阀门常见故障

阀门是安装在管路上用以切断、调节介质流量或改变介质流动方向的重要附件。阀门常见故障和处理方法有以下几个方面：     

不锈钢阀门质量与安全生产

分析了不锈钢阀门的质量与降低能耗、环境污染 ,特别是安全生产的关系 ,指出了不锈钢阀门在国民经济建设中所起的重要作用 ;根据当前阀门生产中存在的一些实际问题 ,提出了提高不锈钢阀门质量 ,保证安全生产的一些有效措施     

简易阀门管道消声器

美国宾夕法尼亚州立大学噪声实验室研制成功一种新型阀门管道消声装置,既能减弱管道和阀门的噪声,又不象普通的附加消声器那样造成压力下降。它是一节具有吸声间壁和挡板的加长管,可以安装在控制阀的下侧,又能同阀门制成一个整体。试验表明该装置可将噪声减弱30分贝左右。(摘自《美国工业导报》)简易阀门管道消声器@叶德成     

小型阀门制造环节存在的普遍问题

本文简要介绍了一些小型阀门制造企业在压力管道阀门设计、制造环节存在的一些普遍问题，以供同行交流探讨，对控制阀门产品出厂质量具有一定的指导意义。     

关阀门

管德岩所在的化工车间,管路纵横交错,密密麻麻,光阀门就有上百个,且大小不一。他是“阀门通”,别看50岁出头了,可是“香饽饽”哩。凡是关阀门的任务,车间头头准交给他去做。去年“五一”检修,管德岩和徒弟小查负责关阀门。小查关,他挨个儿检查,看扣是否拧到位,阀门有没有损坏的,非常挑剔,差一丝一毫都不行。关上1个,打1个记号,师徒俩一下午没闲着,只剩最后5个大阀门了,若是都关上了,就可以投产了。偏偏赶在这时,管德岩家里来了电话,他老伴心脏病犯了。他犹豫再三,不肯离开,直至小查向他作了保证,才勉强回家了。老伴住上了医院,打上了点滴,这…     

阀门噪声控制

阀门噪声(特别是调节阀噪声),是石油化工装置的主要噪声源之一。近几年来,我们在阀门和调节阀的噪声控制方面做了一些工作,初步摸索到一点经验。 首先,要准确地分析和判断噪声产生的主要原因及特性,针对不同的特点采取相应措施。根据实际观察,阀门噪声主要有以下三种情况:为便于分析,以流体流经阀门时的流体状态图为例(见图1)。 常见的第一种情况,由于压力降过大而产生流体动力噪声。当阀门节流大时,断面收缩处流体流动达到临界状态,在阀门的下游会发生强烈的湍流和激波噪声。它往往是以高中频为主的宽频带噪声。特别是当流速接近声速时会产…     

蒸汽阀门爆炸

陕西富平县乳品厂,去年发生了一起蒸汽阀门爆炸事故。阀体出口端顺向爆破,呈三角形破口,与阀盖连接的阀体丝扣同时横向裂开(见图),将阀盖、阀芯、阀杆、手轮等约以14吨力量,斜向冲出3米多远,击在煤堆上。操作者的右侧面部、颈部、双肩、胳臂、手等处严重烫伤,并被汽浪冲出7.7米远,又撞击到铁凳子上,头部撞伤,经抢救无效,死亡。 设备系统见下图: 当时 4吨/时锅炉正常供汽,2吨/时锅炉停运。2号阀门事故前始终是开启状态,3号阀门是事故阀门,两小时前他人洗澡曾开过。2号至3号阀门之间是30米室外管道(草绳石棉灰保温厚25—30毫米),事故前已充满…     

油库阀门橡胶填料防渗漏

过去,油库阀门用油浸石棉盘根作填料,加料方便,密封性、润滑性较好,也有一定的弹性。但耐磨性差,紧几次后,填料就失去了弹性,尤其是在较短时间内汽油可把填料中的润滑脂冲刷掉,失去了密封、润滑作用,产生渗漏。为防止渗漏,我们采用了二硫化钼丁睛耐油橡胶作填料(简称橡胶填料,见图1)。经使用,效果较好。 使用情况 1975年,某油库在主油泵房、铁路鹤管、操作井等五个汽油、三个柴油阀门上采用了橡胶填料,其中七个为压力阀门,一个为真空阀门。在泵房汽油排出阀门使用橡胶填料五年,至今没有渗漏。用力搬动一次,阀门手轮可自转4—5圈,轻便灵活。…     

在用氨制冷压力管道阀门的材质检验研究

本文分析了几起液氨管道系统阀门事故的原因和严重后果,总结了几种阀门材质检验方法对在用氨制冷压力管道阀门的材质检验具有一定的指导意义。     

监管与服务并行推动阀门产业转型发展——关于浙江省阀门产业发展情况的调研

<正>阀门是装备制造业的重要组成元件,是承压锅炉、压力容器和压力管道不可或缺的流体控制部件,广泛应用于石油、化工、电站、长输管线、造船、核工业、各种低温工程、宇航以及海洋采油等国民经济重点领域,并随着应用领域技术参数的发展,越来越显得重要。浙江是块状经济比较明显的省份,产业集群特征明显,对阀门产业依法实施监管,促进产业规范生产,并尽快转型升级,是我省阀门产业科学发展面临的重大问题。为此我们深入阀门产业集聚地,广泛听取行业协会、企业、科研机构的建议和意见,着重从阀门监管和提升两个层面进行了研究和思考,对我省阀门行业的整治和转型升级提出了对策建议。     

