某石化乙烯管道不锈钢法兰开裂原因分析

某石化乙烯管道在耐压试验过程中，由于不锈钢法兰存在裂纹导致泄漏，为保证后续安全生产，有必要进行法兰开裂失效分析。通过法兰基体化学成分光谱分析、力学性能测试，法兰裂纹区域金相观察、断口形貌及腐蚀产物分析、晶间腐蚀试验，对法兰开裂原因进行了研究。结果表明：焊缝附近的不锈钢法兰在焊接时发生敏化作用，在后续腐蚀介质作用下发生晶间腐蚀。采用法兰固溶处理、焊后热处理的措施，可以有效避免焊缝附近法兰的开裂。     

奥氏体不锈钢管道法兰制造安装引起失效案例分析

列举了化工厂中两个典型案例,分别由于制造因素及安装因素造成法兰的失效。在对失效件进行分析研究后发现锻造过程中的表面缺陷,以及焊接材料或工艺的选择不当都是导致法兰后期失效的重要因素。     

乙烯球罐罐顶管线焊缝法兰侧裂纹失效原因分析

针对失效乙烯球罐及其管线,依次对管线焊缝及法兰开展了检测分析,结合宏观检查、化学成分分析、能谱分析及金相分析,查找造成乙烯球罐及其管线失效的原因.最终确认其失效的原因为法兰材料的含碳量超标,大量的碳化物在法兰材料晶界上析出,导致材料晶间抗腐蚀性能大大下降.焊缝焊接处的残余应力引起了法兰裂纹扩展.     

0Cr18Ni10Mo2Ti不锈钢制乙醛精馏塔表面应力腐蚀裂纹产生原因分析

针对0Cr18Ni10Mo2Ti不锈钢制乙醛精馏塔体表面产生裂纹失效的现象,在生产设备上截取分析样品,采用显微组织分析、裂纹扩展路径分析及裂纹断裂面的成分分析等方法,对壳体内表面的裂纹进行分析。结果表明,大量裂纹产生的原因是在乙醛中混入了含有S、Cl元素的介质,对壳体钢板表面产生了晶间腐蚀和点腐蚀,进而在工作应力下产生应力腐蚀,形成了应力腐蚀裂纹。     

2Cr13环状裂纹分析

通过对2Cr13失效试样进行金相宏观及微观检验,对比及分析了裂纹形貌、金相组织,对裂纹产生的原因进行了初步的判断。结果表明,该环形裂纹的裂纹源为原材料中含有的非金属夹杂、异金属或锻造产生的疏松和缩孔。     

基于ANSYS换热器法兰有限元分析及应力评定

为了换热器在运行过程中,法兰结构安全。利用ANSYS有限元分析软件,对换热器壳体法兰在机械载荷和温度载荷共同作用下的应力强度进行了分析,并对其危险截面做了应力评定和强度校核。对壳体法兰不同危险部位进行分析与评定并且合格,这样才能保证其安全可靠地运行。     

16Mn Ⅱ法兰失效分析

针对16MnⅡ法兰失效,从化学成分、硬度、金相组织及力学性能等方面进行专业试验分析。结果表明,金属材料中存在大量魏氏组织,并且晶粒粗大,从而使材料的脆性增加,这是导致法兰开裂的根本原因。本文还提出了预防法兰失效的措施。     

高压集箱凸缘穿透型裂纹失效分析

通过对因出现穿透型裂纹而失效的裂解炉高压集箱凸缘的化学成分检测、金相组织观察以及断裂路径分析,得到其失效的主要原因是：锻造工艺不良在材料内部形成条带状的铁素体组织,为凸缘裂纹的产生和扩展创造了条件;凸缘因安装与结构条件而承受较高水平的安装、操作载荷,导致凸缘发生脆性开裂。     

304L材质法兰开裂案例分析

某石化装置管道焊接施工过程中,发现一些304L材质法兰焊接后在法兰颈端部近焊缝处出现裂纹。针对这一案例,文章从法兰化学成分、金相组织、断口能谱、晶间腐蚀等方面进行了综合分析,最后找出了裂纹产生的原因。由于304L材质法兰在石化装置工程中应用广泛,因而分析其裂纹产生的原因有助于控制工程质量。     

12Cr2MoWVTiB对接焊缝裂纹原因分析及预防措施

12Cr2MoWVTiB(G102)应用于锅炉、压力容器行业高温管排,运行后产生裂纹造成构件失效。对失效件金相组织和硬度研究,并进行不同焊接热循环、焊后热处理系统试验,科学选择制造工艺,预防焊接裂纹产生,为12Cr2MoWVTiB(G102)的应用提供实践经验。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.