BS 7910:2013+A1:2015:2016 Edition
$215.11
Guide to methods for assessing the acceptability of flaws in metallic structures
| Published By | Publication Date | Number of Pages |
| BSI | 2016 | 492 |
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 10 | Foreword |
| 13 | Introduction |
| 14 | Figure 1 Example of integrity management procedure for flaws |
| 16 | 1 Scope 2 Normative references |
| 17 | 3 Symbols and definitions Table 1 Symbols |
| 36 | 4 Types of flaw |
| 37 | 5 General guidance on assessment |
| 39 | 6 Information required for assessment |
| 43 | Figure 2 Linearization of stress distributions |
| 46 | Figure 3 Schematic representation of stress distribution across section |
| 47 | 7 Assessment for fracture resistance Figure 4 Procedure for resolving flaws normal to principal stress |
| 48 | Figure 5 General flowchart for fracture assessment |
| 49 | Figure 6 Flowchart for Option 1 fracture assessment |
| 50 | Figure 7 Flowchart for Option 2 fracture assessment |
| 51 | Figure 8 Flowchart for Option 3 fracture assessment |
| 53 | Figure 9 Flowchart for flaw characterization |
| 54 | Figure 10 Definitions of flaw dimensions |
| 55 | Figure 11 Flaw alignment rules for non-coplanar flaws |
| 56 | Figure 12 Flaw interaction rules for coplanar flaws |
| 58 | Table 2 Coefficient of variation (COV) for tensile properties for ferritic steels Table 3 Elastic modulus |
| 59 | Figure 13 De-rating values for yield/proof strength and tensile strength at temperatures above room temperature in C-Mn steels and duplex stainless steels (DSS): (not applicable to 13% Cr steels) from DNV OS F101 [6] |
| 61 | Table 4 Guidance for determining whether yielding is continuous or discontinuous |
| 68 | Table 5 Minimum of three equivalent (MOTE) Table 6 Values of k0.90 at the lower 20th percentile for the one sided tolerance limit for a normal distribution |
| 78 | Figure 14 Ductile tearing assessment |
| 80 | Figure 15 Example of non-unique solutions Table 7 Limits for slag inclusions and porosity |
| 82 | 8 Assessment for fatigue Table 8 Procedure for assessment of known flaws |
| 87 | Table 9 Stress ranges used in fatigue assessments |
| 89 | Figure 16 Schematic crack growth relationships Figure 17 Recommended fatigue crack growth laws |
| 90 | Table 10 Recommended fatigue crack growth laws for steels in air A) |
| 91 | Table 11 Recommended fatigue crack growth laws for steels in a marine environments A) |
| 93 | Table 12 Recommended fatigue crack growth threshold, DK0, values for assessing welded joints |
| 95 | Table 13 Details of quality category S-N curves |
| 96 | Figure 18 Quality category S-N curves |
| 101 | Figure 19 Quality category approach: assessment of surface flaws in plates under axial loading |
| 103 | Figure 20 Quality category approach: assessment of surface flaws in flat material (no weld toe or other stress raiser) in bending |
| 105 | Figure 21 Quality category approach: assessment of embedded flaws in axially loaded joints |
| 107 | Figure 22 Quality category approach: assessment of weld toe flaws in axially loaded joints |
| 113 | Figure 23 Quality category approach: assessment of weld toe flaws in joints loaded in bending |
| 117 | Table 14 Minimum values of Drj for assessing non-planar flaws and shape imperfections |
| 118 | Table 15 Limits for non-planar flaws in as welded steel and aluminium alloy weldments Table 16 Limits for non-planar flaws in steel weldments stress relieved by PWHT |
| 119 | Table 17 Acceptance levels for misalignment expressed in terms of stress magnification factor, km Table 18 Acceptance levels for weld toe undercut in material thicknesses from 10 mm to 40 mm |
| 120 | 9 Assessment of flaws under creep and creep/fatigue conditions |
| 124 | Figure 24 Determination of temperature Tc at which 0.2% creep strain is accumulated at a stress level equal to the proof strength Table 19 Temperature below which creep is negligible in 200,000 h |
| 125 | Figure 25 Insignificant creep curves for austenitic steels Figure 26 Insignificant creep curves for ferritic steels |
