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Basic calculations 7 Basic calculations 7.1 Factors influencing pipe system design

Binayak Raj

Note: The listed mathematical operations and relations have been simplified as much as possible. Plastic-specific parameters and generally valid factors are partly already integrated into calculation formulae. We have abstained from detailing the derivation or reproduction of single values to abbreviate this section. 7.2 Calculating pipe parameters 7.2.1 Explanation The calculation of thermoplastic pipe systems is especially important for the engineer undertaking a project. This chapter presents the basic principles required for designing plastic pipe systems. However, the practitioner (user) should also be able to acquire the necessary data and standard variables for internally pressure-loaded pipe in a relatively simple manner without spending a lot of time. The mathematical operations are supported by diagrams in the appendices from which most values and data can be read off. Thermoplastic pipe calculations basically occur on the basis of long-term values. The reference stress (V ref) and mechanical (creep) strength (i.e. creep modulus (E cR)) of a pipe system in relation to temperature can be derived from the creep diagram in appendix A1 and the creep modulus curve diagram in appendix A2. The creep rupture curves are based on internal pressure tests on pipe samples filled with water and represent minimum values. If pipe systems are not intended for water but for other flow media, their effects on creep strength properties must be given special consideration.

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Piping Stress Handbook Second Edition

Chakkaphan Leelaphat

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STRESS ANALYSIS OF PIPING SYSTEMS

Raymundo Cordero

Piping stress analysis is a discipline which is highly interrelated with piping layout (Chap. B3) and support design (Chap. B5). The layout of the piping system should be performed with the requirements of piping stress and pipe supports in mind (i.e., sufficient flexibility for thermal expansion; proper pipe routing so that simple and economical pipe supports can be constructed; and piping materials and section properties commensurate with the intended service, temperatures, pressures, and anticipated loadings). If necessary, layout solutions should be iterated until a satisfactory balance between stresses and layout efficiency is achieved. Once the piping layout is finalized, the piping support system must be determined. Possible support locations and types must be iterated until all stress requirements are satisfied and other piping allowables (e.g., nozzle loads, valve accelerations, and piping movements) are met. The piping supports are then designed (Chap. B5) based on the selected locations and types and the applied loads. This chapter discusses several aspects of piping stress analysis. The discussion is heavily weighted to the stress analysis of piping systems in nuclear power plants, since this type of piping has the most stringent requirements. However, the discussion is also applicable to the piping systems in ships, aircraft, commercial buildings, equipment packages, refrigeration systems, fire protection piping, petroleum

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OVERVIEW OF INDUSTRIAL PIPING STRUCTURE DESIGN20200217 86677 11y7fkk

Prathamesh Khake

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Honors List xi Preface xvii How to Use This Handbook xix Part A: Piping Fundamentals Chapter A1. Introduction to Piping Mohinder L. Nayyar

Hikaru Jutshu

Chapter A6. Fabrication and Installation of Piping Edward F. Gerwin A.261 Chapter A7. Bolted Joints Gordon Britton A.331

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Stress Analysis Of Hot Wall Flue Gas Piping At FCCU Plant, Reliance Chapter 1: INTRODUCTION TO STRESS ANALYSIS

Cornnie Olson

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PIPING DESIGN: THE FUNDAMENTALS

Kanayo Okonwanji

The best piping configuration is the least expensive over a long term basis. This requires the consideration of installation cost, pressure loss effect on production, stress level concern, fatigue failure, support and anchor effects, stability, easy maintenance, parallel expansion capacity and others. The expansion loops most commonly used in crosscountry pipelines are L bends, Z bends, conventional 90° elbow and V bends. The principal design codes used for piping design are the ANSI/ASME B31.1 (Code for Power Piping) and ANSI/ASME B31.3 (code for process piping), ASTM A53 B, ASTM A106 B and API 5L carbon steel pipes are the ones used for geothermal fields. The allowable stress is S E =88 MPa for ERW pipe and S E =103 MPa for seamless pipe, S A =155 MPa for operation load, kS h =124 MPa for earthquake load and 258 MPa for combined sustained loads and stress range. Pipe pressure design for the separation station and steam lines is 1.5 MPa, and for brine line ranges from 1.5 to 4 MPa. Pipe diameters are generally 250 to 1219 mm nominal pipe size. The two-phase line can be in the range 50 to 150 m, the steam lines from 2000 to 3000 m and for the brine up to 6000 m long. The total cost of pipe installation can be US$ 600-1,200 per meter of pipe. Pipe configuration needs to be cost conscious; the design can be under 10% of excess pipe to get from point to point straight line distance, which is excellent from a piping material and pressure loss point of view.

