Comparison between Glass and Stainless-Steel Vessels in Differential Scanning Calorimetry Estimation

Differential scanning calorimetry (DSC) provides easy screening for thermal hazard evaluation. Here, we investigate the difference between using glass and stainless-steel vessels on the DSC measurement of exothermic decomposition energy (QDSC) for 41 chemical substances (containing nitro, halogen, peroxide, and sulfur groups, and hydrazine bonds). Two borosilicate glass vessels (capillary and ampule) and one stainless-steel vessel were used. All QDSC values obtained were investigated with reference to the permissible fluctuation range specified by the ASTM (American Society for Testing and Materials) international Both glass vessels produced very similar QDSC values, despite different sample scales. The QDSC values obtained with the glass vessels were generally roughly within the variation tolerance range of the stainless-steel vessel. Notable exceptions were halogen- or sulfur-containing compounds;these exhibited smaller QDSC values with glass vessels in almost all cases. We will investigate whether certain structures in compounds react with stainless steel. The vessel material choice is crucial in evaluating the true reactivity of a substance.

Development of a new irradiation-embrittlement prediction model for reactor pressure-vessel steels

Predicting the transition-temperature shift(TTS)induced by neutron irradiation in reactor pressure-vessel(RPV)steels is important for the evaluation and extension of nuclear power-plant lifetimes.Current prediction models may fail to properly describe the embrittlement trend curves of Chinese domestic RPV steels with relatively low Cu content.Based on the screened surveillance data of Chinese domestic and similar international RPV steels,we have developed a new fluencedependent model for predicting the irradiation-embrittlement trend.The fast neutron fluence(E>1 MeV)exhibited the highest correlation coefficient with the measured TTS data;thus,it is a crucial parameter in the prediction model.The chemical composition has little relevance to the TTS residual calculated by the fluence-dependent model.The results show that the newly developed model with a simple power-law functional form of the neutron fluence is suitable for predicting the irradiation-embrittlement trend of Chinese domestic RPVs,regardless of the effect of the chemical composition.

Research on reasonable winding angle of ribbons of Flat Steel Ribbon Wound Pressure Vessel

Flat Steel Ribbon Wound Pressure Vessels (FSRWPVs) are used in many important industry areas. There is no such kind of pressure vessel exploding on operation for its reasonable structure design. Many explosion experiments on Flat Steel Ribbon Wound Pressure Vessel showed that their limited load pressure is related to the winding angle of the steel ribbons. FSRWPVs with reasonable winding angle have better security and lower cost. Reasonable angels given at the end of this paper facilitate engineering design.

Effect of Pre-Deformation Enhanced Thermal Aging on Precipitation and Microhardness of a Reactor Pressure Vessel Steel

Microstructure evolution in neutron irradiated Reactor Pressure Vessel （RPV） steels was experimentally simulated through an improved degradation procedure in this study. The degradation procedure includes austenitizing at 1 150℃ and water quench, deformation 10% and 30% respectively, and then thermal aging at 500℃ for different period of time. The microstructure of the specimens was analyzed in details using transmission electron microscopy （TEM）. The micro-hardness test results showed that all the hardness curves of undeformed, 10% pre-deformed and 30% pre-deformed specimens have two micro-hardness peaks with the first peak value corresponding to different thermal aging time of 1 hour, 5 hours and 10 hours, respectively. It was revealed that the hardness curves were influenced by the precipitation of Cu-rich precipitates （CRPs） and carbides, deposition of martensite and work hardening.

ESTIMATE OF BURSTING PRESSURE OF MILD STEEL PRESSURE VESSEL AND PRESENTATION OF BURSTING FORMULA

In order to get more precise bursting pressure formula of mild steel, hundreds of bursting experiments of mild steel pressure vessels such as Q235（Gr.D） and 20R（1020） are done. Based on statistical data of bursting pressure and modification of Faupel formula, a more precise modified formula is given out according to the experimental data. It is proved to be more accurate after examining other bursting pressure value presented in many references. This bursting formula is very accurate in these experiments using pressure vessels with different diameter and shell thickness. Obviously, this modified bursting formula can be used in mild steel pressure vessels with different diameter and thickness of shell.

