Flammable gas test

A Tank Explodes during Welding Repairs after Passing a Flammable Gas Test... 

The first day progressed with no problems, and it rained the next day, which prevented further work on the outdoor tank. On the third day, the job resumed with the same two pipefitters and a welder joined the crew. Flammable gas testing of the area was... 

A tank explodes during welding repairs after passing a flammable gas test... 

This can be measured by injecting dust into a premixed flammable gas-air mixture so that the final gas concentration is known. Provided the gas does not condense when pressurized it is possible, with appropriate precautions, to inject the dust using a pressurized gas-air mixture identical to the mixture in the test vessel. This avoids concentration gradients. Because it is a non-standard technique the possibility of estimating the hybrid mixture MIE (HMIE) should be considered (6-1.3). 

In addition to the great dependence of MIE on particle size distribution and the possible accumulation of additives, complicating factors in measuring and applying MIE data include the presence of flammable gas (6-1.3.1) plus the effects of moisture (6-1.6) and possibly increased temperature (6-1.5) relative to the test temperature. 

This approach has not been tested for any dusts that bum heterogeneously such as some metal dusts (A-6-1.2). Also, this large an effect of temperature has not been found by some other workers, it has yet to be confirmed that the effect is not due in part to loss of moisture (6-1.6) or evolution of flammable gas (6-1.3), both of which can have large effects on MIE. 

Immediately after the running test, any compressor intended for toxic, hazardous, flammable, or hydrogen-rich service should be gas tested with an inert gas to the maximum seal design pressure. The test is held at least 30 minutes and the casing and its joints checked for leaks, using a soap bubble method or other suitable means for leak detection. When no leaks are detected, the compressor will be considered acceptable. 

A similar incident occurred on a solids drier. Before maintenance started, the end cover was removed, and the inlet line was disconnected. When maintenance was complete, the end cover was replaced, and at the same time the inlet pipe was reconnected. The final job was to cut off the guide pins on the cover with a cutting disc. The atmosphere outside (but not inside) the drier was tested, and no flammable gas was detected. While cutting was in progress, an explosion occurred in the drier. Some solvent had leaked into the inlet pipe and then drained into the drier [19]. 

It is usual to test for the presence of flammable gas or vapor with a combustible gas detector before maintenance, especially welding or other hot work, is allowed to start. The following incidents show what can happen if these tests are not carried out or not earned out thoroughly. Large pieces of equipment or those of complex shape should be tested in several places, using detector heads at the ends of long leads if necessary (see Section 5.4.2 d). 

Before allowing welding or similar operations on a pipeline that has or could have contained flammable gas or liquid, (1) sweep out the line with steam or nitrogen from end to end, and (2) test at the point at which welding will be carried out. If necessary, a hole may have to be drilled in the pipeline. 

A leak in another heat exchanger allowed flammable gas to enter a cooling-water return line. The gas was ignited by welding, which was being carried out on the cooling tower. The atmosphere had been tested before work started, five hours earlier (see Section 1.3.2). 

Placement of detectors should consider the need for protection from physical damage, weather effects (snow, icing, wind-driven rain, or dust), or direct water hose spray during an area wash down. Detector placement should also allow safe access to perform required periodic testing and inspection. Typical approaches to flammable gas detection layout are ... 

A particularly troublesome mixture is the hybrid, a mixture of combustible dust and flammable gas which can form an explosive mixture in air. Dow requires that reactive chemical testing be employed to determine the proper MF in this unique situation. 

Ethane is a flammable gas present in the exhausts of diesel and gasoline engines, municipal incinerators, and the combustion of gasoline. Inhalation and other exposures cause CNS depression in mammals. Ethane in liquid form results in frostbite,3 and the United States Environmental Protection Agency (USEPA) has listed it under chemical inventory and the test substance database. 

How did a flammable gas enter the pump/piping system Why did the explosion meter tests prove negative What was the fuel within the pump Jobs similar to this were repeated over the past 50 years. Why did it happen at this particular time ... 

A multi-disciplined team interviewed witnesses and performed tests, and the evidence was followed to a sound conclusion. Investigators sent the explosion meters (flammable gas detectors) to the instrument shop for examination. The welding torch was also inspected. Experts found both the torch and the meter behaved satisfactorily. There was speculation that some aquatic life deteriorated and formed methane, but that was not the case. They concluded that the fuel was dissolved methane from the well water system that was routed to the pump seal. Trace amounts of dissolved methane (about 0.02 percent by volume) accumulated in the well water stream flowing through the 3/8-inch-diameter stream on the... 

The cubic law allows the prediction of the course of an explosion of a flammable gas or vapor in a large vessel, based on laboratory tests. It is valid only for the following conditions ... 

The minimum ignition energy is simply the minimum energy necessary to cause the ignition of a mixture of flammable gas and oxidizing gas within the flammable range. It is usually measured by an electrical spark discharge because of the ease of the test. 

Looking at Table 6.6, it is obvious that the inert gases commonly available cover a few points only in density range to comply with the requirements for a test gas given in the p-standards. Thus, a mixture of two test gases A, B with molecular weights MA, Mg can substitute the flammable gas C with molecular weight Me-... 

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