压力容器应力腐蚀与控制措施

应力腐蚀是压力容器腐蚀失效破坏的重要形式,一旦发生脆性断裂,后果将不堪设想。介绍了压力容器中应力腐蚀断裂产生的特征和条件,并从如何降低及消除应力、改善环境和合理选用材料等方面提出了控制应力腐蚀断裂的措施。     

一起压力容器应力腐蚀事故及预防措施

在压力容器制造过程中,由于选材、加工及焊接等原因造成残余应力集中;在使用过程中,由于环境中含有一定浓度的腐蚀介质而发生应力腐蚀,导致事故发生。从压力容器的选材、制造和使用三方面环节分析这次事故发生原因,从而增加预防措施,降低事故发生率。     

压力容器用钢的硫化氢应力腐蚀

对Ｈ２Ｓ应力腐蚀的概念和发生机理进行阐述,提出了防止湿Ｈ２Ｓ应力腐蚀的办法,并举实例加以说明。     

压力容器消除应力技术述评（一）

就几种常见的压力容器消除应力技术的现状（包括标准化情况）及其优缺点进行了详细阐述和评价，并在此基础上提出了压力容器消除应力处理的方向及存在问题。     

在役压力容器H2S应力腐蚀的检验

本文系统介绍了压力容器应力腐主机理和失效方式，并列出了能和Ｈ２Ｓ产生应力腐蚀的和各阁下好在在役压力容器的检验中如何发现应力裂纹和可能产生应力腐蚀的部位。     

压力容器抗应力腐蚀设计的讨论

本文分析了压力容器及设备在湿润硫化氢、氢氧化钠溶液和液氨介质中应力腐蚀开裂的机理和应力腐蚀开裂过程。分析了影响应力腐蚀开裂的环境因素、材料因素和应力因素。讲座了设计中的材料选择和技术要求。通过加强制造过程的管理降低残余应力,是经济有效方法之一。     

H2S应力腐蚀环境下的压力容器用钢的选用探讨

本文通过对湿Ｈ２Ｓ应力腐蚀环境下，Ｈ２Ｓ应力腐蚀的机理及其影响Ｈ２Ｓ２腐蚀的因素的分析，结合工程实践，提出了在不同的Ｈ２Ｓ分压下的压力容器用钢的选材要求，以供工程设计中参考。     

压力容器和压力管道应力腐蚀开裂机理及影响因素分析

压力容器是指盛装气体或者液体,承载一定压力的密闭设备,最高工作压力大于或者等于0.1MPa(表压)的气体、液化气体和最高工作温度高于或者等于标准沸点的液体、容积大于或者等于30L且内直径(非圆形截面指截面内边界最大几何尺寸)大于或者等于150mm的固定式容器和移动式容器;压力管道是指利用一定的压力,用于输送气体或者液体的管状设备,最高工作压力大于或者等于0.1MPa,介质为气体、液化气体、蒸汽或者可燃、易爆、有毒、有腐蚀性、最高工作温度高于或者等于标准沸点的液体,且公称直径大于或者等于50mm的管道,公称直径小于150mm,且其最高工作压力小于1.6MPa(表压)的输送无毒、不可燃、无腐蚀性气体的管道。应力腐蚀开裂是影响压力容器和压力管道失去效果的主要模式之一,就压力容器和压力管道应力腐蚀开裂的机理及影响因素进行分析。     

钢制压力容器焊接残余应力测试分析

应用小孔释放法对系列钢制压力容器手弧焊接接头的焊接残余应力进行测试 ,讨论了焊接残余应力的分布规律及其相关影响因素 ,对加载法消除焊接残余应力的效果进行了初步的验证。结果表明 ,焊接接头的应力不均匀性和不确定性是影响钢制压力容器安全性的关键 ,采用加载法可以有效地改善这种非均匀应力分布状况。     

应力腐蚀开裂的断裂参量研究

根据焊接接头应力腐蚀开裂行为的特点,采用焊接接头力学不均匀性模拟试样,用断裂力学的 K 因子方法和 COD 方法进行研究。结果表明,焊接接头区域硬化层宽度 h 增加时,应力腐蚀裂纹扩展速率 da/dt 显著增加。     

再生器发生应力腐蚀开裂的探讨

针对炼油厂催化装置再生器下部件壁发生开裂的现象，通过分析催化装置近几年原料油田的变化、烟气露点测试结果与现场器壁温度对比，认为这是一种氢应力腐蚀开裂（SCC）。结合氢应力腐蚀特点制定了修复方案，特别是焊前预热、焊后热处理，选择合适的焊条及板材，降低了焊道和热影响区硬度，消除残余应力。并对再生器下部壁采取保温措施，确保再生器下部外壁温高于露点（137℃），使之无法在下部器壁形成水汽冷凝液，有效防止SCC的发生。     

