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涡流检测管材的另一个难点

Another inconvenience that arises during the eddy current testing of heat exchanger tubes is that although phase analysis(measuring defect depth based on the angle on the screen)is usually the best measure of a defect’s depth,it is not perfect.

在用涡流检测热交换管的时候,会发生另外一个麻烦,即使相分析(利用屏幕显示图形的角度来测量缺陷深度)通常是测量缺陷深度的最好办法了恶,但是仍不够完美,下面我们详细介绍

The two eddy current screens shown in the diagram are a bit cluttered because you can see the dent and five defects of an ASME calibration tube that we’ve used for examples in previous articles.The green horizontal signal is,of course,the dent signal.Then,rotated clockwise from this at about 45 degrees,are the through wall hole,followed by the 80,60,40,and 20 percent O.D.pits,all of similar amplitude.Then,superimposed on these is an additional defect larger in amplitude.Just what might this be?

图中的两个图形显示得有些杂乱,你可以看到凹陷和5个缺陷.绿色的水平信号即为凹槽信号.然后,顺时针旋转45度,为通孔缺陷,接下来一次为80%,60%,40%,20%的缺陷,幅度相差不大.然后,这些叠加的是一个额外的幅度更大的缺陷,那么这该是什么呢?

In the ect MAD 8D Eddy Current Software,a new feature has been turned on.This is the ect AutoMAD Analysis Mode,in which the software measures the defect depth of all the defects it encounters in a tube,and then displays a list of up to the 10 deepest defects.This list appears where the Mixer Menu used to be;therefore,appears under the word“Mixer”.The deepest defect encountered is listed as 99 per cent on the I.D.This is,of course,the through hole.(The one per cent error is actually excellent and not to be expected in the field environment.This example was created in a carefully controlled laboratory environment.)Listed below this through wall hole you can pick out the other five outside defects;specifically,the 80,60,40,and 20 per cent O.D.defects,all ranging in amplitude from 1.0 volts to 1.8 volts.(Note that below the 20 per cent O.D.defect is listed a nine per cent I.D.defect.This is,in fact,a 10 per cent I.D.groove,which is not shown on the screen.)

在ECT MAD80D软件里,增设了一个新的功能特点.图中为ECT AutoMAD分析模式,该模式下,软件可以测量所有碰到的缺陷的深度,然后可以显示10个最深缺陷的清单。当Mixer Menu在启用状态下时,便显示在单词Mixer下面。最深的缺陷以99%显示,当然实际上它已经是通孔缺陷(1%的误差实际上已经非常好了,在现场检测时很难达到这个结果的,本案例是在精心控制的实验室环境下得到的)。在清单中接下来便是5个缺陷显示,尤其是80%,60%,40%,20%的缺陷,幅度均在1.0到1.8V之间。

需要注意的是,低于20%的缺陷在清单中以9%显示,但是实际上这是一个10%的槽形缺陷,只是没有在屏幕上显示而已。

Now back to this new,larger defect that appears on the screen,which is marked by the cursors.(Square at the top and a cross at the bottom.)The signal is larger in amplitude;therefore,it is logical to assume that the defect is of greater volume.The angle of this defect is rotated counter clockwise from the 20 per cent O.D.pit;therefore,it would be logical to assume that this is an O.D.pit deeper than the 20 per cent in the calibration tube,but shallower than the 40 per cent,but larger in diameter in order to make up a larger volume.In fact,the data analysis shows this defect as being 36 per cent through the wall on the outside with a magnitude of 2.9 volts.Unfortunately,this is not what the defect is.

现在我们回到屏幕上显示的这个大缺陷,在图中用光标标示出来的(在顶端和底端用方框标示处)。该缺陷幅度大,可以假定其为一个较大的体积型缺陷。其角度是从20%出逆时针旋转所得,所以可以认定其深度深于标准试块的20%的深度,但是浅于40%。但是直径更大。实际上,数据分析显示该缺陷为一个36%,当量为2.9V的缺陷。不幸的是,这不是该缺陷本身。

This signal actually originates from a concentric O.D.groove 3 mm long but only 10 per cent through the wall from the outside!

该信号实际上是一个同轴的3mm长,仅仅距离外表面10%的缺陷产生的。

Apparently and unfortunately if a defect were to grow larger in volume while retaining the same defect depth,its resulting eddy current signal would rotate counterclockwise and the signal would grow in amplitude.In this case,by directly applying phase analysis using a calibration table based on the ASME O.D.pits,this 10 per cent O.D.defect is incorrectly measured as 36 per cent O.D.

