大家知道在ASME V第4章规定：
T-434.1.7.1 Materials With Diameters Greater Than 20 in. (500 mm). For examinations in materials where the examination surface diameter is greater than 20 in. (500 mm), a block of essentially the same curvature, or alternatively, a flat basic calibration block, may be used.
此时可采用平板试块进行校验，但我的问题是此时是否需要考虑耦合修正？
9-28:
如果是直探头检测，可参考T-434.1.7.3 Alternative for Convex Surface. As an alternative to the requirements in T-434.1.7.1 when examining from the convex surface by the straight beam contact technique, Appendix G may be used.即附录G进行修正！
那如果是斜探头，是否需修正，如需要又如何修正？
