Piping account

A centrifugal pump is to be used to extract water from a condenser in which the vacuum is 640 mm of mercury. At the rated discharge the net positive suction head must be at least 3 m above the cavitation vapour pressure of 710 mm mercury vacuum. If losses in the suction pipe account for a head of 1.5 m. what must be the least height of the liquid level in the condenser above the pump inlet ... 

The Piping account covers all process and utility piping, as well as chutes and ducts, above and underground, including ... 

The following items should be excluded from the piping account ... 

Insulation - The take-offs for piping insulation are developed as part of the piping account estimate. The take-offs for equipment insulation are developed by identifying and estimating the outside area of those items requiring insulation. The unit prices in Section 19.5 are used to estimate cost. 

The instrument air distribution system (headers and subheaders) is considered part of the piping account up to the distribution points to the individual users. The lines to the individual instruments and control valves are considered part of the instrumentation account and the cost is included in the instrumentation estimate. 

This shortcut technique is suggested for ballpark estimates of the piping account for liquid flow plants. It must be used together with Section 19.4 and confirmed with the factors in Table 10.1. 

The Piping Account should be increased to at least the minimum. 

Experience in recent organic projects of similar size and scope has shown the Piping Account to be approximately 1.30 of the Equipment Cost. 

So Piping Account = 1981 (Equip. Acct.) x 1.35 = 2,670.0K Prorating the results of the quick estimate we have ... 

Towers and piping account for almost 50%i of equipment costs. 

The commodity thermosets of urea, melamine, and phenolics account for about one-third of building and construction industries resin consumption. Most of this is used for resin-bonded woods such as plywood, particle board, and oriented strand board. High-density polyethylene (HDPE), used primarily for rigid piping, accounts for about 5% of consumption. Other significant resins, accounting for 3-5% of total consumption, include other polyethylenes, unsaturated polyester, and polystyrene. 

A more elaborate equation for calculating the buckling capacity of pipe, accounting for the liquid buoyancy and base flexibility, can be found in the Fiberglass Pipe Design Manual produced by the American Water Works Association (AWWA, 1996). 

Fluoropolymers possess excellent thermal stability and are nearly completely inert to chemical attack. Polytetrafluoroethylene (FIFE), discovered in 1938 by Roy Plunkett at I.E. du Pont de Nemours and Company, is the world s most used fluoropolymer. PIPE accounts for 59% of the fluoropolymers market and its production amounted to some 79,000 metric tons in 2004 [1], Applications exploiting the extraordinary properties of the material are wide-ranging and include gaskets, thread-seal tape, pipe liners, bearings, gears, slide plates, filter bags, medical prosthetics, and architectural material [2,3]. 

The paper presents the results from systematic comparisons of contrast and resolution obtained with different types of radiation sources on steel thicknesses from 5 to 40 mm. These results have been taken into account with the definitions of the European standard for radiographic inspection of weldments (EN 1435) that is approved since 1997. Conclusions from practical investigations on pipe line sites, in petrochcemical plants and in nuclear power stations will be discussed as well. Furthermore, the presentation will stipulate a variety of advantages obtained from the new source in terras of coUimation and radiation protection. 

As a vessel is loaded, it moves downward because of deflection of the load cells and support stmcture. Pipes rigidly attached to a vessel restrict its free movement and assume some portion of the load that cannot be measured by the load cells. This is very detrimental to scale accuracy. Deflection of the load cell is unavoidable deflection of the vessel support stmcture should be minimized. Anything which increases vessel deflection, eg, mbber pads used for shock protection, must be avoided. The total number of pipes should be minimized and be of the smallest diameter, thinnest wall possible. Pipe mns to weigh vessels must be horizontal and the first pipe support should be as far as possible from the vessel. Alternatively, a section of mbber hose or flexible bellows should be used to make the final connection to the vessel. The scale should be caUbrated using weights, not by means of an electrical simulation method, which cannot account for the effects of the piping or test the correct functioning of the scale. 

