GB/T 2970-2016Method for ultrasonic testing of thicker steel plates (English PDF)

Foreword

This Standard is drafted according to the rules given in GB/T 1.1-2009.

This Standard replaces GB/T 2970-2004 Thicker steel plates - Method for ultrasonic inspection. Compared with GB/T 2970-2004, the major technical changes are as follows.

- MODIFY the debugging method for sensitivity of dual-crystal straight beam probes. For the steel plates with the thicknesses of greater than 60mm, the debugging method for testing sensitivity of dual-crystal straight beam probes is consistent with that of single-crystal straight beam probes.

- STIPULATE similar acoustic properties, which is "the acoustic attenuation bias shall be within the range of ± 25%".

- ADD the provisions on the contrast samples of the single-crystal straight beam probes for the steel plates with the thicknesses of greater than 200mm.

- ADD "rectangular groove" to the "dynamic samples".

- MODIFY the test method of defect boundaries and lengths.

- ADD Appendix A (Normative).

1 Scope

This Standard specifies the general requirements, contrast samples, testing instruments and equipment, test conditions and methods, defect determination and assessment, quality grading of steel plates, and testing report of the ultrasonic testing of thicker steel plates.

This Standard is applicable to the ultrasonic testing of the steel plates with the thicknesses of not less than 6mm and used in pressure elements, bridges, buildings, shipbuilding, steel structures, pipelines, moulds, etc. The austenitic stainless steel plates can also make reference to this Standard.

2 Normative references

The following documents are essential to the application of this document. For dated references, only the editions with the dates indicated are applicable to this document. For undated references, only the latest editions (including all the amendments) are applicable to this document.

GB/T 8651 Flaw detection method by the ultrasonic plate wave for metal plates

JB/T 10061 Commonly used specification for A-mode ultrasonic flaw detector using pulse echo technique

3 General requirements

3.1 The surfaces of the tested plates shall be flat and smooth along with uniform thickness. There shall be no droplets, oil stains, corrosions and other dirt.

3.2 During testing, the internal constitutions of the tested plates shall not generate interference echoes affecting the testing.

3.4 The personnel engaged in ultrasonic testing of steel plates shall be trained, and obtained Level 1 qualification certificate and above of professional ultrasonic flaw detection issued by certification authorities.

3.5 It is allowed to scan manually and automatically. It is allowed to use the piezoelectric (contact and immersion methods) and electromagnetic ultrasonic testing methods.

3.6 The adopted ultrasonic wave shapes can be longitudinal waves, transverse waves and plate waves. When using transverse waves as the supplement of the longitudinal wave testing, it shall be agreed upon by the supply and requisitioning parties when ordering goods.

4 Contrast samples

4.1 The materials and acoustic properties of the contrast samples shall be the same or similar with those of the tested steel plates (the acoustic attenuation bias shall be within the range of ± 25%). Furthermore, ENSURE that there are no defects affecting the testing inside.

4.2 When using a dual-crystal straight beam probe to test the steel plates with the thicknesses of not greater than 60mm, the contrast samples being used are shown in Figure 1.

4.3 When using a single-crystal straight beam probe for testing, the contrast samples shall conform to the provisions of Figure 2 as well as Tables 1 and 2.

4.4 When using the piezoelectric or electromagnetic automatic ultrasonic testing method, the long side of the dynamic contrast sample shall be parallel to the calendaring direction. In the meantime, the end surface shall be straight.

It is allowed to make reference to Figure 3 for the preparation of the dynamic contrast sample.

5 Testing instruments and equipment

6 Test conditions and methods

7 Defect determination and assessment

8 Quality grading of steel plates

8.1 For the quality grading of steel plates, SEE Table 4.

8.2 Within the testing area 50mm around the steel plate (when the plate thickness is greater than 100mm, TAKE half of the plate thickness) and within 25mm away from both sides of the groove predetermined line, the single defect indicating lengths shall not be greater than or equal to 50mm.

9 Testing report

The testing report shall include the following contents. […]