毕业论文外文翻译-纸浆和造纸行业中的无水氨压力容器

1、附录一外文原稿:anhydrous ammonia pressure vessels in the pulp andpaper industrythe purpose of this article is to ensure that pulp and paper operating companies, their engineering consultants, and inspection contractors are informed about stress corrosion cracking in anhydrous ammonia service. the informati

2、on was written by a task group of the tappi engineering division nondestructive testing and quality control subcommittee.bacteria in some activated sludge effluent treatment systems require supplementary food. in some cases, this food is provided by ammonia and phosphoric acid which are stored on th

3、e mill site. ammonia is commonly stored as anhydrous liquid ammonia in carbon steel vessels at ambient temperature and 16 bar (250 psig) pressure.these vessels can be subject to stress corrosion cracking (scc).scc could cause release of ammonia, which is a hazardous chemical. scc of carbon steel ves

4、sels in anhydrous ammonia service is somewhat analogous to that experienced in continuous digesters. for example, the importances of stress relief during fabrication and of in-service inspection are common to both. this article concerns storage in horizontal pressure vessels at ambient temperature,

5、as this type of vessel is used in pulp and paper applications. large refrigerated storage tanks are used for atmospheric pressure storage in the chemical industry.history of see in ammonia storage vesselsthe history of scc in carbon steel ammonia storage vessels was reviewed by loginow (1) and is al

6、so briefly summarized in a nace technical committee report entitled "integrity of equipment in anhydrous ammonia storage and handling (2). in the 1950s, liquefied ammonia began to be injected directly into soil for fertilization. failure of carbon steel storage vessels by scc began to occur. th

7、ese failures were unexpected since liquefied ammonia had been used for many years in the refrigeration, chemical, and metal heat treating industries without reported problems.investigation confirmed scc to be the cause of cracking. three recommendations weremade in 1962 that still form the basis of

8、modern codes: pressure vessels should be fully stress relieved. extreme care should be used to eliminate oxygen from ammonia systems. ammonia should contain at least 0.2% water to inhibit scc.loginow reported that adoption of these recommendations practically eliminated scc in carbon steel vessels i

9、n the agriculture industry. however, in a recent western canadian survey scc was found in 100 of 117 field storage vessels inspected by wet fluorescent magnetic particle testing (wfmt) (3).despite the above measures scc continued to occur in road transport tanks constructed from high strength steels

10、, in refrigerated storage vessels and in vessels which had been weld repaired but not subsequently stress relieved. an additional recommendation to limit steel tensile or yield strength was embodied in the u.s. and british ammonia storage codes, respectively (4, 5). ansi k61.1一nominal tensile no gre

11、ater than 70,000 psi (580 mpa) u.k. code一minimum specified yield strength shall not exceed 350 mpa (51,000 psi).practical considerationsthis article is concerned mainly with practical considerations important to pulp and paper mills already possessing anhydrous ammonia storage vessels or planning to

12、 fabricate such vessels. in view of the industry9s experience with scc in continuous digesters the governing objectives should be to control fabrication and inspection to prevent, or at least minimize, in-service problems including over-reaction to relatively minor crack indications. guidance is ava

13、ilable in the published codes and detailed information is available from some ammonia suppliers.fabricationthe two main objectives in fabrication should be to provide the most crack resistant vessel possible at reasonable cost and to ensure that an adequate inspection baseline is available for inter

14、pretation of subsequent in-service inspections.asme section viii division 1 does not require stress relief for anhydrous ammonia storage pressure vessels unless the owner specifies a lethal service designation.the lethal service designation requires radiographic testing (rt) of all butt welded joint

15、s plus post weld heat treatment.ansi k-61.1 -1989, "american national standard safety requirements for the storage and handling of anhydrous ammonia j adds several requirements: fabrication to asme section viii division 1 table uw 12 at a joint efficiency less than 80% is not allowed. inspectio

16、n and testing under ug-90(c) (2) (multiple, duplicate pressure vessel fabrication) is not allowed. steel used for pressure containing parts shall have a nominal tensile strength no greater than 580mpa (70,000 psi). the minimum design pressure for ambient temperature storage shall be 16 bar (250 psig

17、). post weld heat treatment is mandatory and a furnace of sufficient size to accommodate the entire vessel is recommended. welded attachments may be made to pads after post weld heat treatment. horizontal vessels shall be mounted on saddles which extend over at least one third of the shelts circumfe

