金宗公司化工设备的焊接技术
发布日期:2013-01-04
阅读量:1566
审查化工设备的制造工艺除要看设计是否符合现有制造标准外,还要看现有工艺条件下,设计各种要求能否经济的到达。如果遇到困难,可从修改原设计和改进现有工艺条件入手。出现的困难可以说基本来自两类原因,一是结构的问题,另一是材料的问题。

  从制造工艺的角度看,一个好的化工设备结构设计,只就焊接方面而言,至少要妥善考虑以下几个方面的问题:减少焊接残余变形和应力,不出现没有“可焊到性”的结构,尽可能便于焊接。如果一个焊接结构图纸中有的焊缝在现实焊接条件下根本看不到,则称没有“可焊到性,”具体些讲,手工电弧焊时焊工伸不到,看不清,手把摆动不灵活;埋弧自动焊的焊嘴伸不到,就算没有可焊到性。

  内径小于600毫米的长容器或管道,内焊缝一般都没有可焊到性。

  材料的焊接性在过去的文献成为可焊性,从现在的研究结果看,很难说金属材料间不存在可焊性,故用焊接性一词更恰当。

  材料的焊接性是指在一定的工艺条件下,焊接接头能符合质量要求的可能性。详细地说,材料在采用现有的某种焊接方法和工艺措施进行焊接时,能获得高质量的接头,不至于出现裂纹等严重缺陷,不致使机械性能指标和特殊性能指标明显下降的可能性就是该材料的焊接性。如果某种材料采用常见的焊接方法,勿须特殊的工艺措施既能获得高质量的焊接接头,就可以认为该材料的焊接性能良好;若需要采用特殊工艺才能达到要求,则该材料的焊接性一般;若采用特殊焊接方法也不能达到要求,则说明该材料焊接性不良,不适宜进行焊接。

  显然,设计化工设备过程中在选材时,除考虑材料能适应介质、温度和压力等需要外,焊接性也是一个必要考虑的问题。因为,若焊接性不好,材料焊接后焊接接头性能下降很明显,就会出现严重后果,否则难以制造出合格的产品。

  对焊接性影响的是以下物性:1膨胀系数2导热系数3热容量4熔点和沸点5密度

  在某中意义上讲,金相热处理性能是当今对材料焊接性影响最大的一种物性因素,也是最复杂的因素。

  在机械性能方面对焊接性有影响主要是塑性,若材料的塑性不强会在焊接热应力的作用下造成裂纹或提高在使用中发生脆断的倾向。

  焊接工艺是分析焊接性的必然结果,也是保证焊接质量的方法。当然,从理论上分析得到的结果必须经过可靠的实验方法加以评定才是准确的,无论是焊接性的优劣,还是焊接工艺的可靠与否都是如此。生产上使用的工艺必须是经过实验的工艺。

  把这种理论与实验相结合的活动称之为工艺活动。在冶金部门中,也用于化工容器等焊接用金属的开发,以保证供应材料能应用于焊接场合。

  不同的材料具有不同的焊接方法例如炭素结构钢的焊接。

  低碳钢设备的焊接

  焊条手工电焊弧这是低碳钢结构的基本焊接方法,特的适应力很强。

  中碳钢的焊接性较差,含碳量越高越差。主要的焊接缺陷是热裂纹、冷裂纹、气孔和接头脆性、有时热影响区里的强度还会下降。当钢中的杂质较多,焊件钢性较大时问题就越突出。

  所以,中碳钢的焊接工艺重点就是克服上述分析中的各种问题。

  焊接方法根据目前中碳钢焊件的主要任务和理想热过程中的要求,手工电焊弧是最恰当的方法,焊条采用相应强度级别的碳性低氢型焊条;大型铸件的焊接,当修补量较大时可考虑采用手工电渣焊,因为它在焊补大型铸件时都受到好效果,焊补中碳钢时困难肯定不少,填充金属壳与工件相同,焊后与工件一道处理。

  再如低合金耐腐蚀钢的焊接技术

  含铝的钢可用作石油化工中高温抗腐蚀的材料,这类钢是热轧或正火状态使用,没有淬火变脆等问题,焊接时主要是保持焊缝合适的化学成分。

  含铝的耐腐蚀钢焊接时焊缝的合金化是关键,操作规范中要力求快热快冷以尽可能缩短高温停留时间,这样能抑制碳迁移,防止铁素体的带出现象。

 

 

专栏:技术交流
作者: 金宗机械
原文链接: 阅读原文
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FreeMarker template error (HTML_DEBUG mode; use RETHROW in production!)

The following has evaluated to null or missing:
==> langConfig  [in template "public_include/wap/module/version_1/language.html" at line 49, column 14]

----
Tip: If the failing expression is known to be legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??
----

----
FTL stack trace ("~" means nesting-related):
	- Failed at: #if langConfig.status?string = "false"  [in template "public_include/wap/module/version_1/language.html" at line 49, column 9]
	- Reached through: #include "/public_include/wap/module/...  [in template "tpl/2018/03/17/2613443926933696//wap/com_5.html" at line 5, column 1]
	- Reached through: #include "com_5.html"  [in template "tpl/2018/03/17/2613443926933696//wap/displaynews.html" at line 69, column 6]
----

