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1、? 朱连顺 (中国成都化学工程公司) ?压力容器破裂的主要原因是焊接质量低劣,指出了影响焊缝质量的因素,论述了 焊缝结构设计基础及焊缝设计应注意的问题。 ?焊缝结构 焊缝裂纹 手工电弧焊 埋弧自动焊 压力容器成形采用电焊,导致压力容器破坏的 主要原因是焊缝质量低劣。根据国内外压力容器 事故分析,因裂纹而导致事故占总事故的50 % 89 %,英国因裂纹造成的事故占89 %,中国因裂纹 造成的事故占50 %(因焊缝裂纹造成的事故占37. 5 %) 1。因此 ,提高压力容器焊接质量是确保压力 容器安全运行的重要环节。本文就影响焊缝质量 的因素及焊缝设计应注意的一些问题做了探讨。 1? 1. 1设计因
2、素 设计人员往往只注意焊条、 焊丝、 焊剂及对接 焊缝系数。设计院除特殊工况(疲劳、 低温、 大的 温度梯度、 毒性极度危害介质等)对壳体焊缝作说 明外,一般只画节点图或标注焊接结构序号,不作 是否焊透或检验要求等说明。忽略了如何设计出 接管与壳体焊缝形式、 几何尺寸,对焊接工艺缺乏 了解。 某氮肥厂氨合成塔图纸,对接焊缝的设计见 图1a。合成塔外壳设计压力P= 15. 7MPa ,T= 200,?1 200mm76mm(16 + 10 6) 多层卷板。 技术要求栏注明焊接材料J507 ,焊丝16MoSi焊 剂250。 a.筒体对接焊简图 b. U、V形坡口双面手工 c. U、V形坡口正面埋弧
3、自动 电弧焊(环焊缝) 焊背面手工电弧焊(环焊缝) 图1 筒体对接焊简图(焊接方法不同) 从图纸看,手工电弧焊和埋弧自动焊的坡口 形式及尺寸一样,实际上,焊接工艺不同对坡口形 式和尺寸影响很大。当容器壁厚S76 mm时, 正确的做法是U、V形坡口双面手工焊如图1b所 示,U、V形坡口正面埋弧自动焊背面手工电弧焊 如图1c所示。另外,对多层包扎高压容器特别强 调:内筒A类焊缝全焊透,焊后做消除残余应力 热处理,外观检查合格后进行100 %的RT或UT 检验,外表面做机加工或修磨平滑;层板包扎前应 清除铁锈、 油污和影响贴合的杂物;下层包扎前将 前一层C类焊缝磨平滑,各层C类焊缝均应错 开;每层包
4、扎按图样要求钻泄放孔等。焊接工艺 051 化 工 机 械 1999年 朱连顺,男,1942年8月生,高级工程师。四川省成都市,610041。 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. 规程按图样要求和评定合格的焊接工艺制定。图 纸的坡口应当合理准确。 1.2焊接坡口的形状和尺寸主要取决于材料和 焊接工艺 焊接不同材料,焊缝坡口的形状和尺寸也有差 异。如普通碳钢由于焊接热不敏感,可采用高线能 焊接规范,坡口截面应当大些;焊镍、 铬不锈钢时, 坡口截面应当小些,因这种材料焊接热敏感,应采 用低线能
5、焊接,并且避免焊热的多次作用。 焊缝坡口的形状和尺寸与焊接方法有关。手 工电弧焊由于熔深较浅,6 mm以上的钢板就需开 V形坡口;而埋弧自动焊具有深熔的特点,20 mm 以下的钢板可以不开坡口。又如手工电弧焊与气 体保护焊相比,前者的开口角度较大些。这是因为 手工电弧焊的焊条直径较粗,焊缝表面覆盖较厚的 熔渣层,较大的坡口能使焊条伸入坡口底部,便于 脱渣。气体保护焊焊缝表面无熔渣,焊丝直径较 细,故可采用张角较小的坡口。熔化气体保护电弧 焊的V形坡口一般为4550,而手工电弧焊V形 坡口大于60 。 另外,焊缝坡口形式和尺寸的选用,还与制造 厂的加工能力有关,V、X形坡口用半自动切割机即 可制
6、备,其缺点是填充金属较多,焊接效率较低。 U形坡口与V形坡口相比,坡口容积较小。U形 坡口的侧面斜度取决于焊接方法,手工电弧焊和熔 化极气体保护焊可取25,埋弧焊510 范围内。 1.3自觉遵守焊接规范,提高焊工的焊接技术和 知识水平 1.4制造厂应有全过程的质量保证体系 对焊工要求持证上岗,在规定部位打上焊工钢 印。 焊材应保存在相对湿度不大于60 %的库里。 施工环境:风速对手工焊不大于10 m/ s;对气体保 护焊不大于2 m/ s;相对湿度不大于90 %,雨、 雪天 不施焊。焊接工艺按 “压力容器焊接工艺评定” 进 行焊接工艺评定,焊接工艺规程应按图样要求和评 定合格的焊接工艺制定。焊
7、缝外观不允许有裂纹、 夹渣、 气孔、 弧坑和熔渣等。焊前预热:施焊处100 mm范围内预热15 左右;焊件温度低于0 时必 须预热。质量保证体系的每个环节都有文字记录。 2? 2.1焊缝结构设计基础 焊缝的设计是在等强度的基础上,即焊缝与相 邻母材具有相同的强度。一般不需要使用大于规 范图中所示的焊缝尺寸。 2.2焊缝结构设计 2.2.1焊缝坡口设计 坡口及间隙对焊缝质量有直接影响,因此,应 提高坡口尺寸的精度。图纸上焊接接头的形式可 采用序号、 标准代号、 节点图3种表示方法中任意 一种,当采用前两种方式时,必须注明标准号和名 称。 某设计院三类压力容器图纸上技术要求栏 中:焊接材料J507
8、 ,对接焊缝代号标准见节点图。 但装配图中并未见对接焊缝详图,只在部件图中, 有受压元件边缘加工图,如图2a所示。正确的做 法是应在装配图中,分别画出环焊缝、 纵焊缝详细 节点图,如图2b、c所示。 焊缝坡口尺寸不完整、 不准确,制造厂按照图 施工,故难以保证焊接质量。 a.坡口 b.环型焊缝 c.纵焊缝 图2 对接焊缝 151第26卷 第3期 化 工 机 械 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. 2. 2. 2接管与筒体的焊接 美国ASME规范认为,接管设计应最大限度 地降低应力集中。最
9、安全的容器是各部分都具有 最低的总应力(一次应力加应力集中等 ) , 而不是 在一次薄膜应力上取最大的安全系数,不管局部 应力集中。所以,有效降低应力集中值是设计接 管与容器间焊缝时应特别重视的问题。 一部分设计人员对接管与筒体间焊缝不够重 视(除接管直径大,做开孔补强计算外 ) , 大量的接 管设计都不能遵循下面原则: a.焊接接头的强度不低于母材标准规定的 抗拉强度下限。 b.合理选择坡口角度、 钝边高、 根部间隙等 结构尺寸,使之有利于坡口加工及焊透,以减少各 种焊接时产生缺陷。 c.焊缝表示应完整、 准确。当以标准代号标 志焊缝形式时,在引出线尾部分叉处应标注接头序 号、 是否焊透、
10、铲根要求、 检验方法等,如图3所示。 图3 焊缝形式标注示例 在同种工况下,接管的直径及受力不同,应选 择不同焊缝结构。美国ASME规范应力分析篇提 出,不受外载的接头、 仪表接管、 检查孔等可采用部 分焊透或填角焊缝2。我国的压力容器焊接规范 在这方面未有明确规定。某设计院的一类容器图 纸,接管N1、N2、N3、N4、N5分别为250、50、200、25、 20mm ,接术要求:接管与筒体焊接见节点图(图 4) ,这种焊缝结构对直径小的接管,尤其对 ?25mm 3mm接管是很不合理的。因为筒体与接管壁厚 相差4倍,填角焊缝高10mm ,焊缝余高6mm ,焊缝 的金属量太多,使接管产生过热甚至