18、rence. thermal expansion and contraction shall be allowed for and means provided to prevent corrosion between the shell and the saddles.the 1986 british code "storage of anhydrous ammonia under pressure in the united kingdom requires: steel must have specified minimum yield strength less than 3

19、50 mpa (51,000 psi). weld filler must have minimal strength overmatch compared with the base plate. 100% magnetic particle inspection of all internal welds in order to provide a record against which all future inspections of the vessel can be assessed. no welding is permitted after stress relief wit

20、hout subsequent local stress relief. concrete saddles are prohibited. support must be on continuously welded steel saddles attached before stress relief.although the british code does not state that magneti particle inspection should be by wfmt it is generally agreed that wfmt is the most sensitive

21、technique and should be used for inspection of ammonia storage vessels. all inspection should be performed by qualified technicians. snt-tc-1a level ii is a recommended minimum.one pulp and paper company has added the following requirements for fabrication of such vessels: incorporation of a "c

22、orrosion allowance of at least 1.6 mm (1/16 in.) to permit minor defect chasing during in-service inspections and to provide a margin against pitting which may occur if water is allowed to enter an out of service vessel. all weld toes profiled by grinding prior to wet fluoresce nt magnetic particle

23、testing (wfmt). all wfmt indications greater than 1.6 mm (1/16 in.) to be removed by grinding before post weld heat treatment. shear wave ultrasonic testing (ut) of nozzle-to-shell welds permitted if rt is judged impractical. wfmt to be repeated after final hydrotest test of the vessel and the repor

24、t retained by the owner. vessel to be dried completely after hydrotest test and nitrogen padded until filled with ammonia.valves, piping, and fittingsboth the ansi and u.k. codes address piping, valves, and fittings. a detailed summary is beyond the scope of this article, but some points are worth n

25、oting. ansi k61.1 requires all nonrefrigerated ammonia piping to meet the requirements of ansi/asme b31.3 "chemical plant and petroleum refinery piping." the u.k. code states copper and copper bearing alloys shall not be used.ansi/asme b31.3 requires a minimum of 5% of piping welds be radi

26、ographically tested. valves and other apparatus should be rated for ammonia service and should not contain copper or copper alloy components.in one case, a nickel rupture disc corroded to failure at its periphery due to formation of an ammonia solution at a gasketed joint exposed to the weather.inse

27、rvice inspectionvessel entry liquid or gaseous ammonia is hazardous and in some jurisdictions release of ammonia vapor to the atmosphere is prohibited by law. vessels must be properly purged by water and/or steam. detailed procedures for vessel purging and entry are available from ammonia suppliers

28、(6丿.inspection procedures the ansi standard does not address in-service inspection but does state weld repair or alteration must conform to the current edition of the national board inspection code (nbic).the 1992 edition of the nbic includes nonmandatory guidelines for inspection of liquid ammonia

29、vessels (7).these guidelines recommend: power buffing or light sandblasting as surface preparation for inspection all interior welds be examined by wfmt. cracks should be removed by grinding without encroaching on the minimum thickness required by asme section viii and the original design. weld repa

30、irs, regardless of size, should be post weld heat treated wherever possible.light grinding does increase the sensitivity of wfmt compared to sandblasting or power buffing (8). for example the nbic mandates grinding as surface preparation for deaerator inspection. the omission of grinding in the guid

31、elines for ammonia vessel in-service inspection may be due to concern that rough grinding may produce residual stress sufficient to initiate scc in an hydrous ammonia service. if welds have been properly profiled for wfmt on initial fabrication, then grinding for in-service inspection should not be

32、needed.the nbic guidelines also state that other inspection methods such as acoustic emission or ultrasonics may be used and that fracture mechanics may be used to assess the integrity of vessels where complete removal of cracks is not practical.normally the only corrosion that occurs in anhydrous a

33、mmonia vessels is due to water ingress during out of service periods. shallow pitting, however, has been found in the bottom of some vessels beneath oily deposits. the source of oil is presumed to be from compressors used to handle the ammonia.in view of concerns over air contamination due to vessel

34、 entry and residual stress imparted by grinding nonintrusive inspection, techniques like acoustic emission and ut could be considered by vessel owners. the british code does not mention nonintrusive inspection of ambient temperature pressure vessels but does state that, if acoustic emission is to be