| 127 | Figure 27 Schematic behaviour of crack subjected to steady loading at elevated temperature |
| 128 | Figure 28 Schematic representation of crack propagation and failure conditions |
| 129 | Figure 29 Flowchart for overall creep assessment procedure |
| 144 | 10 Assessment for other modes of failure |
| 146 | Figure 30 Schematic diagrams of typical relationships between crack velocity and stress intensity factor during SCC |
| 148 | Figure 31 Types of corrosion fatigue crack growth behaviour |
| 151 | Annex A Evaluation under mode I, II and III loads Figure A.1 Definitions of loading modes |
| 156 | Annex B Assessment procedures for tubular joints in offshore structures |
| 157 | Figure B.1 Assessment method for fatigue crack growth in tubular joints |
| 163 | Annex C Fracture assessment procedures for pressure vessels and pipelines |
| 167 | Annex D Stress due to misalignment |
| 168 | Table D.1 Formulae for calculating the bending stress due to misalignment in butt joints |
| 171 | Table D.2 Formulae for calculating the bending stress due to misalignment in cruciform joints |
| 173 | Annex E Flaw recharacterization Figure E.1 Rules for recharacterization of flaws |
| 174 | Annex F Procedures for leak-before-break (LbB) assessment Figure F.1 The leak-before-break diagram |
| 176 | Table F.1 Guidance on selection of assessment sites around a pipe system |
| 177 | Figure F.2 Flow charts for LbB procedures |
| 182 | Figure F.3 Example characterization of a complex flaw |
| 184 | Figure F.4 Schematic flaw profiles at breakthrough |
| 185 | Table F.2 Advice on growth of surface flaws [160] |
| 186 | Table F.3 Advice on growth of through-wall defects [160] |
| 187 | Figure F.5 Development of flaw shapes for sub-critical growth of surface flaws Figure F.6 Development of flaw shapes for sub-critical growth of through-wall flaws |
| 188 | Figure F.7 Recommended re-characterization of flaws at breakthrough subjected to ductile tearing loading |
| 189 | Table F.4 Crack opening area methods for simple geometries and loading |
| 193 | Table F.5 Summary of short wave length surface roughness values [208] |
| 198 | Table F.6 Particulates in primary system water |
| 199 | Annex G The assessment of locally thinned areas (LTAs) |
| 201 | Figure G.1 Flow chart of assessment procedure |
| 202 | Figure G.2 Dimensions of an LTA |
| 204 | Figure G.3 Dimensions of a bend |
| 205 | Figure G.4 Dimensions of a sphere and vessel end |
| 207 | Figure G.5 Interaction between LTAs |
| 211 | Annex H Reporting of fracture, fatigue or creep assessments |
| 214 | Annex I The significance of strength mis-match on the fracture behaviour of welded joints |
| 216 | Figure I.1 Idealized weld geometry – the parent and weld metals have yield strengths of  and  respectively |
| 217 | Figure I.2 Idealized definition of mis-match ratio, M, and construction of the equivalent stress-strain curve (weighted average of the other two curves) |
| 222 | Annex J Use of Charpy V-notch impact tests to estimate fracture toughness |
| 223 | Figure J.1 Flowchart for selecting an appropriate correlation for estimating fracture toughness from Charpy data |
| 227 | Annex K Probabilistic assessment |
| 231 | Table K.1 Uncertainties in Paris parameter A |
| 232 | Table K.2 Uncertainties in Paris parameter A for the two stage model |
| 233 | Table K.3 Target failure probability (events/year) |
| 234 | Table K.4 Recommended partial factors for different combinations of target reliability and variability of input data based on failure on the FAD |
| 242 | Annex L Fracture toughness determination for welds |
| 252 | Annex M Stress intensity factor solutions |
| 255 | Figure M.1 Through-thickness flaw geometry Figure M.2 Edge flaw geometry |
| 256 | Figure M.3 Surface flaw |
| 258 | Figure M.4 Elliptical integral as a function of a/2c used for the calculation of KI for surface and embedded flaws Figure M.5 Stress intensity magnification factor Mm for surface flaws in tension |
| 261 | Figure M.6 Stress intensity magnification factor Mb for surface flaws in bending |
