Safety is a key priority for all industries, especially for the operators of onshore and offshore oil and gas exploration, process and storage facilities. At these, the risk for fire is high and the consequences potentially very serious due to the presence of flammable hydrocarbons. Both passive fire protection (PFP) and active fire water systems are vital to mitigating this risk.
Rubber-based materials for passive fire protection
Flexibility is often regarded as the number-one characteristic of rubber materials, making them well suited for the manufacturing of seals for tight spaces, as well as to damp movements, vibrations and impacts. In the oil and gas industry, this property needs to be maintained at high industrial process temperatures and in tropical climates as well as at low arctic temperatures.
Risers are used for pumping oil and gas from the seabed to a platform and traditionally are made from rigid steel pipe. If a riser accidentally bursts, large amounts of oil will leak into the sea with catastrophic consequences.
Many types of traditional surface coatings are used on rigid steel risers to protect them against corrosion, collisions and fire. However, as oil and gas exploration moves into deeper waters with floating platforms, there has been a move toward flexible risers that can withstand continual movement from waves and currents. Traditional PFP coatings are not suitable for flexible risers, instead requiring a PFP protection coating that is more flexible, such as Firestop.
Vipo’s ongoing collaboration with major operators led to the development of a flexible fire water piping system, Elastopipe. This integrates a layer of Firestop material within the pipe wall, with the goal to eliminate the disadvantages of the traditionally used metallic piping systems while providing extreme fire resistance.
The importance of a reliable fire water system
Traditionally on offshore oil and gas installations, large seawater pumps connect to a fire water system that consists of a network of valves, pipes, and nozzles. In the event of a fire, the system provides a sufficient flow of water to cool down the structure and extinguish the fire.
The guaranteed function of the fire water system is vital for the safety of oil and gas installations, with systems needing to provide 100% reliability at all times. This is due to the presence of flammable hydrocarbons, which represent a huge risk; the consequences of fire can be fatal if the fire water system fails. This means that every spray nozzle must deliver the amount of water at exactly the right time.
Fire water systems must withstand the severity of a fire to be able to transport water as required. The most severe fire scenario is a jet fire, often caused by the ignition of hydrocarbon gas leaking from a high-pressure vessel or pipe. In a jet fire, a high temperature of greater than +1,100°C is reached nearly instantly, and the turbulent high speed of the gas creates a mix of fuel and air that gives a high combustion rate and higher heat flux (typical test standards are 250 and 350kW/m2).
History shows that in too many cases the fire water system malfunctions, resulting in fatal fires. As traditionally, metals are the most common materials for fire water systems, the main reason for this is corrosion of the piping. Due to it, reduced flow or blockage of pipes, valves, and nozzles occur, especially in the oldest carbon steel, galvanized steel and CuNi piping. Even in modern stainless-steel piping, corrosion can lead to leakages and cracking. By using noncorrosive materials such as rubber and titanium, this issue is eliminated.
A flexible solution
Offering extreme resistance against fire and corrosion, Elastopipe provides an alternative to traditional metal fire water systems and is contributing to the increased safety of high-risk operations all around the world. Made from Vipo’s Firestop technology, the system provides an alternative corrosion free, impact and jet fire resistant solution. The rubber material of the Elastopipe system does not corrode, guaranteeing a 100% corrosion-free system for more than 30 years, as all components that encounter seawater are made of rubber or titanium.
Firestop technology provides extreme jet fire resistance, tested and documented in accordance with the OTI95634- and ISO 22899-standards. During the testing, the standard system including connection materials and support, withstood exposure to a 350kW/m2 jet fire for an hour.
The pipes in a deluge system are dry, and not filled with water until a valve opens. This ‘dry pipe period’ should be as short as possible. A standard requirement for any dry fire water system is for water to fill the pipes and spray out of the most remote nozzle within a maximum of 30 seconds. However, systems should be able to withstand a much longer dry pipe period should a failure occur during valve activation. Therefore, the most critical phase of testing is for five minutes in dry conditions. Elastopipe completed this test, highlighting its extreme fire resistance properties.
Examples of Elastopipe in use
One example of the most common use of Elastopipe is the complete replacement of an existing corroded fire water system on a live producing platform in the North Sea. The original stainless-steel system leaked for many years, with both the maintenance cost and safety risk justifying the replacement of the system of over 13,000m of piping.
The installation across the whole complex, including the process and well-head areas, was completed without influencing daily operations. The flexibility of pipes made it possible to pre-assemble the long spools, providing quick installation without any hot work, reusing some of the old piping as secondary support. Compared to the originally planned replacement with rigid metallic piping, the project was finished a year earlier and at 30% less than the estimated cost.
For FPSOs (Floating Production Storage and Offloading) the unique flexibility of the Elastopipe system is a key benefit. Like other floating vessels, FPSOs are constantly moving because of wind and waves. The Elastopipe rubber material absorbs tension and vibrations, reducing the stress on support and valves.
For instance, following a fire on an FPSO in a field off Western Australia, urgent repairs to the existing fire water system were needed to fulfil contractual obligations. A fast-track Elastopipe replacement was chosen.
A temporary Elastopipe deluge system was installed before the existing steel pipes were removed and the permanent Elastopipe installation completed. This method ensured that full fire protection was retained throughout the project. The fast-track project was carried out by ten expert rope-access pipe fitters and two supervisors working independently, without disturbing activity onboard or impacting production.
The flexibility and light weight of the deluge system allowed rapid installation due to swift configuration in confined spaces. The first two modules were completed in just a month, and all seven modules were finished with full-scale testing within three months.
The flexibility of the Elastopipe system makes it easy to modify routing and avoid obstacles by bending the Elastopipe to achieve the required shape. In one case, a uniquely designed round FPSO required modification of its equally novel fire water system design for operation on a new field, and much of the original Elastopipe system was reused. This was achieved by disconnecting the pipe in one end and simply bending it in the new direction and re-connecting.
Since 2001, Vipo’s Elastopipe system has been in operation in harsh arctic conditions close to the North pole. The system has been exposed to rough handling when ice is removed from the vessel with axes and sledgehammers, and also in the landing area, where pipes are often hit when goods and containers are loaded.
With a pipeline wall thickness of approximately 15mm of rubber, the robustness and wear resistance properties of the system make it ideal for operation in cold climates, even without heat tracing. Samples taken during regular inspection show no degradation of material even after over 20 years of rough operation, with no maintenance required.
In another example, for applications in warmer climates where resistance to heat and sunlight are required, Elastopipe has been used for more than 15 years following the successful replacement of corroded fire water piping on installations off the coast of Qatar. This alleviated the fact that extreme temperatures and higher salt content in seawater accelerated corrosion, increasing safety and lowering maintenance costs.
Summary
Operators all around the world have more than 20 years’ experience with rubber-based flexible fire water piping systems. Increased safety is the most important feature, and even after operation in the most demanding environments, flexible rubber-based systems are proven to maintain safe operating standards. Installations can be completed without disturbing the ongoing processes, making them ideal for alternative uses in other demanding applications within traditional land-based industries, defence and shipping.
For more information, go to www.viposolutions.com