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Significance of and suggested limits for the stress in pipe lines Rossheim Markl

Gerardo Soriano

T he Significance of, an d Suggested L im its for, the S tress in P ipe Lines D u e to th e C o m bined Effects of P re ssu re a n d E x p an sio n By D. B. ROSSHEIM1 and A. R. C. MARKL,2 NEW YORK, N. Y. T h is p a p er h a s b e e n p r e p a r ed a s a v e h ic le fo r d is c u s s io n o f t h e fo llo w in g b a s ic p r o b le m s , o n w h ic h a g r e e m e n t m u s t be r e a c h e d t o e s t a b lis h a s a tis f a c to r y w o r k in g-s tr e s s b a s is for p ip e l i n e s : 1 P ro p er a llo w a b le s t r e s s e s fo r c o m b in e d p r e ssu r e a n d e x p a n s io n e ffe c ts. 2 I n flu e n c e o f a n d l i m i t s for lo c a liz e d s tr e s s e s u n d e r s t a t i c a n d r e p e a te d lo a d in g. 3 C a p a c ity o f b o lte d j o i n t s t o w it h s t a n d e x p a n s io n e ffe c ts w it h o u t le a k a g e o r d a m a g e t o fla n g e s, b o lt s , or g a s k e ts. 4 E ffect o f p r e sp r in g in g , s e lf-s p r in g in g , c r e e p , a n d y ie ld in g o n o p e r a tin g a n d o f f-s t r e a m s t r e s s e s. A n a t t e m p t h a s b e e n m a d e t o p o in t o u t v a r io u s a s p e c t s o f e a c h is s u e , r a th e r t h a n l im i t t h e p r e s e n t a t io n t o t h e p e r so n a l v iew s o f t h e a u t h o r s. D URING the last decade, economic considerations and new processes in the power, oil-refinery, and chemical industries have produced a trend toward large-scale units and high operating temperatures and pressures. With the attendant in crease in line sizes and wall thicknesses, the subdivision of pipe lines into convenient runs with expansion bends soon proved entirely inadequate; instead, today most piping for severe service is carefully analyzed for forces and stresses, full advan tage being taken of the inherent flexibility by minimizing the num ber of anchors, guides, or other restraints. A natural consequence of this improved accuracy in evaluating thermal effects is the necessity for a review of stress limitations as they apply to ex pansion stresses alone and in combination with internal pressure. This problem has received the active consideration of Subgroup No. 3 on Expansion and Flexibility, Subcommittee No. 8 on Fabrication Details of the Code for Pressure Piping (ASA B31) who, functioning with the Applied Mechanics and Power Divi sions of the A.S.M.E., have sponsored this symposium. This paper has been prepared as a vehicle for discussion of the following basic problems, on which agreement must be reached to establish a statisfactory working-stress basis for pipe lines. An attempt has been made to point out various aspects of each issue, rather than limit the presentation to the personal views of the authors. 1 Proper allowable stresses for combined pressure and expan sion effects. 2 Influence of and limits for localized stresses under static and repeated loading, such as in bends and corrugated pipe. 3 Capacity of bolted joints to withstand expansion effects without leakage or damage to flanges, bolts, or gaskets. 1 M echanical Engineer, M. W. K ellogg Co. M em. A .S .M .E. 2 A ssistant M echanical Engineer, M. W. K ellogg Co. Contributed b y the Pow er D ivision and presented at the Annual M eeting, Philadelphia, P a., Decem ber 4-8 , 1939, of T h e A m e r i c a n S o c i e t y o f M e c h a n i c a l E n g i n e e r s. N o t e : S tatem en ts and opinions advanced in papers are to be under stood as individual expressions of their authors, and n ot those of the Society. 