The weld joints in the reactor pressure vessel (RPV) of Boiling Water Reactors (BWR) are required to beexamined periodically for assurance of structural integrity. Ultrasonic phased array examination tech-nique has been developed in authors’ laboratory for inspection of the top flange to shell circumferentialweld joint in RPV of BWRs, which are in operation in India since the late 1960s. The development involveddetailed simulation studies for computation of focal laws followed by validation on mock-up. The paperbrings out the limitations of the conventional ultrasonic technique and how this can be overcome bythe phased array approach for the weld joint under consideration. The phased array technique wassuccessfully employed for field examination of this weld joint in RPV during the re-fuelling outage.