected to the frequent tests and inspections.
Chapter 4: Conclusions and Recommendations
Introduction
So, this is how the product is used today and where the customers are today. There is the value proposition offered by the opportunity to expand the natural gas distribution system to deliver more affordable, cleaner, and more efficient energy services to customers, communities, and industry (especially mining industry) located off of the existing distribution system and in more remote areas.
Natural gas is in abundant supply, affordable, clean, versatile, safe, and reliable. On affordability, for all energy users, any reduction in energy costs while enjoying the same level of comfort or maintaining the same or improved level of service or production output is a significant benefit. It means money in the pockets of consumers – for families in their homes, or for businesses to become more competitive and to expand and grow. Therefore, the LNG must be prevented from leaks and catastrophes so that the customers continue to enjoy the benefits.
Recommendations
The recommended best practices are to follow the standards and the operational manuals. The testing procedures need to be carefully adhered. The historical records must be maintained to analyze any occurrence of leaks and the reasons of the leakage. In effect from the installation time itself the best practices must be followed as has been recommend in the research.
The facilities of the existing system shall be used as much as possible. Existing as-built drawings, technical specifications, and soil surveys belonging to the terminal shall be reviewed. Existing as-built drawings, technical specifications, and soil surveys belonging to the terminal shall be submitted to the contractor after signing the Contract. (API, 2003)
Engineering studies of the equipment and systems (including piping) shall be carried out and Process Flow Charts, cross-sections, and layouts shall be drawn. Calculations, specifications, and material lists belonging to equipment and systems shall be prepared. (ABS Consulting, 2004)
P&ID of the each equipment and system (inlet and outlet piping included) shall be drawn. The indication of piping, instruments and main equipments of the P&ID drawing shall be prepared in accordance with the Employer’s proposal. (ABS Consulting, 2004)
All documents shall be submitted in metric units. This expansion project of BOTAŞ LNG Terminal shall be carried out according to the projections of NFPA 59A last edition. (ABS Consulting, 2004)
Firm addresses that can realize the production and/or installation of equipments and systems in question for each equipment and system (required valve, pipe, fittings materials included) and submission durations shall be determined and reported to the Employer.
Approximate cost of each equipment and system (including required valve, pipe, fittings materials) shall be determined. . (API, 2003)
The technical specifications of all equipments and systems and complete Construction Specification documents belonging to Capacity Increase Project shall be prepared. This shall be composed of two parts. First part shall consist of General Specifications to be used by the Employer for the Capacity Increase Project Construction Tender (EPC-Engineering (detail) – Procurement – Construction). The second part shall be composed of Data Books that can be used during the realization of the EPC stage if needed. (SIGTTO, 2000)
General layout plan and assembly drawings of equipments/systems (for example cabling/piping etc) shall be prepared. (SIGTTO, 2000)
The total approximate cost of the Detailed Engineering, Procurement and Construction (EPC) Work for LNG Capacity Increase Project Constructıon Tender, which shall be bid as a result of the LNG Terminal Capacity Increase Engineering Consulting Service, shall be determined. (SIGTTO, 2000)
All kinds of equipments and their technical specifications necessary for fire detection system in the tank to be constructed and in all additional equipments shall be determined and necessary design and engineering services shall be supplied. (US EPA).
Existing Deluge valve fire protection water system and its capacity shall be analyzed. Equipments and technical features of the equipments of necessary changes and additions in the system for the new tank shall be determined and their design and engineering studies shall be carried out. (US EPA).
All kinds of existing electrical equipments such as all energy supplies, low voltage-medium volate switch gear systems, transformers including BOTAŞ Main Transformer Center for the newly constructed tank and all additional equipments shall be analyzed. Required changes and additions (a new transformer, a new low voltage power switch system, a new powerswitch building, panels, etc.) shall be designed. Drawing the electricity single line schedule, equipments to be used and technical characteristics of the equipments shall be determined. (Marmara Ereğlisi Lng Terminal, n.d.)
An analyze shall be carried out as to whether the existing metering station including mechanical and electronic metering apparatus and equipments as a whole is in accordance with the FMS_Fiscal Metering Station standards or not and shall be reported to the Employer. The design, engineering, project preparation and cost determination studies to be done for the partial revision, renovation and/or complete system renovation as a result of the carried out analyze shall be realized so as to include the addition of a new 20” metering run to the existing system. (Marmara Ereğlisi Lng Terminal, n.d.)
The sufficiency of existing modules and I/O cards in the existing DCS and FSC systems for the equipments to be added in the scope of this project shall be analyzed and the list and technical specifications of required equipments shall be determined and design and engineering studies shall be carried out. (Marmara Ereğlisi Lng Terminal, n.d.)
Recommendations for Further Research
In the Human resource front to deal with one of the main questions to be addressed in the next level of research is beyond the technology. The technology discussed above takes care of most of the issues related to leaks and has the very advance alarm and control systems as highlighted in the research. However, safely manning the expanding fleet is equally critical. The challenge facing the industry in this area can be highlighted by the fact that there us a growing demand of LNG in domestic as well as industrial markets due to low cost and lower risk as compared to other fuel. It is not surprising to hear therefore, that the shortage of skilled personnel affecting the whole industry is particularly acute for LNG carriers. Given the planned expansion, thousands of additional officers are going to be required for the LNG trade, and that is in addition to those that would be needed to maintain present manning levels following retirement of existing personnel.
The recruits should be joining an industry that is proud of its safety record over the last forty years. The experience that has achieved and maintained this record will now be diluted increasingly, making it harder for newcomers to gain the necessary skills to take the industry forward. Most experienced LNG operators, have increased their training afloat to the limit that available berths will allow. In addition, further training is available ashore, over and above that required for the issue of a Liquefied Gas Tanker Endorsement.
The SIGTTO Training Project has developed competency standards for all ranks, around which training courses may be based. Interested parties such as charterers have expressed an interest in accepting training in accordance with the SIGTTO guidelines, along with their experience profile, as evidence of a seafarer’s suitability for employment in LNG vessels. (SIGTTO, 2000). Hence the need of the hour is to get the trained personnel to handle LNG based installations. Institutes like SIGTTO would be needed to train the prospective recruits.
References
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