显然而且不幸的是,如果一个缺陷信号体积增大而缺陷深度不变得情况下,其涡流信号将逆时针旋转并且幅度增大。在本案例中,直接用ASME标准试块做相位分析,这个10%的缺陷就被测得为36%。

The same is true if the defect was a 100 per cent through wall hole.If you drill holes of different diameters in a calibration tube and measure the eddy current response,you will notice that the larger the diameter of the hole,the more the hole rotates counter clockwise.

当缺陷为100%的通孔缺陷时,也同样成立。如果你在校准管子上钻不同直径的孔,测量其涡流信号,你就会发现直径越大的孔,其信号逆时针旋转越大。

This problem becomes even worse for defects on the inside of the tube wall.One reason that this problem is greater on the inside(assuming that these tubes are being inspected from the inside)is that the most important part of the defect is the part in the deepest part of the flaw.This part is farthest from the probe;therefore,the probe has the least sensitivity to it.The eddy current signal is more due to the shallower portion of the defect closer to the probe.The result is that very large diameter pits on the I.D.can easily be interpreted as being much less deep than they actually are.

该问题在管子内壁缺陷上表现尤其厉害。一个原因是缺陷中最关键的部分是缺陷最深的地方。缺陷就会离探头最远,因此,探头机会接收到最低的灵敏度。涡流信号在浅表面里探头最近的地方是最强的。结果就是直径大的内壁缺陷会容易理解成比起实际深度浅的缺陷。

So,what can be done about it?The most common advice you will hear in eddy current testing is to make the defects in your calibration tube as close to the size and shape of the defects you are trying to measure as possible.As a result,you may need more than one calibration table to correlate phase to defect depth if you have more than one defect type in a tube.Actually,the ect MAD 8D Software has multiple tables,which can be selected by the user depending upon the type of damage that is being measured.

那么,有什么可以做得呢?通常的建议是做一个尺寸和形状跟预期结果都相近的试块。结果是,你可能需要更多的校准表格来关联缺陷深度,你还得建立一个以上的管材的缺陷类型。这里,我们ECT MAD 8D软件内置了多个表格,在检测过程中,你可以根据预期检测的缺陷类型来选择相应的表格。

An example of how this may occur could be a water cooled condenser.This type of tube may have multiple,small diameter pits caused by corrosion,but the occasional very large diameter pit caused by erosion where an object had been stuck in the tube.Based on noting the amplitude difference,the Inspector analyzes with the appropriate calibration table and accurately measures the defect depth.

这种情况发生的一个实例就是水冷凝管。这种管子会发生很多种,小直径的由于腐蚀而成的缺陷,但是也会偶尔出现大直径的腐蚀缺陷。在观察幅度差异的基础上,检测员可以根据合适的校准表格来分析数据,进而准确的测出缺陷深度。

ECT 48 Specifications参数

ECT 48 Main Features特点

PROBE TYPES探头形式
Differential, Absolute, and Send/Receive
with industry standard 4-Pin MS Connector

The ect 48 Eddy Current System, designed for inspecting ferro and non-ferromagnetic heat exchanger tubes,has up to four simultaneous injection frequency channels and two mixers.
ECT 48个涡流系统,用于检测铁和non-ferromagnetic热交换器管,有四个同时注入频率通道和两个搅拌机。

BRIDGE IMPEDANCE 75 ohm

  • Simultaneous Injection (SI)
  • Simultaneous Sampling (SS)
  • Up to 12,000 Hz sample rate, each channel, allows up to 10 feet per second probe speed at over 100 samples/inch.
  • 12000 Hz采样率,每个通道,允许10英尺每秒探测速度超过100样本/英寸。
  • Automatic data analysis.
  • 自动数据分析
  • Save and recall unlimited test setups.
  • 测试结果无限制保留和重复使用
  • Defect signals are highlighted in real time during recording or playback.
  • 记录和回放时,缺陷信号实时突出标示
  • Four independently selected simultaneous frequencies.
  • 4个独立选择的同步频率
  • Digital Signal Processing (DSP) HP & LP filtering provides lower noise.
  • 数字信号处理(高通和低通过滤提供低噪音水平)
  • Independent horizontal and vertical display scaling.
  • Signal phase and amplitude measurement functions.
  • 独立的水平和垂直显示, 信号相位,幅值测量功能
  • Defect depth measurement functions.
  • 缺陷深度测量功能
  • Standard printer interface.
  • 标准打印接口
  • Single keystroke data acquisition.
  • 单键数据获取
  • Single keystroke data playback with analysis.
  • 单键数据回放和分析
  • Optional ect 48 Data Analysis Software.
  • 可选ECT48 数据分析软件
  • Optional ect Frequency Transforms* use eddy current signals in the frequency domain, making it easy to distinguish between magnetic inclusions, roll stops, and serious defects.
  • 可选频率转换器,用涡流信号在频率范围内,使其容易区分磁性夹杂,滚轮停印和严重的缺陷
  • Optional ect Data Storage Software stores and recalls eddy current signals on disk.
  •  
  • Optional ect Report Software reads the defect listprovided by
    the ect 48 Data Analysis Software and provides tube sheet maps
    color-coded based on defect depth.
  • 16 16-Bit Analog-to-Digital Conversion so all channels are sampled in
    the same microsecond.

