Tank Storage Magazine v10 i06


Volume: 10
Issue: 6
Date Published: October 27, 2014



Adding value in a changing world

Vopak’s terminal in Hamburg has a capacity of almost 700,000m3, used for storing base oil, heavy fuel oil, gasoil and diesel as well as bunker fuel and niche products like sulphuric acid and CO2. The closure of local refineries in Germany has increased demand for imports of gasoil and diesel and as a result Vopak is expanding and upgrading its oil storage capacity. It will add 65,000m3, to be commissioned in 2015. ‘This is just one of three changes we see happening in the German bulk liquid storage market,’ Janhein van den Eijnden, MD of Vopak Germany, explains. ‘The German refinery industry, like elsewhere in Europe, is under a lot of pressure, both economically as well as environmentally. This has already led to the closure of two north German refineries, and will most likely see more closures in the coming years. This trend will see more import requirements, especially for diesel and heating oil. Most of this will go through existing terminals because former refinery sites have difficulties offering the flexibility and segregation that purpose built independent storage terminals can offer.’

An insight into Germany's inland storage

October 2014 and a chill wind has pierced hopes that European economies had finally emerged from the wreckage of the 2008 financial crisis. The International Monetary Fund warned of a 40% chance of a triple-dip recession in the coming months and a 30% chance of deflation. Most ominous was the news from Germany, for so long the powerhouse of the ailing eurozone. Markets across Europe tumbled as the Federal Statistics Office released figures showing a 5.8% slump in the sales of German goods overseas, the sharpest drop since January 2009, while German industrial production fell more than economists forecast in August in the latest sign that the outlook for Europe’s largest economy is deteriorating. In October Berlin shocked markets when its growth forecast for this year and next year were pruned, to just 1.2% for 2014, down from 1.8% in April, and to 1.3% in 2015, down from 2% just six months ago. Certainly profits at German power companies have fallen sharply as the country grapples with the realities of Energiewende, the dramatic policy shift away from fossil fuels and nuclear energy and towards renewables.

Looking into the Cushing crystal ball

Cushing stocks have dropped from 40 Mbbl in January 2014 to just over 19 Mbbl at the end of July 2014, and currently hover in the low 20 Mbbl range. The precipitous drop, an average of 125 kb/d, indicates that demand for domestic barrels is strong and continues to be strong today as Gulf Coast refineries take as much domestic crude oil as they can get. Stare at Cushing long enough and it reveals a glimpse into what the future holds for Gulf Coast refining. On 21 January 2014, Cushing MarketLink, the southern part of the Keystone XL pipeline, began pumping oil from Cushing south to Nederland, where it has access to Port Arthur and Houston markets. Since that time, inventory at Cushing has decreased to levels not seen since 2003-2008 and are likely approaching tank bottoms. During this period, PADD III stocks quickly increased to record high levels, peaking in May. After May, refinery utilisation also reached record levels, which led to declines in both Cushing stocks and PADD III stocks, as imports were mostly flat. Currently, PADD III stocks have re-entered their historical range and remain at the high end of that range, while Cushing stocks remain at nearly the lowest point since 2005. The immediate effect of MarketLink coming online was a large inventory transfer from Cushing to PADD III.

Playing to win

Globally, there were 22 oil and gas terminal and storage transactions last year and 36 transactions in 2012, according to analysis1 by London-headquartered EY. The two largest transactions in 2013 involved gas storage assets: one in the US, the drop down of assets into Plains All American Pipeline, in a $939 million (€736 million) deal, and in Europe, the sale of Hungarian gas supply and storage assets to the MVM Group by German utility company E.ON for $850 million. An important transaction in the oil storage sector last year was the acquisition by Buckeye Partners of Hess Corporation’s network of 20 oil product terminals, primarily on the US East Coast and the Caribbean, in a $850 million deal. This year to date has seen a healthy pace of transactions involving storage and terminals, with one of the largest to date, in terms of the disclosed transaction value, being Oiltanking sale to Enterprise Products Partners, of Oiltanking’s entire interest in US crude oil and oil products storage provider Oiltanking Partners, announced on 1 October. Enterprise paid a total consideration of approximately $4.41 billion to Oiltanking Holding, comprised of $2.21 billion in cash and 54.8 million Enterprise units. Enterprise also paid $228 million to assume notes receivable issued by Oiltanking Partners. Oiltanking Partners, through its wholly owned subsidiaries, Oiltanking Houston and Oiltanking Beaumont, owns and operates marine terminals and tank storage assets on the Houston Ship Channel and in Beaumont, Texas with a total of 12 ship and barge docks and some 24 million barrels of crude oil and oil products storage capacity on the Texas Gulf Coast.

