Firewater system

Firewater Systems. These systems are best laid out by contractors or other specialists. National Fire Protection Association (NFPA) rules will spell out required coverage, typical pump size, and other standard items. A small jockey pump will maintain system pressure at all times. 

Some licensees have a switch to bypass RCIC high steam tunnel temperature trips. Some licensees are evaluating improvements to prevent seal LOCAs from loss of seal cooling which are most important for W plants, but B W licensees identified improvements related to alternate seal flow capability under loss of power conditions. The use of high temperature seals is noted for some W plants. Many PWR IPEs identify AFWS improvements. These include additional backup water supplies such as the firewater system and redundant pump cooling capability. Other reliability... 

Process system emergency safety features (i.e. ESD, isolation, depressurization and blowdown) should be considered the prime safeguards for loss prevention over fire protection measures (i.e. fireproofing or barriers, firewater systems, manual fire fighting). 

Corrosion failure of a carbon steel elbow released propane vapors that exploded in the FCC unit that impacted all utilities and firewater system 300,000,000 loss... 

Firewater Reliability - A mathematical model of the ability of the firewater system to provide firewater upon demand as required by the design of the system without a component failure, e.g., a Mean Time Between Failure (MTBF) analysis. 

Firewater supply sources can be the city public water main, a dedicated storage tank and pumps, or the most convenient lake, river or if an offshore installation the open sea. Brackish or salt water supplies can be used if suitable corrosion protection measures are applied to the entire firewater system if it is planned to be used for an extended life (i.e., grater than five years). If a short life span of the facility is expected, short corrosion resistant materials may be used (i.e., carbon steel, galvanized steel, etc.), provided periodic testing indicates their integrity is still adequate and scale or corrosion particles do not affect operational efficiency. 

Small capacity pumps commonly referred to as "jockey" pumps are provided on a firewater system to compensate for small leakages and incidental usage without the main pump(s) startup. They are set to start 0.70 to 1.05 kg/sq. cm. (10 to 15 psi) above the start up pressure of main firewater pumps. In some cases a cross-over from the utility water system can be used in place of a jockey pump, however a check valve is installed to prevent drain down of the firewater by the utility water system. Jockey pumps do not require the... 

The firewater system should be dedicated to firewater usage. Utilization for process or domestic services, erodes the function and capability of the firewater system, particularly its pressure, possibly during an emergency. 

Typically a network of firewater systems mains is provided in a facility that form loops. These can be segregated into sections or legs and the performance of each can be determined by flow test. Flow tests release quantities of water that are measured and graphed. Performing an initial acceptance baseline test and recording the results from year to year can portray the performance of the firewater system and projections of the useful life of the system can be determined. 

Firewater systems - tanks, pumps, underground pipe. 

Safety Systems. Major expenditures here include the flare system (the flare structures and large lines extending throughout the plant) and the firewater system (high-capacity pumps and extensive piping). Safety systems, fortunately, are usually given particular attention. At this study phase, the main thrust should be to check the completeness of licensor equipment lists for cost estimation purposes. 

When pump A was restarted at 2200 hours, the temporary cover on the open flange (where the pressure relief valve would normally have been) failed, and a large quantity of light hydrocarbon hquid and vapor spewed out. Shortly afterward it found a source of ignition and the initial explosion and fire occurred. The tire then escalated with more explosions at 2220 hours, 2250 hours and a final huge explosion happened at 2320 hours. There were also other factors which made control of the tire difficult or impossible - e.g., the switches to start the firewater system were located too near... 

Table 19.7 Advantages and Disadvantages of Firewater Systems System Advantages Disadvantages...

In an emergency when water is required to extinguish a fire, having a reliable firewater system that can handle stagnant water is of vital importance. Figures 7.1 la and b show two examples of MIC within such systems. 

Excellent fire resistance. Even at very high temperatures titanium is fire resistant. This is important for applications such as petrochemical plant and firewater systems for offshore platforms, where its ability to survive a hydrocarbon fire is an essential factor. 

Companies generally prepare a safety manual that summarizes and indexes their various occupational safety policies, programs, and procedures. Table 4.1 provides a sample Table of Contents for such a manual. Background information, such as the design of the firewater system, will be provided in process safety documents. Many of the topics listed in Table 4.1 are discussed in other parts of this book. 

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