BS ISO 10803:2011 pdf free download – Design method for ductile iron pipes.
where DN is the nominal diameter of pipe as defined in ISO 2531 and ISO 7186, in millimetres.
Nominal pipe wall thicknesses for various classes in accordance with ISO 2531 are given in Table A.1 and nominal pipe wall thicknesses for pressure and gravity pipe classes in accordance with ISO 7186 are given in Table A.2.
5.2 Design safety factors
The minimum pipe wall thickness, ‘‘min’ shall be calculated with a design safety factor of 2,5 for the maximum allowable operating pressure (i.e. PMA as indicated in ISO 2531 and ISO 7186) and a design safety factor of 3 for the allowable operating pressure (i.e. PEA as indicated in ISO 2531 and ISO 7186).
NOTE This allows field testing of installed ductile iron pipelines in compliance with ISO 10802 by application of test pressures up to the allowable test pressures given in ISO 2531 and ISO 7186.
NOTE 2 For pipelines under railroads or airports or subjected to heavy construction traffic, special requirements can apply according to the respective national standard and regulations.
6.3 Soil and pipe interaction
The bedding reaction angle depends on the installation conditions (bedding, sidefill compaction) and on the pipe diametral deflection (especially for large sizes).
The modulus of soil reaction, E’, of the sidefills depends on the type of soil used for the embedment and upon the trench type (see Annex D). In the absence of applicable standards or other data, the values of E’ indicated in Table 1 may be used at the design stage for five typical trench types and for six soil groups (see Annex E for the classification of soils).
These data are valid for pipes laid under embankments as well as in trenches.
A preliminary geotechnical survey should be carried out to facilitate identification of the soil and proper selection of E’ values.
E’ values given in Table I apply when trench shoring is left in place or removed in such a way as to allow compaction of sidefill against the native trench wall; otherwise, reduced E’ values should be applied.
In very poor ground conditions, it may be necessary to use soil stabilization matting to prevent migration of embedment with resultant loss of soil reaction modulus, E’.
The following soil groups classify different soils for embedments, i.e. soils which are used for placement in the trench surrounding the pipe, compacted or uncompacted, to provide support for the pipeline. These groups classify naturally occurring soils as well as manufactured materials. The groups are also for use in classifying undisturbed trench wall materials.
a) Soil group A: angular graded stone (6 mm to 40 mm), also including a number of fill materials which have regional significance, such as crushed stone, crushed gravel, pea gravel and crushed shells.
b) Soil group B: coarse; grained soils with little or no fines. No particles larger than 40 mm.
c) Soil group C: coarse; grained soils with fines and fine-grained soils with medium to no plasticity, with more than 25 % coarse particles, liquid limit less than 50 %.
d) Soil group D: fine; grained soils with medium to no plasticity, with less than 25 % coarse particles, liquid limit less than 50 %.
e) Soil group E: fine; grained soils with medium to high plasticity, liquid limit greater than 50 %.
f) Soil group F: organic soils.