68.보일러 및 압력용기에 대한 침투탐상검사(ASME Sec.V Art.6)에 따른 침투탐상시험에서 시험체 온도가 정상범위를 벗어날 때 침투액의 성능을 알기 위해 사용되는 비교시험편은?

해설

[ASME Sec.V Art.6] [MANDATORY APPENDIX III - QUALIFICATION TECHNIQUES FOR EXAMINATIONS AT NONSTANDARD TEMPERATURES] III-630 MATERIALS A liquid penetrant comparator block shall be made as follows. The liquid penetrant comparator blocks shall be made of aluminum, ASTM B209, Type 2024, 3/8 in. (10 mm) thick, and should have approximate face dimensions of 2 in. × 3 in. (50 mm × 75 mm). At the center of each face, an area approximately 1 in. (25 mm) in diameter shall be marked with a 950°F (510°C) temperature indicating crayon or paint. The marked area shall be heated with a blowtorch, a Bunsen burner, or similar device to a temperature between 950°F (510°C) and 975°F (524°C). The specimen shall then be immediately quenched in cold water, which produces a network of fine cracks on each face.