Planning and Concepts the individual scenarios, also in practical examples. Standard temperature-time curve (ETK) The fire development according to the standard temperature-time curve in accordance with ISO 834-1 is also known as a cellulosic fire, which is a classic scenario in structural engineering. The standard temperature-time curve simulates a fire as it is caused when burning building materials on the basis of cellulose (wood, paper or other building materials with comparable heat flows). It had already been developed in the 1920´s. In doing so, one assumes a slow increase in temperature where the temperature of 1,000°C is reached only after approx. 90 minutes. The use of systems that have been tested in accordance with the standard temperature-time curve are, due to the actual fire scenarios to be expected in the petrochemical industry, generally not recommend. Exceptions are areas where hydrocarbon fires are not to be typical (administration, closed operating rooms, etc.) Hydrocarbon curve (HC) The hydrocarbon curve (hydrocarbon fire curve in accordance with ISO 834-1/ BS476 Pt. 20/ANSI/UL 1709/EN 1363-2) was created in the 1970´s in order to be able to provide a better representation of the technical fire protection requirements in the petrochemical industry and in the offshore sector (see figure 1). As opposed to the standard temperature-time curve, the temperature with this fire scenario increases to more than 1,000°C within a few minutes (see figure 3). Classically, the systems tested according to the standard temperature-time curve generally fail here. The maximum temperature under this scenario is approx. 1,100°C. Modified hydrocarbon curve (HCM) The modified hydrocarbon curve (HCM) was created in order to give a better representation of today's requirements. It was developed in France in order to give a better representation of fire protection in tunnel constructions. The HCM curve reaches peak temperatures of 1,300°C. Other fire curves for the protection of tunnel constructions are e.g., the ZTV-ING curve / RABT curve or the Rijkswaterstraat(RWS) curve that, however, play a subordinate role in the industry (see table 1). With a classic hydrocarbon fire (HC curve) one differentiates between Pool-Fire and Jet-Fire. The Worst-Case scenario is a combination of both fire types. Pool-Fire A Pool-Fire is a fire that occurs when a fluid on the basis of an hydrocarbon (e.g., petrol) ignites and burns uncontrolled. The heat flow occurring in the process is very high (approx. 150 kW/m²). As the combustible materials frequently stream in uncontrolled, long fire scenarios with continuously high heat development are not unusual. Jet-Fire If a fluid or gas based on hydrocarbon escapes under high pressure and ignites, this is known as a Jet-Fire. Similar to a Pool- Fire, even with a higher heat flow (approx. 250 kW/m²) with a temperature of 1,180 °C (according to ISO 22899-1/OTI 95 634) is generated by this compression. The test has currently been adapted to the increased conditions of the petrochemical industry, especially in the offshore sector. A heat flow of approx. 350 kW/m² at 1,300 °C is reached here (OTI 95 634 extended furnace temperature). As further requirements, corrosion protection and thermal shock resistance, resistance against explosion overpressure (up to approx. 4 bar overpressure), reduc- Table 1: Overview of different fire curves Curve ETK Hydrocarbon (HC) Modified Hydrocarbon (HCM) Standard(s) ISO 834 DIN4102-2 BS476 EN 1336-2 ISO 834 Eurocode 1 IMO Res.A.754(18) EN 1363-2 ISO 834, modified for the application in France usable according to DIN 4102/ EN 1364/ BS 476 DNV, Lloyds, ANSI/UL 1709 t after 90 Min. ca. 1,000 °C 1,100 °C 1,300 °C 1,000 °C reached after >90 Min. ca. 5 Min. ca. 5 Min. Use structural engineering petrochemical industry tunnel fire protection FeuerTRUTZ International 2.2016 5 ❯❯ Fig. 2: With fire protection for the natural gas storage facility Peckensen, the fittings, the flange caps and the connecting pipelines are particularly critical system parts.
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