11、焊穿。另外, 从焊缝设计等强度理论,也不需要这种结构。 图4 接管与筒体焊缝 3? 压力容器的焊接质量是个系统工程,在我国 跨过设计和制造两个独立的体系,因此在抓设计 质量的同时也要抓制造质量。设计者应学习了解 制造、 焊接方面的知识,以便根据不同材料、 不同 焊接工艺设计出合理的焊缝坡口形式。另外,要 加强焊接质量保证体系,对焊工要求、 焊接工艺规 定、 焊接材料保管、 施焊环境、 焊前预热及焊缝外 观检查等方面必须有全过程的质量保证体系。 对不受外力的温度计、 液面计、 仪表、 检查孔 等接管与筒体焊接,应按实际情况规定可否允许 部分焊透或填角焊等。 GB985288/ 3中H= -p 2
12、 的规定是否合理? 按此规定U、V形坡口两侧深度相等,只是多一种 机加工形式。笔者认为改H= 102 mm为宜。 因为这种坡口多用于厚壁筒体环焊缝,外侧U形 坡口深度大,施工方便,省焊接金属;内侧V形坡 口深度小,机加工简单,施工量小,结构合理。 ? 1 钱逸等.压力容器安全技术基础.北京:中国劳动出版 社,336 2 ASME Boiler and Pressure Vessel Code. An Internation2 ally Recognized Code ,Section. Rule for Construction of Pressure Vessels. Division 22
13、Alternative Rules. ASME Boiler and Pressure Vessel Committee Subcommittee on Pressure Vessels. 1995. (AD D26)AD - 621 (收稿日期:19982122 14) 251 化 工 机 械 1999年 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. ABSTRACTS Researches on energy consumption mechanism and energy2 saving p
14、rinciples of hydrocyclones.?. Optimum Energy2Saving Principles. Chu Liangyin , Chen Wenmei , Li Xiaozhong , Liu Peiklun(Sichuan University ,Chengdu ,Sichuan ,China) (125) A study was made of the matching optimum of the saving energy and the reinforced separation performance of hydrocy2 clones. The r
15、esults show that the reduction of energy consump2 tion and the reinforcement of separation performance of hydrocy2 clones were in good agreement ,and an optimum energy2saving principle was proposed of considering both the saving energy and the reinforced separation performance ,the influence laws of
16、 en2 ergy consumption coefficients and the operation cost criterion were studied ,the basical data of an optimum structure assembly were systematically given when hydrocyclones took various pro2 cess indexes as objective functions ,and the design guide of opti2 mum saving energyof the hydrocycloneso
17、perating in variouspro2 cess working conditions was provided. K ey Words : Hydrocyclone , Energy Consumption , Saving Energy ,Separation Performance ,Optimum Influences of axisymmetrical inlet with revolving passages on the separation characteristics of cyclone separators. Diao Y ongfa(Xian Jiaotong
18、 University , Xian Shaanxi , China) Jin Weiwei (Xian University of Architect & T echnology ,Xian , Shaanxi ,China) Shen Henggen Xu Jinyuan(Xian Jiaotong Uni2 versity ,Xian ,Shaanxi ,China)(130) The inlet of a single2inlet cyclone separator was made the axisymmetrical inlet with a revolving passage ,
19、i. e. the double2in2 let passage lengths were the same as the single2inlet passage lengths for the non2axisymmetrical gas flow in the single2inlet cyclone separators. The influence of the axisymmetrical inlet with a revolving passage on the separation performance of cyclone sep2 arators was analysed