Investigation on the temperature distribution and strength of flat steel ribbon wound cryogenic high-pressure vessel

By analyzing heat transfer on the wall of fiat steel ribbon wound vessel （FSRWV）, a numerical model of temperature distribution on the entire wall （including inner core wall, flat steel ribbons, outside cylinder of jacket and insulating layer） was established by the authors. With the model, the temperature distribution and the length change in the vessel walls and flat steel ribbons in low temperature are calculated and analyzed. The results show that the flat steel ribbon wound cryogenic high-pressure vessel is simpler in structure, safer and easier to manufacture than those of conventional ones.

Recent development in standards of steels used for pressure vessels in China

In this paper,five items of standards of steels used for pressure vessels which are issued recently or about to be issued and put into effect have been introduced.The differences of standards mentioned above and the former standards and the primary qualifications have been formulated.These qualifications indicate that,some qualifications of national standards of steels used for pressure vessels are on the international advanced level.

Load Bearing Capacity and Safety Analysis for Strain-hardening Austenitic Stainless Steel Pressure Vessels

By increasing the yield strengths of austenitic stainless steels for pressure vessels with strain hardening techniques,the elastic load bearing capacity of austenitic stainless steel pressure vessels can be significantly improved.Two kinds of strain hardening methods are often used for austenitic stainless steel pressure vessels：Avesta model for ambient temperature applications and Ardeform model for cryogenic temperature applications.Both methods are obtained from conventional design rules based on the linear elastic theory,and only consider the hardening effect from materials.Consequently this limits the applications of strain hardening techniques for austenitic stainless steel pressure vessels because of safety concerns.This paper investigates the effect of strain hardening on the load bearing capacity of austenitic stainless steel pressure vessels under large deformation,based on the elastic-plastic theory.Firstly,to understand the effect of strain hardening on material behavior,the plastic instability loads of a round tensile bar specimen are derived under two different loading paths and validated by experiments.Secondly,to investigate the effect of strain hardening on pressure vessels strength, the plastic instability pressure under strain hardening is derived and further validated by finite element simulations.Further,the safety margin of pressure vessels after strain hardening is analyzed by comparing the safety factor values calculated from bursting tests,finite element analyses,and standards.The researching results show that the load bearing capacity of pressure vessels at ambient temperature is independent of the loading history when the effects of both material strain hardening and structural deformation are considered.Finite element simulations and bursting tests results show that the minimum safety factor of austenitic stainless steel pressure vessels with 5% strain hardening is close to the recommended value for common pressure vessels specified in the European pressure vessel standard.The proposed study also shows that in the strain hardening design of austenitic stainless steel pressure vessels,the calculation for plastic instability pressure could use theoretical formula or finite element analyses based on geometrical dimensions and material property parameters before strain hardening,but a 5%strain should be employed as a design limit.The proposed research can be used for the strain hardening design of austenitic stainless steel pressure vessels safely.

INVESTIGATION OF INFLUENCE OF HYDROGEN ATTACK ONFATIGUE PROPERTIES OF PRESSURE VESSEL STEELS

Influence of hydrogen attack on mechanical and fatigue properties of 1020, 15CrMo and 2.25Cr-1Mo steels has been studied, which were exposed to gaseous hydrogen at pressure of 18MPa and 300-480℃ for up to 480h. The results of fatigue test showed that hydrogen attack (HA) resulted in an obvious change in fatigue properties of 1020 and 15CrMo steels, however, 2.25Cr-1Mo steel showed a lower susceptibility to hydrogen attack due to the addition of Cr and Mo. Fatigue crack behaviour for 1020 steel is attributed to hydrogen attack damage and the crack closure induced by the rough cracking surface, which lead to a valley on △Kth～HA% plot. The change in the fatigue behaviour of 15CrMo steel is possibly caused by severe surface decarburization.

Stress Corrosion Cracking of Pressure Vessel Steel and Countermeasures by Titanium-Based & Cerium-Based Inhibitors in Subcritical Aqueous Environment

An overview of a severe kind of environmentally-assisted cracking-stress corrosion cracking (SCC) of pressure vessel steel (PVS),such as stainless steel 304, alloy 600,690 and other nickel-based alloys in subcritical (～300 ℃) aqueous environment was given. The mechanisms of SCC of metals under this inclement surrounding were briefly generalized. Herein,some pragmatic solutions to mitigate the SCC susceptibility and retard its propagation were presented. The titanium and cerium-based inhibitors addition countermeasure was highlighted.

