Flange leak

The hydrostatic test is, in one sense, a method of examination of a vessel. It can reveal gross flaws, inadequate design, and flange leaks. Many beheve that a hydrostatic test guarantees the safety of a vessel. This is not necessarily so. A vessel that has passed a hydrostatic test is probably safer than one that has not been tested. It can, however, stiU fail in service, even on the next appheation of pressure. Care in material selection, examination, and fabrication do more to guarantee vessel integrity than the hydrostatic test. 

Figure 3-lb. Because a rupture disc was fitted to the wrong side of a vacuum support, the flanges leaked, covering the reactor with candy. ... 

An explosive decomposition in an ethylene oxide (EO) distillation column, similar in its results to that described in Section 7.3.2, may have been set off by polymerization of EO in a dead-end spot in the column base where rust, a polymerization catalyst, had accumulated. Such deadends should be avoided. However, it is more likely that a flange leaked the leaking gas ignited and heated an area of the column above the temperature at which spontaneous decomposition occurs. The source of ignition of the leak may have been reaction with the insulation, as described... 

The process involved in the incident is concerned with the separation of crude into three phases. The crude is pumped into a two stage separation process where it is divided into three phases oil, gas, and water. The water is cleaned up and dumped to drain. The remaining mixture of oil and gas is then pumped into the main oil line where it is metered and sent on for further processing. A simplified process diagram is shown in Figure 7.1. The case study described here is centered on a flange leak in one of the oil pipeline pumps (pump A) and its associated pressure relief valve piping. 

Do not install liquid-filled flanges above electrical cables. A flange leak will douse the cables with liquid. 

The shortest time known for a vessel to rupture from recorded incidents is thought to be 10 minutes. Rupture periods calculated for less than ten minutes should therefore not be assumed, as the historical evidence and the typical growth of a hydrocarbon fire would indicate that the immediate rupture of a vessel does not occur. Further investigations may be carried out verity if fire exposure conditions could produce such results (e.g., flange leak, gas fire exposures, etc.). 

Heat exchangers that may develop flange leaks. 

The major potential pollutants from the various solvent refining subprocesses are the solvents themselves. Many of the solvents, such as phenol, glycol, and amines, can produce a high BOD. Under ideal conditions the solvents are continually recirculated with no losses to the sewer. Unfortunately, some solvent is always lost through pump seals, flange leaks, and other sources. The main source of wastewater is from the bottom of fractionation towers. Oil and solvent are the major wastewater constituents. 

The flange leak was taped over, and the exhaust-steam pressure dropped back to 100 mm Hg. The steam required to drive the turbine fell by 18 percent. This incident is technically quite similar to losing the downcomer seal on a distillation tower tray. Again, it illustrates the sort of field observations one needs to combine with basic technical calculations. This is the optimum way to attack, and solve, process problems. 

OTHER Maintenance 1. Equipment failure, flange leak, catalyst changeover in reactor, etc. Process stops. Ensure all pipes and fittings are constructed of the right materials and arc stress relieved. 

Use of the chromatograph with gas samples at an absolute pressure of 1 mm Hg has been possible. This has allowed in some special cases the detection of leaks in a system that could not be evacuated to a better pressure than this. The manway between the inner and outer shells of one of the dewars had such a leak. Since the inner shell was filled with nitrogen at the time and the outer flange would leak air, a sample analysis readily provided information that an inner flange leak was present. 

The refinery had experienced a long history of frequent flange leaks and occasional fires during exchanger startups. Typically, as the exchanger system temperature rose from ambient temperature to 500°F there were hydrocarbon leaks at gaskets until the temperatures lined out. 

Starting up the Tesoro Naphtha Hydrotreater unit heat exchangers resulted in hazardous flange leaks of hydrocarbons and small fires rontinely occurred. The CSB stated the PH A evaluations of this activity did not provide effective methods to eliminate the... 

Fan failure can cause extreme vibration resulting in line flange leaks. Also, failed fan blades can damage piping and endanger personnel. Vibration switches that can be set to shut the fan down before vibration reaches a destructive level are recommended for aU air coolers. Also, Umiting the maximum tip speed to 50 m/s will decrease the vibration and noise levels of the air cooler. 

August 1956-October 1956 Flushing of flange leak-detector tubes to remove chloride contamination... 

The probability of occurrence is determined for each basic event (Table 6.4) and the severity of the same basic events is as shown in Table 6.5. The risk estimation and ranking of these basic events can be carried out. For the pipe flange leak event, the probability of occurrence was... 

Weighted mean for event pipe flange leak is calculated as follows ... 

Therefore from Figure 6.18, the pipe flange leak event will be prioritised by Moderate with a support value of 3.68. Similarly, the weighted means can be calculated for all the other events within the system. Table 6.8 shows the results of these calculations. The risk ranking of the events associated with the Gilson winch can be easily obtained from Table 6.8. 

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