20、 in the fieldsof the inlet gas volume ,the dust concentration at inlet ,the resistance loss of cyclone separators. The calculation comparison of grading separating efficiency shows that the separation performance of the new type cyclone separa2 tors is not only superable to that of the single2inlet
21、cyclone sepa2 rators,but also to that of Strairmand high2efficient cyclone sepa2 rators. K ey Words :Cyclone Separator ,Inlet With Revolving Pas2 sage ,Axisymmetry ,Separation Characteristics ,Influence Researches on the welding seam stress of pressure vessels of titanium. Chen Jiguang( Yueyang Univ
22、ersity , Yueyang , Hunan , China) Li Gangling ( South China University of T echnology , Guangzhou ,Guangdong ,China)(133) The failure of pressure vessels of titanium wasproven to be origanatingfrom their welding seam through tests ,the stress of welding seams was strongest at the 510mm location from
23、 the welding seam roots ,was the 2. 283. 51 times of the bidirec2 tional intensificated calculating value of the cylinders ,and some new research themes of strengthening the welding seam strength and lowering the stress peak value of welding seams were pro2 posed. K ey Words :Pressure Vessel of Tita
24、nium ,Stress of Welding Seam , Welding Seam Root Influences of the magnetic pole structure on the seal per2 formance of magnetic fluid. Huo Liping ,An Qi ,Cai Renliang (East China University of Science and T echnology ,Shanghai , China) (136) The influences of compound modes and stage numbers of mag
25、netic poles ,of magneticfield directionof magnetic source ,and of seal clearance in a magnetic fluid seal apparatus on the seal performance were studied. The experimental results show that the seal performance of magnetic fluid became better with the in2 crease of the stage numbers and the reduction
26、 of seal clearance , and was related with the compound forms of magnetic poles and the magnetic field direction. K ey Words :Magnetic Fluid ,Seal of Magnetic Fluid ,Seal Performance Application researches on the rotary disc dynamic mem2 brane filtration technology for bacterium2enzyme separation pro
27、cess in enzyme preparation production. Wang Xiaojing , Su Wei ( Tianjin University , Tianjin , China) Yin Xin( Tianjin Maleable Cast Iron Plant ,Tianjin ,China)Jin Dingwu(Tianjin U2 niversity ,Tianjin ,China)(139) Through the experiments of the rotary disc dynamic mem2 brane filtration plants ,the b
28、acterium2enzyme separation of the fermentation liquids of2amylase and 2709 basic protease were made using the nuclear hole membrane. The experimental results show that the dynamic membrane filtration technology was avail2 able for the bacterium elimination in enzyme fermentation liquids in enzyme pr
29、eparation industries. K ey Words :Dynamic Filtration Membrane ,Enzyme Prepa2 ration ,Bacterium2Enzyme Separation Effects of retarder TBC on the automatic oxygenation of sulfite. Xiong Rongchun ,Wei Gang(Beijing Universityof Chemi2 cal T echnology ,Beijing ,China) Zhang Xinmin( The Ministry of Scienc