In configurations more complex than pipes, eg, flow around bodies or through nozzles, additional shearing stresses and velocity gradients must be accounted for. More general equations for some simple fluids in laminar flow are described in Reference 1. 

The concepts behind the analysis are not difficult. The piping system is simply a stmcture composed of numerous straight and curved sections of pipe. Although, for straight pipe, elementary beam theory is sufficient for the solution of the problem, it is not adequate for curved pipe. However, by the iatroduction of a flexibiUty factor, to account for iacreased flexibiUty of curved pipe over straight pipe, and a stress intensification factor, /, to account for... 

RoUed-zinc products in the form of strip, sheet, wire, and rod have many and varied commercial appUcations. Strip is formed into dry-ceU battery cans, mason jar covers, organ pipes, grommets, eyelets, and many other objects, some of which are subsequentiy brass or chromium plated (jewelry, medaUions, bathroom accessories, etc) (132). The zinc—carbon dry-ceU appUcation accounts for about one half the roUed-zinc consumption in the United States (see Batteries). Sheet zinc is used in photoengraving and also in the constmction of roofing and other architectural uses. Special high grade zinc with a... 

Type I (Normal). This is the general purpose Pordand cement used for all appHcations where special properties are not needed. Common appHcations include concretes for paving, building doors, roof decks, reinforced concrete buildings, pipes, tanks, bridges, and other precast concrete products. In 1989 Type I and Type II accounted for over 92% of the Pordand cement produced in U.S. plants. Exact data are not available that separate Type I and Type II Pordand cement, but it can be assumed that Type I production was much greater than Type II. 

Radiation differs from conduction and convection not only in mathematical structure but in its much higher sensitivity to temperature. It is of dominating importance in furnaces because of their temperature, and in ciyogenic insulation because of the vacuum existing between particles. The temperature at which it accounts for roughly half of the total heat loss from a surface in air depends on such factors as surface emissivity and the convection coefficient. For pipes in free convection, this is room temperature for fine wires of low emissivity it is above red heat. Gases at combustion-chamber temperatures lose more than 90 percent of their energy by radiation from the carbon dioxide, water vapor, and particulate matter. 

The correclion (Fig- 6-14rZ) accounts for the extra losses due to developing flow in the outlet tangent of the pipe, of length L. The total loss ror the bend plus outlet pipe includes the bend loss K plus the straight pipe frictional loss in the outlet pipe 4fL /D. Note that = 1 for L /D greater than the termination of the curves on Fig. 6-14d, which indicate the distance at which fully developed flow in the outlet pipe is reached. Finally, the roughness correction is... 

Contributing to f are losses for the entrance to the pipe, the three sections of straight pipe, the butterfly valve, and the 90 bend. Note that no exit loss is used because the discharged jet is outside the control volume. Instead, the V v2 term accounts for the kinetic energy of the discharging stream. The Reynolds number in the pipe is... 

Work Performed in Pumping To cause liquid to flow, work must be expended. A pump may raise the liquid to a higher elevation, force it into a vessel at higher pressure, provide the head to overcome pipe friction, or perform any combination of these. Regardless of the service required of a pump, all energy imparted to the liquid in performing this sei vice must be accounted for consistent units for all quantities must be employed in arriving at the work or power performed. 

For straight metal pipe under internal pressure the formula for minimum reqiiired w thickness is applicable for D /t ratios greater than 6. Tme more conservative Barlow and Lame equations may also be used. Equation (10-92) includes a factor Y varying with material and temperature to account for the redistribution of circumferential stress which occurs under steady-state creep at high temperature and permits slightly lesser thickness at this range. 

Comprehensive analysis shall take into account stress-intensification factors for any component other than straight pipe. Credit may be taken for the extra flexibility of such a component. 

Since pipe flow is more nearly isenthalpic, the flash fraction x is found from an enthalpy balance between the stagnation point and a point z downstream. Accounting for changes in potential energy, kinetic energy, and heat added or removed from the pipe Q, x is given by ... 

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