1.1 This European Standard specifies the dimensional tolerances for steel upset forgings made on horizontal forging machines. The second part of this European Standard applies to hot upset forgings, in the delivery condition, made in carbon and alloy steels. The tolerances specified apply to forgings not exceeding 250 kg in mass or 2 500 mm maximum dimension. Tolerances for heavier or layer forgings are subjected to negociation. This European Standard does not apply to steel drop and press forgings (see prEN 10243-1). 1.2 For forgings produced in horizontal forging machines forging grade F tolerances only are provided. This tolerance grade provides an adequate standard of accuracy for the majority of applications and is capable of being complied with by commonly used forging equipment and production methods. The tables showing dimensional tolerances are based on the R20 series of preferred numbers (see ISO 3). The annex A gives for information some examples of application of these tolerances for different types of closed die forgings. 1.3 Any occasional instances may necessitate the use of tolerances wider than those indicated, e.g. specially complicated designs ; steels having particularly difficult forging characteristics. In such cases these standard tolerances can form only a basis on which to agree modifications appropriate to the particular circumstances. 1.4 This European Standard does not include ranges of special tolerances closer than grade F. Consideration of special tolerances whilst frequently encountered, are highly individual, and vary widely. They are best dealt with by consultation at the design stage and shall be agreed between the purchaser and the supplier. This approach will ensure that optimum use is made of the forging process in fulfilling the purchaser's special requirements at the lowest additional cost.