Designing compliant tank storage overfill protection systems

The overriding driver in defining the requirements of tank overfill protection has been the Buncefield incident. The Buncefield Major Incident Investigation Board initial report (in particular paragraphs 63, 65 and 66) made reference to ‘the overriding need to ensure the integrity of the primary means of containment; in other words, to make sure that liquid does not escape from the vessels in which it is normally meant to be confined’. It also demonstrated that ‘overtopping a tank with highly flammable fuel is more likely to produce a potentially explosive mixture than pooling from a lower level escape, such as may result from a tank failure.’ It further emphasised that ‘the most urgent focus of attention should be on preventing loss of primary containment and, should that occur, inhibiting rapid large scale vaporisation and any subsequent dangerous migration of a flammable vapour.’ From this report E,I,C&A engineering services provider GSE Systems concluded that it would be appropriate to direct its I,C&A engineering focus towards maintaining primary containment and giving consideration to the top of tank design and high/high-high (‘hi hi’) detection. The aim being to minimise the formation of large vapour clouds in the event of overfill, by early detection of the tank filling up and increasing the SIL layers of protection by building in dual redundancy. This formed the basis of GSE tank storage overfill protection systems strategy when designing new, or modifying existing tank farm installations, with particular emphasis on tank overfill protection.

Metering or gauging

Tank gauging remains invaluable for terminal tank operators as a means to measure product inventory. For custody transfer into and out of tank terminals, however, the metering system is the preferred and more cost-effective method of measurement, thanks to an accuracy that can be 10 times that of tank gauging. Tank gauging is usually appropriate for taking inventory and, under ideal conditions, can even be used for custody transfer measurement. However, the conditions and factors that affect the calculation of tank volume introduce a larger degree of uncertainty and potential for bias error than what exists for metering. To accurately measure the volume of liquid in a storage tank by tank gauging, a number of factors have to be considered. For example, tank volume is subject to imperfections in the tank – deformations due to hydrostatic pressure and temperature changes, deadwood (volume of piping, mixers and other internal objects in the tank) and floating roof effects. While these imperfections are taken into account during the certification of the tank capacity tables (TCTs), which are used to calculate product volume in tanks, additional tank deformations are always possible. Those could include a diaphragm effect on the tank bottom, sinking when full of product and returning to normal when empty; and uneven sediment accumulation on the tank bottom, which may build up on one side of tank. Because TCTs typically are based on external measurements of the tank, unaccounted-for erosion of the steel plate on the inner wall of the tank could also add error to the volume measurement. The initial TCTs usually cannot account for these deformations, although constant tank mixing may mitigate some of these effects. TCTs are verified every three to five years; errors may go undetected and uncorrected for years before their next calibration.

Why pressure transducers are almost always the best wireless liquid level sensors

Pressure transducers are impressive level sensors. They have been an industry staple for years now – and for good reason. They are versatile, rarely upset by environmental variables, inexpensive, easy to install, and require very little (if any) programming. The operating principle of a standard piezoresistive pressure sensor is its strength. It employs a diaphragm with an embedded circuit to continually measure pressure. The circuit, called a Wheatstone Bridge, changes resistance with the flex of the diaphragm. The resistance change is directly proportional to the pressure exerted on the transducer diaphragm. A level measurement is then inferred from the pressure of the liquid depth. This works so well because there are few variables that affect pressure relative to level – particularly in controlled environments.