| 262 | Figure M.7 Extended flaw geometry |
| 263 | Figure M.8 Embedded flaw |
| 264 | Figure M.9 Stress intensity magnification factor Mm for embedded flaws in tension (at point nearest material surface) |
| 265 | Figure M.10 Stress intensity magnification factor Mb for embedded flaws in bending |
| 266 | Figure M.11 Corner flaw geometry |
| 268 | Figure M.12 Corner flaw at hole geometry |
| 272 | Figure M.13 Through-thickness flaw in cylinder oriented axially |
| 273 | Table M.1 a) M1 for axial through-thickness in cylinders: membrane loading |
| 274 | Table M.1 b) M2 for axial through-thickness flaws in cylinders: membrane loading |
| 275 | Table M.1 c) M3 for axial through-thickness flaws in cylinders: bending loading |
| 276 | Table M.1 d) M4 for axial through-thickness flaws in cylinders: bending loading |
| 277 | Figure M.14 Internal surface flaw in cylinder oriented axially |
| 278 | Table M.2 Mm and Mb for axial internal surface flaw in cylinder |
| 279 | Figure M.15 Extended internal surface flaw in cylinder orientated axially Table M.3 Mm and Mb for extended axial internal surface flaw in cylinder |
| 280 | Figure M.16 External surface flaw in cylinder oriented axially Table M.4 Mm and Mb for axial external surface flaw in cylinder |
| 281 | Figure M.17 Extended axial external surface flaw in cylinder Table M.5 Mm and Mb for extended axial external surface flaw in cylinder |
| 283 | Figure M.18 Through-thickness flaw in cylinder oriented circumferentially |
| 284 | Table M.6a) M1 for circumferential through-thickness flaws in cylinders: membrane loading |
| 285 | Table M.6b) M2 for circumferential through-thickness flaws in cylinders: membrane loading |
| 286 | Table M.6c) M3 for circumferential through-thickness flaws in cylinders: bending loading |
| 287 | Table M.6d) M4 for circumferential through-thickness flaws in cylinders: bending loading |
| 288 | Figure M.19 Internal surface flaw in cylinder oriented circumferentially |
| 289 | Table M.7 Mm and Mb for circumferential internal surface flaw in cylinder |
| 290 | Figure M.20 Fully circumferential internal surface flaw in cylinder Table M.8 Mm and Mb for extended circumferential internal surface flaw in cylindrical shell |
| 291 | Figure M.21 Fully circumferential external surface flaw in cylinder |
| 292 | Table M.9 Influence coefficients at points A and B for an equatorial through‑thickness flaw in a sphere |
| 294 | Figure M.22 Through-thickness flaw in spherical shell |
| 295 | Figure M.23 Flaws in bars and bolts |
| 298 | Figure M.24 Fully circumferential flaw in a round bar |
| 300 | Figure M.25 Welded joint geometries |
| 301 | Figure M.26 Transverse load-carrying cruciform joint Table M.12 Values of v and w for axial and bending loading |
| 306 | _GoBack |
| 307 | Annex N Allowance for constraint effects |
| 313 | Figure N.1 Schematic showing curve fitting of low constraint test data to obtain a and k |
| 315 | Figure N.2 Modifications to the Option 1 failure assessment curve for various values of the material parameters, a, k, and constraint levels, b (< 0), using Equation N.23 with k = 3. For a = 0 or b = 0 the curves reduce to the Option 1 curve |
| 316 | Figure N.3 FAD analysis for (a) fracture initiation and (b) ductile tearing |
| 318 | Table N.1 Polynomial coefficients defining bT for CCT [326 to 328] Table N.2 Polynomial coefficients defining bT for CCBT |
| 319 | Table N.3 Polynomial coefficients defining bT for DECT [311], [326], [328] Table N.4 Polynomial coefficients defining bT for SECT |
| 320 | Table N.5 Polynomial coefficients defining bT for SEB [311, 326, 328] Table N.6 Polynomial coefficients defining bT for 3PB |
| 321 | Table N.7 Polynomial coefficients defining bT for SCT [329] |
| 322 | Table N.8 Polynomial coefficients defining bT for SCB [329] |
| 323 | Table N.9 Polynomial coefficients defining bT for CISLCCT [326], [330] |
| 324 | Table N.10 Polynomial coefficients defining bT for CISSCCBT [331] |
| 325 | Table N.11 Polynomial coefficients defining bT for CISSCCT [331] |
