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Phased Array Dipper Handle Inspection for Shovels and Draglines

Phased Array Inspection of Mining Dipper Handles


The dipper handle is a critical component of many shovels and draglines involved in excavation at surface mines. This component allows for the raising and lowering of the dipper basket in conjunction with the boom. A failed dipper handle can cause safety issues as well as loss of profit based on overall machine down time. Therefore, efficient inspection and repair of these components is critical.

Box type dipper handles are typically rectangular and contain bulk head supports that are internally fillet welded for strength reinforcement to the dipper handle. Unfortunately, this design creates a geometry that can be difficult to inspect and repair if cracks in the weld or side walls are found. Crack repair often necessitates cutting a window into the side frame to allow access to the defect.

A fast and accurate inspection is very important, because the repair process can be involved and time consuming. A fillet/T weld is recommended to be inspected from at least two surfaces. Unfortunately that’s not possible with dipper handles since the entire area, except one surface, is enclosed. Cracks often occur at the toe of the fillet weld and can move into the sidewall.

Schematic of fillet weld in Dipper Handle. Note access window cut out for repair of weld cracks.
Schematic of fillet weld in Dipper Handle. Note access window cut out for repair of weld cracks.

The Solution: Phased Array vs. Conventional Ultrasound

With a manual phased array flaw detector, inspection of the weld is initiated by rastering the probe in and out of the weld area and down the weld. The advantage of using a phased array detector is derived from the multiple angles that are available and the image shown on the phased array units.

The Solution: Phased Array vs. Conventional UltrasoundThe Solution: Phased Array vs. Conventional Ultrasound

On the other hand, with a flaw detector using conventional ultrasound it is difficult to decipher the geometry of the weld versus cracks in the weld or side walls. Conventional flaw detectors can only image a single angle off a fillet weld at a time. Furthermore, they are only sensitive to cracks that are perpendicular to the set angle. Multiple probes of varying angles can increase the probability of crack detection or other flaw, but that approach is very time consuming.

Summary: Advantages of the Phased Array Method

  • Time Savings, 50% or more due to less pull back scan distance and faster defect assessment and one probe versus multiple probes of varying angles
  • Increased probability of detection due to multiple angles
  • Less false calls due to geometry with aid of imaging
  • Data files of indications (S-scans) can be saved with all raw data for aid in reviewing and discussing indications for proper disposition

Equipment Used

  • OmniScan or EPOCH Phased Array Flaw detector (EPOCH 1000i or OmniScan SX most common)
  • 16 element or greater phased array probe
  • Shear wave phased array wedge
  • Couplant

Final comment:

Dipper handles can be an important but challenging inspection for conventional ultrasound due to access, geometry of the weld and inherent limitations of the conventional method. But when the inspection is performed with a phased array flaw detector, the operator gains from time savings as well as from better and more accurate detection and assesment rates.

For a customer testimonial on the subject please visit the video section of the website.

Olympus IMS

OmniScan X3系列的每台探伤仪都是一款功能齐备的相控阵工具箱。其创新型全聚焦方式(TFM)和高级相控阵(PA)功能助力您充满信心地识别缺陷,其性能强大的软件功能和便捷的工作流程有助于提高您的检测效率。
轻便的单组Omniscan SX探伤仪装有一个方便用户阅读的8.4英寸(21.3厘米)触摸屏,可提供性价比很高的检测解决方案。OmniScan SX有两种型号:SX PA和SX UT。SX PA是一个16:64PR仪器,它与仅使用UT技术的SX UT一样,配备有一个用于脉冲回波、一发一收或TOFD(衍射时差)检测的常规UT通道。
OmniScan MX2现在不仅可以与带有一个UT通道的相控阵模块(PA2)及一个用于TOFD(衍射时差)检测的双通道常规超声模块(UT2)配套使用,还可以使用一些创新型软件程序。这些软件程序更进一步提高了业已相当成功的OmniScan MX2平台的性能。
这类专用于相控阵应用的探头的频率范围在0.5 MHz到18 MHz之间,其标准配置为16、32、64或128个晶片。特殊的探头可以最多装配几百个晶片。
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