35、 used for spherical storage vessels, a reference base should be taken during initial hydrotesting. nonintrusive inspection is being used in other industries (9).vessel refilling safety procedures should be established for refilling a vessel that has been emptied for inspection. it is also very impor

36、tant to purge the vessel of air to prevent the occurrence of scc. detailed instructions are available from ammonia suppliers (10). if a vessel is not to be returned to service immediately after inspection, then care should be taken to dry it and possibly nitrogen-pad it depending on the time it will

37、 remain out of service.inspection frequency neither the ansi document nor the nbic deals with inspection frequency. the british code recommends the following: wfmt inspection of 100% of all internal butt welds within the first three years of service wfmt re-inspection within 2 years if significant d

38、efects are found subsequent to no significant defects being found, any subsequent inspection should include wfmt of all tee junctions and 10% of the total length of butt welds in no case should the subsequent examination interval exceed 6 years.it is apparent from the above that latitude can exist f

39、or in-service inspection techniques andfrequencies. each owner should determine inspection frequency in conjunction with the appropriate authority. some jurisdictions require a 3-year inspection frequency.summarythe use of carbon steel pressure vessels for storage of anhydrous ammonia in the pulp an

40、d paper industry could be a non-event or deteriorate into a cycle of inspection and repair. this article has highlighted major concerns related to scc. there is a wealth of additional information available on all considerations related to these vessels from the ansi and british codes, the nace docum

41、ent, ammonia suppliers, and the current technical literature. the american institute of chemical engineers (aiche) holds the annual aiche ammonia safety symposium aimed at finding ways to safely manufacture, transport, and store ammonia and related chemicals. the proceedings of these symposia are pu

42、blished by aiche it is recommended that any owner of such vessels keep aware of current expertise.reid is materials and corrosion section head with macmillan bloedel research, 4225 kincaid st., burnaby, bc, canada v5g 4p5.task group members: craig reid; r.s. charlton, levelton associates consulting

43、engrs.; r.c. faloon, mqsinspections inc.; and w. e boudreau, belle testing inc.literature cited1. loginow,a.w., materials performance 25 (12): 18(1986).2. nace technical committee report 5ai92, integrity of equipment in anhydrous ammonia storage and handling, houston, nace storage tank, spokane, 199

44、2.3. stephens, j. d. and vidalin, f., 1994 aiche ammonia symposium notes. american institute of chemical engineers, new york, p. 9.4. compressed gas association inc.，american national standard safety requirements for the storage and handling of anhydrous ammonia ansi k61-1989, arlington, va, 1989 (c

45、ga pamphlet g2 1989).5. storage of anhydrous ammonia under pressure in the united kingdom, london, her majesty's stationery office, 1986. (health and safety booklet hs/g 30)6. cominco fertilizers (u.s.) inc., decommissioning an ammonia storage tank, spokane, 1992.7. the national board of boiler

46、and pressure vessel inspectors, national board inspection code: a manual for boiler and pressure vessel inspectors, columbus, oh, 1992, p.197.8. reid, j. c. and reid, c., tap pi 1992 engineering conference proceedings, tappi press, atlanta, book i, p.163.9. conley, m. j., sture, a., and williams, d.

47、, "ammonia vessel integrity program: a modern approach, 1990 aiche ammonia symposium notes. new york, aiche, 1990.1() cominco fertilizers (u.s.) inc., "commissioning an ammonia storage tank： spokane, 1992.附录二外文翻译：纸浆和造纸行业中的无水氨压力容器本文的目的是为了确保纸浆和纸张经营公司，他们的工程顾问，承建商了解 在脱水氨设备中的应力腐蚀开裂现象。这篇资料是由美国纸浆

48、与造纸工业技术协 会无损检测工程部和质量控制小组委员会共同编写。细菌生存在一些活性污泥污水处理系统中需要充足的食物。在某些情况下， 这种食品是氨和磷酸的储存现场。氨通常以无水液氨的形式贮存在室温和 1.6mpa (250磅)的压力的碳钢容器中。这些容器可能会受到应力腐蚀开裂(scc)o应力腐蚀开裂可能导致氨泄露， 这是一种危险化学品。用于无水氨设备的碳钢容器屮的scc是有点类似于连续 蒸煮罐的经验。例如，减少压力的引入在生产和在役检查过程都是很常见的。本 文关注在常温下的卧式压力容器，像这类型容器通常用于纸浆和造纸的应用。大 型冷藏储罐在化工行业一般是常压储存。scc在氨储罐的历史scc在碳钢

