Floor trenches

Process Area Floor Trench Design Considerations... 

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... 

Corrosion resistant masonry is generally more commonly used in floors, trenches, and pits or catch basins. Other applications are chimneys, basically fire brick, and the lining of process vessels. Both are highly specialized and are covered in other chapters in detail. 

Floor or trench drams, sumps and sinks that discharge to ground surface... 

Discharge pipes can be located in trenches covered by floor plants, and there is no technical reason against laying the pipes directly on the ground, but provision must be made for drainage. 

A typical interior trench or floor gutter is shown in Figure 14. Note the rounded bottom shape and the canted or rounded bends of the lead conductive flooring. Also, note the requirement for rounding bearing surfaces of the cover, which prevents damage to the lead floor surfacing. 

A trench should be designed to collect and control spills within only one con-tainment/drainagezone in order to prevent the trench from becoming a source of fire spread from one zone to another. Trenches can be designed into the perimeter of solid floors on elevated levels of a process structure. Trenches... 

A drainage system includes a containment system using solid, impermeable floors with perimeter features (curbing, floor slope, or trenches) to limit and control the spread of liquids and a collection system (floor drains or trenches, catch basins, sumps, piping, and manholes) to direct the liquids into a gravity drain system that routes them to an appropriate location out of the unit. 

Figure 8-2. Typical Floor Drain and Trench Layout...

Trenches formed into the floor can provide a higher drainage flow rate than conventional floor drain boxes, resulting in minimal depth of the liquid runoff within the area served. Illustrations of drainage trenches are shown in Chapter 7, Figure 7-3. 

Catch basins should be provided for each fire zone of the process area to collect the flow from the floor drains and trenches. All catch basins within the process area battery limits should be sealed for vapor control. Catch basin seals should be of types that are easily cleaned out. P-traps should not be used. Catch basins require a periodic check to verify that a liquid seal is in place and clean-out plugs are installed. 

Shores should be located 18 to 24 inches from the floor and the lip of the trench. 

Pressure effects on equilibria in liquids or solids are generally less spectacular than temperature effects, at least at the pressures normally encountered in chemical engineering (a few tens of megapascals) or in the environment (hydrostatic pressures in the ocean trenches exceed 100 MPa, but about 40 MPa would be more typical of the ocean floors). Higher lithostatic pressures are, of course, found beneath the Earth s surface, reaching 370 GPa (0.37... 

Systematic sampling on a two-dimensional grid is used for characterizing large areas of surface soil floors and walls of excavation pits and trenches and for the verification of decontaminated surfaces cleanup. An example of a systematic sampling... 

There are several types of environments on Earth where significant water exists at prevalent low temperatures such that ice and liquid aqueous solutions commonly coexist permafrost, snow, glaciers, lake and river ice, sea ice, and parts of the atmosphere (polar troposphere, global upper troposphere, and stratosphere). In addition, the deep sea floor occurs at temperatures very close to the freezing point of water. For example, temperatures in the oceanic abysses hover around 2°C at a maximum hydrostatic pressure of 1100 bars (10,660 m) in the Mariana Trench (Yayanos, 1995). Table 4.1 summarizes some of these environments. Furthermore, in some permafrost and sea-floor environments, the presence of nonpolar gases under pressure can stabilize a modified form of ice known as gas hydrates even where temperatures are not quite low enough for ordinary ice to form. 

Marine sediments cover the ocean floor to a thickness averaging 500 m. The deposition rates vary with topography. The rate may be several millimetres per year in nearshore shelf regions, but is only from 0.2 to 7.5 mm per 1000 years on the abyssal plains. Oceanic crustal material is formed along spreading ridges and moves outwards eventually to be lost in subduction zones, the major trenches in the ocean. Because of this continual movement, the sediments on the seafloor are no older than Jurassic in age, about 166 million years. 

Trenches—The deep, trough-like depressions in the ocean floor that oceanic crust descends into when it is destroyed. 

Polyester coatings find application in tank linings and floors. In both cases, the systems are generally used as laminates. Owing to the resis-tancy over a wide range of pH they do well in effluent trenches and buffer tanks (Figure 9.3). 

The university trained engineer usually thinks first of metal (steel, alloy, etc.) when designing chemical equipment-something easily shaped and erected, not occupying more space than is needed. Both architects and engineers think of concrete first when they think of floors, dykes, trenches, sumps, pits, etc., because they are easily formed and poured. 

Gutter or trench, sloped from ends to center, drains through wall, down floor on opposite side. Note expansion joint next to trench, 2 brick out from trench wall. Peripheral expansion joint on adjacent floor continues through trench and across brick capping. 

When the layer of asphalted glass fabric is completed, a second Vs" of hot asphalt is applied over the fabric, providing a thickness of For floors, this is the accepted finished thickness for a hot asphalt membrane. However, for the lining of trenches and tanks, where a hydrostatic head will be encountered, the normally accepted thickness is and a second layer of glass fabric and a third layer of hot asphalt should be applied. 

Some safety engineers have become obsessed with fears of safety problems with hot asphalt, although very few injuries or accidents have been traceable to it over the several centuries that it has been used industrially. Asa result, there have been many efforts to substitute cold asphalt putties for hot asphalt as a membrane material. These materials and their limitations have been discussed above. As a membrane for floor installations, such putties are often usable providing they are never subject to a standing liquid head, but less frequently for trenches and pits. Remember, if asphalt emulsions are put in service before all the water has dried out of them, they can reemulsify and may be washed out. 

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

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