Failure Analysis of Physical Explosion due to Gas Jetting from High-Pressure Pipeline

Jetting of the combustible gas with high pressure is a prelude to bringing into action of the chemistry explosion of gas cloud. Comparing with the leakage and diffusion of combustible gas and the chemistry explosion effect of gas cloud, the distribution of pressure, temperature and velocity formed by high-pressure gas jetting after the destruction of a pipeline, has been paid less attention to in the related field. There are a few fundamental data on the subject of evaluation of physical explosion parameters. In this paper, a physical explosion case of hydrogen gas transported through a high-pressure pipeline is reported, and a cause analysis of the explosion accident is proposed. Numerical simulation yields the field state parameters and the damage characteristics in the process of high-pressure gas jetting. In front of the leakage gas flow, a shock wave forms due to high-pressure gas jetting. The physical explosion can trigger the combustion of leaked hydrogen gas. Though the pressure rapidly attenuates behind the shock wave, a relatively high velocity is maintained until the control valve in the pipeline system is closed down or the jetting finishes. In the given accident case, the shock wave pressure reaches an order of 1 MPa and the temperature reaches 200–300 °C. This temperatures is obviously less than the igniting temperature of hydrogen gas, 400 °C. But the combustion of leaked gas may be triggered by the spark caused by the impact of instrument plates. Since the instrument plates near the leaking port of pipeline has been damaged already before the leaked gas burns, the electric spark from the line short or the strike spark between metal parts are also completely possible to trigger this combustion.     

Pipeline Corrosion,Modeling and Analysis

Degradation of pipelines is the result of the continuous attack by the environment of these conduits like climate change (temperature, rate moisture in the ground, etc.…) that may lead to a corrosive environment. The design and the maintenance of these conduits and pipelines is a challenge for oil industry seen the serious consequences which can occur because of several reasons, example: defects of the cracks types, rust…, etc. Which can cause escapes of the transported matter or ruptures of these conduits with all that involves like economic loss and pollution of the environment.     

天然气管道大孔泄漏速率的建模与分析

通过对天然气管道泄漏过程的分析,建立了气体的大孔泄漏模型。对大孔泄漏过程存在的3种状态进行讨论分析,验证了在高压情况下只存在管内亚临界流、孔口临界流和管内孔口都是临界流两种情况,在低中压情况下只存在管内亚临界流、孔口临界流和管内孔口均为亚临界流两种情况,并且分析了不同泄漏点和不同压力情况下发生泄漏的速率变化情况。采用本文的计算模型可以较好的计算出不同泄漏孔径的泄漏速率,为长输管道的定量风险评价提供依据。     

一起拒爆事故的调查分析

从矿山一起拒爆破事故的调查分析入手,按照一定的程序,逐一排除其他影响因素如操作问题、炸药、雷管产品质量问题,找出真正的拒爆原因,即高压失敏.由于设计的缺陷,在同一孔内两段装药间隔过近而采用不同延时起爆时,会导致先爆药段对后爆药段的动态高压作用,使炸药失去雷管感度而拒爆.最后,针对在爆破设计和施工中如何预防高压失敏问题,提出一些应预关注的建议.     

变阻障碍物对管道内瓦斯爆炸的影响

为探究障碍物阻塞比变化率对瓦斯爆炸的影响,分别建立平均阻塞比为0.6、 0.3的受限空间物理模型,基于Charlette湍流燃烧模型,利用Fluent软件对阻塞比变化率依次为0、 0.05、 0.10、 0.15的障碍物条件下的爆炸火焰、湍流转捩、压力波耦合过程进行大涡模拟(LES)。研究结果表明：火焰经过障碍物会产生回流卷吸效应。在平均阻塞比为0.6的工况组A中,当阻塞比变化率为0.10、 0.15时,火焰锋面更加尖锐,火焰传播速度峰值更高,平均传播速度更高,到达超压所需时间更短,超压峰值更大。在平均阻塞比为0.3的工况组B中,各工况平均传播速度相同,随着阻塞比变化率的增大,到达超压所需时间更长,超压峰值更大。     

Failure Analysis of a Natural Gas Pipeline Rupture

From aviation accidents to pipeline explosions, the National Transportation Safety Board is often called to determine probable cause and make safety recommendations, as they did in the aftermath of the 2010 San Bruno pipeline explosion.     

天然气加气站管道爆裂分析

加气站天然气管道在加气时突然发生爆裂。采用宏观检验、化学成分分析、硬度测试、金相检验和扫描电镜分析等方法对其进行了爆裂原因分析。结果表明：该管道的内壁在天然气高压冲刷下,沿纵向加工方向产生硫化物选择性腐蚀,形成纵向沟槽,产生应力集中并使管道有效尺寸减少,承受压力的能力减弱,最终在薄弱处的弯头外侧产生爆裂。     

煤气管道堵塞物成份分析

煤气管道堵塞物采用四分法缩分试样,经过干燥、灼烧、溶解、滴加硫氰化钾,得知样品中含有水、有机物、氨、硫化物、二氧化硅及铁离子。采用滴定法测定试样中硫离子,EDTA滴定法测定铁离子,硅钼黄分光光度法测定二氧化硅。     

某天然气管道内腐蚀问题探析

某输气管线自2006年10月投产以来,至今该段管道已经发生5起管道泄漏事件,泄漏点均在管道底部.通过对失效管道的壁厚测量、理化试验、腐蚀产物分析、防腐蚀层测试,并结合施工档案,可认定该管道是由于CO2和细菌腐蚀所造成破坏.通过清管排出管道内壁中残留积水及提高输送管输天然气的洁净度,有效地降低了管道发生内腐蚀的风险.     

