BS EN 13445-2-2021 pdf free download.Unfired pressure vessels Part 2: Materials
4.2 Special provisions
4.2.1 Special properties
Where the behaviour of a material can be affected by manufacturing processes or operating conditions,to an extent that would adversely affect the safety or service life of the pressure vessel, this shall be taken into consideration when specifying material.
Adverse effects may arise from:
— manufacturing processes: e.g. degree of cold forming and heat treatment;
— operating conditions: e.g. hydrogen embrittlement, corrosion, scaling and ageing behaviour of the material after cold forming.
4.2.2 Design temperature above 20 °C
4.2.2.1 A material shall only be used for pressure parts within the range of temperatures for which the material properties required by EN 13445-3:2021 are defined in the technical specification for the material. If the technical delivery condition does not contain the specific material values required for the allowable temperature TS the values required in EN 13445-3:2021 for the design shall be determined by linear interpolation between the two adjacent values. Values shall not be rounded up.
For other than austenitic and austenitic-ferritic stainless steels, the specified value of R eH (R p0,2 ) at room temperature (RT) may be used for temperatures less than or equal to 50 °C. Interpolation between 50 °C and 100 °C shall be performed with the values of RT and 100 °C and using 20 °C as the starting point for interpolation. Above 100 °C linear interpolation shall be performed between the tabulated values given in the table.
4.2.2.2 As the impact properties may be affected by long or frequent holding of the material at elevated temperatures, it is presupposed that the temperatures and periods of exposure to elevated temperatures be recorded for review during in-service inspection. The influence of such exposure upon the lifetime expectancy shall be estimated and recorded.
For operations such as drying and cleaning of pressure vessels, steels with specified low temperature properties but without elevated temperature 0,2 % proof strength values may however be used at elevated temperatures for drying and cleaning processes provided that the values of 0,2 % proof strength used in design calculations for elevated temperatures shall be obtained by multiplying the specified minimum yield strength values at 20 °C by the factor given in Table 4.2-1.
4.2.3 Prevention of brittle fracture
The requirements in Annex B shall apply.
4.2.4 Design properties in the creep range
4.2.4.1 Creep properties of base material
For interpolation and extrapolation of creep properties given in the materials standard, see EN 13445-3:2021, Clause 19.
When creep properties are not available from a materials standard, they shall be determined using EN ISO 204:2009.
4.2.4.2 Creep properties of weldments
Creep properties of weld joints subjected to stresses normal to the weld can differ significantly from those of the base material.
For the design of vessels in the creep range, this is taken into account in EN 13445-3:2021 by making use of a weld creep strength reduction factor
c z obtained from tests on weldments. If no data are available,
a default value of
c z is used.
An acceptable method to determine
c z by cross-weld tests is given in Annex C (see also [17]).
4.2.5 Specific requirements for steels for fasteners
Fasteners include bolts, studs and nuts.
Free cutting steel shall not be used. Bolting made of carbon steel or Ni alloy ferritic steel with > 3,5 % nickel shall not be used above 300 °C.
The specified minimum tensile strength of bar material of ferritic and martensitic steel for bolts shall not exceed 1 000 MPa. The minimum elongation of bar material after fracture shall be at least A 5 = 14 %.
Impact requirements for ferritic and martensitic steels are specified in B.2.2.4.
Bolt material with a design temperature below −160 °C shall be impact tested at −196 °C.
Hydrogen embrittlement, fatigue or relaxation properties shall be taken into account where appropriate.
NOTE 1 Detailed requirements on the surface condition and internal soundness of the bar can be necessary for some applications.
NOTE 2 Materials for fasteners compliant with the requirements of this standard should be certified on the basis of EN 10204:2004.BS EN 13445-2 pdf download.