AWS C3.8M-C3.8:2011 pdf download.Specification for the Ultrasonic Pulse-Echo Examination of Brazed Joints
4.4 Examination Techniques. This specification details two techniques for the inspection of braze joints. The contact technique is normally associated with a manual“hand scan" of the test area. Using this technique, the ultrasonic sys-tem's A-scan is viewed by the inspector and defects are identified during scanning with no B scan or C-scan image doc-umentation. The immersion technique is associated with an automated scan of the brazed joint controlled by a computer system using B-scan and/or C-scan outputs to view the inspection results.
4.4.1 Contact Technique. The inspection shall be conducted using a flat focused transducer in the pulse echo mode.The ultrasonic beam shall be normal to the inspection surface during inspection. The requirements of ASTM E 114 shall be used during work instruction development and testing.
4.4.1.3 Sensitivity. The ultrasonic sensitivity shall be demonstrated on a reference standard representative of the brazement to be inspected. The reflected signal from the reference standard's rejectable indication shall be at a minimum 80% full-screen height. The scanning sensitivity shall be no less than six decibels greater in amplitude than the stan-dard's rejectable indication. The inspection threshold shall be set to 40% of full-screen height or as approved by the Organization Having Quality Responsibility. All indications exceeding this level shall be held for evaluation. The ultra-sonic system shall have an alarm function capable of signaling the inspection threshold and shall be used during the inspection.
4.4.1.5 Work Instructions. The ultrasonic work instructions shall be documented and approved by a Level 3 cer-tified in accordance with NAS 410. The work instructions shall document all necessary parameters to reproduce the inspection and certify that the discontinuities in the reference standard can be found. This work instruction shall be avail-able during the inspection and for customer review.
4.4.2.1 Sensitivity. This ultrasonic sensitivity shall be demonstrated on a reference standard at the same water path as the inspection. The reflected signal from the reference standard's rejectable indication shall be at a minimum 80% full-screen height. The inspection threshold shall be set to 40% of full-screen height. All indications exceeding this level shall be held for evaluation. The ultrasonic system shall have an alarm function set at 40% and shall be used during the inspection.
4.4.2.2 Threshold. The inspection threshold shall be set to 40% of full screen height. All indications exceeding this level shall be held for evaluation. The ultrasonic system shall have an alarm function set at 40% and shall be used during the inspection.AWS C3.8M-C3.8 pdf download.