30、e and T echnology ,Beijing ,China) Zhang Xiaodong(Beijing University of Chemical T echnology ,Beijing ,China) (143) A study was made of the effectsof retarder TBCon the au2 tomatic oxygenation of sulfite through tests. The results show that the reaction primer of free radical chain copper ion can ac
31、celerate the reaction between sulfite andoxygen ,thefree radical absorbent retarder TBC can inhibit the reaction by eliminat2 ing the free radical generated in the oxygenation process of sul2 fite ,the pH,alkalinity ,and hardness of water have no effects on the reaction. The test results provide imp
32、ortant identification for the free radical mechanismof oxygenation of sulfite , and efficient methods of preventing sulfite failure in storage. K ey Words :Sulfite ,Retarder TBC,Free Radical Reaction , Initiator ,Radical Absorbent Calculation andanalyses of the axial thrust of the rotor in the high
33、pressure cylinder of a CO2centrifugal compressor under the condition of various rotary speeds andflowrates.Xi Guang , Wang Shangjin(Xian Jiaotong University ,Xian ,Shaanxi ,Chi2 na) (147) The change laws of the axial thrust of the rotor in the high pressure cylinder of a CO2centrifugal compressor in
34、 the working condition of various rotary speeds andflow rates were studied ,the accident cause of axis damage of the rotor in the high pressure cylinder of a CO2centrifugal compressor in the starting process was revealed based on measuring the performance curves of the impellers of the rotor. Some m
35、ethods of controlling the axial thrust and preventing the axis damage were proposed for the characteristics of 520 000t/ a urea plants in production. K ey Words :Centrifugal Compressor ,Rotor in High Pressure Cylinder,Non2Uniform Working Condition ,Calculation of Axial Thrust Welding seams of pressu
36、re vessels and their structure de2 sign. Zhu Lianshun(Chengdu Chemical Engineering Corporation , Chengdu ,Sichuan ,China) (150) 581第26卷 第3期 化 工 机 械 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. It was concluded that most of the crack causes were because of the bad welding q
37、uality ,the factors affecting welding seams quality were proposed ,the design basesof welding seam structure and the key problems in welding seam design were described. K ey Words :Welding Seam Structure ,Welding Seam Crack , Hand Arc Welding ,Submerged2Arc Automatic Welding Analyses of stress and d
38、eformation of the circle seam butt2 welding of cylinders.Ji Rundong(LianyungangJunior Colledge of Chemical T echnology ,Lianyungang ,Jiangsu ,China) (153) The stress and deformation of the circle seam butt2welding of thin2wall cylinders were discussed and analysed by using the approximate calculatio
39、n method of column shell theory ,the law was quantitatively given of the after2welding resdual stress and deformation varying with the sizes and welding conditions of cylinders. K ey Words :Thin2Wall Cylinder ,Butt2Welding Seam ,Stress and Deformation Application of fluoroplastics2graphite plate hea
