Detail of GB/T 37910.1-2019

Introduction of GB/T 37910.1-2019

Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative. GB/T 37910 consists of the following two parts under the general title Non-destructive testing of welds - Acceptance levels for radiographic testing: ——Part 1: Steel, nickel, titanium and their alloys; ——Part 2: Aluminium and its alloys. This is Part 1 of GB/T 37910. This part is developed in accordance with the rules given in GB/T 1.1-2009. This part has been redrafted and modified in relation to ISO 10675-1: 2016 Non-destructive testing of welds - Acceptance levels for radiographic testing - Part 1: Steel, nickel, titanium and their alloys. The main technical differences with respect to ISO 10675-1: 2016 and their justifications are as follows: ——As for the normative references, adjustments of technical differences are made to this part to keep them in line with the technical conditions in China. The adjustments are embodied in a concentrated way in Clause 2 "Normative references", specifically as follows:  ISO 17636-1 is replaced by GB/T 3323.1 modified in relation to international standard (see Clause 1, Clause 3 and Annex A);  ISO 17636-2 is replaced by GB/T 3323.2 modified in relation to international standard (see Clause 1, Clause 3 and Annex A);  ISO 17637 is replaced by GB/T 32259 modified in relation to international standard (see Clause 4);  ISO 6520-1 is replaced by GB/T 6417.1 which is identical to the international standard (see Clause 5, Table 2, Table 3 and A.1);  According to ISO 5817, the acceptance requirement that the clustered (localized) porosity shall be of spherical pores is added, so as to be convenient for practical application (see Table 2). This part was proposed by and is under the jurisdiction of the National Technical Committee on Welding of Standardization Administration of China (SAC/TC 55). Non-destructive testing of welds - Acceptance levels for radiographic testing - Part 1: Steel, nickel, titanium and their alloys 1 Scope This part of GB/T 37910 specifies the acceptance levels for indications from imperfections in butt welds of steel, nickel, titanium and their alloys detected by radiographic testing. If agreed by the parties to the contract, the acceptance levels may be applied to other types of welds or materials. The acceptance levels are related to welding standards, testing standards, specifications or codes. This part is used to assess whether a weld meets the requirements specified for a weld quality level by comparing the sizes of imperfections permitted by this part with those revealed by a radiograph or figure of the weld when carrying out radiographic testing in accordance with GB/T 3323.1 or GB/T 3323.2. 2 Normative references The following referenced documents are indispensable for the application 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. GB/T 3323.1 Non-destructive testing of welds - Radiographic testing - Part 1: X- and gamma-ray techniques with film (GB/T 3323.1-2019, ISO 17636-1: 2013, MOD) GB/T 3323.2 Non-destructive testing of welds - Radiographic testing - Part 2: X- and gamma-ray techniques with digital detectors (GB/T 3323.2-2019, ISO 17636-2: 2013, MOD) GB/T 6417.1 Classification and explanation of imperfections in fusion welded joints (GB/T 6417.1-2005, ISO 6520-1: 1998, IDT) GB/T 32259 Non-destructive testing of welds - Visual testing of fusion-welded joints (GB/T 32259-2015, ISO 17637: 2003, MOD) ISO 5817 Welding - Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding excluded) - Quality levels for imperfections 3 Testing technique Depending on the weld quality level, radiographic testing in accordance with Class A or Class B in GB/T 3323.1 or GB/T 3323.2 shall be carried out, as shown in Table 1. Table 1 Radiographic testing technique classes Quality levels in accordance with ISO 5817 Testing technique classes in accordance with GB/T 3323.1 and GB/T 3323.2 Acceptance levels in accordance with this part B B 1 C Ba 2 D A 3 a The minimum number of exposure for circumferential weld testing corresponds to the requirements of Class A of GB/T 3323.1 and GB/T 3323.2. 4 General Welded joints shall be visually tested and evaluated in accordance with GB/T 32259 before radiographic testing. The acceptance levels of this part are basically valid for evaluation of imperfections (see Table 2) which cannot be detected and evaluated by visual testing. Surface imperfections (see Table 3, such as undercut and excessive penetration, surface damage, weld spatter, etc.) which, due to object geometry, cannot be evaluated, but where the interpreter suspects the ISO 5817 quality levels are not fulfilled, shall be subject to more specific testing. When quantification of undercut and/or excessive penetration by radiographic testing is required, process procedures using test exposures may be applied in order to establish a basis for approximate quantification in accordance with the requirements of ISO 5817. Whether quantification is required shall be specified. 5 Acceptance levels The acceptance levels for indications are shown in Table 2 and Table 3. The types of imperfections are selected from ISO 5817 and defined in GB/T 6417.1. See Annex A for imperfection number. The symbols used in Table 2 and Table 3 are as follows: ——A: sum of projected areas of indications related to each L×Wp, in % (see Annex B); ——b: width of excess penetration of weld, in millimeters; ——d: diameter of pore, in millimeters; ——dA: diameter of pore envelope area, in millimeters; ——h: width of indication, or the width or height of surface imperfection, in millimeters; ——L: any 100mm testing length of weld, in millimeters; ——l: length of indication, in millimeters; ——s: nominal butt weld thickness, in millimeters; ——t: base material thickness, in millimeters; ——Wp: width of the weld, in millimeters; ——∑l: summary length of imperfections within L, in millimeters. If the distance between any adjacent imperfections is less than or equal to the major size of the smaller imperfection, it shall be regarded as an imperfection. See Annex C for the calculation of the sum of imperfection areas. Indications shall not be divided into different ranges L.

Contents of GB/T 37910.1-2019

Foreword i 1 Scope 2 Normative references 3 Testing technique 4 General 5 Acceptance levels Annex A (Informative) Guide to the imperfections of radiographic testing Annex B (Informative) Examples for area percentage (%) of imperfections Annex C (Informative) Calculation of the sum of acceptable imperfection areas