Weld failure

Welded structures often have to be tested nondestructively, particularly for critical application where weld failure can he catastrophic, such as in pressure vessels, load-bearing structural members, and power plants. 

Tube e] ansion after welding has been found useful for low and moderate pressures. In high-pressure service tube rolling has not been able to prevent leakage after weld failure. 

The initi MIC examples studied in the 1970s were weld failures of stainless steel piping that saw only potable drinking water. The numbers of water-exposed systems that have been verified as being affected by MIC are legion. 

St. Croix, VI, Refinery Fire Pipeline weld failure 10,500,000 loss... 

Massive metallurgical weld failure of liquid propane tank... 

Weld failure on hydrogen line caused high pressure jet fire onto the support of a 100 foot reactor which failed and spread incident. 

In general, SoC describes the short-term changes of battery parameters whereas SoH describes the long-term changes. SoH determination does not need to be carried out continuously. Periodic measurements (e.g., once a week) are adequate for most applications. The period of measurement depends on the application. Extrapolation of SoH measurements allows a prediction of battery life. Sudden battery failures, however, also occur, e.g., cracking of a faulty weld. Failures such as these are very difficult to predict. To determine the SoH, it is necessary to know the actual SoC or to measure the SoH, always at the same SoC (i.e., full SoC). 

Selected postweld transverse tensile properties for a variety of Ixxx aluminum alloys are shown in Table 5.5. Natural aging times were not reported. Although not always identihed, the failure location is most often in the soft HAZ. Transverse weld failures correspond directly with hardness minima where failure location is shown to move further into the HAZ... 

Weld failure is the most severe problem in offshore and refinery pipelines. Figure 9.7 shows a random leak in the weld of pipelines. This problem is more concerned with the proper welding, followed by a quality check and postcoating over that. 

Other possible adverse effects of steel oxidation are fastener and weld failures due to oxide jacking. 

Surface and barrier layers sometimes crack or, if thermoplastic, suffer from weld failures. These are the regions that initiate stress corrosion cracking. 

Circumferential weld failures due to comer drops were noted forboth caskslzes above a dr<9 height of 15 ft. However, no attempts were made to get hlgh-qirality welds and, in some cases, weld penetration was less than 50%. 

The only circumferential weld failure that occurred in a horizortal drop was found on a 1.4-ton cask dropped 28 ft. The cask had been previously dropped 15 ft on the same Bide. 

The welded seams on the vapor degreasing tank offer a potential hazard risk. Failure of any weld point below the liquid level would obviously result in loss of some or all of the liquid solvent into the surrounding concrete pit area. Considering the stress of liquid mass inside the tank, as well as the temperature extremes associated with solvent heating and off-gas coohng, the possibility of weld failure occurring sometime during the life cycle of this system must be carefully evaluated. 

STRUCTURAL Tank Weld Failure Solvent leak into outer 3D Remote possibility 1. Install uni-body tank... 

A generic safety assessment of core shroud weld failures was provided by the U.S. BWR Owners Group in 1994. Plant-specific assessments were provided in response to USNRC Generic Letter (GL) 94-03 [6.9]. 

The end sealing welds of the fuel pin are magnetic force resistance welds which as made have a considerable flash inside and out. This is machined off externally. Mechanical tests on such welds in the as manufactured and hydrided conditions, at room temperature and at 150°C, 200°C and 290°C, show that under most conditions failure occurs in the can wall away from the weld. Only with hydrided specimens (2-300ppm) at the lower temperatures did some weld zone failures occur. With the exception of certain fuel pins Irradiated in the Halden BWR, no weld failures have occurred in experimental irradiations. 

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