1.1本规程提供了对用于制造纸巾、纸张和纸板产品的杨基和蒸汽加热纸干燥器（SHPD）进行声发射（AE）检查的指南。 1.2本规程要求加压至正常运行期间使用的水平。加压介质可以是高温蒸汽、空气或气体。干燥器在运行的加热和冷却期间也会受到很大的应力。声发射数据可能在这些时间段内收集，但该测试超出了本文件的范围。 1.3声发射测量用于检测和定位发射源。其他无损检测（NDT）方法可用于进一步评估声发射源的重要性。 1.4 单位- 以国际单位制或英寸-磅单位表示的数值应视为标准值。每个系统中规定的值可能不是精确的等效值； 因此，每个系统应相互独立使用。将两个系统的值合并可能会导致不符合标准。 1.5 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全和健康实践，并确定监管限制的适用性。 ====意义和用途====== 5.1铸铁Yankee干燥器直径可达6.7 m[22 ft]，长度为7.3 m[24 ft]，重量为91000 Kg[100吨]或更多（参考 图1 图1扬基烘干机滚筒 ). 血管厚度测量可从纸/纸巾机操作员处获得。铸铁是一种脆性金属，没有特定屈服点。扬克干燥机必须保持特定的尺寸公差。当加压扬克式或蒸汽加热式纸干燥器（SHPD）保持静止时，它会快速充满冷凝液。 在一个小时内，蒸汽加压扬克或SHPD可以填充一半的冷凝液，使机架和地板上的重量加倍。一些扬基队的老板有公司要求，铸铁扬基队烘干机保持静止 1. / 2. 小时，则需要旋转。如果洋基队要在更长时间内保持静止，则需要获得许可。该问题应在检查前与负责人讨论。 5.2扬基干燥器在加热罩下运行。护罩靠近扬基壳体，只允许容器上半部分有英寸的间隙。 5.3铸铁蒸汽加热纸机干燥器直径为2米[6英尺]或更大，长度可能为9米[30英尺]。 5.4随着应力增加，灰铸铁的弹性模量持续降低。谨慎的做法是，不要对灰铸铁材料施加超过其工作应力水平的应力。 5.5发现的缺陷与任何铸造和机加工产品中的缺陷相同。 已尝试在紧凑拉伸试验中表征铸铁的强度特性。在TAPPI赞助的一项实验室研究中，三分之二的铸铁紧凑拉伸试样发生了意外故障。根据这一经验，需要注意的是，裂纹的萌生和扩展速度超过了预期，导致在工艺停止之前发生脆性断裂。这两个试件的失效证明了这些材料中裂纹的增长速度，以及一旦裂纹开始增长，材料就无法阻止裂纹。在每一种情况下，裂纹发展都非常迅速，而且没有任何警告。（参见 注1 .) 注1 — Alleveto，C.和Williams D.，杨基干燥器壳体材料的声发射评估，1991年TAPPI工程会议论文集，第475-480页。 5.6 最大检查压力- 铸铁容器的最大允许工作压力是根据ASME（第八节）基于厚度、半径和材料强度值的压力计算设定的，不会超过10 bar[160 psi]和230°C[450°F]（ASTM A278）。 当容器加压时，异常现象会在低于正常填充压力的压力下产生排放。从历史上看，如果铸铁压力边界出现损坏，AE活动将在负载/应力水平低于工作压力的50%时开始。缺陷小至3 mm[ 1. / 8. 在中。]在蒸汽加压至工作压力期间，使用AE发现。 5.7压力增量不得超过每分钟0.35巴[5磅/平方英寸]。如果加压介质是蒸汽，扬基筛应该已经过预热过程。 5.8如有必要，在旋转杨克干燥器以去除任何冷凝液后，可对杨克干燥器进行后续检查。 5.9 增压时间表- 加压应以允许在30分钟内达到最大检查压力的速率进行。在加压过程中，不需要保持压力；然而，它们可能对AE测量以外的原因有用。达到最大检查压力时保持的压力可能高达30分钟。 5.10过量的背景噪声可能会扭曲声发射数据或使声发射测量无效。用户必须了解以下常见的背景噪声源:（可测量的流动噪声）；物体与容器的机械接触；来自起重机的电磁干扰（EMI），以及来自附近广播设施和其他来源的射频干扰（RFI）；管道或软管连接处泄漏，或雨滴。如果无法消除或控制背景噪声，则不应使用此做法。 5.11其他无损检测方法可用于评估声发射源的重要性。磁粉、超声波和射线照相检查已用于确定产生声发射的缺陷的周向位置、深度和尺寸。使用其他无损检测方法的程序不在本规程范围内。

1.1 This practice provides guidelines for carrying out acoustic emission (AE) examinations of Yankee and Steam Heated Paper Dryers (SHPD) of the type to make tissue, paper, and paperboard products. 1.2 This practice requires pressurization to levels used during normal operation. The pressurization medium may be high temperature steam, air, or gas. The dryer is also subjected to significant stresses during the heating up and cooling down periods of operation. Acoustic Emission data maybe collected during these time periods but this testing is beyond the scope of this document. 1.3 The AE measurements are used to detect, as well as, localize emission sources. Other methods of nondestructive testing (NDT) may be used to further evaluate the significance of acoustic emission sources. 1.4 Units— The values stated in either SI units or inch-pound units are to be regarded as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standards. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. ====== Significance And Use ====== 5.1 Cast iron Yankee dryers can be up to 6.7 m [22 ft] in diameter, 7.3 m [24 ft] long, and weigh 91,000 Kg [100 tons], or more (refer to Fig. 1 FIG. 1 Yankee Dryer Drum ). Vessel thickness measurements are available from the paper/tissue machine operator. Cast iron is a brittle metal and has no specific yield point. Yankee dryers must maintain specific dimensional tolerances. When a pressurized Yankee or steam heated paper dryer (SHPD) remains stationary, it fills with condensate at a rapid rate. In an hour, a steam pressurized Yankee or SHPD can fill half way with condensate, doubling the weight on the frame, and the floor. Some Yankee owners have corporate requirements that a cast iron Yankee dryer remain stationary for 1 / 2 hour, then rotation is required. Permission is required, if the Yankee is to remain stationary for more time. This issue should be discussed with the responsible person prior to the examination. 