PD 6539:1994

Committees responsible
Foreword
Guide
1. Scope
2. Normative references
3. Symbols
4. General restrictions and information requirements
5. Crack behaviour at high temperature
6. Assessment procedure
Annexes
A. (informative) Bibliography
B. (normative) Materials data
C. (normative) Calculation procedure
D. (normative) The assessment of defects in weldments
E. (normative) Linearization of stresses
F. (normative) Assessment to include creep-fatigue
     loading
G. (informative) Worked example
Tables
B.1 Constants used to derive creep crack propagation
     rates
B.2 Typical values of fracture toughness (based on the
     value of K1 at 0.2 mm crack extension)
G.1 Operating conditions
G.2 Selected materials data
G.3 Stress category
G.4 Data at beginning of each month for deepest point
     of crack
G.5 Data at beginning of each month for crack growth
     along surface
Figures
1. Schematic behaviour of crack at elevated temperature
2. Schematic representation of crack propagation and
     failure conditions
3. Flow sheet for the assessment procedure
4. Defect characterization
B.1 Derivation of strain versus time curves from iso-
     strain curves
B.2 Strain hardening construction to obtain incremental
     strains
B.3 Construction to estimate creep damage in block
C.1 Division of operating history into blocks of
     constant stress and constant temperature
E.1 Linearization of stresses
G.1 Defect dimensions
G.2 Thermal stress distribution in the region of the
     defect
G.3 Margin against fast fracture for high pressure
     start-up
G.4 Creep crack growth for period August 1990 to
     July 2005
G.5 Increase in creep damage from start of operation in
     April 1985 to July 2005
List of references

Gives guidelines for assessing the significance of defects in components that operate in the creep range. Coverage includes: general restrictions and information requirements; crack behaviour at high temperature. Also gives symbols, tables, diagrams and annexes.