Brick red shale

Table 15-1 Ranges of Chemical Composition and Mineralogical Phases Present in Acid Brick (Red Shale and Fireclay)...

There are four major categories of corrosion resistant brick red shale, fireclay, refractory, and carbon. Each type has somewhat different properties and compositions. However, all resist attack by most acids and are fired at 2000°F/1093°C therefore, they are capable of handling process temperature at least that high. Their application temperatures, however, are determined by their resistance to thermal shock. In general, red shale is for ambient temperatures, fireclay for temperatures up to 1000°F/538°C, and refractory brick up to 3000 F/1649 C. 

Brick Construction Brick-lined construction can be used for many severely corrosive conditions under which high alloys would fail. Common bricks are made from carbon, red shale, or acidproof refractory materials. Red-shale brick is not used above 175°C (350°F) because of spalhng. Acidproof refractories can be used up to 870°C (1,600°F). 

Acid Brick Acid brick, also called acid resistant or acid proof brick (covered by ASTM C279), are of two major types (1) Red shale, the predominant brick in CRM construction and (2) Fireclay, another common brick in CRM applications. These two acid brick are the most widely used masonry units in CRM structures and linings, including floors, trenches, sumps, vessels and chimney... 

In phosphoric acid production plants, both red shale and fireclay brick have excellent resistance to all concentrations of phosphoric acid at temperatures up to 250°F, provided the acid contains no HF. If HF is present in the phosphoric acid, carbon brick construction must be used. As a rough rule-of-thumb, HF levels above 50 ppm in phosphoric acid require tank linings of carbon brick bonded and jointed with a carbon (or barytes) filled furan mortar over a suitable membrane to match the steel or concrete substrate structure. 

The manufacturing processes for red shale and fireclay brick are very similar. One of three shaping techniques is used in brick fabrication extrusion, dry... 

Red shale and fireclay acid brick are probably the most widely used masonry materials in chemically-resistant systems. Many scrubbers, trenches, floors. 

Dimensions The dimensions of fireclay brick may differ from red shale s. Fireclay sizes can be modular (9" x 4.5" x 2.5" or 3") or the same as red shale (8" X 3.75" X 2.25" or 4.5"). Fireclay acid brick tends to be more dimensionally true than red shale and is available in a wider variety of masonry shapes (domestically). Fireclay is also used to fabricate many tower intervals such as packing supports, saddles, spargers, and feed boxes to name a few. 

In general, silica brick offers superior acid resistance over red shale or fireclay (again with the exception of HF). Silica is also very resistant to chlorine, organic solvents and many other non-alkaline chemicals. 

Thermal Expansion and Thermal Shock Resistance In many situations it is difficult to directly substitute silica brick for red shale or fireclay. Changes in design might be needed to avoid subjecting the silica brick to destructive tensile or shear stresses during operation because of expansion differences. The thermal expansion of the specialty type silica product (Type 2) is much less than that of acid brick. The vitreous silica material which contains some crystalline Si02 (Type 1) has a thermal expansion that closely matches that of acid brick at temperatures less than 800°F. Above that temperature, the expansion is much less. 

Irreversible Growth Irreversible brick growth is not a problem with high purity silica materials as it is with red shale or fireclay. 

Concrete floor areas in a pulp and paper mill are frequently lined to prevent deterioration of the concrete. These linings can consist of red shale brick, quarry tile, or an aggregate filled resin (referred to as a monolithic floor lining). Floor linings are primarily used in areas exposed to very aggressive chemicals such as in the bleach plant and paper mill. 

A red shale brick or quarry tile floor is usually installed over a hot or cold applied mastic membrane. The mastic is applied to the concrete floor then the brick or tile are set with a resin cement. The resin cement can be a furan, a polyester or an epoxy depending on the anticipated exposure conditions. If high temperatures and constant exposure to aggressive chemicals are anticipated, the brick or tile will be bedded in the mortar as well as having mortar joints. 

The furan polymers are used as binders in mortars and grouts to achieve chemically resistant brick floors (e.g., carbon brick and red shale brick) and linings. In addition to exhibiting superior chemical resistance, these floors have excellent resistance to elevated temperatures and extreme thermal shock [2,6,7],... 

Brick lining protection can be used for many conditions that are severely corrosive even to high-alloy materials. It should be considered for tanks, vats, stacks, vessels, and other similar equipment items. Brick shapes commonly used for such construction are made of carbon, red shale, or acid-proof refractory materials. Carbon bricks are useful for handling alkaline conditions as well as acid, while the shale and the acid-proof refractory materials are used primarily for acid solutions. Carbon can also be used where sudden temperature changes are involved that would cause spalling of the other two materials. Red shale bricks generally are not used at temperatures above 118.88°C (300°F) because of poor spalling resistance. Acid-proof refractories are sometimes used at temperatures up to 871°C (1600°F). 

Red shale brick is the most frequently used brick in chemically resistant masonry construction. It meets type L in ASTM C-279 specification. 

Fireclay bricks are more dimensionally true than red shale bricks and are available in many shapes. Because of this they are preferred in work where uniformity of joints in the masonry is important. 

Greater thicknesses of carbon brick are required than of red shale or fireclay brick to reach thermal drops equivalent to those of shale or fireclay bricks. This is the result of the much greater heat conductivity of carbon. 

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