Issue 07.98
Radiographic Examination of Piping Welds According to EN
LINDE AG Process Engineering and Contracting Division Orig.: TAW/Reiche
Checked: TAW/Mei.
LINDE STANDARD
Appr.: TAN/Hent.
LS-Class: EM, BM Descriptors: Examination, Radiographic, Welding, Piping EN
135-05 Total 6 Pages
Replaces Issue 06.98
Table of Contents 1 2 3 4 5 6 7 8 9
Page Scope ............................................................................1 Purpose.........................................................................1 Reference Documents .................................................1 Requirements to be met by the NDT-Agency............1 Surface Preparation .....................................................2 Technique of Testing ...................................................2 Extent of Testing ..........................................................3 Evaluation and Test Report ........................................4 Number of films............................................................5
Test Report Radiographic Examination RT see LS 135-05 F1
1
Scope
This standard covers workshop and field welds and contains basic requirements for the radiographic examination of circumferential and branch welds of piping with wall thicknesses ≤ 40 mm in process plants according to EN regulations 1). Where ever project- and component-specific requirements/specifications are more stringent, they shall have priority over those of this standard.
2
Purpose
This standard is addressed to the NDT-Agency and specifies technical details for the radiographic examination of piping welds, on the basis of the below listed standards.
3
Reference Documents
EN 444
General - principles for the radiographic examination of metallic materials using X-rays and gamma-rays. EN 462-1/2/3 Image quality of radiographs. EN 473 Qualification and certification of NDT personnel. EN 584-1/2 Industrial radiographic film classification of film systems. EN 1435 Non-destructive examination of welds; radiographic examination of welded joints. EN 12062 Non-destructive examination of welds; general rules for metallic materials. EN 12517 Radiographic examination of welded joints (acceptance levels). EN 25580 Industrial radiographic illuminators; minimum requirements. EN 25817 Arc - welded joints in steel (quality levels). EN 26520 Classification of imperfections in metallic fusion welds, with explanations. EN 30042 Guidance on quality levels for imperfections. When using ionizing radiation local or national or international safety precautions shall be strictly adhered to.
4
Requirements to be met by the NDT-Agency
The NDT-Agency shall fulfill the requirements according to EN 12062 para. 6 and 7.
___________ 1) The extent of testing for piping according to Pressure Vessel Regulation/TRR 100 is included.
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LS 135-05
Issue 07.98
LINDE AG Process Engineering and Contracting Division
Surface Preparation
The surface of weld and heat affected zone on both sides of the weld shall be free from discontinuities, which could either conceal defects or lead to false interpretations. See requirements of EN 1435 para. 5.2 and EN 12062 para.10.3.
6
Technique of Testing
6.1 Evaluation of the Radiographs For purposes of ensuring a correct correlation of film and welding seam to be tested each radiograph and welding seam shall be marked unambiguously and durably, namely: • Marking of welding seam by stamping, engraving or durable colour marking with test No., zero point, direction of measuring; • Film identification by exposed lead letters with consecutive test No., film No., special code letters (F = tracer shot, K = control shot, N = completely rewelded, R = repair weld) and marking of the area to be interpreted (by means of an exposed lead measuring tape for welds > DN 50 mm, for welds ≤ DN 50 mm lead letters are to be used), for heat treated welding seams the date of testing in addition; • Test numbers shall be used once only for a project! 6.2 Evaluation of the Radiographs Requirements see EN 1435 para. 6.7 and 6.8. 6.3 Arrangement of Exposures, Number of Films Requirements see EN 1435 para. 6.6. Table 4 shows a recommendation for the number of films. Double-wall exposures shall be made with collimator only. 6.4 Selection of Film/Screens Film size preferable 10 x 12 cm, 10 x 24 cm or 10 x 48 cm. Correlation of a few manufacturer trademarks of film types to the classification according to EN 584 part 1, see Table 1. Table 1: Types of Films and Classification acc. to EN 584 Part 1 Classification Agfa Gevaert C1 Structurix D2 C3 Structurix D4 C4 Structurix D5 C5 Structurix D7 1) Manual development 2) Automatic development Fluorescent screens are not permitted. 6.5 Image Quality Indicators (IQI) Requirements see EN 1435 para. 5.7.
Fuji IX 50 IX 80 IX 100 1) IX 100 2)
Kodak Industrex DR Industrex MX Industrex T Industrex AX
LINDE AG Process Engineering and Contracting Division
Issue 07.98
LS 135-05
Page 3
6.6 Gammagraphy of Steel Requirements see EN 1435 para. 6.2.2 Table 1 (thickness range). The exception rule in para. 6.2.2 which give the option to reduce the minimum penetrated thickness to 10 mm for Ir 192 and 5 mm for Se 75 will be accepted, if all of the following conditions have been fulfilled: • • • • •
Minimum image quality values acc. to EN 1435 appendix B; Source dimensions max. 2,0 x 2,0 mm; Film class C 3, films shall be vacuum-packed; Film screens for wall thicknesses ≤ 10 mm: Pb 0,1/0,1 mm; for wall thicknesses > 10 mm: Pb 0,02/0,02 mm; Exposure time ≥ 30 s.
