1、AUDIT FOR CHINESE STRESS ENGINEER A) UNDERSTANDING CAESAR II 1. What kind of calculation and evaluation is not covered by C2 in piping system? 蠕变分析，管道或设备的局部应力分析，管道失稳等How to check if piping system expose to buckling problem by using C2? 负压、偶然荷载、集中荷载、埋地管的土壤约束等荷载都会引起管道的失稳；但 CAESAR II 并不能评定管道的失稳（需要借助压力容
2、器设计软件进行管道的失稳设计） ；CAESAR II addresses negative pressures as follows: the absolute value of the longitudinal pressure stress (PD/4t) term is added to the appropriate code equations; pressure thrust forces applied to expansion joint ends will be compressive; and buckling is not addressed in CAESAR II临界
3、失稳压力： CDEIPmc3214E弹性模量（MPa） ；I截面惯性矩（mm4/mm） ；v泊松比，0.350.45；Dm管道平均直径；C椭圆修正系数， ，r1椭圆管道的弯曲半径，r0圆形管道半径；310/r允许的管壁冲击荷载： 5.030)/(2)( mwDEIBRFSN2. Global/local loads in C2 output, The reason why we need the local elements loads? 为了获得作用在设备管口上准确的外载，以进行局部应力分析；另外通过局部坐标推力的分析，可以仔细察看管道单元内部的相互作用关系，协助发现问题，并尽快找到答案。3
4、. On input sheet, what is different for Force, Uniform load, Rigid element with weight. -the temperature base of Elastic modulus input?集中力（力或弯矩作用于管道上一点，一般模拟外载力的作用效果，对于一些额外重量，如支架根部，最好不用力来输入，因为如果计算地震，这些质量都不存在。 ） 、均布载荷（荷载均布于管道所有点上，我们一般用它来模拟雪载） 、带重量的刚性件（横向刚度无穷大横向没有弯曲，刚性件只传导位移和力，我们一般用它来模拟阀门，管道设备等，但要注意，刚性
5、件有直径何壁厚，他们对他的横向变形会有影响。 ） 。软件缺省的弹性模量是冷态的。但用户可以选择。4. What is non-linear system? Area there any special cautions in input/output for non-linear case? 非线性系统就是：依据胡克定律 F=K*X，我们认为 k 是变化的。管道在使用支架、吊杆，支架加间隙，摩擦力的情况下，系统变成非线性的。管系从冷态热态或热态偶然工况过程中由于非线性约束的作用导致管系刚度发生改变；如果你输入过多的非线性支架，可能导致软件计算不收敛。陷入时循环。我们一般先判断，根据直观感觉决定
6、一些点，加入非线性约束。其他处根据计算结果，在调整支架。5. How to check the lift-off support point? What should Engineer check for lift-off problem? What is hot sustained stress? 检查约束报告，垂直方向受力为 0 的点即支架托空点；支架托空点应考虑采用弹性支吊；Hot sustain stress计算热态持续应力。依据 B31.3 Appendix P, 用户可以校核热态持续应力。主要是考虑支架脱空情况下持续应力。Generally Hot sustained stress
7、 is carried out by removing the support at the point of lift off , and in another, Bourdon test means were larger than unbending test means. In both data sets, there was a large and significant pretest bending effect, which enhanced the magnitude of unbending test minus pretest scores. These results
8、 were consistent with our theory but not the theories of Walker and Shank. The variance of unbending test matches, 3-4 times that of Bourdon test matches, reflected the task difficulty. We propose that subjective obtuse angle contraction that exceeds real obtuse angle contraction explains the fact t
9、hat unbending effects are larger in subjective than in real contours.10. What are different for Hot load setting and Cold load setting? 答：热态荷载设置和冷态荷载设置的区别：冷态荷载：W、P热态荷载：W、T 、PSUS=W+P; OPE=W+P+T11, Are there any special caution for load combination method to get valid stress and support load? If syste
10、m include the non-linear case, how to prepare load combination for each stress (SUSOCC, EXP)? 答: SELECT COMBINATION METHOD FOR COMBINATION CASES ONLY Summary of most commonly used combination types: ALG - signed algebraic combination disp./force level Scalar - signed combination disp./force/stress l
11、evel ABS - unsigned combination disp./force/stress level Detailed Description of all combination types: ALG - Combine the displacement vectors and the force vectors ALGebraically and calculate the stresses from the combined forces. Displacements are the algebraic combination of the displacement vect
12、ors. Forces are the algebraic combination of the force vectors. Stresses are not combined; stresses are calculated from the algebraically combined forces. ALG would typically be used to calculate EXP code stresses. Scalar - Combine the displacement vectors, the force vectors, and the stress scalars.