Installation considerations for automatic tank gauging

Choosing the right automatic tank gauge can seem like a simple process – just look for the sensor that offers the performance needed at the lowest price. The reality is more complex. Different sensor technologies operate in vastly different ways, which directly affects how they are installed and the possible need for costly tank modifications. Depending on the technology used, these tank modifications can significantly overshadow the cost of the level transmitter itself. To prevent costly unforeseen issues, there are several key areas to understand about the level transmitter and tank before purchasing. They include the tank type, presence of stilling well and process connection opening. Most automatic tank gauging systems measure three factors: product level, interface level, and temperature to allow for temperature compensated inventory monitoring. In aboveground storage tanks, this means using one of three technologies: magnetostriction, radar or servo level transmitters. Of the three, radar is the newest technology for automatic tank gauging. A radar level transmitter determines the liquid level in the tank by taking a time of flight measurement by sending a microwave signal and waiting for the return reflection from the liquid. Radar is available as either ‘through the air’ radar or guided wave radar. The difference between the two types of radar is the ‘through the air’ radar sends the microwaves focused by an antenna through the air to determine the liquid level. Guided wave radar, on the other hand, sends the microwaves through a pipe or metal braid to help guide the path of the microwaves. For large aboveground storage tanks, the most commonly used technology is the ‘through the air’ radar (referred to in this article as simply radar). The radar level transmitter is a non-contact level technology which has the advantage of not being in contact with the product. This has allowed radar to develop an installed base in applications with highly viscous liquids. The disadvantage of non-contact level transmitters is that additional process instruments are needed to measure interface level and temperature.

EPA no longer supports VOC emissions software for storage tanks

US companies with petroleum products and other organic liquids have long utilised the US Environmental Protection Agency’s (EPA) software, latest version TANKS 4.09D released 3 October 2005, to estimate emissions of volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) from storage tanks. This software has always been difficult to use for companies with multiple facilities and numerous tanks as, among other things, it only runs on a single desktop, using a runtime version of Microsoft Visual Basic. After many years of neglect and a lack of updates to correct errors, EPA will no longer support the software as it is outdated and not functional reliably on newer versions of Microsoft’s Windows operating system1. What options do companies have? EPA recommends the use of the equations and algorithms specified in AP-42 Chapter 72 for estimating VOC emissions from storage tanks. The equations specified in AP-42 Chapter 7 have been developed over a number of years by EPA and, in part, using information supplied by the API.

VTT Vasiliko opens in Cyprus

Nearly four years after its conception, VTT Vasiliko in Cyprus (VTTV) will begin its operations in November 2014. The facility, which is owned by a subsidiary of VTTI, comprises of 28 tanks and 544,000m³ of storage capacity for white products, available for both commercial and strategic stocks. At the moment Cyprus keeps its compulsory stocks mainly in Greece and the Netherlands. However, with this storage capacity now available in Cyprus, VTTV says it is a good opportunity for Cyprus to store its compulsory stocks on homeland and at a lower cost. With several customers lined up and contracts signed the company is already looking ahead to its next growth phase. Phase two is currently under licensing and would create an additional 13 tanks and an extra capacity of 305,000m³, primarily for fuel oil and crude oil. This is expected to begin next year and be complete by the end of 2016.

How the VTT Vasiliko tanks were built

Jacking-up tanks is gaining popularity around the world as more tank builders are switching from the conventional (bottom-up) erection method to the jacking (top-down) method largely due to the absolute safety the latter affords by eliminating working at heights. Coupled with this are other factors, such as eliminating the need for a large boom crane and voluminous scaffolding, which were traditionally required. The main reason why the jacking up of new tanks was not adopted by many global tank builders until now is because of the limitation of not being able to use automatic girth welders.

Mechanisation of storage tank welding

The growth of the oil and gas industry continues to increase demand for welders. This demand has created a shortage of skilled welders and, as a result, mechanised welding, is a cost-effective solution. Simply put mechanised welding machines are power tools for welders. Mechanical, motorised motion control replaces the welder’s manual activity. A knowledgeable, qualified welder is required to control the machine to ensure that the welds are of acceptable quality. With that said the use of mechanisation makes it easier to maintain a quality weld, at a faster rate, with less fatigue. In the tank storage industry there are quite a few ways mechanisation can be used. Mechanisation offers solutions for all of the different types of welding required on the smallest to the biggest of storage tanks.