Benchmarking of two-phase flow through safety relief valves and pipes

This paper compares calculated results for two-phase flows through safety relief valves and pipes using the TPHEM, CCFLOW and RRERSP computer programs. These studies were conducted to locate errors in the programs as well as to further our understanding of how each program worked. For most low-to-moderate viscosity flow examples, and for the frozen flow examples, the program results agreed despite differences in the calculation methods. Current thinking is that the TPHEM computer program gets better results for high viscosity flows through safety relief valves (nozzles) and for pipe down flows. This is because this program successively iterates nozzle flows to achieve results consistent with the choke pressure, temperature and quality and successively iterates pipe flows to achieve results consistent with the pipe length. Safety relief valve flows from the RRERSP computer program are reduced by the inlet pipe non-recoverable pressure loss. This effect is significant for several cases.     

Safety studies on hydraulic proportional valves with electrical position feedback.

The authors analysed a proportional valve with electrical position feedback for its failure behaviour. Several failures were introduced into the feedback loop, especially into the 2 solenoids and the inductive position transducer. The behaviour of the valve for square and ramp reference signals was recorded and systematically analysed. It was shown that failures could be detected by monitoring the residual signal from the equipment under control or the residual signal from the sensor. It was possible to achieve the safe position within twice the normal response time of the valve by switching off the current of both solenoids. The application of these results for a new generation of safe proportional valves is discussed. The use of the results of these investigations obviates the need for redundancy of the electrical position monitoring arrangement in a safe proportional valve.     

A viscosity correction factor for shear-thinning liquid flows in safety valves

At the moment there is lack in the existing standards of a sizing procedure for media of more complex rheological behavior than Newtonian. A formulation for the generalized Reynolds number to calculate the viscosity correction factor and size safety valves for the flows of shear-thinning media is proposed in this work. The various formulations in the literature are validated in their accuracy of estimation of the mass flow rates of aqueous solutions of polyvinylpyrrolidone. Among them the generalized Reynolds number defined using the wall viscosity of the annulus between the seat and the disk gives the highest accuracy without overestimating the measured mass flow rates. On the base of these results this generalized Reynolds number is recommended for introduction in the next review of both ISO 4126-1 Part 1 and API 520 for the sizing of safety valves for shear-thinning media.     

Sizing of safety valves for multi-purpose plants according to ISO 4126-10

Multi-purpose plants are frequently protected with mechanical safety devices like safety valves or bursting disks. Due to many changes of recipes it must be checked regularly whether the safety devices are sufficiently sized. But the sizing procedure of individual safety devices can be very tedious. Therefore energy specific relief areas (effective relief area per kW of energy input) have been determined for approx. 60 typical solvents. They are indicated for reactors with safety devices which have a set pressure of 7 bar (abs) or 11 bar (abs). These values are independent of the size of the reactors for vaporizing systems and arbitrary safety valves. The energy specific relief areas allow the minimum required relief area quickly to recalculate if the energy input of the reactor is known. In addition, the application of solvents in multi-purpose plants can be evaluated from a safety point of few.The energy specific relief areas are calculated based on a relief of two-phase gas/liquid mixtures. The data have been determined with the non-equilibrium HNE-DS method, which takes into account the boiling delay of the liquid in the safety device and the slip between gases and liquids. The method is recommended in the international standard ISO 4126 part 10. In addition, practical advice and possible improvements are outlined. The method leads to significantly smaller relief areas than according to the API 520. For multi-purpose plants with available safety devices this method allows for a considerable expansion of the application range of reactors.     

Sizing pressure relief valves in flashing and two-phase service: an alternative procedure

In view of the greater accuracy of the ω HEM correlation and the resulting conservative PR valve sizing (relative to the traditional PR valve sizing methods), the ω HEM-based flow calculations are recommended for all situations where flashing or two-phase flow occurs within the PR valve. However, as with any correlation, the accuracy of the ω HEM correlation results drops as the system to which it is applied diverges from the data used to develop it. Analysis of 15 different systems representative of actual refinery streams indicate that for fluids with a wide boiling range and for very non-ideal systems such as those containing hydrogen, the HEM correlation underpredicts the mass flux significantly (i.e. overpredicts the PR valve size). Since the large deviations are on the conservative side, the procedure will result in excessively large PR valves that may cause problems because of chattering of the PR valves, but would not present potential for vessel failure. The majority of the deviations are a result of the fact that the simplifying assumptions built into the correlation for single component do not truly characterize the actual flashing behaviour of many multicomponent fluids. The alternative approach presented, in which the correlation parameter ω is based on the actual flashing behaviour, eliminates nearly all the deviations and significantly improves the results of the correlation regardless of the system analysed. For trouble systems (those containing more than 0.1 wt% hydrogen and for some multicomponent fluids with a nominal boiling range greater than 80°C (150°F), the alternative approach should be used to define the correlation parameter ω. Use of this alternative approach is valid for any system (and will improve the accuracy of the correlation) but does require an additional flash calculation. However, for other systems the original formulation of ω is adequate and can be used.     

