Concrete foundation

Mid-1984 materials and labor factors have been reported for over 30 equipment types (13). The commodity materials include factors for concrete foundations, piping, steel supports, instmmentation, insulation, electrical, and painting. InstaHation labor factors are given for each of the commodity... 

Girth-gear drives can cause the concrete foundations to fail if not designed to resist harmonic vibrations (Saxer and Van der Heuvel, 31st IEEE Cement Industiy Conference, 1989). 

Installation and fixing The assembly should be installed in a room that is well ventilated (except for outdoor assemblies), on a rigid concrete or steel foundation to eliminate vibrations. A simple and more common practice of fastening on a separate steel foundation frame is illustrated in Figure 13.48. The assembly may also be fixed on a concrete foundation... 

The anodically produced acid is neutralized by the alkaline mortar (CaO). Corrosion is then possible only if the supply of alkali at the steel surface is consumed and the steel becomes active. This process is possible only under certain circumstances after a very long incubation period. Apparently in steel-concrete foundations the possible current densities are so small that this case never arises. The possibility of danger has to be verified with thin outer coatings where deliming has been noticed on the steel surface. 

A similar danger of corrosion lies in cell formation in steel-concrete foundations (see Section 4.3). Such steel-concrete cells are today the most frequent cause of the increasing amount of premature damage at defects in the coating of new steel pipelines. The incidence of this type of cell formation is increased by the connection of potential-equalizing conductors in internal gas pipelines and domestic water pipelines [25], as well as by the increased use of reinforcing steel in concrete foundations for grounding electrical installations [26]. 

Figure 10-10 shows the voltage cones for four different steel-concrete foundations [27]. Pipelines in the vicinity of such foundations are affected by these voltage cones (see Section 9.2), which can quickly lead to corrosion damage, particularly in pipelines that have some defects in their coatings. 

In the case of higher protection current densities and protection currents, interference can occur on nearby installations not covered by the protection. The danger of anodic interference must be investigated by making measurements and prevented by taking appropriate measures [7] (see Section 9.2). For the same reasons, anode systems should not be installed near steel-reinforced concrete foundations. 

The danger of corrosion is in general greater for pipelines in industrial installations than in long-distance pipelines because in most cases cell formation occurs with steel-reinforced concrete foundations (see Section 4.3). This danger of corrosion can be overcome by local cathodic protection in areas of distinct industrial installations. The method resembles that of local cathodic protection [1]. The protected area is not limited, i.e., the pipelines are not electrically isolated from continuing and branching pipelines. 

For efficient current distribution, steel-reinforced concrete walls should be provided at the wall entrance of pipes and at least 1 m around them and up to the soil surface with at least 2 mm thick electrically insulating layers of plastic or bitumen. This is also recommended if the pipelines are laid in soil parallel to steel-reinforced concrete foundations and the closest spacing is smaller than twice the pipe diameter or smaller than 0.5 m [2]. 

Fig. 12-5 Voltage cone AU and pipe/soil potentials at a wall entrance in a steel-reinforced concrete foundation.

Installations with Small Steel-Reinforced Concrete Foundations... 

Pumping or compressor stations are necessary for the transport of material in pipelines. These stations are usually electrically separated from the cathodically protected long-distance pipeline. The concrete foundations are much smaller than in power stations and refineries. Since the station piping is endangered by cell formation with the steel-reinforced concrete foundations, local cathodic protection is recommended. 

In the local cathodic protection of the bottoms of flat-bottomed tanks, cell formation with steel-concrete foundations is of little importance since the surfaces are relatively small, in contrast to the installations in Sections 12.2 to 12.5. On the other hand, connected components of the installation, such as cables and grounds, take up considerable protection current. On account of the large foundations of flat-bottomed tanks, which are often bare or only poorly coated, polarization to the protection potential is only possible with very negative on potentials. In tank foundations with the... 

Although the containment dike was large enough to hold the entire contents of the lank, the lank ruptured so suddenly that a torrent of 3.8 million gallons generated a wave of oil Uiat splashed over the embankment. The tank, 56 feel high and 120 feet in diameter, was erected in 1986 on a newly enlarged concrete foundation that previously had supported a smaller receptacle. The tiuik was constructed of steel 40 years old, which presumably contains less carbon and was more brittle lh ui steel manufactured more recently. 

Grounding plates or lattices made of pure copper, while displaying good current-carrying capacities, do not provide a particularly low resistance due to the depth at which they can be buried. The third alternative is to bury lengths of copper tape around the installation. The use of reinforced concrete foundations for grounding electrodes has also recently been considered. 

Mounting configuration and operating envelope Industrial standards, such as the rathbone severity chart, assume that the machine is rigidly mounted on a suitable concrete foundation. Machines mounted on deck-plate or on flexible foundations have higher normal vibration profiles and cannot be evaluated using these standards. 

The following is a list of recommendations that builders can use to utilize the foundation as a mechanical barrier to radon entry. Foundation walls and floor slabs are often constructed of poured concrete. Plastic shrinkage, and therefore cracking, is a natural function of the drying process of concrete. Many factors, such as the water/cement/aggregate ratio, humidity, and temperature, influence the amount of cracking that occurs in a poured concrete foundation. Cracking may be minimized by... 

Liquid in quantities exceeding 10,000 gal (3.8 m3) is stored in vertical tanks mounted on a concrete foundation.9... 

The bottom of the baseplate between stmctural members shall be open. When the baseplate is installed on a concrete foundation, accessibility shall be provided for grouting under all load carrying members. The bottom of the baseplate shall be in one plane to permit use of a single level foimdation. 

L.4.3 Approximately 10 to 25 mm (0.5 to 1 in.) of the top of the cementitious foundation material should be scarified with a chipping hammer before the grout is applied. This procedure is recommended to remove low-strength, high-porosity concrete in this area. The concrete foundation should be allowed to cure for at at least 7 days prior to this surface preparation. 

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