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API Publ 4740:2005 pdf download

API Publ 4740:2005 pdf download.A Decsion-maker’s Guide to In-situ Burning.
What is It?
In-situ means ‘in place.” In-situ burning refers to the controlled burning of oil spilled from a vessel, facility, pipeline, or tank truck close to where the spill occurred ASTM. 2003a. For spills on open waler, responders usually have to collect and contain the oil using lire-resistant booms, because the oil has to be a minimum thickness to be ignited and sustain burning. In ice-infested waters. the ice can act as a natural boom, keeping the oil thick enough to burn, In-situ burning can also refer to burning of oil inside a vessel before it discharges.
In-situ burning of spills on land occurs more oten than on water because the oil doesn’t emulsify. submerge. or spread into thin shcens as quickly. and the oil is usually more accevsihle. Most of the time. in-xitu burning on land is conducted shortly after a spill is discovered, when the oil is still thick.
Ignition Sources
A lire can be started with a range of ignition sources, Irom a simple match to more sophisticated equipment (see Figure 4 and 5). The ignition source is used to provide enough heat for a long enough period so that some of the oil vaporizes and the vapors ignite. Heavy oils require longer heating time and a hotter flame to ignite, compared to lighter oils. A key goal during an on-water burn is to ignite as much of the oil surface as possible. so that the oil is heated enough to form vapors and sustain the burn.
Specialized ignition sources include the “Helitorch.” an incendiary device that hangs from a helicopter and drops a burning napalm- like substance (CELLED CASOLfl%E) Onto the area tobe burned (Figure 5). The Hclitorch requires a highly traincd flight crew to operate the equipmenl effectively. The gelled gasoline is loaded into a 55-gallon tank on the llelitorch. The fuel is pumped through a nozzle and ignited with propane jets. The falling stream of burning fuel separates into individual glohuics that burn for 4 — 6 minutes. igniting the oil or other combustible material. Its success rate is high, and it has ignited crude oil in winds up to 16 knots (30 km/hr). Helitorches are commercially available, being first developed for lire-fighting and forestry management. They arc safe because they allow ignition from a distance, thus keeping people removed from the open lire.
Spill responders hasc also developed simple ignition devices that can be quickly put together following a spill on water using readily available materials. Examples include:
• Diesel-soaked rags or a roll of toilet paper.
• Oil-soaked sorbent material.
• A sandwich “haggle” filled with gelled gasoline that is allowed to drift mm oil contained in a fire boom or by ice. or
• Marker flares (e.g., road flares).
Burns of oil spills on land or wetlands have been ignited using flame or drip torches, flares and hare guns. blowiorches, and oil— soaked rags or sorbents. A common accelerant used in drip torches at prescribed bums is a ‘70:30 mis of diesel and gasoline.
How is In-situ Burning Conducted?
On Water
In-situ burning is conducted differently for spills on water versus land. On water, spilled oil rapidly (within hours) spreads into very thin slicks that are too thin to burn. Therefore, unless the response is very rapid. the oil has to be collected and concentrated into thicker slicks, The oil may also emulsify and evaporation may remove most of the burnable components. making burning of collected oil difficult or unachievable beyond the first 12 — 24 hours after it is spilled. Thus, on water in-situ burning is primarily considered an option for incidents with a continuous release source (e.g.. a well blow-out) or when oil is trapped in ice.
OI Thickness Requirements
Fresh crude oil has to be at least I millimeter (mm) thick before it can be ignited on water, whereas oil that has undergone extensive weathering may need to be at least 2 mm — 5 mm (see Figure 6). Heasy fuel oils need to be contained to maintain at least a 10 mm or nearly one-half an inch slick thickness. Once ignited. a burn will continue until the oil slick is less than about 2 mm 3 mm.


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