| 327 | Table N.12 a and k defined with respect to T/rY for n = 5 |
| 328 | Table N.13 a and k defined with respect to T/rY for n = 6 Table N.14 a and k defined with respect to T/rY for n = 7 |
| 329 | Table N.15 a and k defined with respect to T/rY for n = 8 Table N.16 a and k defined with respect to T/rY for n = 9 |
| 330 | Table N.17 a and k defined with respect to T/rY for n = 10 Table N.18 a and k defined with respect to T/rY for n = 11 |
| 331 | Table N.19 a and k defined with respect to T/rY for n = 12 Table N.20 a and k defined with respect to T/rY for n = 13 |
| 332 | Table N.21 a and k defined with respect to T/rY for n = 14 Table N.22 a and k defined with respect to T/rY for n = 15 |
| 333 | Table N.23 a and k defined with respect to T/rY for n = 16 Table N.24 a and k defined with respect to T/rY for n = 17 |
| 334 | Table N.25 a and k defined with respect to T/rY for n = 18 Table N.26 a and k defined with respect to T/rY for n = 19 |
| 335 | Table N.27 a and k defined with respect to T/rY for n = 20 |
| 336 | Table N.28 a and k defined with respect to Q for n = 5 |
| 337 | Table N.29 a and k defined with respect to Q for n = 6 Table N.30 a and k defined with respect to Q for n = 7 |
| 338 | Table N.31 a and k defined with respect to Q for n = 8 Table N.32 a and k defined with respect to Q for n = 9 |
| 339 | Table N.33 a and k defined with respect to Q for n = 10 Table N.34 a and k defined with respect to Q for n = 11 |
| 340 | Table N.35 a and k defined with respect to Q for n = 12 Table N.36 a and k defined with respect to Q for n = 13 |
| 341 | Table N.37 a and k defined with respect to Q for n = 14 Table N.38 a and k defined with respect to Q for n = 15 |
| 342 | Table N.39 a and k defined with respect to Q for n = 16 Table N.40 a and k defined with respect to Q for n = 17 |
| 343 | Table N.41 a and k defined with respect to Q for n = 18 Table N.42 a and k defined with respect to Q for n = 19 |
| 344 | Table N.43 a and k defined with respect to Q for n = 20 |
| 345 | Annex O Consideration of proof testing and warm prestressing |
| 347 | Figure O.1 Schematic illustration of a proof test argument (following [3]) |
| 349 | Figure O.2 Typical warm prestress cycles |
| 352 | Annex P Compendium of reference stress and limit load solutions for homogeneous and strength mis‑matched structures |
| 354 | Table P.1 Calculation of bending stresses as functions of moments |
| 358 | Figure P.1 Double edge cracked plate under tension |
| 360 | Figure P.2 Extended embedded flaw in a plate |
| 370 | Figure P.3 Circumferential internal and external surface flaws in thick-walled cylinders under combined tension and bending |
| 371 | Table P.2 Values of v for bending loading |
| 373 | Table P.3 Coefficient Qu for various joint design classifications |
| 374 | Figure P.4 T and Y joints under a) axial load, b) in-plane and out-of-plane bending |
| 375 | Figure P.5 K joints under a) axial load and b) in-plane and out-of-plane bending |
| 376 | Figure P.6 X and DT joints under a) axial load and b) in-plane and out-of-plane bending |
| 377 | Figure P.7 Classification of plasticity deformation patterns for mis-matched structures, [367] |
| 381 | Figure P.8 Centre cracked plate under tension w = (W − a)/h |
| 385 | Figure P.9 Double edge cracked plate under tension |
| 389 | Figure P.10 Single edge cracked plate under pure bending |
| 391 | Figure P.11 Fully circumferential internal flaws in thin-walled pipes/cylinders under tension |
| 392 | Figure P.12 Centre through-thickness flaws in clad plates under tension [372], [373] |
| 394 | Figure P.13 Through-thickness flaw in a clad plate with repair weld |
| 395 | Annex Q Residual stress distributions in as-welded joints Table Q.0 Validity ranges for as-welded residual stress distributions in ferritic steels |
| 397 | Figure Q.1 Components of longitudinal residual stress distribution for plate butt welds and pipe axial seam welds (austenitic steel) Table Q.1 Components of longitudinal stress and  for plate butt welds and pipe axial seam welds (austenitic steel) |