5.2 Yankee dryers operate under a heated hood. The hood is in close proximity to the Yankee shell and allows only inches of clearance for the top half of the vessel. 5.3 Cast iron steam heated paper machine dryers are 2 m [6 ft] in diameter, or more, and may be 9 m [30 ft] long. 5.4 Grey cast iron experiences a continuing reduction in elastic modulus as it is stressed to increasing higher levels. It is prudent not to stress grey cast iron material beyond its operating stress level. 5.5 Flaws to be found are the same as those in any cast and machined product. Attempts have been made to characterize strength properties of cast irons in compact tension tests. In a TAPPI sponsored laboratory study, two out of three cast iron compact tension specimens experienced unplanned failures. From that experience it was cautioned that cracks initiated and grew faster than expected resulting in brittle fracture before the process could be halted. The failure of these two coupons demonstrated the rate in which cracks can grow in these materials and the material’s inability to stop a crack once it begins to grow. In each case, crack advance was extremely rapid and without warning. (See Note 1 .) Note 1 — Alleveto, C., and Williams D., Acoustic Emission Evaluation of Yankee Dryer Shell Material, 1991 TAPPI Engineering Conference Proceedings, pages 475-480. 5.6 Maximum Examination Pressure— Maximum Allowable Working Pressure for cast iron vessels is set based on ASME (Section VIII) pressure calculations based on thickness, radius, and material strength values, and will not exceed 10 bar [160 psi] and 230°C [450°F] (ASTM A278). When vessels are pressurized, anomalies produce emission at pressures less than normal fill pressure. Historically, if there is damage in a cast iron pressure boundary, AE activity will begin at load/stress levels less than 50 % of operating. Defects as small as 3 mm [ 1 / 8 in.] have been found using AE, during steam pressurization to operating pressure. 5.7 Pressure increments should not exceed 0.35 bar [5 psi] per minute. If pressurization medium is to be steam, the Yankee should have been through the warm-up process. 5.8 Yankee dryers may receive a subsequent examination, if necessary, after the Yankee is rotated to remove any condensate present. 5.9 Pressurization Schedule— Pressurization should proceed at rates that allow achieving maximum examination pressure within a 30 minute period. During pressurization, pressure holds are not necessary; however, they may be useful for reasons other than measurement of AE. Pressure hold upon achieving maximum examination pressure may be up to 30 minutes. 5.10 Excess background noise may distort AE data or render the AE measurements useless. Users must be aware of the following common sources of background noise: (measurable flow noise); mechanical contact with the vessel by objects; electromagnetic interference (EMI) from cranes, and radio frequency inter¬ference (RFI) from nearby broadcasting facilities and from other sources; leaks at pipe or hose connections, or rain drops. This practice should not be used if background noise cannot be eliminated or controlled. 5.11 Other Non-destructive test methods may be used to evaluate the significance of AE sources. Magnetic particle, ultrasonic, and radiographic examinations have been used to establish circumferential position, depth, and dimensions of flaws that produce AE. Procedures for using other NDT nethods are beyond the scope of this practice.