某天然气管线腐蚀穿孔失效分析

为了解决某天然气输送管线的腐蚀穿孔失效问题,确定造成输气管道腐蚀失效的主要因素,采用扫描电子显微镜、EDS、XRD等分析方法,对某天然气输送管线失效位置进行了宏观形貌、微观形貌、材质及腐蚀产物等的分析研究.结果表明:失效管段处于低洼易积水处,局部腐蚀及穿孔主要发生在6点钟方向.通过元素成分分析和力学性能分析,确定管线材...     

Mechanical Response of a Buried Pipeline to Explosion Loading

In order to study the stress-strain response of a buried pipeline with internal pressure under the ground explosive, a numerical calculation model of the buried pipeline with internal pressure was established. The dynamic process of the buried pipeline was simulated after the explosion on the ground. Effects of internal pressure, magnitude of TNT, wall thickness, and buried depth on the stress-strain of pipeline were studied. The results showed that the region of high stress and plastic strain presented to the upper pipeline and extended toward axial direction, and then extended toward circumferential direction under the ground explosion. With the increasing of internal pressure, the high-stress zone fades away, the plastic strain zone and deformation of pipeline decrease. The stress and deformation of buried pipeline increase with the magnitude of TNT increases, but they decrease with the increasing of buried depth and wall thickness. Those results can provide theoretical basis and reference for pipe laying of oil-gas pipeline, safety evaluation, and maintenance, etc.     

N2O基单组元气体推进剂的爆炸事故分析

针对新型N₂O基单组元气体推进剂在发动机试车过程中发生的爆炸事故,通过推进剂的基础安全特性实验与管道阀门的结构分析,开展了事故原因分析。气体推进剂点火能量的实验结果表明,临界点火能量在0.25~0.50 mJ之间。在实验管道中的火焰传播速度能达到410 m/s。临界着火温度的实验结果显示,样品的最低着火温度为135 ℃。阀门的工作原理与结构分析结果显示,在阀门通电开启过程中,会对活塞上方4.06 mL的气体产生压缩作用。根据绝热方程计算可知,气体在压缩过程中温度可升至193.7 ℃。对比实验与理论计算可以推知,阀门启动过程中的压缩作用,可能是发生爆炸事故的根本原因。     

输气管道储气调峰方式的选择分析

在天然气管线工程中，为解决系统的供需矛盾，向用户安全、稳定地供气，必须选择合适的储气方式。本文介绍了如何确定城市天然气的几种调峰量，再确定几种储气方式储气量，从而比较分析选出合理的储气方式。     

天然气长输管道施工技术浅析

随着我国天然气和石油工业的不断发展,对天然气管道施工的要求越来越高。长输管道因其距离长、管径大、压力高,对施工中的技术提出了更高的要求。文章还就天然气长输管道施工中的一些关键技术进行了分析。     

海底油气长输管道内腐蚀现状的评估分析

为给海管腐蚀防护提供科学依据,确保油气输送安全,通过失重挂片、电感探针、H2S和CO2含量检测、细菌测试、超声波测厚、水质分析、扫描电子显微镜(SEM)以及X射线衍射(XRD)等技术手段对某海底油气长输管道内腐蚀现状进行评估,为海管腐蚀防护提供科学依据,确保油气输送安全。结果表明:该海管内腐蚀控制整体良好;海管底部由于水相和沉积物的作用,其均匀腐蚀速率大于上部和中部;腐蚀类型以介质中细砂的冲刷腐蚀为主,同时可能存在H2S和硫酸盐还原菌(SRB)等带来的局部腐蚀。另外,海管有结垢的趋势。根据评估结果,给出了该海管腐蚀防护和完整性管理的建议。     

3G客户关系稳定度建模与应用

为了定量评价使用3G业务的客户与运营商之间的关系,对3G客户的稳定度进行了研究,提出了基于数据挖掘(DM)和层次分析法(AHP)的3G客户关系稳定度模型。将模型应用于某电信公司,得出3G客户稳定度评分分布。该模型为运营商更有效地开展3G客户关系维系及服务等工作提供了有力支撑。     

Corrosion Induced Explosion of a High-Pressure Fire-Extinguishing Gas Cylinder

The failure of a high-pressure fire-extinguishing cylinder was investigated. Failure was induced by internal surface corrosion and stress corrosion cracking (SCC) due to condensation of carbonic acid. In internal surface, especially the area near the bottom of the exploded cylinder, severe corrosion was characterized by local pits. SCC initiated from these local corrosion pits was observed by metallurgical analysis. Microstructure of the failure cylinder near the internal surface consisted of multiple-banded structure and the banded structure could accelerate local corrosion initiation and propagation. The corrosion products built up on the fracture surface were primarily ferrous carbonate (FeCO₃). The determination of moisture in fire-extinguishing gas was also examined.     

油气管线热电偶套管断裂原因分析

某炼油厂油气管线上的一个热电偶套管发生断裂,使用时间仅6个月。对断裂套管进行了断口形貌、材质成分、金相组织等分析。结果表明,套管断裂主要原因是管线中油气流的冲击和湍流作用,引起套管的共振．进而产生疲劳断裂。