13、 Displacements are the algebraic combination of the displacement vectors. Forces are the algebraic combination of the force vectors. Stresses are the scalar combination of the stress scalars. The Displacements and Forces of an ALG case and Scalar case are equivalent. There may be variation at the st
14、ress level, since in an ALG combination the stresses are calculated and in a Scalar combination the are combined. For example: Load Case 1: Bending stress = 100 psi, due to X-moment Load Case 2: Bending stress = 100 psi, due to Z-moment Algebraic (vectorial) sum = sqrt(100*100 + 100*100) = 144 psi S
15、calar sum = 100 + 100 = 200 psi Scalar would typically be used to sum (SUS + OCC) code stresses. SRSS - Combine square root of the sum of the squares (SRSS) of the displacements, square root of the sum of the squares (SRSS) of the forces, and square root of the sum of the squares (SRSS) of the stres
16、ses. Displacements are the the square root of the sum of the squares of the displacements of all cases included in the combination. Forces are the the square root of the sum of the squares of the forces of all cases included in the combination. Stresses are the the square root of the sum of the squa
17、res of the stresses of all cases included in the combination. SRSS would typically be used to combine seismic directional components. ABS - Combine the ABSolute value of the displacements, the ABSolute value of the forces, and the ABSolute value of the stresses. Displacements are the sum of the abso
18、lute value of the displacements of all cases included in the combination. Forces are the sum of the absolute value of the forces of all cases included in the combination. Stresses are the sum of the absolute value of the stresses of all cases included in the combination. MAX - Compare the ABSOLUTE v
19、alues of the displacements, forces, and stresses and report the MAXimum displacement, the MAXimum force, and the MAXimum stress value of the cases combined (retaining the original sign). Displacements are the displacements having the maximum ABSOLUTE values of all the load cases included in the comb
20、ination. Forces are the forces having the maximum ABSOLUTE values of all the load cases included in the combination. Stresses are the stresses having the maximum ABSOLUTE values of all the load cases included in the combination. MAX would typically be used to report the greatest restraint loads from
21、 among a selected set of load cases. MIN - Compare the ABSOLUTE values of the displacements, forces, and stresses and report the MINimum displacement, the MINimum force, and the MINimum stress value of the cases combined (retaining the original sign). Displacements are the displacements having the m
22、inimum ABSOLUTE values of all the load cases included in the combination. Forces are the forces having the minimum ABSOLUTE values of all the load cases included in the combination. Stresses are the stresses having the minimum ABSOLUTE values of all the load cases included in the combination. SIGNMA
23、X - Compare the displacements, forces, and stresses and use the the MAXimum displacement, the MAXimum force, and the MAXimum stress value of the cases combined (i.e., sign is considered in the comparison). Displacements are the maximum SIGNED values of all the displacements from each case included i
24、n the combination. Forces are the maximum SIGNED values of all the forces from each case included in the combination. Stresses are the maximum SIGNED values of all the stresses from each case included in the combination. SIGNMAX would typically be used in conjunction with SIGNMIN to report the envel
25、ope of restraint loads from among a selected set of load cases. SIGNMIN - Compare the displacements, forces, and stresses and use the the MINimum displacement, the MINimum force, and the MINimum stress value of the cases combined (i.e., sign is considered in the comparison). Displacements are the mi
26、nimum SIGNED values of all the displacements from each case included in the combination. Forces are the minimum SIGNED values of all the forces from each case included in the combination. Stresses are the minimum SIGNED values of all the stresses from each case included in the combination. SIGNMIN w
27、ould typically be used in conjunction with SIGNMAX to report the envelope of restraint loads from among a selected set of load cases. NOTE: Load case results are multiplied by any associated scale factors prior to performing the combination/comparison. SUS=W+P; OPE=W+P+T如果出现非线性工况：则二次应力和偶然应力的评定准则为：EX
28、P=Dope-Dsus；OCC=(OCC+OPE)-OPE+SUS12 How to model the closely spaced miter and widely spaced miter bend. What are they? 答：13. Output review 输出结果查看-Code stress, Bending stress, Torsion stress, axial stress, 3D-max intensity -规范合成应力，弯曲应力，扭转应力，轴向应力，空间最大应力强度；- The reason why C2 does not show the allowabl
29、e value for operating load 因为 B31.1 和 B31.3 规范不计算热态应力。- APPENDIX PALTERNATIVE RULES FOR EVALUATING STRESS RANGE(a) This Appendix provides alternative rules for evaluating the stress range in piping systems. It considers stresses at operating conditions, including both displacement and sustained load
30、s, rather than displacement stress range only. The method is more comprehensive than that provided in Chapter II and is more suitable for computer analysis of piping systems, including nonlinear effects such as pipes lifting off of supports. (b) The paragraph numbers of this Appendix, except for par
31、a. P300, correspond to those of Chapters I and II of the base Code. The prefix P is used. (c) In the application of these alternative rules, all of the provisions of Chapters I and II of the base Code apply, except those that are specifically modified by this Appendix.P300.2 DefinitionsReplace the d
32、efinition of severe cyclic conditions with the following: severe cyclic conditions: conditions applying to specific piping components or joints in which SE, computed in accordance with para. P319.4.4, exceeds 0.8SoA as defined in para. P302.3.5(d) and the equivalent number of cycles N in para. P302.
