Steel Tube Handbook - 2018

8 In practice, pressure tubes are assigned into testing categories type TC2, tested by combining two non-destructive tests: - Eddy current testing (testing leak tightness). Testing by overpressure at the request of the customer by agreement. - Ultrasound for longitudinal defects (non destructive testing). Legend and comments NDT - Non-destructive examination (testing) EN 10216-1 - Standard contains only carbon steel Testing methods E - Eddy Current - eddy current (EN ISO10893 - 1 and 2). (Tests marked in overview 1.2.1, 1.2.2 and 2.1.1) Encircling coil - levels of permissibility E1H, E2H, E3H, E4H (hole diameter in the reference standard, depending on the dia- meter of the tube D - see the table in the standards) Rotary probe coil - levels of permissibility E2, E3, E4, E5. Testing the tubes with D≥ 4 mm. F - Flux Leakage - stray flux (EN ISO10893-3). (Tests marked in overview 2.1.2 and 2.2.2) Levels of permissibility F2, F3, F4, F5, F6. Testing the tubes with D> 10 mm. U - Ultrasound - longitudinal imperfections EN ISO 10893 -10 - Transverse imperfections EN ISO10893-10 - Duality EN ISO10893 - 8 (for a wall thickness of 5 mm) - Check the wall thickness EN ISO10893 -12 (from 4.5 to 5 mm of wall thickness) (Tests marked in overview 2.1.3, 2.2.1, 2.3, 2.4 and 2.5.) Levels of permissibility to EN ISO10893 - 10 - U1, U2, U3, U4, U5, U6 Subclasses A, B, C, D. Testing the tubes with D≥ 10 mm and the ratio D / T> 5 For smaller values by agreement, below the value of 4 the ultrasound test is not performed. Levels of permissibility and the notch depth Subclass - minimum depth of the notch (mm) of a standard in % of the wall T: 1 3 A 0,1 2 5 B 0,2 3 10 C 0,3 4 12,5 D 0,5 5 15 6 20 Subclasses A, B, C, D are valid for cold formed and machined tubes. Subclass C and D are valid for hot rolled tubes. Other values of acceptance levels as in EN - after agreement. Testing for transverse imperfections, duality and checking the wall thickness - only after agreement. For testing according to ASTM and API 5L - see page 102 (leakage test), page 31 (NDT) Leak tightness testing and NDT for pressure tubes according to EN standards EN 10216 – 1 EN 10216 – 2, 3, 4 Quality TR 1 or TR 2 Testing category TC 1 or TC 2 Carbon steel - the type of quality is a part of steel brand Carbon steel - choice of TC1 or TC2 Alloy steel - only TC2 1. Leak tightness testing Required for all tubes. Select from the methods: 1.1 Testing by internal overpressure Selection is from the lesser value of pressures: 1.1.1 70 bar 1.1.2 the pressure value according to the formula P = 20x (SXT) / D, where S = 70% of the minimum specified yield strength in MPa (pressure in bars) 1.2 Non-destructive testing according to EN ISO 10893-1 (E) Electromagnetic testing - Eddy current. Preference from the methods: 1.2.1 encircling coil - the diameter of the borehole in reference to standard is dependent on the tube diameter D (Table is in the standard) 1.2.2 rotary probe coil – reference standard notch with depth of 12.5% of nominal wall thickness T (min. 0.5 mm, max 1,5 mm). Notch width is less than depth, length min 50 mm 2. Non-destructive testing - longitudinal imperfections 2.1 Quality TR2 select from: 2.1.1 Eddy current (E) - EN ISO 10893-2 2.1.2 Stray flux (F) - EN ISO 10893-3 2.1.3 Ultrasound (U) - EN ISO 10893-10 Class of eligibility 3, subclass C 2.2 Testing categories TC2 mandatory select from: 2.2.1 Ultrasound (U) - EN ISO10893-10 Class of eligibility U2, subclass C 2.2.2 Stray flux (F) EN ISO10893-3 Class of eligibility F2 Transverse defects (2.3) and laminar (laminar defects) (2.4) - testing only after agreement - Ultrasound 2.3 Test for transverse defects EN ISO 10893-10 U2C 2.4 Test for duality EN ISO10893-8 U2 2.5 Measurement of wall thickness EN ISO 10893-12 Tube testing according to EN 10216 standard Table 3