| 398 | Figure Q.2 Components of transverse stress distribution for plate butt welds and axial seam welds (austenitic and ferritic steels) Table Q.2 Components of transverse stress and  for plate butt welds and axial seam welds (austenitic and ferritic steels) |
| 399 | Figure Q.3 Components of longitudinal stress distribution for pipe butt welds (ferritic and austenitic steels) Table Q.3 Components of longitudinal stress and  for pipe butt welds (ferritic and austenitic steels) |
| 400 | Figure Q.4 Components of transverse stress distribution for pipe butt welds (ferritic steels) |
| 403 | Table Q.4 Components of transverse stress and  for pipe butt welds (ferritic steel) Table Q.5 Components of transverse stresses and  for pipe butt welds (austenitic steel) |
| 404 | Figure Q.5 Components of longitudinal stress distribution for plate to plate T-butt welds (ferritic steels) |
| 405 | Table Q.6 Components of longitudinal stress and  for plate to plate T-butt welds (ferritic steels) |
| 406 | Figure Q.6 Components of transverse stress distribution for plate to plate T-butt welds (austenitic and ferritic steels) Table Q.7 Components of transverse stress and  for plate to plate T-butt welds (ferritic and austenitic steels) and longitudinal stress and  for plate to plate T-butt welds (austenitic steels) |
| 407 | Figure Q.7 Components of longitudinal stress distribution for tubular T-butt welds (ferritic steels) Table Q.8 Components of longitudinal stress and  for tubular T-butt welds (ferritic steels) |
| 408 | Figure Q.8 Components of transverse stress distribution for tubular T-butt welds (ferritic steels) |
| 409 | Table Q.9 Components of transverse stress and  for tubular T-butt welds (ferritic steels) |
| 410 | Figure Q.9 Residual stress profile for repair welds (transverse and longitudinal) Table Q.10 Components of transverse and longitudinal stress distribution for repair welds (ferritic and austenitic steels) |
| 411 | Figure Q.10 Finite surface crack in an infinite width plate |
| 412 | Table Q.11 Geometry functions for a finite surface flaw in an infinite width plate – deepest point of the flaw |
| 413 | Table Q.12 Geometry functions for a finite surface flaw in an infinite width plate – intersection of flaw with free surface |
| 415 | Figure Q.11 Extended surface flaw in an infinite width plate Table Q.13 Geometry functions for an extended surface flaw in an infinite width plate |
| 416 | Annex R Determination of plasticity interaction effects with combined primary and secondary loading |
| 419 | Figure R.1 Non-dimensional stress intensity factors for through-thickness flaws with through-wall self‑balancing stress distributions |
| 421 | Annex S Information for making high temperature crack growth assessments |
| 423 | Figure S.1 General form of a creep curve defining the average and secondary creep strain rates |
| 424 | Figure S.2 Derivation of strain versus time curves from iso-strain curves |
| 425 | Table S.1 Mean uniaxial creep properties for different steels for short (<10 000 h) and long term tests |
| 427 | Table S.2 Constants used to derive creep crack growth rates in mm/h and C* in MPamh−1 |
| 434 | Annex T Guidance on the use of NDT with ECA |
| 438 | Figure T.1 Assessment of flaw tolerance using ECA |
| 439 | Figure T.2 Assessment of detected flaw |
| 441 | Table T.2 Examples of inspection capabilities for back surface flaws |
| 442 | Table T.3 Examples of inspection capabilities for flaws at the accessible surface |
| 447 | Table T.4 Capabilities for detection and length measurement of surface-breaking flaws by MPI ([416]) |
| 448 | Table T.5 Flaw detection capability for liquid penetrant testing [444, 445] |
| 451 | Annex U Worked examples in fatigue assessment using the quality category approach Figure U.1 Butt weld containing embedded flaw |
| 452 | Figure U.2 Derivation of actual quality category for a flaw |
| 453 | Figure U.3 Fillet weld containing a surface flaw |
| 454 | Figure U.4 Obtaining the required quality category |
| 455 | Figure U.5 Obtaining the quality category for the flaw |
| 458 | Bibliography |