33、3.5(d) exceeds 7000; or other conditions which the designer determines will produce an equivalent effect.P302.3.5 Limits of Calculated Stresses Due to SustainedLoads and Displacement Strains. Replace para.302.3.5(d) with the following. Footnotes and nomenclature are the same as found in para. 302.3.
34、5(d). (d) Allowable Operating Stress Limit. The greater of the maximum operating stress and maximum operating stress range, Som, in a piping system (see para. 319.4.4) shall not exceed the allowable operating stress limit, SoA (see paras. 319.2.3 and 319.3.4) calculated by eq. (P1a). The operating s
35、tress is the calculated stress at any operating condition, including pressure, weight and other sustained loads, and displacement. Occasional loads (see para. 302.3.5) are not required to be included. The operating stress range is the range of stress between any two operating conditions, including t
36、he ranges between operating conditions and a sustained case with the piping at ambient temperature. When the computed stress range varies, whether from thermal expansion or other conditions, SE is defined as the greatest computed operating stress range. The value of N in such cases can be calculated
37、 by eq. (P1d)P319.4.4 Flexibility Stresses. Paragraph 319.4.4 is applicable, except that subparagraph (a) and eq. (17) are replaced with the following: (a) The stress due to bending, torsion, and axial loads shall be computed using the reference modulus of elasticity at 21C (70F), Ea, except as prov
38、ided in para. 319.2.2(b)(4), and then combined in accordance with eq. (P17a) to determine the operating stress, So, and eq. (P17b) to determine the operating stress range, SE. Som is the greater of the maximum operating stress, So, and maximum operating stress range, SE, which shall not exceed the a
39、llowable stress, SoA, in para. P302.3.5(d). SE is the maximum operating stress range, which is used in calculating N in para. P302.3.5(d) and in determining if the pipe is under severe cyclic conditions.The definitions in para. 319.4.4 apply, with the following additional definitions: Ap p cross-sec
40、tional area of the pipe Fa p axial force, including that due to internal pressure ia p axial force stress intensification factor. In the absence of more applicable data, ia p 1.0 for elbows and ia p io from Appendix D for other components. Sa p stress due to axial force p iaFa/ApP319.4.5 Required We
41、ld Quality Assurance. Paragraph 319.4.5 applies, except that SoA replaces SA.P319.5 ReactionsReplace para. 319.5 with the following: Reaction forces and moments used to design restraints and supports for a piping system, and to evaluate the effects of piping displacement on connected equipment, shal
42、l be based on the maximum load from operating conditions, including weight, pressure, and other sustained loads; thermal displacement; and, where applicable, occasional loads. The reactions shall be calculated using the modulus of elasticity at the temperature of the condition, Em (Ea may be used in
43、stead of Em when it provides a more conservative result). The temperature of the condition may differ in different locations within the piping system. Where cold spring is used in the piping system, experience has shown that it cannot be fully assured. Therefore, the reactions shall be computed both
44、 with the assumption that only two-thirds of the design cold spring is present, and with four-thirds of the design cold spring present. 274 If it is necessary to determine the reactions at ambient temperature, the designer shall consider loads at that condition, including the design cold spring and
45、self springing of piping. Self springing may occur if the operating stress in the piping system exceeds the yield strength of the material or if the piping operates at temperatures in the creep range of the material. P319.5.1 Maximum Reactions for Simple Systems.Paragraph 319.5.1 is not applicable.P
46、319.5.2 Maximum Reactions for Complex Systems.Paragraph 319.5.2 is not applicable.- The calculated operating stress is valid to evaluate a system? 热态应力不作为管道评定的标准；- The displacement of EXP is useful? 是- How to read the reaction load on nozzle and sign(direction) of load 选择 SUS 和 OPE 工况查看”Restraint su
47、mmary”14. How to evaluate the reaction force due to cold spring? 答：OPE1=W+P1+CS; OPE2=W+P1+CS15. How to model and design the thermosyphon reboiler which is attached to adjacent vessel by clip support? 答：使用 Node Cnode 将加热炉与其它设备关联16. What are regeneration 再生, decocking 脱焦, steam-out 蒸汽外接? How to apply this temperature modes to stress analysis? 答：Design TemperatureThe design temperature is the temperature at which the allowable stresses f