Impact of flood water on the technical condition of natural gas transmission pipeline valves

Maintaining the reliability of a transmission system's operation is an extremely important issue in the context of ensuring the continuity of gas delivery to customers. Threats to maintaining the reliability of a transmission system's operation may appear at any stage of transmission, and the most common reasons for this are corrosion, material defects or accidental damage. The paper presents the impact of flood water on transmission valves in the context of possible threats to ensuring the technical safety of gas supplies. Hazards are described which relate to the chemical composition of flood water, which may cause corrosion of valve elements and risk of loss of gas pipeline stability caused by flooding. In the context of the design of a natural gas transmission network, the strength aspects and the phenomenon of corrosion are described. The results of tests related to a specific example are presented. The finite element method (FEM) is used to build ball valve models. Two types of valves are modelled for nominal pipeline diameters of 50 mm (DN50) and 200 mm (DN200). The results of the presented analysis show that the leak tightness of the tested valve flange connections was mainly influenced by changes in their operating conditions because the occurring additional forces and moments caused significant changes in the load balance of the flange connections.     

Partial stroke testing of process shutdown valves: How to determine the test coverage

Partial stroke testing (PST) has recently been introduced as a semi-automatic means to test process shutdown valves. Normally, this type of testing does not disturb the process and can detect many of the failures that traditionally have been revealed only by functional testing. The fraction of all dangerous failures that are detected by PST is called the PST coverage and is decisive for the effectiveness of the PST. So far, limited guidance on how to determine the PST coverage has been given. This paper discusses the application and limitations of PST and suggests a new procedure for how to determine the PST coverage factor.     

气体管道中阀门内漏声发射信号特性研究

针对石化企业气体阀门内漏在线诊断问题,设计并建立气体截止阀内漏检测实验装置,根据声发射技术理论与实验相结合研究截止阀内漏特性,对比不同压差下信号参数分布规律。结果表明,阀门泄漏率与信号振幅和平均信号电平ASL均呈指数分布,与能量和均方根AERMS呈对数分布,并拟合了泄漏率与AERMS的函数关系式。因此,可以综合各对应关系对阀门是否泄漏进行检测,并利用泄漏率与AERMS的函数关系式定量估算阀门泄漏率。     

Dynamic behaviour of direct spring loaded pressure relief valves in gas service: II reduced order modelling

A previous study of gas-service direct-spring pressure relief valves connected to a tank via a straight pipe is continued by deriving a reduced-order model for predicting oscillatory instabilities such as valve flutter and chatter. The reduction process uses collocation to take into account a finite number N of acoustic pressure waves within the pipe, resulting in a set of 2N+3 ordinary differential equations. Following a novel non-dimensionalization, it is shown analytically that the model can exhibit, at experimentally realistic parameter values, instabilities associated with coupling between the valve and acoustic waves in the pipe. The thresholds for each instability are such that for a given flow rate, the first mode to go unstable as the inlet pipe length increases is the quarter-wave mode, then a three-quarter wave, a 5/4-wave etc. Thus the primary mode of instability should always be due to the quarter wave. In the limit of low flow rates, a simple approximate expression is found for the quarter-wave instability threshold in the form of inlet pipe length against mass flow rate. This threshold curve is found to agree well with simulation of the full model. For higher flow rates there is a need to include fluid convection, inlet pressure loss and pipe friction in order to get good agreement. The reduced model enables the dependence of the stability curve on key dimensionless physical parameters to be readily computed.     

Reducing the risk level for pipelines transporting carbon dioxide and hydrogen by means of optimal safety valves spacing

In many countries where electricity generation is based on their natural resources of fossil fuels a need arises to implement new power engineering technologies that allow carbon dioxide capture. Simultaneously, efforts are made to find new energy carriers which, if fired, do not involve carbon dioxide emissions. Hydrogen is one of such fuels with this future potential which is now becoming increasingly popular. Obviously, this means that the two gases mentioned above – carbon dioxide and hydrogen – will be produced in large quantities in future, which in many cases will necessitate their transport over considerable distances. If a pipeline failure occurs, the transport of the gases may pose a serious hazard to people in the immediate vicinity of the leakage site. This paper presents an analysis of the possibility of reducing the level of risk related to pipelines transporting CO₂ and H₂ by means of safety valves. It is shown that for a 50 km long and a 0.4 m diameter pipeline transporting gas with the pressure of 15 MPa the individual risk level can be reduced from 1·10⁻⁴ to 6.5·10⁻⁷ for CO₂ and from 1·10⁻⁶ to 6·10⁻¹⁰ for H₂. The social risk can be diminished in similar proportions.