Preliminary of Piping and Pipeline Engineering：管道和管道工程初步精品.pdfVIP

Preliminary of Piping and Pipeline Engineering Fundamental The seven fundamental areas of competence in the mechanical engineering discipline are (1) materials. (2) design, (3) construction, (4) inspection, (5) testing, (6) maintenance, and (7) operations. In each of the seven fundamental areas, the responsible engineer must make a series of decisions to achieve the optimum and most cost-effective operation. The following checklists summarize the key decision points related to piping and pipeline activities. Piping Design 1. Internal Pressure 1.1 Pressure Design of Piping 1.1.1 Thin wall approximation Consider a straight section of pipe filled with a pressurized liquid or gas. The internal pressure generates three principal stresses in the pipe wall : as illustrated in Figure 1-1: a hoop stress σr . When the ratio of the pipe diameter to its wall thickness D/t is greater than 20 the pipe may be considered to thin wall. In this case, the hoop stress is nearly constant through the wall thickness and equal to PD σ = h 2t P = design pressure, psi D = outside pipe diameter, in t = pipe wall thickness, in The longitudinal stress is also constant through the wall and equal to half the hoop stress PD σ = 1 4t The radial stress varies through the wall, from P at the inner surface of the pipe