40、t exchang2 ers in the production of aluminium sol.Wang Shihong ,Yin Xix2 iang,Ma Zhongfu (Lanzhou Petroleum Processing & Chemical Complex ,Lanzhou ,Gansu ,China) Yi Gewen ,Liu Gang(Res. Inst of Chem. Mach of the Ministry of Chem. Indu ,Lanzhou ,Gansu , China) (157) The selection and application of f
41、luoroplastics2graphite plate heat exchangers in theproduction of aluminium sol werepresent2 ed. These exchangers have advantages in application comparison with other kinds of exchangers. The high corrosion resistance , high efficient heat exchange ,and seal give these heat exchangers a long service
42、life. K eyWords : PlateHeatExchanger ,Fluoroplastics , Graphite ,Application ,Corrosion Development of the LHSY211.5 Ndouble2spiral cone2shape mixers. WangJun(Chemical Machinery Plant ,Lanzhou Chemical Industry Corporation , Lanzhou ,Gansu ,China) (159) The characteristics , structure , design and m
43、anufacture of major components of the LHSY211.5N double2spiral cone2shape mixers were presented ,and the assembly and test2run of the ma2 chine were described. K ey Words :Double2Spiral Cone2Shape Mixer ,Design ,Man2 ufacture T echnology Overhaul technology of 800 m2forced circulating evapora2 tors.
44、 Guo Xugong ,Lin Qiwen(Zhongzhou Aluminium Plant ,Chi2 na Great Wall Aluminium Corporation ,Jiaozuo ,Henan ,China) (162) It was presented of the technical problems and treatment methods in the overhaul of replacing tubes in the heating cham2 bers of 800 m2forced circulating evaporators in Zhongzhou
45、Alu2 minium Plant. K ey Words :Forced Circulating Evaporator ,Heating Cham2 ber ,Expansion Tube ,Shell Side ,Tube Side A study on the manufacturing technology of the big2diame2 ter, thin2w all vessels of titanium? ? ?deacidificating columns. Kang Shichen , Niu Hai (Shenyang TV University , Shenyang
46、, Liaoning, China) Lin Ruiguang ( Shenyang Thin Plate Plant , Shenyang ,Liaoning ,China)(165) The design ,manufacture ,check ,and some characteristics of deacidificating columns of titanium were discussed. K ey Words :Titanium ,Deacidificating Column ,Manufactur2 ing T echnology Retrofit of stuffing
47、 boxes of 512 circulating gas compres2 sors.Luo Qiangyin ,Fang Kejun ,Wei Zhiqiang(Synthesis Ammo2 nia Plant ,Juhua Share Corporation ,Quzhou ,Zhejiang ,China) (167) The structure defects of old stuffing boxes were analysed , and a retrofit plan was presented. K ey Words : Circulating Air Compressor
48、 , Stuffing Box , Structure Retrofit Research status and development of the reinforced shell and tube heat exchangers. Cui Haiting , Yao Zhongpeng ,Wang Ruijun(Beijing University of T echnology ,Beijing ,China) (168) The structure characteristics , reinforced results , suitable working conditions , and application were analysed in detail of re2 inforced heat exchangers based on the reinforced mechanism of the reinforced heat transfer ,a theoretical