Welding Quality: Acceptance Criteria for Radiographic (RT) and Ultrasonic (UT) Examinations
El hazel Aymen
Lead Mechanical Engineer | API 510 Inspector&API 570 Inspector | Oil and Gas, Chemical industry |Asset integrity specialist| welding inspection |QA/QC engineer
I. Introduction
ASME VIII Div. 1 sets clear acceptance criteria for weld quality during volumetric inspections (RT or UT). This article will outline these specifications in a simple manner, as described in paragraph UW-51.
ASME VIII Div. 1 UW-51 places specific restrictions on UT (Ultrasonic Testing) inspections:
a) Weld thickness t ≥ 1/4 inch (6 mm).
b) When weld thickness t ≥ 1 inch (25 mm), UT inspection requires the concurrence of the user and must be documented in the manufacturer's data report.
II. Acceptance Criteria
The NDE weld acceptance criteria, as specified in ASME BPVC VIII Div. 1: UW-51, are based on weld thickness t and the largest dimension e for elongated indications (other than cracks). The criteria state that the weld must be free of:
1) Any indication characterized as a crack or a zone of incomplete fusion or penetration.
2) Any other elongated indication on the radiograph with a length e verifies:
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3) Aligned indications where the total length 𝐞𝐱𝐜𝐞𝐞𝐝𝐬 𝐭 within a 𝟏𝟐𝐭 span and If l is the 𝑙𝑒𝑛𝑔𝑡ℎ of the 𝐥𝐨𝐧𝐠𝐞𝐬𝐭 𝐢𝐦𝐩𝐞𝐫𝐟𝐞𝐜𝐭𝐢𝐨𝐧, then the distance between all imperfections 𝑠ℎ𝑎𝑙𝑙 𝑏𝑒 𝑔𝑟𝑒𝑎𝑡𝑒𝑟 than 6l.
4) For full details on rounded indications, refer to Mandatory Appendix 4.
Comprehensive Examples of Weld Defects in Radiographs in API 577
These weld acceptance criteria are also applicable to ASME BPVC VIII Div. 2, CODAP Div. 1, and BS EN 13445.
El hazel Aymen
aymen.elhazel@gmail.com
QC ENGINEER (NDT, CP, COATING, WELDING) || ASSET INTEGRITY || ENERGY ANALYST
4moFor the UT requires, first it is stated the weld thickness should be >= 6mm. This means UT cannot be conducted on Welds with thickness not more than 6mm Secondly, for weld thickness > 25 mm. Approval of the client is required. And the approval needs to be documented in the manufacturer's data report. My question is, 1. Why don't we need the Client's approval for weld thickness between 6 mm and 24 mm. And what kind of approval is the code referring to. I want to understand why the code is saying we need the Client's approval for some thickness range and for other thickness range we do not need any approval 2. In the 2nd requirement, which manufacturer's data report was the code referring to. And why do we have to document it in the manufacturer's data