6.7 Gammagraphy of Aluminium Requirements see EN 1435 para. 6.2.2 Table 1 (thickness range).
7
Extent of Testing
• Minimum extent of testing (with concentration on assembly welds) acc. to Table 2, material groups see Table 3. • For site welds the first three welds of each welder shall be radiographed 100 %, in addition to the requirements specified in Table 2. • Extent of testing for dissimilar welds between different types of material 100 % for piping > DN 25. • Extent of random testing for circumferential and branch welds at proportional coverage of the welders involved. • At detection of unacceptable imperfections, for ≤ DN 300 two further welds welded by the same welder shall be completely tested for each weld to be repaired (for > DN 300 only one spot film on two further welds). If unacceptable imperfections are found again double extent of testing is required. At a new defective weld(s) every weld of the welder involved shall be tested. • Repetition of radiographic testing after performed repair of welds. • Extent of testing prior to pneumatic test: Acc. to table 2, but at least 10 % or more shall be tested depending on the applicable national safety regulations. In case of manufacturers with well established safety procedures and proven safety records, the extent of testing may be reduced for work shop fabrication, in compliance with the national safety authorities, but not less than specified in table 2. T-joints with longitudinal welds shall be tested 100 % (not applicable to longitudinal welds which have been already non-destructively examined or pressure tested at the manufacturer’s work shop). • Extent of testing for underground piping, which cannot be subjected to a hydrostatic testing prior to filling of the pipe trench: at least 25 % shall be tested. Table 2: Extent of Testing for circumferential and branch welds Fluid Properties 1)
Piping Parameter 2)
Testing Group 1)
Extent of Testing % for Material Group 3) I II III 5 10 25 10 25 100 10 25 100 5 10 25 10 25 100
Combustible, toxic or caustic C1 > DN 25 and p × DN ≤ 2000 Combustible, toxic or caustic A1 > DN 25 and p × DN > 2000 Extremely toxic > DN 25 A2 C3 Liquid gas plants with pressure vessel ≤ 3 t 4) all DN, all p Liquid gas plants with pressure vessel > 3 t 4) all DN, all p A3 or conveying of liquid gas or several pressure vessels All the other fluids, e.g. air, water, vapor, > DN 25 and p < 63 D 5 gases contained in air(O2, N2, Ar, He) D 10 > DN 25 and p ≥ 63 1) Classification is made by LINDE. 2) DN = nominal size, p = max. allowable working pressure (bar); DN 25 corresponds to NPS 1. 3) See Table 3. 4) Capacity.
10 25
25 100
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LS 135-05
Issue 07.98
LINDE AG Process Engineering and Contracting Division
Table3: Material Groups Material Group
I
II
III
8
Type of Materials Unalloyed C-steels Fine grain steels (C-Mn-steels) with a minimum yield strength < 370 N/mm2 Heat-resisting Mo-steels (≤ 0,65% Mo) Cr Ni steels with a ferrite content in the weld deposit > 3 % AlMg 4,5 Mn (5083) Fine grain steels with a minimum yield strength ≥ 370 to < 430 N/mm2 Heat-restisting Cr-Mo-steels < 5% Cr Ni-steels for low temperature service ≤ 3,5% Ni Ferrite-free austenitic steels with ≤ 3% deltaferrite in the weld deposit Duplex steels (50 % ferrite - 50 % austenite) Other aluminium alloys than listed under I Fine grain steels with a minimum yield strength ≥ 430 N/mm2 Heat-resisting Cr-Mo-(V)-alloyed steels ≥ 5% Cr Copper and copper alloys Ni-steels for low temperature service > 3,5% Ni Titanium and titanium alloys, Ni-basis alloys (e.g. Inconel 625)
Evaluation and Test Report
Evaluation of radiographs acc. to: EN 12517 - Radiographic examination of welded joints (acceptance levels). EN 25817 - Arc - welded joints in steel (quality levels). EN 30042 - Guidance on quality levels for imperfections The consideration of higher requirements e.g. quality level B can be convenient, e.g. to prevent repeated pressure tests because of leakage (porosity). Test report according to LS 135-05 F1 (example; the use of own forms with comparable content is permissible).
