﻿ 简化FPSO在中拱中垂工况下管路应力分析
 舰船科学技术  2022, Vol. 44 Issue (8): 90-94    DOI: 10.3404/j.issn.1672-7649.2022.08.018 PDF

1. 江苏科技大学 能源与动力学院，江苏 镇江 212003;
2. Ogarev Mordovia State University, Saransk Russia

Simplified FPSO pipeline stress analysis under the condition of hogging and sagging
WANG jun1, MA Li-chen1, CHEN hao1, CHEN jing-sheng1, Anton Kolgatov1,2
1. School of Energy and Power, Jiangsu University of Science and Technology, Zhenjiang 212003, China;
2. Ogarev Mordovia State University, Saransk Russia
Abstract: Due to the FPSO's service in the deep sea environment, the hogging/sagging due to the influence of waves, sea breeze, towing and other working conditions, resulting in the deformation of the hull, the relative movement of the modules and the displacement of the pipeline, and the continuous increase in tonnage due to the continuous increase of FPSO production larger, the complexity and compactness of the pipeline also continue to increase. In the stress analysis of the FPSO piping system, the traditional sagging condition requires a lot of man-hours for analysis, verification, and inspection, and the potential man-hours reach 2500 hours. In this paper, the CAESAR II software commonly used in the industry is used to calculate the thermal expansion coefficient through the combination of the additional displacement of the pipeline caused by the deformation of the hull and the thermal expansion displacement to replace the traditional working condition analysis method, and verify the accuracy of this method, provide technical reference for the production and design of FPSO piping systems.
Key words: FPSO     sagging and hogging     stress analysis     flexible design     CAESAR II
0 引　言

1 应力分析规范

1.1 一次应力

 $\sigma _L\leqslant [\sigma]_h 。$ (1)

1.2 二次应力

 $\sigma _E\leqslant f[1.25([\sigma]^c+[\sigma]^h)-\sigma_L 。$

2 消防水系统应力分析

FPSO消防水系统位于主甲板，管道特点：管径尺寸大跨越空间长、工况复杂、空间狭窄、操作工况温度和压力不高。根据AVEVA Marine™中的主甲板消防水系统，等效建立CAESAR II三维模型如图1所示。

 图 1 主甲板消防水系统模型 Fig. 1 Fire water system model on the main deck
2.1 边界条件设置

2.2 工况考虑

 图 2 船体中拱中垂示意图 Fig. 2 Schematic diagram of hull mid-arch sagging

2.3 工况组合

3 中拱中垂工况简化及验证

 图 3 支架附加位移输入 Fig. 3 Support additional displacement input

3.1 中拱中垂常规应力分析方法

 图 4 位移量为0的管子位置 Fig. 4 Tube position with zero displacement
3.2 中拱中垂简便分析方法

CAESAR II可以在温度框中直接输入膨胀系数（长度/长度）来代替温度[9]，因此可以在温度框下直接输入材料为A106B的管子在操作温度下热胀系数与中拱中垂带来的船体变量之和简化管系在中拱中垂工况下的应力分析。由表5工况组合可得在环境温度为11℃时，分别计算出最高温度下中拱操作工况热胀系数之和T1、最低温度下中垂操作工况热胀系数之和T2、最高温度下中拱极端操作工况热胀系数之和T3、最高温度下中垂极端操作工况热胀系数之和T4，如表6所示。

T1T4输入到模型中，可得工况模型如图5图8所示。

 图 5 T1工况模型 Fig. 5 T1 working condition model

 图 6 T2工况模型 Fig. 6 T2 working condition model

 图 7 T3工况模型 Fig. 7 T3 working condition model

 图 8 T4工况模型 Fig. 8 T4 working condition model
3.3 应力分析结果验证

FPSO主甲板消防水系统一共考虑了6种热胀工况，其中工况L24考虑了最大温度差下的中拱与中垂船体变形量之差，此时的工况最为保守，产生的误差最大，因此只要考虑工况L24的2种分析方法产生的误差，2种分析方法误差如图9所示。

 图 9 L24工况下2种仿真方法误差 Fig. 9 Errors of two simulation methods under L24 conditions

 图 10 误差过大处 Fig. 10 Where the error is too large

 图 11 支管补偿臂处热胀系数补偿 Fig. 11 Thermal expansion coefficient compensation at branch pipe compensation arm

 图 12 修正后的L24工况下2种仿真方法误差 Fig. 12 The error of the two simulation methods under the modified L24 condition

L24工况最大热胀应力占比为59.6%，此时仿真误差范围为−7.4%～−9.1%。因此可以看出，在最保守的热胀应力工况下，采用简便方法分析的应力结果符合相关规范。

4 结　语

 [1] 张建. 深海FPSO关键管路应力分析[D]. 镇江: 江苏科技大学, 2015. [2] 程久欢, 雷俊杰, 纪志远. FPSO上部模块管道支架位移计算方法[J]. 石油工程建设, 2018, 44(5): 32-36. CHENG Jiu-huan, LEI Jun-jie, JI Zhi-yuan. Calculation method of FPSO upper module pipeline support displacement[J]. Petroleum Engineering Construction, 2018, 44(5): 32-36. DOI:10.3969/j.issn.1001-2206.2018.05.008 [3] ROBLETO R, WILLIAMS J. Efficiency and economy of automating displacements for FPSO pipe stress analysis[C]//Offshore Technology Conference, 2010. [4] 刘亚江. CAESARII管道应力分析理论[J]. 管道技术与设备, 2003(2): 6-9. LIU Ya-jiang. CAESARII pipeline stress analysis theory[J]. Pipeline Technology and Equipment, 2003(2): 6-9. DOI:10.3969/j.issn.1004-9614.2003.02.003 [5] 刘镜军. 浮式生产储油船管道应力分析[J]. 化工设备与管道, 2007(2): 47-50. LIU Jing-jun. Stress analysis of the pipeline of a floating production and storage tanker[J]. Chemical Equipment and Piping, 2007(2): 47-50. DOI:10.3969/j.issn.1009-3281.2007.02.014 [6] 唐永进. 压力管道应力分析[M]. 北京: 中国石化出版社, 2010. [7] 王战勇, 范威, 张巍伟, 等. FPSO上部模块管道应力工况研究[C]// 压力管道技术研究进展精选集——第四届全国管道技术学术会议, 2010: 97−100. WANG Zhan-yong, FAN Wei, ZHANG Wei-wei, et al. Research on FPSO upper module pipeline stress conditions [C]//Selected Collection of Research Progress in Pressure Piping Technology-The Fourth National Conference on Piping Technology, 2010: 97−100. [8] 程久欢, 纪志远, 雷俊杰. FPSO船体管道应力分析方法研究[J]. 石油和化工设备, 2020, 23(8): 17-20. CHENG Jiu-huan, JI Zhi-yuan, LEI Jun-jie. Research on stress analysis method of FPSO hull pipeline[J]. Petroleum and Chemical Equipment, 2020, 23(8): 17-20. DOI:10.3969/j.issn.1674-8980.2020.08.005 [9] CAESAR II 2013. Computer Software, Intergraph[R]. Huntsville, AL, USA, 2013.