Microstructure and properties of S30403+Q345R roll-bonded clad steel plate for pressure vessels

To meet the demand of the domestic pressure vessel industry for roll-bonded clad steel plates, Baosteel has developed an S30403 ＋ Q345R roll-bonded clad steel plate. Comprehensive inspections of the composition, microstructure, and properties are made to systematically evaluate the steel plate in the normalized and normalized ＋ stress relieved states. The results show the cladding interface of the S30403 ＋ Q345R roll-bonded clad steel plate has high shear strength, the base metal has good properties, and the mechanical properties of the steel plate head and tail are uniform. The performance is fully consistent with the technical requirements of the roll-bonded clad steel plate for pressure vessels.

Development of S11306+SA516Gr70 roll-bonded clad steel plate for pressure vessels

To meet the demand of the pressure vessel industry, Baosteel has developed an S11306 ＋ SA516Gr70 roll-bonded clad steel plate. Comprehensive inspections of the composition, microstructure, and properties are performed to systematically evaluate the steel plate in normalized state and normalized ＋ stress relieved state. The results show the cladding interface of the Sl1306 ＋ SA516Gr70 roll-bonded clad steel plate has high shear strength, and the base metal has good mechanical properties. The performance is fully consistent with the technical requirements of the roll-bonded clad steel plate for pressure vessels.

大壁厚不锈钢复合板压力容器建造关键技术及应用

在大壁厚不锈钢复合板压力容器的建造过程中,通过深入研究其技术要点和难点,优化焊接接头结构设计,成功形成了一套完整的新型建造关键技术。这套技术不仅优化了焊接接头结构,还创新了一系列施工方法,包括筒体加热卷制、接头坡口机加工、接管内壁耐蚀层TIG/FCAW自动堆焊、不锈钢衬管液氮冷套、球形封头内壁耐蚀层带极埋弧堆焊、纵环缝窄间隙埋弧自动焊以及管口接头马鞍型埋弧焊等。这些新型建造关键技术的应用,在提高压力容器质量效果的同时,也带来了显著的经济效益,为行业同类型设备的建造提供借鉴。在未来的研究中,可以进一步探索这些技术在其他领域的应用,以实现更广泛的技术交流和合作。同时,对于大壁厚不锈钢复合板压力容器的建造,仍需不断深入研究其材料特性、工艺参数和施工方法,以不断提高设备的性能和安全性。

三代核电反应堆压力容器低合金钢焊缝性能对比分析

通过模拟国内三代核电压水堆反应堆压力容器环焊缝,分别采用国产焊接材料和进口焊接材料,在焊接工艺性能、焊缝金属化学成分、拉伸、冲击韧性、落锤和低周疲劳试验等方面进行了对比分析。结果表明,国产和进口焊接材料的焊接工艺性能和焊缝金属力学性能均相当;焊接试件不同厚度取样位置的焊缝金属-28.3℃冲击吸收能量平均值都大于90 J,有较大的设计裕量。该国产焊接材料已应用于国内某三代核电机组反应堆压力容器,为进一步推广应用提供技术支撑。

抗压容器钢在模拟工业码头大气环境下的腐蚀行为研究

为探究抗压容器钢在模拟工业码头大气环境下的腐蚀行为,利用失重分析、EDS、XRD和电化学方法研究了不同模拟加速试验周期下抗压容器钢Q235和16MnNiVR钢的腐蚀行为。结果表明:抗压容器钢Q235和16MnNiVR钢在模拟工业海洋大气环境试验中,其腐蚀速率先呈现上升趋势,随着锈层由疏松逐渐变致密,腐蚀速率会发生不同程度地下降。在此加速试验下2种钢的腐蚀产物化学性质一致,所发生的腐蚀行为差异是由金属基材表面腐蚀产物致密性所致,在东南沿海工业海洋大气环境腐蚀因子作用下,16MnNiVR钢的耐蚀性可达到Q235钢的1.6倍。