LINDE AG Process Engineering and Contracting Division
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Issue 07.98
LS 135-05
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Number of films
For branch welds the number of films shall be selected as a function of the diameter ratio, but at least 2 films. Table 4: Recommendation for the number of films per circumferential weld Pipe Dimensions Diameter
NPS
Outside diameter mm
0,5 - 2 3
21,3-60,3 88,9
4
114,3
6
168,3
8
219,1
10
273,0
12
323,9
continued
Double-Wall Exposure Wall Thickness Range
mm 0,5 - 8,7 0,5 - < 5,5 5,5 - 20 0,5 - 19,5 0,5 - < 11 11 - 26 0,5 - < 2,6 2,6 - < 20 20 - 30 0,5 - < 10 10 - < 21,7 21,7 - 30 0,5 - 29 0,5 - 36 0,5 - < 8,5 8,5 - 35 0,5 - < 11 11 - 21,9 0,5 - 40 0,5 - 36 0,5 - < 19,4 19,4 - 40 0,5 - < 4,4 4,4 - 38 0,5 - 40 0,5 - 40 0,5 - < 30 30 - 40 0,5 - < 15 15 - 40 0,5 - < 11 > 11 - 40 0,5 - < 6,5 6,5 - 40 0,5 - 40 0,5 - < 23 23 - 40
Radiation source: Isotope Focus-Film Distance: Pipe outside diameter + 20 mm (Collimator)
Central Exposure Radiation source: X-ray tube Focus-Film Distance: Pipe outside diameter + 100 mm
Number of films/ film length 1) Number of films/ film length 1) Number of films/ film Test Categ.A Test Categ. B Test Categ. A Test Categ. B length 1) EN 1435 2) EN 1435 3) EN 1435 2) EN 1435 3) 2/12 cm 4) 2/12 cm 4) 2/12 cm 4) 2/12 cm 4) 2/12 cm 4) 2/12 cm 4) 2/12 cm 4) 2/12 cm 4) 3/12 cm 5) 3/12 cm 5) 3/12 cm 5) 3/12 cm 5) 4/12 cm 1/48 cm 5/12 cm 6/12 cm 4/12 cm 5/12 cm 6/12 cm 6/12 cm 7/12 cm 8/12 cm 4/24 cm 2/48 cm 5/24 cm 4/24 cm 5/24 cm 5/12 cm 6/12 cm 4/24 cm 2/48 cm 5/24 cm 4/24 cm 5/24 cm 5/24 cm 6/24 cm 4/48 cm 2/48 cm 5/24 cm 4/24 cm 5/24 cm 5/24 cm 6/24 cm 3/48 cm 3/48 cm 4/48 cm 4/48 cm 5/24 cm 4/48 cm 5/24 cm 6/24 cm
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LS 135-05
Issue 07.98
LINDE AG Process Engineering and Contracting Division
Table 4 (concluded) Pipe Dimensions Diameter
Double-Wall Exposure Wall Thickness Range
Radiation source: Isotope Focus-Film Distance: Pipe outside diameter + 20 mm (Collimator)
Radiation source: X-ray tube Focus-Film Distance: Pipe outside diameter + 100 mm
Number of films/ film length 1) Number of films/ film length 1) Number of films/ film mm Test Categ.A Test Categ. B Test Categ. A Test Categ. B length 1) EN 1435 2) EN 1435 3) EN 1435 2) EN 1435 3) 14 355,6 0,5 - < 10,5 3/48 cm 3/48 cm 10,5 - 40 4/48 cm 0,5 - < 9 4/48 cm 9 - 40 5/48 cm 0,5 - 40 4/48 cm 0,5 - < 32,5 5/24 cm 32,5 - 40 6/24 cm 16 406,4 0,5 - 20 3/48 cm 4/48 cm 5/48 cm 3/48 cm 0,5 - < 12 4/48 cm 12 - 40 5/48 cm 18 457,0 0,5 - 40 4/48 cm 4/48 cm 6) 4/48 cm 5/48 cm 4/48 cm 20 508,0 0,5 - 40 4/48 cm 4/48 cm 7) 4/48 cm 5/48 cm 4/48 cm 24 609,6 0,5 - 40 5/48 cm 26 660,0 0,5 - 40 5/48 cm 28 711,0 0,5 - 40 5/48 cm 30 762,0 0,5 - 40 6/48 cm 32 813,0 0,5 - 40 6/48 cm 36 914,0 0,5 - 40 7/48 cm 40 1016,0 0,5 - 40 8/48 cm 42 1067,0 0,5 - 40 8/48 cm 48 1219,0 0,5 - 40 10/48 cm 52 1321,0 0,5 - 40 10/48 cm 56 1420,0 0,5 - 40 11/48 cm 60 1524,0 0,5 - 40 12/48 cm 64 1620,0 0,5 - 40 13/48 cm 68 1727,0 0,5 - 40 13/48 cm 72 1820,0 0,5 - 40 14/48 cm 76 1930,0 0,5 - 40 15/48 cm 80 2020,0 0,5 - 40 15/48 cm 1) The number of the films has been determined according to EN 1435 and shall be the basis for the account on film price, under the condition that 100% of the weld length is evaluable. 2) "Increase in wall thickness" by a not vertical exposure ≤ 20 %. 3) "Increase in wall thickness" by a not vertical exposure ≤ 10 %. 4) Elliptical imaging, staggered by 90°. 5) Elliptical imaging, staggered by 60° 6) Only for wallthickness up to 16 mm. 7) Only for wallthickness up to 20 mm. NPS
Outside diameter mm
Central Exposure
Revision: Completely revised. Previous Issues: 03.71; 06.83; 08.84; 10.84; 10.87; 07.89 , 03.95 Copyright reserved.
