Piping Design Economy

For line size calculations, several companies use economical pressure drops. This is the most direct approach because available pressure differences are readily accessible from the process flow diagram. A hydraulic slide rule has been developed for fast and convenient liquid flow calculations. 

Line sizes based on velocity limitations are calculated only in special cases where corrosion, erosion or deposits on the pipe wall have to be accounted for or where critical flow conditions exist. 

Valves are generally line size. The maximum control valve size is line size. In most applications, control valves are one size smaller than line size. When a larger pressure drop is available, control valves can be two or three sizes smaller than line size. 

Sometimes it is feasible to compare piping costs and the cost of control valve assemblies. Increased line size will give a higher proportion or pressure drop of the total line loss for controlling. Perhaps a smgdler control valve can be chosen. Money spent to increase line size should be less than the savings for a smaller control valve assembly. 

Safety devices should be piped with a minimum of inlet pipe runs because excess pressure drop before a safety valve will affect its operation. For a minimum of discharge piping, relief valves are located high on a tower in open relief systems. In closed systems relief valves are located just above the relief header. 

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ADDmoNAL References ASHRAE Handbook and Product Directory Fundamentals, American Society of Heating, Refrigerating and Air Conditioning Engineers, Atlanta, 1981. Turner and Malloy, Handbook ofThermcd Insulation Design Economies for Pipes and Equipment, Krieger, New York, 1980. Turner and Malloy, Thermal Insulation Handbook, McGraw-Hill, New York, 1981. 

Electrical and pipe penetrations may be brought into the building underground. Based on economy and design, this type of entry may be preferred. 

Metallic pipe systems comprise the majority of applications. Metallic pipe, tubing, and pipe fittings are divided into two main categories seamless and welded. Both have advantages and disadvantages in terms of economy and function. Specifications governing the production of these products dictate the permissible mechanical and dimensional variations, and code design calculations account for these variations. 

Superheated steam will lead to economy in a simple engine equal to that obtained with saturated steam in a compound. The engine and piping must be especially designed for the superheat used. 

JSFR utilizes the advantage of economy of scale by setting the electricity output of 1500 MWe and it has an economic competitiveness that benefits from advanced design, such as simplified and compact structure of the reactor, integration of the intermediate heat exchanger (IHX) and the primary circulation pump, shortened piping layout, and reduction of loop number. Furthermore, a special effort has been made to meet the safety requirements, which include enhancement of passive safety capabilities and the in-vessel retention of degraded core under a core disruptive accident. 

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