4 Effect of prespringing, self-springing, creep, and yielding on operating and off-stream stresses R esume of Simple Stresses I nvolved A pipe line is essentially a pressure vessel, the internal pressure causing a radial stress at the inner face which is converted into circumferential stress on the way through the wall, leaving zero radial stress at the outer surface; at any point the sum of the radial and hoop stresses varies inversely as the radius, while their difference is the same at all points. These are the laws of Lam<5 which involve the assumption of a uniform or zero longitudinal stress. Following this reasoning, in a closed cylinder the longi tudinal stress equals the product of the pressure and the internal area divided by the cross-sectional area of the wall, and has the same value throughout the thickness. While most runs of piping are not technically closed cylinders, the same longitudinal stresses occur due to pressure effects on the projections of elbows, there being a complete absence of longitudinal pressure stress only in straight runs between vessels of infinite rigidity and such including frictionless expansion joints. Under temperature changes with free expansion no stresses are introduced. However, ordinarily, expansion is restrained by the equipment to which the pipe line is attached, as well as anchors, guides, solid hangers, or supports. In calculating a line for expansion, the ends are commonly assumed completely fixed; this connotes three forces and an equal number of moments in the case of a problem in space, resulting in longitudinal bending stresses in two mutually perpendicular planes and torsional stress about the pipe axis, as well as two shears and a normal stress. With the assumption of hinged ends, the end moments reduce to zero, a condition which would be fully realized only in a frictionless ball-and-socket joint. Ac tually, an intermediate condition of restraint will prevail in practice due to sympathetic deflections, rotations, or distortions of the equipment to which the pipe is attached. On the other hand, cases will arise where external movements of the ends tend to increase rather than decrease their degree of fixity; in addition, guides, solid or spring supports, and hangers often inhibit free deformation of the line and thus add to the stresses. To avoid additional complexity, the weight of the piping is commonly neglected in flexibility calculations. In heavy pipe lines spring hangers are often used to balance the dead-load effects when the line is at working temperature, and solid hangers can be similarly employed in neutral locations. Properly de signed supports appear to offer the most suitable means for handling this effect, which can then be disregarded in the stress analysis of most lines. Where piping is not insulated, the heat loss from the exposed surface produces a temperature drop through the metal thick ness causing longitudinal and circumferential stresses of equal magnitude which may be evaluated by the formulas of Lorenz (l).3 Since the outside surface is relatively colder, tensile 3 N um bers in parentheses refer to the Bibliography at the end of the paper.

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Design of Pressure Pipes

praveen reddy

The design methods for buried pressure pipe installations are somewhat similar to the design methods for gravity pipe installations which were discussed in Chap. 3. There are two major differences: 1. Design for internal pressure must be included. 2. Pressure pipes are normally buried with less soil cover so the soil loads are usually less. Included in this chapter are specific design techniques for various pressure piping products. Methods for determining internal loads, external loads, and combined loads are given along with design bases. Pipe Wall Stresses and Strains The stresses and resulting strains arise from various loadings. For buried pipes under pressure, these loadings are usually placed in two broad categories: internal pressure and external loads. The internal pressure is made up of the hydrostatic pressure and the surge pressure. The external loads are usually considered to be those caused by external soil pressure and/or surface (live) loads. Loads due to differential settlement, longitudinal bending, and shear loadings are also considered to be external loadings. Temperature-induced stresses may be considered to be caused by either internal or external effects. Hydrostatic pressure Lamé's solution for stresses in a thick-walled circular cylinder is well known. For a circular cylinder loaded with internal pressure only, those stresses are as follows:

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PROCESS PIPING DESIGN HANDBOOK - VOLUME 2 [Advanced Piping Design]

Muhammad Nasrullah

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