ECT 48 Accessories附件
INCLUDED ACCESSORIES

  • Power Cord
  • Manual

OPTIONAL ACCESSORIES

  • Carbon Steel Filter Amplifier for simultaneous Remote Field and
    Near FieldTM inspecting of ferrous tubes
  • ect 48 Data Analysis Software
  • ect 48 Frequency Transform Software*
  • ect Report Software
  • Built-in DVD writer
  • Transit Case
  • Separate Data Analysis System
  • Available in Micro Dock configuration
  • 1。碳钢过滤器同时远程领域和放大器附近FieldTM亚铁管的检查
    2。ECT 48数据分析软件
    3 ECT 48 *频率转换软件
    4 ECT48 报告软件
    5。内置的DVD的作家
    6。交通情况
    7所示。单独的数据分析系统
    8。在微码头配置

ect 48 Ordering Information
The ect 48 Micro Dock Eddy Current System has many more features than can be described on this brochure.
ECT 48微涡流系统有许多更多的功能比可以描述在这个手册。

FREQUENCY CHARACTERISTICS频率

RANGE范围:40 Hz to 5 MHz Stability稳定性 + 100 PPM

TRANSFER CHARACTERISTICS转换特性, 4 Frequencies, One Probe4个频率,一个探头

SENSITIVITY灵敏度:135 Volts/Ohm min. at 30 kHz at max. gain setting

GAIN增益:90 db at maximum gain setting最大增益条件下90分贝

DRIFT飘移:Less than 0.1 Volts per hour at 60db gain with probe
60分贝下不足0.1V

NOISE噪音: Less than 30 mV P-P at nominal gain正常增益条件下小于30mV

LP Filter: 5 to 1,000 Hz

HP DSP FILTER: 0.1 to 14 Hz

LP DSP FILTER: 12 to 1,440 Hz

BALANCE平衡: High speed successive approx. electronic balance高速连续电子平衡

MULTIPLEX MODE多通道模式: 32 Channels

STORAGE DISPLAY MODES WITH 1280 x 1024 SCREEN 储存显示模式带1280x1024显示屏

12 XY Impedance Planes and 2 Strip Charts
12个XY独立平面和两个Strip Charts

EDDY CURRENT CHANNEL CONTROLS通道控制

GAIN增益: 999 Linear Steps线性

PHASE相位: 360 Degrees

FREQUENCY频率: 20 Hz – 5 MHz in 1 Hz Steps

VOLTS/DIVISION电压: Separate Horiz. & Vert.水平和垂直 .06, .13, .25, .5, 1, 2, 4, 8, 16 V/Div

BALANCE平衡: Each channel independent or all simultaneously每个通道独立或者所有通道同时

POSITION定位: + Full Screen, Horizontal and Vertical全屏,水平和垂直

MIXER CONTROLS

INPUT PHASE输入相位: 360 Degrees

OUTPUT PHASE输出相位: 360 Degrees

HORIZ. WEIGHT水平重量: 0 – 999%

VERT. WEIGHT垂直重量: 0 – 999%

VOLTS/DIVISION电压: Separate Horiz. & Vert水平和垂直. .06, .13, .25, .5, 1, 2, 4, 8, 16 V/Div

POSITION定位: + Full Screen, Horizontal and Vertical全屏,水平和竖直

CANCEL取消: Automatic自动

SYSTEM CONTROLS系统控制

SAMPLE RATE取样速率: 100 Hz to 12 kHz, All Channels Simultaneously

CODE COMPLIANCE规范标准

Meets or exceeds ASME Section V & XI requirements

POWER REQUIREMENTS电源要求

VOLTAGE电压: 90-130 and 185-270 Vac auto selected

FREQUENCY频率: 50-60 Hz

POWER功率: 100 Watt Max

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