气瓶安全与检验问答(十八)

问:气瓶进行水压试验过程中,应注意哪些事项?答:在试验装置、压力表、量管、衡器、试验用水、待试瓶、试验条件及操作步骤等,都符合ＧＢ/Ｔ9251—1997《气瓶水压试验方法》规定的情况下,应注意下列事项。1 为使受试瓶在水压试验压力下,瓶体膨胀不受外力影响,除瓶口螺纹试压接头外,试验前必须卸掉套于气瓶的防震胶圈,放开试验架上紧固气瓶的夹具。严禁使用机械顶压瓶口的试压堵头。2 为避免气瓶沾染物互相污染,禁油气瓶、不禁油气瓶和特气气瓶,必须按气瓶类别分室分机进行水压试验。其它设备和工器具也必须分室设置和配备。3 为准确测定…     

37Mn钢气瓶开裂原因分析

某37Mn钢气瓶在进行水压试验时发生漏水现象,对气瓶进行检查后发现气瓶存在撕裂状开裂。通过对开裂气瓶的宏观形貌、化学成分及微观形貌进行分析和检验,查明了其开裂原因。结果表明:引起气瓶撕裂状开裂的主要原因是其原材料钢管存在外折叠缺陷。     

高压气瓶容积全变形值计算表的制法

鉴于国家劳动总局修订的《气瓶安全监察规程》已经颁布,气瓶容积全变形值简化式已改为原式。为此,本刊1974年第4期刊出的刊的孙萍辉同志的“气瓶全变形计算表”不再适用。为适应新的《规程》,作者写了下文。由于本刊篇幅关系,不再全表刊登,仅将制法与举例的表段列出,供读者参考。在收到孙萍辉同志的稿件后,我们陆续收到:自贡东方锅炉厂动力科张和平同志、齐齐哈尔铁路局氧气厂奚风涛同志,云南东川矿务局机修厂制氧站郝士魁同志,重庆钢铁公司动力厂制氧站刘升春同志等关于按“七九”规程编制的气瓶全变形计算方面的来稿,均不再重登,特此致谢。     

《气瓶检验》、《高压气瓶容积全变形值简易计算表》出版消息

<正>孙萍辉编著,马昌华主审,劳动部锅炉压力容器安全监察局审定和推荐使用的教材《气瓶检验》及其附册一《高压气瓶容积全变形值简易计算表》,已分别由中国劳动出版社和劳动部锅炉压力容器安全杂志社出版。《气瓶检验》一书共分三篇:第一篇为气瓶构造、原始标志、颜色标记、瓶阀及其故障排除;第二篇为瓶装气体的潜在危险、充装检查、储存检查、运     

“高压气瓶容积全变形值计算表”已在上海出单行本

<正>本刊1980年第1期曾刊出孙萍辉同志的“高压气瓶容积全变形值计算表的制法”一文。鉴于篇幅关系,没有将计算表全表刊登,仅将制法与举例的表段列出。刊出后,有些读者来信要求索取全表。现在该     

国家标准修改通知单

ＧＢ 172 5 9-1998《机动车用液化石油气钢瓶》第 2号修改单本修改单经国家质量技术监督局于 2 0 0 0年 7月 2 5日以质技监标函 [2 0 0 0 ]10 6号文批准 ,自 2 0 0 0年 12月 1日起实施。现对ＧＢ 172 59- 1998《机动车用液化石油气钢瓶》作如下修改 :条文号标准原内容更改后的内容1范围………克分子 %…………摩尔 %……2引用标准ＧＢ/Ｔ 92 51- 1997气瓶水压试验方法…… ＧＢ/Ｔ 92 51- 1997气瓶水压试验方法ＧＢ 92 52 - 88气瓶疲劳试验方法……3 1 5指未按设计的技术要求装配组合部件 ,……的是……指未安装设计要求的组合部件 ,……的…     

深冷文献消息(国内部分)