Order from chaos

As assets and facilities age, the continued demonstration of fitness to operate over an extended lifetime is essential. But with so much data available, how can you tell what you really need to worry about? Asset integrity management is needed for a multitude of reasons. Most importantly, it is used for facilities which are being operated past their original design life. Legislators and governments require a structured and well documented demonstration of fitness to operate major assets. This data can also be used to enable better decision making and to ensure the correct balance of profit and safety. Invariably, operators of large, complex assets such as petrochemical plants and oil and gas production facilities have an array of work processes and systems intended to deliver these objectives. What may be missing is an alignment of these process and systems to deliver clarity, and the correct focus on criticality.

Hungary's first aluminium pontoon type internal floating roof

Lukoil has installed the first aluminium (skin & pontoon) floating roof with primary and secondary wiper seals at two 2,000 m3 storage tanks in Hungary. Hungary-based Tanxperts, the investor’s mandated inspector, managed the whole project and elected to install roofs from CTS Netherlands over the more traditional carbon steel internal floating roof. The biggest challenge, according to Tanxperts, was convincing the authorities that the technology complied with local regulations such as MSZ EN 14015:2005, due to the fact all the licencing parties used defective standards and reguleations.

Geldof finalises new tank terminal for ADPO in Port of Antwerp

Earlier this year Antwerpbased ADPO, a provider of logistics services as well as storage and handling, awarded a contract to the Belgian company Engicon nv (Geldof), total engineering and steel construction project contractor, for the design, construction and installation of 57 storage tanks for its new LLH (Liefkenshoek Logistic Hub) in the Port of Antwerp. Now, six months later, Geldof has placed the last storage tank on its foundation. The new terminal provides ADPO with an extra storage capacity of 37,500m³.

Retrofitting leak detection

Tank Storage magazine speaks to Niels Knoops- Wesenick, MD of leak detection technology provider Wolftank Adisa, about the protection of storage tanks Q Why is the tank an asset to be maintained? A The construction of a new storage tank is a high investment in an asset that, over the entire lifecycle, is exposed to harsh conditions such as environmental influence and storage of chemically aggressive goods. The operation of a storage tank therefore requires periodic maintenance to avoid steel corrosion, product loss as well as safety and environmental risks.   Q How can I ensure that my asset does not lose its value? A Alongside periodic maintenance, we recommend that tanks are equipped with an automatic and continuous 24/7 monitoring system. This provides detailed information and ensures a constant knowledge and awareness of the integrity of your tank.   Q What does the 24/7 monitoring consist of? A In order to enable the launch of a leak detection system, it is necessary to have a tank with an interstitial surveillance space created by a double wall. Monitoring systems provider Wolftank Adisa has developed a system to install a second wall that it calls DOPA. The interstice is connected to a local or remote leak detection system that identifies variations by registering the surveillance pressure. The system analyses these variations automatically and allows the preview of deviations from the default operative conditions, such as a loss of the interstice monitoring pressure, and can even identify manipulation of the system.

The world's first double skinned hydrochloric acid tank

Back in 2011, UK-based terminal operator Simon Storage needed a lining system for its hydrochloric acid tanks at its Seals Sands site in Teesside. The first obstacle it faced was to locate a coating which would be fully resistant to hydrochloric acid. UK-based Abfad went to several of its resin suppliers and discussed two potential coatings that would offer suitable protection for the tank. Abfad then made some free film resin samples to be immersed in the acid to physically test the resistance of the selected coating. Both the resin manufacturer and Simon Storage agreed to test the samples over a two year period. After which time it was deemed that the tests had been successful for the chosen coating and it was resistant to the hydrochloric acid. Abfad was then commissioned to review the project and formulate all engineering aspects to be able to double skin the tank floor areas and importantly up to the top of the wall sections. Abfad’s research team reviewed all aspects of the project, including the weight of the double skin materials, and developed a method to ensure that the 13m high wall sections would be fully secure during the installation process and after the double skin liner was fully installed.

