Explosive decompression

From the above table it is seen that the coated filler accommodates more carbon dioxide leading to blistering in the seal, which is known as explosive decompression. It becomes evident that rubber compounds that have low permeation rates are chemically resisting the permeation of gases and are the best to minimize blistering due to the cavity or vacuoles in the rubber or polymer matrix. 

The following table 12.2 [5] shows the effects of four important filler variables on the physical properties of a sealing compound, 

Key t Increases i Decreases - No significant change N Goes through a maximum  

Static modulus, extrusion resistance blister resistance 

The function of cross link requires no elaborative discussions in the matter of product design since the implications of the same on the physical properties are quite obviously mentioned in many textual treatises on cross linking of rubbers. The cross link density directly affects physical properties such as heat build up, tear strength and elongation, too. 

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Cracks, splits, and other fractures, perhaps caused from an excess of absorption—with ensuing swelling and weakening—or from explosive decompression (ED) fracturing in high-pressure gas situations... 

Explosive Decompression in Solid Elastomer Sections—The Nature of ED Damage... 

FIGURE 23.13 Explosive decompression (ED) in soft transparent elastomer bubbles of carbon dioxide (CO2) several days after decompression. 

Explosive Decompression in Solid Elastomer Sections—Predominantly O-ring and Other Seals... 

FIGURE 23.14 Explosive decompression (ED) damage in a fluoroelastomer O-ring seal section left and miscellaneous samples of a nonfluorinated oil-field elastomer right obtained using pressure vessels such as those shown in Eigure 23.15. 

Ways to Lessen Risk of Explosive Decompression (ED) Damage for Sealing Elastomers in Service... 

Explosive decompression in the oil field operating conditions due to pressure or temperature shifts can cause catastrophic seal rupture. 

Differences in the types of carbon black used in the oil field service lead to the seal explosive decompression problems. The molecular weight of the base rubber also is very critical. 

B.J. Briscoe and S. Zakaria et al. Imperial College London-UK, "Role of Interfacial Quality on Gas Induced damage of Elastomer Composites" Presented at "Explosive Decompression Seminar" June 4, 1990 Red bank NJ, USA. Dan Hertz, Seals Eastern Inc Energy Group Educational Symposium, September 24-25,1991. 

Explosive decompression in pressurized hose and seals can result in damage only after several decompression cycles, i.e. as a result of fatigue. Tests were made42 which produced fracture surfaces similar to those from explosive decompression and the importance of maximum strain, temperature, void size and void position was highlighted. 

The ISO and the ASTM oxygen method and the ASTM air pressure method call for the pressure to be released slowly at the end of the exposure but ISO does not point out that this is to avoid porosity. Presumably, in the worst case it could be a test for explosive decompression. 

Explosive decompression Cells equilibrated with nitrogen gas at high pressure and disruption occurs upon their sudden release into atmospheric pressure. 

Potential energy Rupture of pressure vessels, pipes or ducts. Bulkhead rupture. Consider issues such as pressure vessel containment, damage to areas subjected to very high/low temperature, explosive decompression, etc. 

Disintegration is carried out with a homogenizer (Potter or Dounce), a mixer (Waring blender), or pulverization with quartz sand in a mortar. Explosion decompression has also been applied. 

Table 5.2 [5] shows the effects of four important filler variables on the physical properties of a sealing compound, those being quantity, surface area, structure and surface reactivity. The resistance to blistering, or explosive decompression, is found to increase with an increase of all the four variables. Table 5.2 shows how these properties change as each of these variables increases. It should be studied in conjunction with Figure 5.1, from which the specific properties can be optimized. Since each of these variables can affect properties differently, and cross-link density of the compound will have yet another effect, (shown Figure 5.1), the choice of properties to be optimized should be selected very carefully, and should be limited. 

Explosive decompression High-pressure extrusion Effect of corrosion inhibitors Effect of hydrogen sulphide Steam/add resistance Methanol resistance... 

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