<正>926101L型泵结构设计分析夏君,史小锋《石油机械》1992 №8 1~7926102 高压无缝气瓶的水压试验危险性探讨     

自制气瓶水压试验设备简介

我车间在自制电动350公斤/厘米2试压泵以后,于1977年9月自制成气瓶水压试验机和气瓶倒水机各一台。同年10月由重庆市劳动局组织十二个兄弟单位对全套设备和气瓶水压机试验方法进行了鉴定,认为合格。经三个月的使用,效果很好。本设备结构简单,制造容易,外形整齐,操作方便,极大地减少了操作工人的劳动强度,提高了生产率。设备简况参见附图。     

气瓶安全与检验问答(二十五)

问:乙炔管道的水压试验压力和气密性试验压力是怎样规定的,试验时应注意什么?答:管道水压试验压力为:1 管道工作压力小于0 7MPa时,水压试验压力为2 2MPa ;2 管道工作压力在0 7～0 15MPa时,水压试验压力为3 2MPa ;3 压缩机后的高压管道,水压试验压力为管道工作压力的2倍。在试验过程中,先升压至水压试验压力,保压10min ,然后将压力降至气密性试验压力,进行外观检查,如无破裂、变形、渗水和降压现象,则认为水压试验合格。水压试验合格后,再以气压进行气密性试验。气密性试验压力为工作压力的1 2 5倍。试验时升压至气密性试验压力后,…     

余杭气瓶试压机厂通过液化石油气钢瓶水压机鉴定

2000年11月4日,余杭气瓶试压机厂“YS-16／15型旋转式液化石油气钢瓶水压试验机省级新产品鉴定会”在余杭临平召开,有19位代表参加。在听取厂方该机设计及试制总结、标准化审查报告、经济效益分析报告、报产条件分析报告、用户使用报告等后,逐项进行了审议与讨论。鉴定会认为,该机设计合理,结构紧凑,性能可靠,操作方便,自动化程度高,水压试验效果好。产品性能经省检测所检测,附合企业标准。经用户使用,可减轻劳动强度,提高工作效率,适应性强,功能齐全,使用性能好。产品为省内首创新产品,性能达到国内先进水平。鉴定委员会同意通过省级新产品鉴定,可以投入批量生产。 YS-16／15型旋转式液化石油气钢瓶水压试验机技术参数如下：顶紧气缸QGA125×200,4只,16工位;摆线针轮减速机WB120-WD-11-1100;主机支架旋转速度1．93r／min;每次上机试压瓶数4只;灌水时间1～2min;保压时间1min;水压试验压力3．2MPa;进水压力>0．3MPa;气源压力0．6MPa;外形尺寸2800×1140×2140mm。该机采用16工位四工位同时进水、试压,然后旋转90°,180°自动倒水,因而提高了工效。 余杭气瓶试压机厂是一家研制、开发、生产、销售气瓶检测设备的专业企业,并是国家技术监督局定点单位。 (顾福民)     

Investigation of plastic zones near SCC tips in a pipeline after hydrostatic testing

Stress corrosion cracking (SCC) is an important failure mechanism for oil and gas pipelines. In the past, hydrostatic testing has been frequently used to assess and mitigate stress corrosion cracking. It is commonly agreed that an effective hydrostatic test not only eliminates critical crack-like flaws, but also blunts the sub-critical crack tip thereby suppressing further SCC propagation. However, little study has been done on the plastic deformation that results from the high stress intensity at the crack tip due to hydrostatic testing pressure and its possible role in subsequent SCC propagation. In this study, microstructural details were examined of an API 5L X52 SCC-containing pipe removed from field service. Plastic deformation generated by the hydrostatic testing pressure was revealed by using high-resolution imaging of a focused ion beam (FIB) microscope. The existence of the microscopic plastic zones around some crack tips suggests that caution should be taken when setting up pipeline hydrostatic tests.     