High temperature linings for sulphur storage tanks

Liquid sulphur storage tanks are used worldwide in crude oil refineries and natural gas plants to store liquid sulphur in very large volumes. Sulphur storage tanks are most commonly used as part of the gas treating system in sour crude oil refineries and gas sweetening facilities to temporarily store liquid sulphur produced in the sulphur recovery plant. These tanks are usually field erected and most commonly constructed of carbon steel. Even though in recent years there has been significant progress with regards to the mechanical design of sulphur storage tanks, they are still plagued with corrosion issues and internal corrosion is considered to be the main cause of longevity and safety issues. Unlike external corrosion that can be easily identified, internal corrosion is out of sight and can therefore go unnoticed, causing catastrophic consequences. As a result of internal corrosion, sulphur storage tank service life has been reported to be as low as five years, although general storage tanks demonstrate a life of 30 years. Sulphur storage tank failures cannot not only lead to loss of revenue and increased costs through downtime and replacement, but can also have a critical human health and environmental impact. Due to the combustible and toxic nature of sulphur, leaking sulphur tanks can be a significant source of environmental pollution to soil, groundwater, streams and lakes, resulting in contamination of drinking water. In addition, fire, explosion and inhalation of dangerous vapours present further critical concerns. Such scenarios may result in asset owners facing strict financial penalties from environmental regulatory institutions and as a result, damage their reputation on a local and international level.

Low thermal conductivity CUI coatings

The benefits to industry of insulating tanks, process equipment and pipework to reduce energy usage and the risk of personal injury by burns cannot be overstated. An unfortunate downside, however, is that if corrosion of the underlying steelwork is initiated, it often proceeds un-noticed until dangerous loss of wall thickness results or, even worse, catastrophic failure occurs leading to loss of containment. Corrosion under insulation (CUI) is therefore a major concern to facility maintenance engineers. Steel will corrode when it is in contact with water and oxygen. If water can penetrate the insulation there is a likelihood that corrosion will result. Examples of possible causes are: 1. Poor choice of insulation – material such as mineral wool, fibreglass and calcium silicate can absorb water from rain, deluge systems or leaks in the system. In addition, certain insulation materials contain chlorides which will accentuate galvanic corrosion and can also induce stress corrosion cracking of austenitic stainless steel. 2. Poor design or installation of the insulation, especially at problem areas such as cut outs for nozzles, valves and flanges, etc. 3. Mechanical damage to insulation as part of plant operation or maintenance activities. 4. Insulation not being correctly replaced after inspection or maintenance activity. 5. Degradation of sealants by natural weathering, thermal oxidation or UV degradation. 6. Water condensation, particularly on refrigerated or chilled water systems, but also on hot surfaces when there is temperature cycling. 7. Absorption of airborne moisture in factories where steam is predominantly the heating medium.

An introduction to valves & gauges for shop fabricated tanks

Today’s systems are typically designed to comply with current National Fire Protection Association (NFPA) code requirements, International Fire Code (IFC) code requirements, and/ or California’s Air Resource Board (CARB) requirements. The Environmental Protection Agency (EPA) has additional requirements for spill prevention, control and countermeasures (SPCC) mandating written plans in addition to meeting code requirements. These systems are required to include overfill prevention, spill containment, anti-siphon protection, normal venting, emergency venting, gauges, and overfill alarms. A properly designed system requires several different components for safe operation.

The fuel for success

Based in Phoenix, Arizona, Caljet operates five state-ofthe art storage tank farms, unloading facilities, dispensing terminals and customer focused operations. Handling about 50% of the motor fuels that are consumed in this market place, the company operates 24 hours a day, 365 days a year. Caljet serves as the link between the refinery and the carrier. Refiners transfer their product to Caljet by rail, pipeline and truck where it is unloaded and stored. Carriers then load the product into their trucks at Caljet dispensing racks and deliver it to their customers. Products stored and dispensed at Caljet include leaded, regular unleaded and premium unleaded petrol; diesel; biofuels; specialty fuels; aviation fuel and lubricity additives. The operation loads more than 12,000 trucks per month and is projected to pump more than 1 billion gallons of fuel and additives this year. Today, after several major expansions, Caljetoperated facilities consist of: • 1,020,000 barrels of storage capacity for refined and renewable fuels, with 130,000 barrels of storage to be added in 2015 • 14 high-speed 500-gpm truck-loading lanes • Six high-speed truckoffloading lanes • 38 railcar-offloading positions • A well equipped and fully staffed laboratory.