Vessels leak testing

Containment Vessel Leak Test Reactor Vessel IHX SG IryPump RV Shielding Plug 1ry sys. Pressure Test 2rysys. Pressure Test... 

Containment Vessel Leak Test Reactor Vessel IHX... 

When a plant was being leak-tested with nitrogen after a shutdown, a leak was found on a manhole joint on the side of a vessel. The pressure was blown off, and a fitter was asked to remake the... 

Similarly, pressure tests (at pressures above design, as distinct from leak tests at design pressure) are intended to detect defects. Defects may be present—if we were sure there were no defects, we would not need to pressure-test—and therefore we must take suitable precautions. No one should be in a position where he or she may be injured if the vessel or pipework fails (see Section 19.2). 

The accident investigation found that the leak test should have been conducted with a hydraulic procedure and not air and that the vessel should have been protected with a relief device. In addition, the fitters should have taken more time to check out the gauge to ensure that it was correct for this application. 

The stratification test program described here utilized a 70-ft vacuum-jacketed test vessel. The test vessel was a 4-ft-diameter x 6-ft-long stainless steel inner tank supported within a 6-ft-diameter outer tank by means of four legs, several tie rods, and a sway bar. The inner tank was designed for a working pressure of ISOpsig at liquid-hydrogen temperature. Its upper and lower domes w ere insulated with 1 in. of multilayer insulation to minimize inadvertent heat leak to the test fluid. Removal of the outer tank dome (Fig. 2) provides ready access to the inner tank. A 14-in. manhole in the upper dome of the inner tank provides access to the tank interior. 

Leak testing is not only mandatory for testing pressure vessels, it is recommended for all process lines and analytical equipment. Besides the... 

Final assemblies should be pressure-tested and leak-tested to ensure their integrity. Laboratory workers are strongly advised to consult an expert on high-pressure work as they design, build, and operate a high-pressure process. Finally, extreme care should be exercised when disassembling pressure equipment for repair, modification, or decommissioning. Protective equipment should be worn just in case a line or vessel that is opened contains material under pressure. 

Work is being planned to determine if the CPF in PWR vessels is acceptably low when small surface flaws (approximately 4-6 mm - 0.16-0.24 in - in depth) are postulated at the vessel inner surface and normal reactor start-up, shut-down and system leak testing occur along the allowable P-T boundaries defined by reguiatory requirements, the ASME evaluation procedures, and procedural and hardware constraints. 

Vessel and pipework leak test, according to a suitable method. 

Vendor should perform the leak tests as per standard practice for all components which should operate under high vacuum—main vessel, evaporator and absorber (helium leak test may be asked for), etc. 

Additional safety considerations apply to the use of microwave technology. First, the equipment should be operated in strict accordance with instructions to ensure that no detectable amounts of microwave radiation will escape. Leak tests should be conducted on a regular basis by a trained technician. Vessels or other objects made of metal should never be placed in the oven chamber. Microwave equipment must also never be operated empty (i.e.. in the absence of a sample solution, water, acid, etc.), since the magnetron might be destroyed by reflected radiation. The behavior of unknown samples should be tested on a small scale (see above). 

Storage banks, both portable and stationary, are to be inspected periodically for (1) corrosion of vessels and supports, (2) condition of pressure relief devices, (3) proper operations of shutoff valves, and (4) condition of manifold piping. A leak test with soap solution or other appropriate leak detection equipment should be performed periodically at maximum operating pressure. 

The problem is that initially a large vapor space filled with air is in the vessel. To avoid a dangerous gas mixture the air must first be evacuated. There is also the possibility of leaks into the vessel whilst it is under vacuum. The PLC therefore carries out a leak test stage before starting the hydrogen feed. This test also reduces the risk of hydrogen leaks from the vessel once the pressure is positive. 

Leak Test—Pressurize the cylinder only using an inert gas source. Do not exceed the vessel s maximum rated working pressure or that of the relief device. Helium is extremely reliable. Its ability to reveal small leaks surpasses... 

The vessel should be leak tested prior to coating. The assembled package should be dry function tested to ensure proper operation. Any plastic piping should also be hydrotested. 

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. 

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. 

Failures of pressure vessels are veiy rare. Many of those that have been reported occurred during pressure test or were cracks detected during routine examination. Major failures leading to serious leaks are hard to find. 

The use of vibration analysis is not restricted to predictive maintenance. This technique is useful for diagnostic applications as well. Vibration monitoring and analysis are the primary diagnostic tools for most mechanical systems that are used to manufacture products. When used properly, vibration data provide the means to maintain optimum operating conditions and efficiency of critical plant systems. Vibration analysis can be used to evaluate fluid flow through pipes or vessels, to detect leaks, and to perform a variety of non-destmctive testing functions that improve the reliability and performance of critical plant systems. 

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