静压支承摩擦副变形流热力耦合求解与实验

摩擦副变形对静压支承摩擦学性能有显著影响,不均匀变形会引起润滑油膜破裂和干摩擦,严重时导致静压支承摩擦失效。针对环形缝隙节流静压支承,运用计算流体动力学、弹性理论和有限元法对静压支承摩擦副变形进行流热力耦合求解,得到了旋转速度和工作台自重对支承摩擦副变形的影响规律和摩擦失效机理。并进行了实验验证,数值模拟结果和实验值吻合较好,验证了数值模拟方法的正确性。研究结果表明:随着旋转工作台转速增加,间隙油膜温度升高,热变形增大。工作台自重产生摩擦副的弹性变形对热变形有均匀化作用,但其挤压效应会加大热变形,造成工作台和底座的变形为内边靠近外部开口的喇叭状。工况继续恶劣,润滑油黏度急剧下降,局部油膜迅速变薄,出现干摩擦润滑,导致静压支承摩擦失效。     

聚酰亚胺纤维与碳纤维缠绕复合气瓶性能对比研究

本文主要研究高性能国产聚酰亚胺纤维在复合材料气瓶上的应用,并表征其与进口碳纤维的性能差距.采用国产聚酰亚胺纤维进行缠绕成型工艺优化与复合材料性能测试分析,在测试数据及工艺优化基础上针对其进行了复合材料气瓶的强度设计.分别采用聚酰亚胺纤维、进口T300、T700以及T800碳纤维缠绕成型复合材料气瓶,进行水压爆破压强的测试,并引进声发射检测技术对其在水压过程中的损伤信号进行监测分析.结果表明聚酰亚胺纤维缠绕工艺性良好,与树脂界面结合优异,适用于湿法缠绕成型工艺.复合材料拉伸强度达到1 708 MPa,纤维的强度发挥率高达80%,相比于碳纤维复合材料其呈现出较好的断裂韧性,有利于减少复合材料气瓶在水压下的应力损伤.缠绕成型的聚酰亚胺纤维复合材料气瓶容器特征系数(PV/W)高达32.2 km,其在航空航天、医用、汽车、核工业等领域具有广阔的应用前景.     

Buckling of filament-wound composite cylinders subjected to hydrostatic pressure for underwater vehicle applications

The buckling and failure characteristics of moderately thick-walled filament-wound carbon–epoxy composite cylinders under external hydrostatic pressure were investigated through finite element analysis and testing for underwater vehicle applications. The winding angles were [±30/90]_FW, [±45/90]_FW and [±60/90]_FW. ACOS, an in-house finite element program, successfully predicted the buckling pressure of filament-wound composite cylinders with 2 ∼ 23% deviation from the test results. The analysis and test results showed that the cylinders do not recover the initial buckling pressure after buckling and that this leads directly to the collapse. Major failure modes in the test were dominated by the helical winding angles.     

The importance of multiaxial stress in creep deformation and rupture

This paper investigates the importance of multiaxial stress states by considering several distinct testing techniques used in assessing both creep deformation and creep damage accumulation. The requirements of testing programmes to determine the necessary data are discussed in respect of sensitivity and interdependence of the principal and hydrostatic stress ratios.     

爆炸加载条件下工业纯铁的冶金效应

针对内部爆炸加载的工业纯铁圆管和爆炸成形弹丸非常高的宏观塑性变形,对相应的微观组织进行了观察。结果表明：塑性变形时纯铁内发生动态回复和动态再结晶。这与冲击波引起的绝热温升和塑性变形功产生的绝热温升有关;动态回复和动态再结晶的软化作用使纯铁具有较高的塑性变形能力。     

Optimal laminations of thin underwater composite cylindrical vessels

This paper deals with the optimal design of deep submarine exploration housings and autonomous underwater vehicles. The structures under investigation are thin-walled laminated composite unstiffened vessels. Structural buckling failure due to the high external hydrostatic pressure is the dominant risk factor at exploitation conditions. The search of fiber orientations of the composite cylinders that maximize the stability limits is investigated. A genetic algorithm procedure coupled with an analytical model of shell buckling has been developed to determine numerically optimized stacking sequences. Characteristic lamination patterns have been obtained. FEM analyses have confirmed the corresponding significant increases of buckling pressures with respect to initial design solutions. Experiments on thin glass/epoxy and carbon/epoxy cylinders have been performed. The measured buckling pressures appear to be in good agreement with numerical results and demonstrate the gains due to the optimized laminations.     

