1.1 本规程提供了用于工业气体分配或储存的无缝压力容器（管）的声发射（AE）检查指南。 1.2 这种做法需要加压至高于正常使用的水平。加压介质可以是气体或液体。 1.3 本规程不适用于低温环境中的容器。 1.4 声发射测量用于检测和定位发射源。必须使用其他无损检测（NDT）方法来评估声发射源的重要性。其他无损检测技术的程序不在本规程范围内。看见 注1 . 注1: 剪切波、角束超声检测通常用于确定产生声发射的缺陷的周向位置和尺寸。 飞行时间衍射（TOFD），超声波检测也常用于缺陷尺寸。 1.5 以国际单位制或英寸-磅单位表示的数值应单独视为标准值。每个系统中规定的值不一定是精确的等价物；因此，为确保符合本标准，每个系统应独立使用，且两个系统的值不得组合。 1.6 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、健康和环境实践，并确定监管限制的适用性。 第节给出了具体的预防说明 7. . 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 出于安全考虑，监管机构（例如美国运输部）要求定期检查用于运输工业气体的容器（见《联邦法规》第49节）。声发射检测已被接受为普通静水压试验的替代方法。 在普通水压试验中，测量容器的体积膨胀。 5.2 普通水压试验后一年内不应进行声发射检查。看见 注释2 . 注2: 凯撒效应与第二次加压期间预期的排放减少有关。普通水压试验使用相对较高的压力（167 % 正常工作压力）。（见《联邦法规》第49节。）如果在这种加压后过快进行声发射检查，声发射结果将对较低的检查压力（即与声发射检查相关的较低压力）不敏感。 5.3 加压: 5.3. 1. 天然气行业的一般做法是使用低增压率。这种做法提高了安全性，减少了设备投资。声发射检查应在加压速率下进行，使容器变形与施加的载荷平衡。目前的典型做法是使用大约3.45 MPa/h[500]的速率 磅/小时]。 5.3.2 气体压缩机加热加压介质。加压后，随着气体温度与环境条件平衡，容器压力可能会下降。 5.3.3 缺陷排放是由缺陷扩展和二次源（例如，裂纹表面接触和包含的轧屑）引起的。二次源可以在整个容器加压过程中产生排放。 5.3.4 当容器内的压力较低，且气体为加压介质时，流速相对较高。流动气体（湍流）和夹带颗粒的冲击可以产生可测量的排放。考虑到这一点，声发射数据的采集可能在大于启动压力的某个压力下开始（例如， 1. / 3. 最大检查压力）。 5.3.5 最大试验压力- 与缺陷生长相比，严重缺陷通常从二次源产生更多的声发射（即，更多事件，峰值幅度更高的事件）。当容器加压时，缺陷在低于正常填充压力的压力下产生排放。最大检查压力为10 % 大于正常填充压力允许测量缺陷中二次源和缺陷生长的排放。 5.3.6 增压时间表- 加压速率应不产生加压介质的噪声，并使容器变形与施加的载荷平衡。不需要保持压力；然而，它们可能对AE测量以外的原因有用。 5.4 过量的背景噪声可能会扭曲声发射数据或使其无用。用户必须了解以下常见背景噪声源:高充气率（可测量的流动噪声）；物体与容器的机械接触；来自附近广播设施和其他来源的电磁干扰（EMI）和射频干扰（RFI）；管道或软管连接处泄漏； 空气中的沙粒、昆虫或雨滴。如果无法消除或控制背景噪声，则不应使用此做法。 5.5 替代程序见ISO 16148和CGA C18。这些包括单个容器的静水压验证加压和使用模态分析技术的数据解释

1.1 This practice provides guidelines for acoustic emission (AE) examinations of seamless pressure vessels (tubes) of the type used for distribution or storage of industrial gases. 1.2 This practice requires pressurization to a level greater than normal use. Pressurization medium may be gas or liquid. 1.3 This practice does not apply to vessels in cryogenic service. 1.4 The AE measurements are used to detect and locate emission sources. Other nondestructive test (NDT) methods must be used to evaluate the significance of AE sources. Procedures for other NDT techniques are beyond the scope of this practice. See Note 1 . Note 1: Shear wave, angle beam ultrasonic examination is commonly used to establish circumferential position and dimensions of flaws that produce AE. Time of Flight Diffraction (TOFD), ultrasonic examination is also commonly used for flaw sizing. 1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined. 1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 7 . 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 Because of safety considerations, regulatory agencies (for example, U.S. Department of Transportation) require periodic examinations of vessels used in transportation of industrial gases (see Section 49, Code of Federal Regulations). The AE examination has become accepted as an alternative to the common hydrostatic proof test. In the common hydrostatic test, volumetric expansion of vessels is measured. 5.2 An AE examination should not be performed for a period of one year after a common hydrostatic test. See Note 2 . Note 2: The Kaiser effect relates to decreased emission that is expected during a second pressurization. Common hydrostatic tests use a relatively high pressure (167 % of normal service pressure). (See Section 49, Code of Federal Regulations.) If an AE examination is performed too soon after such a pressurization, the AE results will be insensitive to a lower examination pressure (that is, the lower pressure that is associated with an AE examination). 5.3 Pressurization: 5.3.1 General practice in the gas industry is to use low pressurization rates. This practice promotes safety and reduces equipment investment. The AE examinations should be performed with pressurization rates that allow vessel deformation to be in equilibrium with the applied load. Typical current practice is to use rates that approximate 3.45 MPa/h [500 psi/h]. 5.3.2 Gas compressors heat the pressurizing medium. After pressurization, vessel pressure may decay as gas temperature equilibrates with ambient conditions. 5.3.3 Emission from flaws is caused by flaw growth and secondary sources (for example, crack surface contact and contained mill scale). Secondary sources can produce emission throughout vessel pressurization. 5.3.4 When pressure within a vessel is low, and gas is the pressurizing medium, flow velocities are relatively high. Flowing gas (turbulence) and impact by entrained particles can produce measurable emission. Considering this, acquisition of AE data may commence at some pressure greater than starting pressure (for example, 1 / 3 of maximum examination pressure). 5.3.5 Maximum Test Pressure— Serious flaws usually produce more acoustic emission (that is, more events, events with higher peak amplitude) from secondary sources than from flaw growth. When vessels are pressurized, flaws produce emission at pressures less than normal fill pressure. A maximum examination pressure that is 10 % greater than normal fill pressure allows measurement of emission from secondary sources in flaws and from flaw growth. 5.3.6 Pressurization Schedule— Pressurization should proceed at rates that do not produce noise from the pressurizing medium and that allow vessel deformation to be in equilibrium with applied load. Pressure holds are not necessary; however, they may be useful for reasons other than measurement of AE. 5.4 Excess background noise may distort AE data or render them useless. Users must be aware of the following common sources of background noise: high gas-fill rate (measurable flow noise); mechanical contact with the vessel by objects; electromagnetic interference (EMI) and radio frequency interference (RFI) from nearby broadcasting facilities and from other sources; leaks at pipe or hose connections; and airborne sand particles, insects, or rain drops. This practice should not be used if background noise cannot be eliminated or controlled. 5.5 Alternate procedures are found in ISO 16148 and CGA C18. These include hydrostatic proof pressurization of individual vessels and data interpretation using modal analysis techniques