不同储存容器对凤香型基酒储存前期风味形成的探究

该研究通过连续两年对不同储存容器中基酒的理化指标、挥发性风味物质的追踪测定及感官品评的方法,探究不同储存容器对凤香型基酒储存过程中风格特点形成的影响。结果表明,两年期间,不锈钢罐和陶坛储存基酒中pH缓慢降低,总酸升高不到3%,总酯含量分别降低5.45%、6.75%;酒海(凤香型白酒特有储存容器)因碳酸钙的引入和良好的透气性加速了酯类物质的水解、挥发性酸类物质的排出及醇、醛的氧化作用,使得基酒pH显著升高,总酸和总酯明显降低,下降率分别约75%和34%。陶坛和酒海良好的透气性有利于基酒老熟和邪杂味排入环境,尤其是酒海储存凤香型白酒中蜜香突出和酒海味明显。通过对58种挥发性物质进行主成分分析和热图分析发现,采用不同储存容器储存一年的基酒特征风味物质及其相似,但与新产基酒及储存两年基酒都具有显著性差异;不锈钢罐和陶坛储存两年的基酒特征风味物质较为接近。新酒中丁酸丁酯、乙酸乙酯、丁酸乙酯、丁酸等低分子酯类、酸类物质含量较高,使得新酒放香大、新酒味、酸臭味较重。储存一年的基酒中8-甲基壬酸、辛酸、辛酸己酯等挥发性物质含量较多,甜香、水果香味突出。储存两年的基酒中异戊酸乙酯、乙酸丁酯等酯类及己醇、异戊醇等醇类较多,使得基酒具有菠萝香、水果香、花香等风味,尤其是酒海储存两年基酒中较高含量的壬酸乙酯、己酸丙酯使得基酒甜香、老窖香突出,还赋予基酒独有的蜜香。

12Cr5Mo压力容器制造监督检验及工艺优化

以某单位首次试制造12Cr5Mo耐热钢制压力容器为例,介绍了耐热钢制压力容器制造监督检验过程中的质量控制,重点描述了12Cr5Mo的材料入库检验控制、焊接相关过程的控制、热处理的工艺控制过程。通过分析压力容器本体上不同受压元件之间的焊接结构形式以及12Cr5Mo的材料性能,根据提供的焊接工艺评定、焊工资格项目、热处理工艺,发现相关部分焊评焊工资质不覆盖问题。通过优化热处理工艺和选择合适焊评焊工,最终顺利通过了无损检测及耐压试验。

基于机器视觉的钢制压力容器焊缝缺陷X射线检测方法

为降低由钢制压力容器焊缝缺陷引起的事故发生概率,提出基于机器视觉的钢制压力容器焊缝缺陷X射线检测方法。使用机器视觉系统以及X射线技术,获取钢制压力容器焊缝图像并提取焊缝区域特征,将焊缝缺陷整合成熔焊、虚焊、焊穿三大类别;基于焊缝区域特征的提取结果,提取钢制压力容器的焊缝缺陷面积、缺陷亮度以及波形等缺陷特征,构建缺陷分类器,实现钢制压力容器焊缝缺陷X射线检测。实验结果表明:钢制压力容器焊缝缺陷检测时,随着待检测焊缝图像的增加,F1值较高,实际缺陷检测结果的主观判断效果明显,细节检测效果好。

目视检验技术在核电站特殊场景中的研究与应用

目视检验是无损检验的重要方法之一,被广泛应用于产品设备制造、安装和使用的各个阶段。役前和在役检查期间需要对AP1000核电站钢制安全壳及其整体附件进行目视检验,以发现不允许的表面缺陷并及时处理。由于钢制安全壳结构的特殊性,需开发专用的目视检验装置进行检验。本文介绍了对不可达区域进行目视检验所采用的设备和具体的检验技术,对后续AP1000机组钢制安全壳的目视检验具有一定的指导意义。

超级双相不锈钢S32750压力容器封头成形工艺

系统探讨了S32750超级双相不锈钢压力容器封头的成形工艺。通过对S32750超级双相不锈钢的化学成分、金相组织、力学性能和耐腐蚀性能的分析,确定了该材料具有高强度、良好的焊接性能和耐腐蚀性能。基于材料特性和相关标准规定,制定封头的成形工艺,采用两步法成形:冷冲压预成形和热冲压终成形。成形过程的关键控制点包括原材料验收、划线下料、边缘准备、冷热冲压成形、恢复性能热处理等。成形后,对封头的形状尺寸、厚度、硬度及铁素体含量等进行检测,验证了成形工艺的有效性。在封头母材上进行拉伸、冲击、晶间腐蚀等试验,结果表明封头的力学性能和耐腐蚀性能得到了良好恢复。