BS 7910:1999

Committees responsible
Foreword
Introduction
1 Scope
2 Normative references
3 Symbols and definitions
4 Types of flaw
5 Modes of failure and material damage mechanisms
6 Information required for assessment
7 Assessment for fracture resistance
8 Assessment for fatigue
9 Assessment of flaws in plant operating at high
    temperatures
10 Assessment for other modes of failure
Annexes
A (normative) Evaluation under combined direct and
                shear stresses or mode I, II and III
                loads
B (informative) Assessment procedures for tubular
                joints in offshore structures
C (informative) Fracture assessment procedures for
                pressure vessels and pipelines
D (normative) Stress due to misalignment
E (normative) Flaw re-characterization
F (informative) A procedure for leak-before-break
                assessment
G (normative) The assessment of corrosion in pipes and
                pressure vessels
H (normative) Reporting of fracture, fatigue or creep
                assessments
I (informative) The significance of weld strength
                mismatch on the fracture behaviour of
                welded joints
J (informative) Use of the results of Charpy V-notch
                impact tests to indicate fracture
                toughness levels
K (normative) Reliability, partial safety factors,
                number of tests and reserve factors
L (normative) Fracture toughness determination for
                welds
M (normative) Stress intensity factor solutions
N (normative) Simplified procedures for determining
                the acceptability of a known flaw or
                estimating the acceptable flaw size
                level 1 fracture procedures
O (informative) Consideration of proof testing and warm
                prestressing
P (normative) Calculation of reference stress
Q (informative) Residual stress distributions in
                as-welded joints
R (normative) Determination of plasticity interaction
                effects with combined primary and
                secondary loading
S (normative) Approximate numerical integration
                methods for fatigue life estimation
T (informative) Information for making high temperature
                crack growth assessments
U (informative) Worked example to demonstrate high
                temperature failure assessment procedure
Bibliography
FIGURES
1 Linearization of stress distributions
2 Schematic representation of stress distribution
    across section
3 Procedure for resolving flaws normal to principal
    stress
4 Flow chart - General methods
5 Flow chart - Level 1
6 Flow chart - Level 2
7 Flow chart - Level 3
8 Flaw dimensions
9 Planar flaw interactions
10 Level 1 FAD
11 Level 2 FADs
12 Level 3C FAD with assessment locus for a known flaw
13 Example of non-unique solutions (schematic)
14 Schematic crack growth relationships
15 Recommended fatigue crack growth laws
16 Quality category S-N curves
17 Assessment of surface flaws in axially-loaded
    material for simplified procedure
18 Assessment of surface flaws in flat material
    (no weld toe or other stress raiser) in bending for
    simplified procedure
19 Assessment of embedded flaws in axially-loaded
    joints for simplified procedure
20 Assessment of weld toe flaws in axially-loaded
    joints for simplified procedure
21 Assessment of weld toe flaws in joints loaded in
    bending for simplified procedure
22 Determination of the temperature Tc at which 0.2%
    creep strain is accumulated at a stress level equal
    to the proof strength
23 Determination of the time t(T) to achieve an
    accumulated creep strain of 0.2% at a stress level
    equal to the proof strength
24 Schematic behaviour of crack subjected to steady
    loading at elevated temperature
25 Schematic representation of crack propagation and
    failure conditions
26a Flow chart for overall creep assessment
27 Schematic diagrams of typical relationships between
    crack velocity and stress intensity factor during
    stress corrosion cracking
28 Types of corrosion fatigue crack growth behaviour
B.1 Assessment methodology for fatigue crack growth in
    tubular joints
C.1 Algorithm for pressure vessel flaw assessment
E.1 Re-characterization of flaws for ligament failure
    by ductile mechanisms under dynamic loading
F.1 The leak-before-break diagram
G.1 Flow chart of assessment procedure
J.1 Flow chart for selection of appropriate correlation
K.1 Evaluation of F L for single primary stress
M.1 Through-thickness flaw geometry
N.1 Relationship between actual flaw dimensions and the
    parameter for surface flaws
O.1 Typical warm prestress cycles
Q.1 Typical residual distributions in welded joints
R.1 Values for P1 for defining Kr
T.1 Derivation of strain versus time curves from
    iso-strain curves
U.1 Flaw dimensions
TABLES
1 Limits for slag inclusions and porosity
2 Procedure for assessment of known flaws
3 Stress ranges used in fatigue assessments
4 Recommended fatigue crack growth laws for steels
     in air
5 Recommended fatigue crack growth laws for steels
     in a marine environment
6 Recommended fatigue crack growth threshold, values
     for assessing welded joints
7 Details of quality category S-N curves
8 Minimum values for assessing non-planar flaws and
     shape imperfections
9 Limits for non-planar flaws in as-welded steel and
     aluminium alloy weldments
10 Limits for non-planar flaws in steel weldments
     stress relieved by PWHT
11 Acceptance levels for misalignment expressed in
     terms of stress magnification factor Km
12 Acceptance levels for weld toe undercut in material
     thickness from 10 mm to 40 mm
13 Temperature below which creep is negligible in
     200 000h
D.1 Formulae for calculating the bending stress due to
     misalignment in butt joints
F.1 Guidance on selection of assessment sites around a
     pipe system
J.1 Estimation of T27j from Charpy energies measured at
     other temperatures
K.1 Target probability of failure (events/year)
M.1a Mm* for axial through-thickness flaws in cylinders
     - Pressure loading
P.1 Values of x for bending loading
Q.1 Parametric ranges for recommended residual stress
     distributions
R.1 Tabulation as function of Lr and Kps /(K1p/Lr)
T.1 Constants used to derive creep crack propagation
     rates in mm/h
U.1 Operating conditions

Defines methods for assessing the acceptability of flaws in all types of components and structures. The procedures can be used for analysing flaws in structures made from other metallic materials and in non-welded components and structures as well as the emphasis being on welded fabrications in austenitic and ferritic steels and aluminium alloys. These can all be applied at the design, fabrication and operational phases of a structure's life.