ISO 4761:2022 pdf download.Non-destructive testing of welds — Phased array ultrasonic testing (UT- PA) for thin-walled steel components — Acceptance levels
This document specifies acceptance levels for the phased array ultrasonic testing technique (UT-PA) of full-penetration welds in low-alloy and/or fine-grained steels in the wall thickness range from 3,2 mm to 8 mm which correspond to the quality levels of ISO 5817.
These acceptance levels are applicable to indications detected according to ISO 20601.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 5577, Non-destructive testing — Ultrasonic testing — Vocabulary
ISO 20601, Non-destructive testing of welds — Ultrasonic testing — Use of automated phased array technology for thin-walled steel components
ISO 23243, Non-destructive testing — Ultrasonic testing with arrays — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5577, ISO 20601 and ISO 23243 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Symbols
l indication length
l 1 , l 2 length of individual indications
l c corrected length
l cu cumulative length
l w weld length
t thickness
5 Sensitivity setting and levels
The setting of the sensitivity shall be performed on a 1,0 mm diameter side-drilled hole as specified in ISO 20601, this is also the reference level. This sensitivity setting shall be used for the subsequent
testing.
Three levels as defined in ISO 5577 are to be used:
a) reference level, level defined by the echo amplitude of a defined reference reflector;
b) acceptance level, level defining limits for acceptance regarding echo height, position, classification (if applicable) and number of indications or size of discontinuities;
c) evaluation level, level above or below which indications shall be evaluated or examined further.
All levels are linked to the reference reflector and are specified in Clauses 8 and 9.
6 Acceptance levels
Three different acceptance levels are defined. The relation between these acceptance levels and the quality levels as mentioned in accordance with ISO 5817 are given in Table 1.
7 Evaluation of indications
Indications detected when applying ISO 20601 and having an amplitude above the evaluation level (reference level -12 dB) shall be evaluated according to the specified acceptance level by using the
indication length and maximum amplitude. Unless specified otherwise, indications from the object geometry, such as weld reinforcement, are considered not relevant.
For two-sided testing, Clause 8 shall be applied. For single-sided testing, Clause 9 shall be applied.
The length of an indication shall be determined by measuring the length along the weld using the 6 dB drop method. Only for unfocused sound beams in lateral direction, a length correction may be applied according to Formula (1).
When reporting of indications below the acceptance level is specified, the details for reporting shall also be specified.
8 Acceptance criteria for two-sided testing
8.1 General
When indications are detected, length and maximum amplitude shall be determined in accordance with Clause 7.
Indications shall be evaluated according to their acceptance level and the acceptance criteria listed in this clause.
All indications with an amplitude greater than the reference level -12 dB shall be evaluated for acceptance by using the criteria given in 8.2, 8.3 and 8.4.
8.3 Transverse indications
When detection of transverse indications is specified, these indications are only acceptable if amplitude and length can be determined and meet the acceptance levels stated in 8.2.
8.4 Cumulative length of indications
The cumulative length of all individually acceptable indications above the evaluation level shall be calculated within a specified section of weld length, l w , as the sum of lengths of both single indications and linearly aligned indications (see Figure 4).ISO 4761 pdf download.ISO 4761 pdf download
