Leak estimation

A tank 100 ft in diameter and 20 ft tall is filled with crude oil to within 2 ft of the top of the tank. One accident scenario is that a 6-in-diameter line connected to the bottom of the tank might break loose from the tank, allowing crude oil to drain out. If a 30-min emergency response time is required to stop the leak, estimate the maximum amount of crude oil (in gallons) leaked. The tank is vented to the atmosphere, and the specific gravity of crude oil is 0.9. 

Leak Estimation - A mathematical model of the probability and amount of potential hydrocarbon releases that may occur from selected processes or locations. 

Perform post-compound hERG current measurements with E-head. For pre- and post-compound hERG current measurement provide stimulus Fh -70 mV for 20-s holding, Fstep -60 mV for 160 ms (for leak estimation), 100-ms step back to -70 mV, 1-s step to +40 mV, 2-s step to -30 mV, and 500-ms step to -70 mV (see Note 5). 

Up to the discovery in October 1978 of a very small sodium leak estimated at 10 g/year across the primary vessel, RAPSODIE did not experience any safety problems and provided considerable fuel data (maximum BU 26 %). Later in 1982 a larger nitrogen leak appeared across the double wall of the reactor (fig. 2.1). The area of this leak was estimated at 0,5 cm2. Because the sodium double containment was not assured, it was decided to close the reactor. Nevertheless is was possible to carry out a series of end-of-life tests just before closing down the reactor. The reactor was finally closed on April 15 , 1983. 

By listening to the sound emitted from leaking tanks, it is possible to estimate not only the existence of, but also the location of, leaks in tank bottoms. Much work needs to be done in this area before it can be considered rehable. 

A vacuum system can be constmcted that includes a solar panel, ie, a leak-tight, instmmented vessel having a hole through which a gas vacuum pump operates. An approximate steady-state base pressure is estabUshed without test parts. It is assumed that the vessel with the test parts can be pumped down to the base pressure. The chamber is said to have an altitude potential corresponding to the height from the surface of the earth where the gas concentration is estimated to have the same approximate value as the base pressure of the clean, dry, and empty vacuum vessel. 

Systematic Operating Errors Fifth, systematic operating errors may be unknown at the time of measurements. Wriile not intended as part of daily operations, leaky or open valves frequently result in bypasses, leaks, and alternative feeds that will add hidden bias. Consequently, constraints assumed to hold and used to reconcile the data, identify systematic errors, estimate parameters, and build models are in error. The constraint bias propagates to the resultant models. 

To determine the amount of air leak in an existing system, estimate the total volume of the system. Operate the ejector to secure a pressure somewhat less than 15 inches Hgabs. Then isolate the ejector from the system. Measure the time required for a rise in pressure in the vessel (say 2 inch Hg). It is essential that the absolute pressure does not rise above 15 inches Hg abs during this time. The following formula will then give the leakage ... 

First, one must estimate air or other gas leakage into the vacuum system. Of course every effort is made to keep it as tight as possible. The author is aware of possible leak points being sealed with polystyrene, which produces an excellent seal. When tests cannot be made, one must use rules of thumb. Many such rough estimating techniques exist. 

Many manufacturers will estimate maximum glycol losses to be 1 lb or. 1 gal per MMscf. Improper operation can increase the actual glycol losses to 1, 10, or even 100 gallons per MMscf. One leaking pump can waste 35 gallons per day (Ballard, 1977). 

Failure of the integrity of the DjO system in sequence 5 resulted from a small leak in the DjO system and failure of the operating personnel to isolate the leak which dominated the sequence. The probability of the small leak that challenges of the tank used to pressurize seals for the main circulating pumps was estimated to be 0.5 0.21 g. 

A reactor was prepared for maintenance and washed out. No welding needed to be done, and no entry was required, so it was decided not to slip-plate off the reactor but to rely on valve isolations. Some flammable vapor leaked through the closed valves into the reactor and was ignited by a high-speed abrasive wheel, which was being used to cut through one of the pipelines attached to the vessel. The reactor head was blown off and killed two men. It was estimated that 7 kg of hydrocarbon vapor could have caused the explosion. 

The worst disaster in the history of the chemical industry occurred in Bhopal, in the state of Madhya Pradesh in central India, on December 3, 1984. A leak of methyl isocyanate (MIC) from a chemical plant, where it was used as an intermediate in the manufacture of the insecticide car-baryl, spread beyond the plant boundary and caused the death by poisoning of more than 2,000 people. The official figure was 2,153, but some unofficial estimates were much higher. In addition, about 200,000 people were injured. Most of the dead and injured were living in a shanty town that had grown up next to the plant. 

In a later paper, Brasie (1976) gives more concrete recommendations for determining the quantity of fuel released. A leak potential can be based on the flashing potential of the full amount of liquid (gas) stored or in process. For a continuous release, a cloud size can be determined by estimating the leak rate. For a combined liquid-vapor flow through holes of very short nozzles, the leak rate (mass flow per leak orifice area) is approximately related to the operating overpressure according to ... 

Pipe Break Frequency Estimation for Nuclear Power Plants Nuclear 19 occunences of pipe failures (breaks), supplemented by expert-opinion estimates Leaks of 1 gpm for 2 inches in diameter pipe 50 gpm tor all pipe for 81 nuclear plants 101. 

The report presents the findings from the analysis of the RCP failures. Estimates of the annual frequency for the spectrum of leak rates induced by RCP seal failures and their impact on plant safety (contribution to coremelt frequency) are made. The safety impact of smaller RCP seal leaks was assessed qualitatively, whereas for leaks above the normal makeup capacity, formal PRA methodologies were applied. Also included are the life distribution of RCP seals and the conditional leak rate distributions, given a RCP seal failure the contribution of various root causes and estimates for the dependency factors and the failure intensity for the different combinations of pump designers and plant vendors. 

To estimate tlie potential iiupaet on tlie publie or tlie environment of aeeidents of different types, the likely emergeney zone must be studied. For example, a liazardous gas leak, fire, or explosion may eause a toxie cloud to spread over a great distance. The minimum atmospheric dispersion model. Vtirious models can be used tlie more difficult models produce more realistic results, but tlie simpler and faster models may provide adequate data for planning purposes. A more tliorough discussion of atmospheric dispersion is presented in Part 111 - Healtli Risk Assessment. 

The experimental principle is illustrated in Fig. 3. The interaction of the polymer with the liposomal membranes causes the perturbation of the bilayer. This perturbation follows the leakage of calcein from the liposome. Calcein in high concentration in the liposome is self-quenched, but has strong fluorescence intensity by the leak from the liposome. Therefore, the extent of the membrane interaction can be estimated quantitatively from the fluorescence spectroscopy. 

Estimate acceptable air leakages resulting from leakage around static and rotary seals, valves, access ports, and other items of mechanical nature required for process operation from the following equations and the specific leak rates 0 indicated in Table 6-8, which is based on w < 10 lb/hr. 

Estimate air inleakage for individual system specific leak rates, 0, from Table 6-8 [22] and from (w < 5 Ib/hr)... 

The first step in making labor estimates is to break the job down into activities in a logical sequence. Example work order 123 Work description - Repair ball valve. Leaking. 

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