Piping Details

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Traps should be installed with no bypass valves. These valves tend to leak and waste energy. They also present an easy means to increase capacity by opening them. When the load later decreases, they will result in steam being wasted at a high rate. The proper way to solve the capacity problem is to install a trap having a higher capacity. 

The process trap must be installed such that condensate does not back up into the heat transfer surface. 

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The various items of equipment in the production facility are connected hy valves, fittings, and piping to enable and control flow from one piece of equipment to another. Chapter 9 of Volume 1 discusses factors governing the choice of line size and wall thickness. This chapter describes the various types of valves and fittings commonly used in production facilities and presents some common piping details and specifications. 

The specific piping details used in a project are normally contained in a company pipe, valve, and fittings specification, which addresses the following subjects ... 

Valves, Fillings, and Piping Details. it Kl [Pg.445]

Plant model costs vary depending upon the degree of detail included. Considerable decision making information can be obtained from a set-up of block layout only, and these costs would be extremely small. For a reasonably complete scale piping detail model the costs are reported as O.I to 0.6 percent of the cost of the plant. The large plants over 20 million cost in the lower 0.1 percent range while small plant models cost in the 0.6 to 1.0... 

Paton [15] reports total model costs of 0.4 to 1.0 percent of erected plant costs for a 1 million plant. These are actual costs and do not reflect profits. Material costs are less than 10 percent of total model costs, and usually less than 5 percent. For a. 30 million plant model costs run as low as 0.1 percent. These are for models which include plant layout, piping layout, and piping details. If simpler models are used the costs should be less. 

Figure 1-10. Piping detail isometric flow diagram.

Various designs of pipe hangers and supports are used to support individual pipes. Details of typical supports can be found in the books by Perry et al. (1997) and Holmes (1973). Pipe supports frequently incorporate provision for thermal expansion. 

For vapor-liquid mixtures, the pressure drop in horizontal pipes can be found using the correlation of Lockhart and Martinelli (1949), which relates the two-phase pressure drop to the pressure drop that would be calculated if each phase was flowing separately in the pipe. Details of the correlation and methods for two-phase flow in vertical pipes are given in Perry and Green (1997). 

In Figures 7-95 to 7-108, the many piping details shown will suggest to the piping designer the various schemes that can be used. The importance of these details is that each has been provided with a scale in inches shown on the centerline run of the thermowell. This scale will enable the instrumentation engineer to select a thermowell. With it he can pinpoint the active effective flow area, preferably in the turbulence zone, where the thermal element of the instrument will be located. 

Fig. no. of pipe detail followed by reference to the specific nominal pipe size Indicating dial thermometer with %" dia. bimetallic stem Thermowells for thermobulbs Immersion length starts with dimen-slon given below. Check with the scale shown on fig. Add the length required for the thermobulb. See scale for determining ordering length Thermocouple well... 

American Standards Association graphical symbols are available foi piping detail work (see Fig. 9-2). Other useful symbols are shown r Fig. 3. One type of detailed equipment flow sheet is shown in Fig. 3-9... 

Pressures, temperatures, suspended solids, and their solubilities (and erosive properties) since deposition of some solids inside can reduce life of pipes. Details of feeding system for materials into process reactors and vessels. Diameters of all pipes (and velocities of flowing fluids insides), materials of construction, and their routes. 

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