对焊接件、铸造件中一些穿透性的微小缺陷,如气孔、砂眼、裂纹等,都可以用煤油试验的方法进行检验。以往,做煤油试验,都是用纯煤油。利用煤油对微小缝隙的渗透,使被涂敷在背面的白垩粉吸附出来并产生油斑来发现缺陷。这种纯煤油做渗透剂所产生的斑迹,与白垩粉的颜色差别不明显,往往由于光线的影响辨别困难, For welding parts, castings, some penetrating minor defects, such as porosity, blisters, cracks, etc., can be tested using the kerosene test method. In the past, to do kerosene test, are used pure kerosene. The use of kerosene to penetrate the tiny gap, so that was coated on the back of the chalk powder adsorbed out and produce oil spots to detect defects. This pure kerosene to do the stains produced by penetrant, and chalk color is not obvious, often because of the light of the difficulty of identifying,