Piping ruptures

Successive reflections of the pressure wave between the pipe inlet and the closed valve result in alternating pressure increases and decreases, which are gradually attenuated by fluid friction and imperfect elasticity of the pipe. Periods of reduced pressure occur while the reflected pressure wave is travehng from inlet to valve. Degassing of the liquid may occur, as may vaporization if the pressure drops below the vapor pressure of the liquid. Gas and vapor bubbles decrease the wave velocity. Vaporization may lead to what is often called liquid column separation subsequent collapse of the vapor pocket can result in pipe rupture. 

Since this correction is readily made, the following discussion assumes a fuU-bore pipe rupture, or 0=1. 

Vapor Cloud Explosion as a Consequence of Pipe Rupture at a Chemical Plant... 

No No Flow Excess ammonia in reactor. Release to work area. 1. Valve A fails closed. 2. Phosphoric acid supply exhausted. 3. Plug in pipe pipe ruptures. Automatic closure of valve B on loss of flow from phosphoric acid supply... 

Large-size piping rupture in propane vapor service... 

Realistic release incidents1 Process pipes Rupture of the largest diameter process pipe as follows For diameters smaller than 2 in, assume a full bore rupture. For diameters 2-4 in, assume rupture equal to that of a 2-inch-diameter pipe. For diameters greater than 4 in, assume rupture area equal to 20% of the pipe cross-sectional area. 

This pipe rupture was therefore due to a detonation. The next step in the investigation would include searching for a chemical reaction that would give a detonation. A small vessel could be used as a test. 

Possible hydrate formation in the compressor second stage discharge causing piping rupture due to blockage. 

Coatzacoalcos, Mexico, Chemical Plant, Explosion/Fire Piping rupture caused explosion and fire. 

Case History 2 Pipe Rupture Leads to an LPG Tank BLEVE... 

One of the best known explosion disasters took place in Flixborough, England, in 1974. Nypro Limited manufactured 70,000 tons/year of caprolactam as intermediate for the manufacturing of nylon. This is done by air oxidation of cyclohexane to cyclo-hexanol, with the help of a number of catalysts in the reactors. At that time, cracks developed in the reactor combined with pipe rupture, which released 30 tons of cyclohexane in a cloud. It was ignited by an unknown source and exploded, which resulted in 28 deaths and 36 injured, and the fire burned for 10 days. This disaster was also devastating to the future of the company. 

Sandefjord, Norway 1976 Flammable liquid Pipe rupture ignited, exploded, killing 6 people and causing 10M damage FB CVE... 

Cladding for the reactor vessel is a continuous integral surface of corrosion-resistant material, having -inch (0.56 centimeter) nominal thickness, and a f-inch minimum thickness. The reactor vessel is supported by four vertical columns located under the vessel inlet nozzles. These columns are designed to flex in the direction of horizontal thermal expansion and thus allow unrestrained heat-up and cool-down. The columns also act as a hold-down device for the vessel. The supports are designed to accept normal loads and seismic and pipe rupture accident loads. 

This guideline covers only nonroutine or accidental events. Many hazardous events start with the discharge or loss of containment of a flammable and/or toxic material from a vessel or pipe. These discharges, which may take the form of vapor, liquid, solid, or multiphase vapor-liquid-solid mixtures, may be released into a confined area, such as a dike, building, or an equipment array, or into an open, unconfined area. The sources of these releases could be holes in vessels or pipelines, open pressure-relief devices, pipe ruptures, flange and seal leaks, or catastrophic vessel mptures. The range of releases is illustrated in Figure 2.1. 

Piping Rupture in a Los Angeles Refinery Results in a Vapor Cloud Explosion... 

The failure was preceded by a noticeable steam leak at this piping joint. Attempts were made to tighten to clamp, but this failed to stop the leak. The ensuing clamp fracture and pipe rupture caused an extensive amount of damage within the process building. Fortunately, no one was present in the building at the time of the failure and there were no injuries. 

What if pipe ruptures due to internal corrosion, defective materials, or poor... 

A well-made PVC pipe has outside diameter 150 mm and wall thickness 15 mm. Measurements on this pipe give K c = 2.4 MPa m / and yield stress, ay = 50 MN Assume that the largest flaws are 100-/im cracks and that the calibration factor for the specimens used to measure fracture toughness is 1.12. The pipe is subjected to a test in which the internal pressure is gradually raised until the pipe fails. Will the pipe fail by yielding or brittle fracture in this burst test At what pressure will the pipe rupture ... 

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