Precision of the CE formulae

Carbon equivalent levels are normally quoted to two decimal place but the significance of the second place depends on the precision c the original chemical analysis. The precision of the CE value can b estimated from  

These precisions will generally be better than the corresponding BS ones, because no inter-laboratory errors are included. Such estimates of precision for methods currently used at TWI are showi in Table 3.1. When these figures are used in [3.2], the following results are obtained  

There is thus little point in considering whether a CE level of 0.40 would be preferable to one of 0.42 when using a welding diagram since the steel composition, even with product analysis, is not characterised with sufficient accuracy. This also explains why the 

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