Information Details

Talk about forging high-pressure valves, pipe fittings flaw detection methods

Release Time:

2018-10-16 16:58

  Pipe ultrasonic flaw detection should be in line with JB1151-73 "high-pressure seamless steel pipe ultrasonic flaw detection" provisions.

  Ultrasonic flaw detection of pressurized parts

  1, the starting sensitivity of flaw detection

  Detection depth
  Detection depth ≥ 200 mm for Ф3 equivalent diameter.

  2, the pressurized parts shall not have a dense area of defects and greater than Ф4 equivalent diameter of a single defect.

  Other requirements should be in line with JB755-73 "Pressure Vessel Forging Technical Conditions" relevant parts of the provisions.

  3、Magnetic particle flaw detection

  The workpiece to be flawed by mechanical processing, in the surface oil and iron particles to eliminate clean with circumferential and longitudinal continuous magnetization method for flaw detection.

  As a defect display agent inspection fluid should be used per liter of transformer oil and kerosene 50% of the oil mixture, which is added to 15-30 grams of uniform particle size of magnetic powder, generally sieved with no less than 200 mesh sieve.

  The choice of circumferential magnetization current during flaw detection, as specified in the following formula:

  I = (10 ~ 12) D

  Where: I - magnetization current, A; D - the diameter of the workpiece being probed or the distance to the side, mm.

  For easy detection of defects, the magnetization current can be changed appropriately.

  The longitudinal magnetization value during flaw detection is 3000~10000 A turns, the large length of the coil electromagnetization is within 500 mm, the long workpiece coil magnetization should be segmented, and the segmented magnetization observation area is recommended to be within 200~300 mm.

  The judgment standard is that no cracks are allowed. When there is doubt about the magnetic trace, the coloring method or fluorescence method can be used for verification.

  Non-magnetic material workpiece can be fluorescent, coloring flaw detection method sampling, acceptance regulations by the use of the two sides to negotiate, manufacturing.

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