| Several quality classes can be applied to the inspection of bars. The applicable quality class must be agreed between the buyer and the supplier. Tables 2 and 3 detail the registration level and acceptance criteria applicable to the three quality classes for normal probes. | ||||||||||||||||||||||||
| Table-1. Scanning Scope with Normal Probes | ||||||||||||||||||||||||
| Shape | Scanning Gridlines a, b | % Scan a, b | ||||||||||||||||||||||
| Diameter D or Thickness t, mm | Scan Line c | |||||||||||||||||||||||
| Round | D ≤ 200 | 2 directions at 90º | 100% scanning in an area of at least 180º on the cylindrical surface | |||||||||||||||||||||
| 200 < D ≤ 400 | 3 directions at 60º or 120º | |||||||||||||||||||||||
| Tetragon | t ≤ 150 | 1 line at 2 surface | 100% scanning from two surfaces perpendicular to each other | |||||||||||||||||||||
| 150 < t ≤ 400 | 3 line at 2 surface d | |||||||||||||||||||||||
| Hexagon | t ≤ 150 | 1 line at 2 surface | 100% scanning from at least half adjacent surface | |||||||||||||||||||||
| 150 < t ≤ 400 | 1 line on at least half of the faces | |||||||||||||||||||||||
| a) Additional screening can be done if specifically specified in the inquiry or order. | ||||||||||||||||||||||||
| b) 100% inspection means at least 10% overlap on consecutive probe lines. | ||||||||||||||||||||||||
| c) For Type 1a or 1b, if the presence of a hole prevents reaching the opposite surface, the number of scan lines should be doubled symmetrically. | ||||||||||||||||||||||||
| d) The distance between the guide lines should be equal to the wall thickness for parts up to 200 mm thick. | ||||||||||||||||||||||||
| Manual scanning speed should not exceed 150 mm/s. | ||||||||||||||||||||||||
| Classification of Discontinuities | ||||||||||||||||||||||||
| Discontinuities are classified according to ecodynamic models as follows. | ||||||||||||||||||||||||
| a) | Point Discontinuity; | |||||||||||||||||||||||
| If the echodynamic pattern is less than or equal to 1 and / or a beam width of –6 dB, it is called point discontinuity. | ||||||||||||||||||||||||
| b) | Extended Discontinuity; | |||||||||||||||||||||||
| If the echodynamic pattern is greater than 2 and / or the dimension –6 dB width, it is called extended discontinuity. | ||||||||||||||||||||||||
| c) | Isolated Discontinuities; | |||||||||||||||||||||||
| If the distance d between points corresponding to the maximum of indications of adjacent discontinuities exceeds 40 mm, they are called isolated discontinuities. | ||||||||||||||||||||||||
| d) | Grouped Discontinuities; | |||||||||||||||||||||||
| If the distance d between points corresponding to the maximum of indications for adjacent discontinuities is less than or equal to 40 mm, they are called grouped discontinuities. | ||||||||||||||||||||||||
| Table-2. Quality Classes, Registration Level and Acceptance Criteria for Ferritic and Martensitic Steel Bars | ||||||||||||||||||||||||
| Parameters | Quality Classes | |||||||||||||||||||||||
| 1 | 2 | 3 | 4 | |||||||||||||||||||||
| Recording Level | > 8 | > 5 | > 3 | > 2 | ||||||||||||||||||||
| Equivalent disc-shaped reflector diameter (EFBH) deq mma | ||||||||||||||||||||||||
| The rate of decrease in rear wall echo height, R b,c | ≤ 0,10 | ≤ 0,30 | ≤ 0,50 | ≤ 0,50 | ||||||||||||||||||||
| Accept conditions | ≤ 12 | ≤ 8 | ≤ 5 | ≤ 3 | ||||||||||||||||||||
| EFBH (for isolated point discontinuities) deq mma | ||||||||||||||||||||||||
| EFBH (for large or clustered point discontinuities) deq mma | ≤ 8 | ≤ 5 | ≤ 3 | ≤ 2 | ||||||||||||||||||||
| a) deq = Equivalent disc-shaped reflector diameter. | ||||||||||||||||||||||||
| b) R = Fn / F o,n | ||||||||||||||||||||||||
| Here; | ||||||||||||||||||||||||
| For t ≥ 60 mm, n=1; | ||||||||||||||||||||||||
| For t < 60 mm, n=2; | ||||||||||||||||||||||||
| Fn = amplitude of the nth back wall echo (screen height) | ||||||||||||||||||||||||
| F o, n = the amplitude (screen height) of the nth back wall echo in an accurate region at the same sound distance as Fn | ||||||||||||||||||||||||
| c) If the decrease in the height of the rear wall echo exceeds the recording level, this should be examined in more detail. The R rate is applicable only in case of a sudden decrease in reverb height due to a discontinuity. | ||||||||||||||||||||||||
| Table-3. Quality Classes, Registration Level and Acceptance Criteria for Austenitic and Austenenoferritic Steel Bars | ||||||||||||||||||||||||
| Bar Thickness | Record Level deqa | Acceptance Criteria for Isolated Point Type Discontinuities deqa | Acceptance Criteria for Expanded or Grouped Point Type Discontinuities deqa | |||||||||||||||||||||
| mm | mm | mm | mm | |||||||||||||||||||||
| Class 1 | ||||||||||||||||||||||||
| t ≤ 75 | > 5 | ≤ 8 | ≤ 5 | |||||||||||||||||||||
| 75 < t ≤ 250 | > 8 | ≤ 11 | ≤ 8 | |||||||||||||||||||||
| 250 < t ≤ 400 | > 14 | ≤ 19 | ≤ 14 | |||||||||||||||||||||
| Class 2 | ||||||||||||||||||||||||
| t ≤ 75 | > 3 | ≤ 5 | ≤ 3 | |||||||||||||||||||||
| 75 < t ≤ 250 | > 5 | ≤ 8 | ≤ 5 | |||||||||||||||||||||
| 250 < t ≤ 400 | > 8 | ≤ 11 | ≤ 8 | |||||||||||||||||||||
| Class 3 | ||||||||||||||||||||||||
| t ≤ 75 | > 2 | ≤ 3 | ≤ 2 | |||||||||||||||||||||
| 75 < t ≤ 250 | > 3 | ≤ 5 | ≤ 3 | |||||||||||||||||||||
| 250 < t ≤ 400 | > 5 | ≤ 8 | ≤ 5 | |||||||||||||||||||||
| a) deq = Equivalent diameter of the flat bottom hole. | ||||||||||||||||||||||||