Nonlinear constitutive equations for transient creep of viscoelastic polymers including the effect of hydrostatic pressure

The behaviour of polymers is known to be significantly influenced by the hydrostatic pressure in creep deformation or elastic-plastic deformation. The effect of the third stress invariant on the nonlinear viscoelastic deformation is much smaller than that of the hydrostatic pressure. In this paper, a constitutive equation for transient creep is proposed, which includes the effect of the hydrostatic pressure on the yield function. The creep and plastic strains or the creep strain rate converge to zero with increasing hydrostatic pressure. The proposed constitutive equation is in good agreement with the actual creep data of cellulose nitrate and cellulose acetate, under various combinations of superimposed tensile and hydrostatic loadings.     

Analytical solutions for functionally graded incompressible eccentric and non-axisymmetrically loaded circular cylinders

We study analytically plane strain static deformations of functionally graded eccentric and non-axisymmetrically loaded circular cylinders comprised of isotropic and incompressible linear elastic materials. Normal and tangential surface tractions on the inner and the outer surfaces of a cylinder may vary in the circumferential direction. The shear modulus is taken to vary either as an exponential function or as a power law function of the radius only. The radial and the circumferential displacements, and the hydrostatic pressure are expanded in Fourier series in the angular coordinate, and expressions for their coefficients are derived from equations expressing the balance of mass (or the continuity equation) and the balance of linear momentum. Boundary conditions are satisfied in the sense of Fourier series. For the exponential variation of the shear modulus, the method of Frobenius series is used to solve 4th-order ordinary differential equations for coefficients of the Fourier series. It is shown that the series solutions for displacements and the hydrostatic pressure converge rapidly. Results for eccentric cylinders and non-axisymmetrically loaded circular cylinders are computed and exhibited graphically. Effects on stress distributions of the eccentricity in the cylinders and of the gradation in the shear modulus are illuminated. It is found that in a thin cylinder subjected to cosinusoidally varying pressure on the inner surface, segments of the cylinder between two adjacent cusps in the pressure deform due to bending rather than stretching.     

Effects of fire on small commercial gas cylinders

Current standards on the safety of small portable gas cylinders only define the pressures at temperatures of up to 50 °C and therefore have limited applicability in situations where cylinders are close to fires. Cylinders containing a pressurised liquid butane–propane mixture were heated in a small barbecue. The cylinders underwent a boiling liquid expanding gas explosion (BLEVE) at a liquid temperature of 90–100 °C. Failure was at the rolled seam where gas could escape thus provoking the BLEVE. Previous hydrostatic pressure testing of the cylinders showed that collapse of the spherical cap base occurred at a pressure of 1.8 MPa and that this was followed by failure of the rolled seam at a pressure of 2.0 MPa. These pressures were lower than that required to produce longitudinal cracks in the cylinder wall. Analysis of the pressure created as the temperature is raised by means of the Clausius–Clapeyron equation indicated the temperature for failure of the seam to be about 100 °C. After the BLEVE the cylinder broke into two fragments, an end cap and a tub rocket. The velocity of the tub rocket was estimated to be 65 m s⁻¹, giving a kinetic energy of 309 J. By comparison with the ballistics of rubber bullets it is believed that any injuries will be non-penetrating blunt trauma injuries and be less likely to cause severe injuries than those created by rubber bullets. The range over which the kinetic energy is likely to be capable of creating injuries is estimated to be less than 30 m.