Acid brick

The production room itself should have a minimum ceiling height of 2.5 m and the floors should be watertight and made from concrete with acid brick tiles or other suitable material. The floors should slope appropriately toward drainage points. The walls should be covered with glazed tiles or other suitable material at a minimum height of 1.7 m and the transition between the floor and wall should... 

Thermal insulation effects by limiting the substrate and membrane temperature to prevent thermal damage and (3) Reduce permeation of corrosive fluid to the substrate, thus minimizing its corrosion rate. CRM linings, such as acid brick and monolithic cements, also prevent "wash", which is the removal of the membrane or substrate corrosion products by the circulating medium. Even when the fluid eventually reaches the membrane or substrate surface, the amount is relatively small, thus limiting chemical attack, and any corrosion products are trapped beneath the masonry shield. 

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 sulfuric acid production, acid brick lining of membrane coated mild steel tanks and reaction vessels is considered the most durable and versatile construction material for the sulfuric acid plant. Such linings wiil reduce the steel shell temperature and prevent erosion of the normally protective iron sulfate film that forms in stagnant, concentrated (oxidizing) sulfuric acid. Dilute (red uC ing) sulfuric acid solutions are very corrosive to carbon steel, which must be protected by impermeable (e.g., elastomeric) membranes and acid brick lining systems. Such acid brick linings often employ membranes comprising a thin film of Teflon or Kynar sandwiched between layers of asphalt mastic. 

Carbon Brick Carbon brick, though costing much more than acid brick, is required in some CRM applications because of its high resistance to HF and con-... 

Silica Brick Brick containing about 99% silica is favored over acid brick for very high acid concentrations, especially phosphoric acid. 

Sulfur Mortars Hot melt-and-pour sulfur mortars are ancient, doubtless one of the oldest of all chemical resistant materials still used today. They are very resistant to non-oxidizing acids and weak alkalies below 200°F over a pH range of 0-12. Three types of sulfur mortars are typically employed (1) One containing an all-silica filler with minimum plasticizer, used to bond acid brick (2) A mortar with an all-carbon filler and minimum plasticizer, used primarily to lay carbon brick for nitric-hydrofluoric acid pickling tanks (to clean stainless steels) and the underlying floors and (3) A much more flexible all-silica filled product with double the amount of plasticizer of the other two mortars, used to join vitrified clay (terra cotta) pipe conveying waste acids and other effluent chemicals, and to assemble "pole line hardware" for the power industry. 

Polyester and Vinyl Ester Mortars These two mortars, of which there are many types, are suitable for a pH range of about 0-11 and a continuous service temperature of 225°-230°F. The two related resins, which complement the epoxy resins, resist dilute and concentrated acids and weak alkalies. Their resistance to acid bleaches such as chlorine dioxide and to oxidizing acids such as nitric and chromic is superior to that of other resinous mortars, and they are excellent in acetic acid and related esters. However, polyester and vinyl ester mortars are the poorest resin mortars in other organic chemical exposures including solvents in general. Such mortars are widely used in paper mills and are suitable with acid brick or ceramic tile in the lower temperature zones of mildly acidic utility FGD systems. 

Figure 1-1 Large coal-fired power station with FGD system and two 1,000 foot high chimneys, one containing the tallest acid brick liner in the United States.

The most acid resistant CRM linings and acid brick structures are providing cost-effective protection to the major problem areas of this and many other coal fueled power plant FGD systems. 

Acid-brick laid in acid-resisting mortar over a liquid-tight membrane. 

In tanks where brick wall linings may not be desired, brick floors are sometimes installed in the bottoms to protect the bottoms (and perhaps the bag liner) from steam jets, mechanical abuse and the like. (Canadian Chemical Processing for September 3, 1980, Page 21, provides a case history of three rectangular creosoted Douglas Fir tanks, with 316 stainless tie rods, installed in 1958, and apparently still used by the purchaser at the date of publication for acid/sul-furic cleaning of copper and brass bars up to 50 feet in length. The units are lead-lined, with "acid brick" laid over the lead in the tank bottoms.)... 

If "acid brick" is to be used, the glass-reinforced asphalt membrane is now applied in the usual manner, and the brick laid over it, expansion joints carefully laid out and placed on the usual centers. If a monolithic, whether a %" topping or a polymer concrete, is to be applied, polyethylene separator bars should be set above the cracks around the periphery of every sheet, the monolithic placed, the bars removed, and the cavities thus formed filled with expansion joint sealant. If this is not done, you can be certain that, sooner or later, the monolithic will develop cracks at these points, telegraphing through the surface the pattern of the plywood sheets below it. 

Occasionally, when the chemical exposure or other environmental considerations have dictated the use of a material that cannot be successfully bonded to the substrate, this same principle has found use even in composite linings employing "acid brick" or other rigid internal facings to protect the membrane lining from thermal or mechanical damage. An application of this kind requires the most careful study and construction if it is to be successful, and should not be attempted without the advice of experienced persons. 

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

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