Corrosion 100 face

Stress-Corrosion Cracking. The conditions for SCC to occur are (i) a crack-promoting environment (ii) the susceptibility of material to SCC (iii) tensile stresses must exceed the threshold value. SCC is distinguished by the fact that the stress corrosion faces suffer very low corrosion, even in solutions that cause some damage to the free surfaces. As an example is the SCC of stainless steel at 200°C in a caustic solution or in aerated chloride solution where almost no traces of dissolution are visible on the crack faces (Figure 6.53).84,95 For example, SCC of metals has been by far the most prevalent... 

The necessary conditions for the occurrence of SCC are (i) a crack-promoting environment (ii) the susceptibility of the material to SCC (iii) exceeding threshold value with regard to tensile stresses. One of the distinguishing features of SCC is that stress corrosion faces suffer very low corrosion even in solutions that damage free surfaces. 

Eyes corrosive. face shield. flush with water, take to a doctor. 

One quite general observation is that stress corrosion faces suffer very low corrosion, even in solutions that cause some damage to the free surfaces. As an example. Fig. 5-22 shows very little corrosion of a transgranular fracture surface of a stainless steel in a caustic solution at 200 °C, while... 

Skin redness and from slight to corrosive irritation is caused by direct contact. Acryhc acid is more corrosive than esters. The monomers not only irritate the skin, but may also be absorbed through the skin. Therefore, gloves and protective clothing and shoes or boots should be used in addition to eye (or hiU face) protective equipment. Upon contact, the skin should be flushed with copious amounts of water foUow-up medical attention should be sought. Medical attention should also be obtained if any of the earlier mentioned symptoms appear. 

Calcium carbonate (calcite) scale formation in hard water can be prevented by the addition of a small amount of soluble polyphosphate in a process known as threshold treatment. The polyphosphate sorbs to the face of the calcite nuclei and further growth is blocked. Polyphosphates can also inhibit the corrosion of metals by the sorption of the phosphate onto a thin calcite film that deposits onto the metal surface. When the polyphosphate is present, a protective anodic polarization results. 

Potassium forms corrosive potassium hydroxide and Hberates explosive hydrogen gas upon reaction with water and moisture. Airborne potassium dusts or potassium combustion products attack mucous membranes and skin causing bums and skin cauterization. Inhalation and skin contact must be avoided. Safety goggles, full face shields, respirators, leather gloves, fire-resistant clothing, and a leather apron are considered minimum safety equipment. 

NonmetalHc centrifugal pumps utilize polymers for all components coming into contact with the pumping media. Even the steel (qv) shaft is sleeved with plastic to isolate the shaft from the fluid. Mechanical seals are reversed so that the metal face does not come into contact with the corrosive... 

The potassium hydroxide electrolyte used in alkaline batteries is a corrosive hazardous chemical. It is a poison and if ingested attacks the throat and stomach linings. Immediate medical attention is required. It slowly attacks skin if not rapidly washed away. Extreme care should be taken to avoid eye contact that can result in severe bums and blindness. Protective clothing and face shields or goggles should be worn when filling cells with water or electrolyte and performing other maintenance on vented batteries. 

Accuracy Square-edged orifices and venturi tubes have been so extensively studied and standardized that reproducibihties within 1 to 2 percent can be expected between standard meters when new and clean. This is therefore the order of reliabihty to be had, if one assumes (1) accurate measurement of meter differenfial, (2) selection of the coefficient of discharge from recommended published literature, (3) accurate knowledge of fluid density, (4) accurate measurement of critical meter dimensions, (5) smooth upstream face of orifice, and (6) proper location of the meter with respect to other flow-disturbing elements in the system. Care must also be taken to avoid even sh t corrosion or fouliug during use. 

NOTE Outline drawings for flanged valves shown VS-in raised face machined onto flange, as for 400-lb cast-steel valves 150- and 300-lb cast-steel valves and 2.50-lb cast-iron valves have i/ifi-in raised faces 125-lb cast-iron and 150-lb corrosion-resistant valves covered by MSS-SP-42 have no raised faces. 

In order to facilitate removal and replacement of tubes it is cus-tomaiy to roller-expand the tubes to within 3 mm Vh in) of the shell-side face of the tube sheet. A 3-mm- VH- n-) long gap is thus created between the tube and the tube hole at this tube-sheet face. In some services this gap has been found to be a focal point for corrosion. 

Ceramic or carbon-brick linings are frequently used as facing linings over plastic or membrane linings when surface temperatures exceed those which can be handled by the unprotected materials or when the membrane must be protec ted from mechanical damage. This type of construction permits processing of materials that are too corrosive to be handled in low-cost metal constructions. 

There is no single standard size or shape for corrosion-test coupons. They usually weigh from 10 to 50 g and preferably have a large sur-face-to-mass ratio. Disks 40 mm (IV2 in) in diameter by 3.2 mm Vh in) thick and similarly dimensioned square and rectangular coupons are... 

Figure fl.11 An aluminum cooling water conduit severely attacked by a caustic in service. The large circular hole in the machined face is corroded around its edges. The elliptical hole between the 6- and 7-in. ruler markings was formed by corrosion penetrating the conduit wall. 

Figure 9.2 Longitudinal stress-corrosion cracks in a heat exchanger tnbe the broad gap between the crack faces reveals that high-level residual hoop (circumferential) stresses from the tube-forming operation provided the stress component required for SCC.

Microstructural examinations revealed that the cracks originated on the external surface (Fig. 9.15). The cracks were highly branched and transgranular. The branched, transgranular character of these cracks is typical of stress-corrosion cracking of austenitic stainless steels. The thick-walled fracture faces are also typical of cracking by this mode. 

Figure 11.9 Erosion-corrosion damage on the surface of a brass tube facing the steam inlet nozzle.

Solvent/fume leak- Maintain integrity of gaskets and seals age from casing, gaskets compatible with process materials joints resulting in loss of heck mating faces for corrosion/unevenness, containment. particularly on clad components ... 

This type of seal has the rotary component and face mounted outside the seal chamber. The springs and drive elements are outside the pumped liquid. This reduces the problems associated with corrosion and the accumulation of pumped product clogging the springs. This seal is popular in the food processing industry. The pumped liquid arrives to the inside diameter of the faces and seals toward the outside diameter. The environment outside the pump approaches the OD of the face union. Pressures are limited to about 35 psig. Sometimes this. seal can be mounted either inside or outside the pump. This seal is easy to install, adjust, and maintain. It permits easy access and cleaning of the pump internal parts, often required in the food processing industry. 

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