49、氨储存容器的历史是由loginow （1）审查通过，也是在简要回顾 了 nace技术委员会报告题为“完整的设备在无水氨的储存和处理”（2）。在20 世纪50年代，液氨作为肥料直接注入土壤。碳钢贮存容器由于应力腐蚀开裂而 导致的故障开始出现。这些故障是意外，因为液氨己用于在制冷，化工多年，金 属热处理行业没有报告的问题。调查结果证应力腐蚀是开裂的原因。1962年提岀了三条建议构成了现代条 例的基础：压力容器应充分消除应力。要特别小心是消除氨系统中的氧气。氨应该包含至少0.2%的水，以抑制应力腐蚀开裂。loginow报告说，采用这些建议能有效避免应力腐蚀发生在农业用碳钢容器中。 然而，最近的加拿大

50、西部的调查显示通过湿荧光磁粉探伤检查（wfmt） （3）发 现117处农场的储罐中有100处发生了应力腐蚀开裂。尽管釆用了上述措施，scc仍然发牛在由高强度钢建造的公路运输油罐、 冷藏储存容器以及作了焊接修复却没后续的应力消除的容器。另外一条建议被纳 入美国和英国的氨储存条例，以限制钢材的拉伸或屈服强度。ansi k61.1 名义抗拉强度不超过70,000磅（580兆帕）英国条例指定的最低屈服强度不超过350兆帕（51,000磅）。实用的考虑本文主要关注是实际问题对于已拥有无水氨贮存容器的纸浆和造纸厂或计 划制作这类容器的重要性。以连续蒸发罐中scc的经验来看，执行冃标应该是 控制制造和检验，

51、以避免或至少减少在运行中的问题，包括过度反应相对轻微裂 缝的迹象。从一些氨的供应商提供公开条例和规范资料可以得到相关的指导。 制造制作中的两个主要目标应是提为抗裂容器供合理的成本，并确保为后续在役 检验的解释有适当的检验基线可用。asme第1部第viii节没有要求无水氨存储压力容器要应力消除，除非拥有者 指定了一个致命的部件名称。指定的致命部件需要焊接接头的焊后热处理加所有对接射线检测（rt）。美国国家标准化组织（ansi） k-61.1 - 1989,"美国国家标准无水氨的存储和 处理安全要求”増加了几个要求：制造符合asme第一部第viii节uw12表的效率不能低于80%。基于u

52、g-90（c）检查和测试是不允许的。用于压力容器部件的钢材的标称抗拉强度应当不低于580mpa （70,000psi）o室温储罐的最低设计压力应当为16bar （250 psig）的。必须进行焊后热处理，要求足够大的熔炉来适应整个容器。附件的焊接点 可能要进行热处理卧式压力容器应当安装在鞍座超过至少有一个壳体的周长三分之一。应允 许热膨胀和收缩和给岀以防止壳体和鞍座之间腐蚀的方法。1986年英国章程“英国常压无水氨储存”要求：钢材的指定最低屈服强度必须小于350兆帕（51,000磅）。焊接填充物的最小强度必须高于于比母材强度。100%的内部焊缝磁粉探伤，对未来所有的容器检查提供可以评估的纪录。

53、没有后续局部应力消除的应力消除后允许无焊接混凝土鞍座是禁止的。钢制鞍座连续焊接必须在应力释放之前。虽然英国规范并没有规定磁化粒子检查应当进行湿荧光磁粉实验，人们普遍认 为，wfmt是最灵敏的技术，应该用于检验氨贮存容器。所有的检查应该由合 格的技术人员来完成。snt-tc-1aii级是建议的最低水平。其屮纸浆和造纸公司已对这些容器的制造增加了下列要求：设立“腐蚀裕量”至少1.6毫米（1 / 16英寸），允许在役检验中出现的微小缺 陷，并在容器停止服役期间浸水，对可能出现的腐蚀保持一定的裕度，。湿荧光磁粉探伤（wfmt）检验所有焊接接头前要进行磨削。在焊后热处 理前，大于1.6毫米（1/16英寸