Java stack trace (for programmers):
----
freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...]
	at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:134)
	at freemarker.core.UnexpectedTypeException.newDesciptionBuilder(UnexpectedTypeException.java:80)
	at freemarker.core.UnexpectedTypeException.<init>(UnexpectedTypeException.java:43)
	at freemarker.core.NonHashException.<init>(NonHashException.java:49)
	at freemarker.core.Dot._eval(Dot.java:48)
	at freemarker.core.Expression.eval(Expression.java:81)
	at freemarker.core.BuiltInsForMultipleTypes$stringBI._eval(BuiltInsForMultipleTypes.java:692)
	at freemarker.core.Expression.eval(Expression.java:81)
	at freemarker.core.EvalUtil.compare(EvalUtil.java:111)
	at freemarker.core.ComparisonExpression.evalToBoolean(ComparisonExpression.java:62)
	at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:48)
	at freemarker.core.Environment.visit(Environment.java:327)
	at freemarker.core.Environment.visit(Environment.java:333)
	at freemarker.core.Environment.include(Environment.java:2509)
	at freemarker.core.Include.accept(Include.java:171)
	at freemarker.core.Environment.visit(Environment.java:327)
	at freemarker.core.Environment.visit(Environment.java:333)
	at freemarker.core.Environment.include(Environment.java:2509)
	at freemarker.core.Include.accept(Include.java:171)
	at freemarker.core.Environment.visit(Environment.java:327)
	at freemarker.core.Environment.visit(Environment.java:333)
	at freemarker.core.Environment.process(Environment.java:306)
	at freemarker.ext.servlet.FreemarkerServlet.processEnvironment(FreemarkerServlet.java:946)
	at freemarker.ext.servlet.FreemarkerServlet.process(FreemarkerServlet.java:910)
	at freemarker.ext.servlet.FreemarkerServlet.doGet(FreemarkerServlet.java:769)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
	at com.kenfor.iyong.web.util.filter.NotAllowedToTunFilesFilter.doFilter(NotAllowedToTunFilesFilter.java:154)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
	at com.kenfor.iyong.web.util.filter.InvalidXSSFilter.doFilter(InvalidXSSFilter.java:40)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
	at com.orangefunction.tomcat.redissessions.RedisSessionHandlerValve.invoke(RedisSessionHandlerValve.java:26)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:528)
	at org.apache.coyote.ajp.AbstractAjpProcessor.process(AbstractAjpProcessor.java:873)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:687)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1520)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1476)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:745)

FreeMarker template error: The following has evaluated to null or missing: ==> langConfig [in template "public_include/wap/module/version_1/language.html" at line 49, column 14] ---- Tip: If the failing expression is known to be legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)?? ---- ---- FTL stack trace ("~" means nesting-related): - Failed at: #if langConfig.status?string = "false" [in template "public_include/wap/module/version_1/language.html" at line 49, column 9] - Reached through: #include "/public_include/wap/module/... [in template "tpl/2018/03/17/2613443926933696//wap/com_5.html" at line 5, column 1] - Reached through: #include "com_5.html" [in template "tpl/2018/03/17/2613443926933696//wap/displaynews.html" at line 69, column 6] ---- Java stack trace (for programmers): ---- freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...] at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:134) at freemarker.core.UnexpectedTypeException.newDesciptionBuilder(UnexpectedTypeException.java:80) at freemarker.core.UnexpectedTypeException.(UnexpectedTypeException.java:43) at freemarker.core.NonHashException.(NonHashException.java:49) at freemarker.core.Dot._eval(Dot.java:48) at freemarker.core.Expression.eval(Expression.java:81) at freemarker.core.BuiltInsForMultipleTypes$stringBI._eval(BuiltInsForMultipleTypes.java:692) at freemarker.core.Expression.eval(Expression.java:81) at freemarker.core.EvalUtil.compare(EvalUtil.java:111) at freemarker.core.ComparisonExpression.evalToBoolean(ComparisonExpression.java:62) at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:48) at freemarker.core.Environment.visit(Environment.java:327) at freemarker.core.Environment.visit(Environment.java:333) at freemarker.core.Environment.include(Environment.java:2509) at freemarker.core.Include.accept(Include.java:171) at freemarker.core.Environment.visit(Environment.java:327) at freemarker.core.Environment.visit(Environment.java:333) at freemarker.core.Environment.include(Environment.java:2509) at freemarker.core.Include.accept(Include.java:171) at freemarker.core.Environment.visit(Environment.java:327) at freemarker.core.Environment.visit(Environment.java:333) at freemarker.core.Environment.process(Environment.java:306) at freemarker.ext.servlet.FreemarkerServlet.processEnvironment(FreemarkerServlet.java:946) at freemarker.ext.servlet.FreemarkerServlet.process(FreemarkerServlet.java:910) at freemarker.ext.servlet.FreemarkerServlet.doGet(FreemarkerServlet.java:769) at javax.servlet.http.HttpServlet.service(HttpServlet.java:622) at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) at com.kenfor.iyong.web.util.filter.NotAllowedToTunFilesFilter.doFilter(NotAllowedToTunFilesFilter.java:154) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) at com.kenfor.iyong.web.util.filter.InvalidXSSFilter.doFilter(InvalidXSSFilter.java:40) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) at com.orangefunction.tomcat.redissessions.RedisSessionHandlerValve.invoke(RedisSessionHandlerValve.java:26) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:528) at org.apache.coyote.ajp.AbstractAjpProcessor.process(AbstractAjpProcessor.java:873) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:687) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1520) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1476) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:745)