This standard specifies the dimensions, shapes, masses and tolerances of seamless steel tubes.
This standard is applicable to selection of dimensions, shapes, masses and tolerances while preparing standards of plain-end seamless steel tubes for various purposes.
2 Outside Diameter and Thickness
2.1 Classification of dimensions
Dimensions of steel tubes are classified into common steel tube group (see Table 1), precision steel tube group (see Table 2) and stainless steel tube group (see Table 3).
2.2 Outside diameter
Outside diameter of steel tubes is classified into three series, i.e. Series 1: standardized steel tubes; Series 2: non-standardized steel tubes; Series 3: special-purpose steel tubes.
Outside diameter is classified into Series 1, 2 and 3 for common steel tubes, Series 2 and 3 for precision steel tubes and Series 1, 2 and 3 for stainless steel tubes.
2.3 Dimension tolerances
2.3.1 Selection of dimension tolerances
2.3.1.1 Purposes and technological equipment for manufacturing of steel tubes shall be considered in selection of dimension tolerances.
2.3.1.2 Dimension tolerances adopted for product standards shall give preference to standardized relative deviation and non-standardized dimension tolerances may also apply upon the user's request and product specificity.
2.3.1.3 Unilateral or bidirectional deviation may be selected for dimension tolerances. Generally, symmetrical deviation shall be selected and relative deviation should be selected.
2.3.2 Tolerances on outside diameter
GB/T 17395-1998 The following standards are cited：
