Study and Evaluation of Advanced TOFD Method for Inspection of Polyethylene Pipes but Welding
Study and Evaluation of Advanced TOFD Method for Inspection of Polyethylene Pipes but Welding
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DOI：
10.17265/2159-5348/2015.05.005
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Mohammad;Taghipour
中科院分区：
文献类型：
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作者：
Mohammad;Taghipour
聚乙烯材料有一定的规格，这使得任何一种基于超声波的检测都非常困难。这种材料的声阻抗和声速与常用的超声楔体材料相近。此外，这种材料也是一种高度衰减的超声波材料。为了检测聚乙烯环向焊缝，克服上述问题，采用了一种特殊的TOFD(Time of Flight衍射法)技术，该方法采用低频探头，集中在纵波转变为横波的检测区域。检查的目的是确定表面和内部焊接缺陷的准确位置。为此，选择了两个独立的聚乙烯管，直径10英寸，厚度15 mm，以及直径25英寸，厚度28 mm。共制造了40个人工缺陷，涉及28个不同深度的侧向钻孔和12个表面和亚表面缺口。所有人工创建的缺陷都被以非常好的准确性检测出来。与传统的TOFD方法有2~3 mm的死区不同，用该方法可以检测到0.5 mm的均匀表面缺口。
Polyethylene material has some specification that makes very difficult any kind of inspection based on ultrasonic. The acoustic impedance and sound velocity in this kind of material are near to the materials commonly used in ultrasonic wedges. Also this kind of materials are highly attenuative materials for ultrasound. To inspection of polyethylene circumferential but welds and overcome to all the problems mentioned, the especial technique of TOFD (Time of Flight Diffraction) method which employs low frequency probe and concentrate on the inspection area that longitudinal waves turn into transverse waves has been used. The purpose of inspection is determining the exact location of surface and internal welding defects. For this purpose, two separate polyethylene pipes with 10 inch in diameter, 15 mm thickness and also 25 inch diameter, 28 mm thickness, were selected. In total 40 artificial defects which involve 28 side drill holes in deferent depths and 12 surface and sub-surface notches were created. All artificially created defects were detected with very good accuracy. Unlike the conventional TOFD method which have 2 to 3 mm dead zone, by using the above method even surface notch with 0.5 mm has been detected.