容器斜接管区应力状态的研究

以直径６００ｍｍ、具有两个斜接管的容器为模型，进行了内压作用下的应力测试，并用高精度壳单元的柱壳相贯程序进行了详细计算，得到了容器斜接管区的应力分布规律。同时，从实验数据和ＳＡＰ程序的计算对比中验证了柱壳相贯程序，可用于工程计算     

钛制压力容器的焊缝应力研究

通过试验证明钛容器的破坏都是从焊缝开始的,其焊缝应力以离焊根５～１０ｍｍ处最大,达到了筒体按双向强化计算值２．２８～３．５１倍,并在此基础上提出了加强钛容器焊缝强度研究和如何降低焊缝应力峰值研究的新课题     

Pitting and stress corrosion cracking behavior in welded austenitic stainless steel

The effect of microstructural changes in 304 austenitic stainless steel induced by the processes of gas tungsten arc welding (GTAW) and laser-beam welding (LBW) on the pitting and stress corrosion cracking (SCC) behaviors was investigated. According to the in situ observations with scanning reference electrode technique (SRET) and the breakdown potentials of the test material with various microstructures, the GTAW process made the weld metal (WM) and heat-affected zone (HAZ) more sensitive to pitting corrosion than base metal (BM), but the LBW process improved the pitting resistance of the WM. In the initiation stage of SCC, the cracks in the BM and HAZ propagated in a transgranular mode. Then, the crack growth mechanism changed gradually into a mixed transgranular + intergranular mode. The cracks in the WM were likely to propagate along the dendritic boundaries. The crack initiation rate, crack initiation lifetime and crack propagation rate indicated that the high-to-low order of SCC resistance is almost the same as that for pitting resistance. High heat-input (and low cooling rate) was likely to induce the segregation of alloying elements and formation of Cr-depleted zones, resulting in the degradation in the corrosion resistance.     

对EN13445液压试验有关规定的理解以及国内外相关标准的比较

分析和讨论了EN13445规范对液压试验的有关规定,并与国内外的相关规定进行了比较。结果认为,在确定液压试验压力时可采用直接受压元件材料的相应应力比的最大值进行调整,而不必考虑螺栓材料。     

修正的DecockJ公式

本文分析了ＤｅｃｏｃｋＪ公式的内在缺陷，采用适当的模型对此缺陷进行了修正，并用４１个实验数据进行了计算比较。结果表明，修正的ＤｅｃｏｃｋＪ公式比原式的计算精度更高，同时还表明接管臂部接点邻域内筒体周向弯矩及壳元翘曲对接管应力集中有显著影响。     

Residual stress,microstructure and corrosion behavior in the 316L/Si3N4 joint by multi-layered braze structure-experiments and simulation

In this study, Mo interlayer of different shapes were designed for relieving the residual stress in a Si₃N₄/316L joint by finite element model simulation. It was found that the Mo interlayer designed by half-cylindrical slotting could reduce the residual stress of Si₃N₄ substrate in the joint by shifting the maximum residual stress from Si₃N₄ to the 316L substrate. The formation of Ag based solid solution in the seam could further reduce the maximum residual stress of Si₃N₄ due to the low yield strength of Ag. Ultimately, the maximum residual stress of Si₃N₄ in the joint was decreased significantly. Furthermore, the microstructure and corrosion behavior of the Si₃N₄/316L joint were also studied in detail. When Mo/Ag was inserted into the seam as a composite interlayer, the corrosion resistance of the Si₃N₄/316L joint was improved by the change in corrosion mechanism from pitting of Cu-rich phase to the uniform corrosion of both 316L and Mo.     

大型储气筒水压试验的应力测定与分析

采用水压试验的方法对某大型储气筒的强度进行了检验,得出了容器的应力分布情况并与理论结果进行了比较分析,结果表明该容器的设计强度是合理的。     

Environmental effects on cover cracking due to corrosion

This paper examines the environmental conditions under which the time to cracking of concrete, due to pressure caused by rust production on the surface of steel bars, is short. To determine this time, volume compatibility is assumed, which allows for compaction of all materials affected by the pressure, including the rust itself. A fracture mechanics concept is also used to signal cover failure. The model reveals that time-to-cover-cracking is a function of the rust production and the strength of the system to resist the resulting pressure. It is found that the highest corrosion rates are towards the end of autumn and the beginning of spring, when humidity reaches relatively high values with moderate temperatures. On the other hand the highest resistance of the system to corrosion production is during summer, since the humidity is low. In addition, rust pressure drops during summer due to creep; water moves out of the concrete which also deforms, giving more space into which the rust can expand. Structures exposed to humid summers would suffer from high rust production and rapid cover spalling. The model can assist in the decision-making process to identify when a bridge is more likely to corrode, which could indicate that new materials, like fibre reinforced polymers might be the most suitable design solution despite their higher initial cost.