Drainage maintenance

Number of days since last accidental release of hazardous material. This measure distinguishes between routine emissions (such as from storage tank vents, or low pressure steam discharges) and accidental emissions resulting from maloperation or breakdown. Events that might count would be safety valve releases, accidental releases into inappropriate drainage systems and unconfmed spills during maintenance. 

Operating and Maintenance Costs mechanical details must account for the peculiarities of the system fluids (coking, suspended particles, immiscible fluids, etc.) and accommodate the requirements for drainage, cleaning (chemical or mechanical), corrosion, etc., in order to keep the daily costs of operation and downtime to a minimum. 

Holes for drainage must be adequate to drain the column in a reasonable time, yet not too large to interfere with tray action. Draining of the column through the trays is necessary before any internal maintenance can be started or before fluid services can be changed, when mixing is not desirable. The majority of holes are placed adjacent to the outlet or downcomer weir of the tray. However, some holes are placed in the downcomer inlet area or any suspected low point in the mechanical layout of the column. 

Condensation should be reduced by allowing free circulation of air, or by air-conditioning. Storage tanks should be raised from the ground to allow air circulation and access for maintenance and provision should be made for complete drainage (Fig. 9.16). 

With ammonia, oil sinks to the bottom and does not go into solution with the refrigerant. Ammonia condensers, receivers and evaporators can be distinguished by the provision of oil drainage pots and connections at the lowest point. Automatic drainage and return of the oil from these would have to depend on the different densities, and is veryrarely fitted. The removal of oil from collection pots and low-point drains is a periodic manual function and is carried out as part of the routine maintenance. The halocarbons are all sufficiently miscible with oil to preclude the possibility of separate drainage in this way. 

The invisible structure is more expensive but there are maintenance savings and capital savings for drainage. 

Drainage class, tile drainage, soil characteristics, and initial SOC levels can also impact SOC maintenance requirements (Arrouays and Pelissier 1994 Zach et al. 2006 Clay et al. 2007). If the SOC maintenance requirement is related to the SOC level, then the range of values reported by Barber (1978), Wilts et al. (2004), Larson et al. (1972), and Frye and Blevins (1997) may be related to these differences. To assess the impact of SOC level on maintenance requirements, data from Barber (1978), Wilts et al. (2004), Larson et al. (1972), and Frye and Blevins (1997) were analyzed using the Clay et al. (2006) approach (Table 8.1). For these calculations, a common soil depth (0-15 cm) and root to shoot ratios suggested by Johnson et al. (2006) were used. Across the sites, located in the central USA, the analysis suggested that in plowed fields, 15.5% of the SOC contained in the surface 15 cm must be returned annually (Fig. 8.5). The 0-15 cm soil zone was selected because soil data from this zone are available in many studies. 

Drainage areas can be defined by the process fire area, which has been established by the spacing, segregation and arrangement provisions for the facility. Open drainage channels should be used where they will not interfere with the use of the area, i.e., crane access, maintenance activities, etc. They should be designed to minimize erosion, and if excessive velocities are encountered they should be paved. No more than 5 m/s (15 ft/s) velocity should be allowed in paved surface runoff channels or troughs. 

Many of these enclosures are designed to meet certain standards. For example, the American Society of Sanitary Engineers (ASSE) has developed Standard 1060, Performance Requirements for Outdoor Enclosures for Backflow Prevention Assemblies. If an enclosure will be used to house a backflow preventer, this standard specifies the acceptable construction materials for the enclosure, as well as the performance requirements that the enclosure should meet, including specifications for freeze protection, drainage, air inlets, access for maintenance, and hinge requirements. ASSE 1060 also states that the enclosure should be lockable to enhance security. 

No open process or chemical sewer drains should be under or in the drainage zone from a fired process heater since the heater could ignite flammable vapors present in the process/chemical sewer. Where pro-cess/chemical sewer drains are required at a fired heater during cleanup and maintenance, the drain openings should be sealed by a gasketed and bolted cover prior to startup of the heater. 

At the Fabius Coal Preparation Plant in Jackson County, Alabama, a constructed wetland treatment system was built to treat acid drainage from a coal pile. In 1985, the total cost of the wetlands was 43,000. The annual costs from 1985 to 1990 were approximately 13,000 due to repairs and extensive monitoring. In 1991, operation and maintenance costs were estimated to be 1000 annually (D12459E, p. 164). 

Surrounding atmosphere Other consumables Drainage Cleaning Maintenance Exterior packing... 

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