54、）所有wfmt迹象要被磨削。如果射线探伤不符合实际，可以使用横波超声波检测（ut）。容器水压试验后重复进行wfmt,由业主保留的测试报告。容器水压试验后要完全干燥，并且进行充氮保护直至填充氨。阀门，管道及配件ansi和英国压力容器规范都对管道，阀门和配件进行了论述。详细摘要已经超 出了本文的范围，但有些要点是值得注意的。ansi k61.1要求所有的非冷却氨管道要满足符合ansi / asme b31.3的 规定“化工厂和石油精炼厂管道。”英国压力容器规范规定铜及铜合金轴承不得使用。ansi / asme b31.3要求5%以上管道焊缝需要x线测试。阀门和其他设备应使 用标准的的氨部件，并且不

55、能含有铜或铜合金成分。在一个案例中，一个镀银爆破片腐蚀失效原因在于衬垫上的氨溶液的形成在役检查容器引进。液态或气态氨是危险化学品的，而且某些司法管辖区的法律禁止氨蒸 气释放到大气屮。容器必须用水或蒸汽妥善清除。从氨供应商获取详细的清洗和 引进说明（6）。检查程序。ansi标准不涉及在役检查，但要求焊接修复或改装，必须符合现行 版国家检测局规范（nbic）。该nbic 1992年版包括液氨储罐非强制性的检查指导。这些指导原则建议：抛光或喷砂表面处理为检查做准备所有的内部焊缝进行wfmt检测。裂缝应磨削处理以符合asme第八节规定的最小设计厚度。焊缝，不论尺寸，都应进行焊后热处理。轻微磨削相对喷砂

56、处理和电学抛光可以增加wfmt灵敏性相（8）o例如，nbic 要求磨削作为除氧检测的表面处理的准备。在氨储罐的在役检查指导中磨削的遗 漏可能是由于担心粗磨可能产牛的残余应力以致产牛应力腐蚀开裂。如果在初始 制造过程中焊缝因wfmt产生了合适的变形，那么在在役检查中磨削就没有必 要了。该nbic准则还规定，如可能使用声发射或超声波等检查方法，断裂力学可用于 评估那里的容器完整性裂缝彻底清除是不实际的。通常，腐蚀只发牛在无水氨储罐，是因为在停止运行期间渗入水。浅点蚀已发现在有些容器底部的油性沉淀物。油源被假定为从用来处理氨的压缩机。针对由于容器引进而产生的空气污染问题和磨削无损检测产生残余应力的问

57、题， 采用如声发射技术和ut的技术可以由使用者考虑。英国规范并没有提及常温常 压容器的无损检测，但指出了，如果声发射检测要用于球形储存容器，应当在初 始水压试验采取相应的参考。无损检测应用于其他行业。储罐填充。应该为因检查而清空的容器填充建立一个安全规程。这对于净化容器 空气防止发生应力腐蚀开裂是非常重要的。从氨供应商获取详细说明（10）。如 果容器在检查后没有被立刻送冋返修，然后应注意干燥，并有可能氮封它取决于 停止服役的时间。检查频率。无论是ansi文件或nbic没有处理检骑频率。英国规范建议如下：在首三年服役期wfmt100%检查所有内部的对接焊缝如果在两年内发现重大缺陷进行重新检查，继

58、无发现明显缺陷后，后续的任何检查应对所有t型接头和的对接焊缝总 长度的10%进行wfmt检测在任何情况下后续检查的时间间隔超过6年。从上述可以很明显看出在役检查技术和频率存在一定范围。每个使用者应与结合 相关部门确定检查频率。有些管辖区需要3年的检查频率。总结对纸浆和造纸工业的碳钢无水氨储存压力容器的使用可能是一个非活动或进入 检查和维修的恶性循环。本文重点关注的是应力腐蚀开裂。从ansi和英国规范, nace文件，氨储罐供应商和现行的技术文献可以获取的大量有关注意事项的信 息。在美国化学工程师学会（aiche）举行的年度合成氨安全研讨会旨在发现在 安全生产，运输和储存氨及相关化学品的方法。这些专题讨论的会议记录aiche 公开发表。它建议任何此类容器的所有人应及时了解当前的专业知识。里德材料和麦克米兰布勒德尔研究，4225金凯德街，本拿比，bc,加拿大v5g 4p5腐蚀科科长。工作组成员：克雷格里德；r.s.查尔顿levelton协会咨询工程部。r.