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1 Translated English of Chinese Standard: GB/T NATIONAL STANDARD OF THE PEOPLE S REPUBLIC OF CHINA GB ICS H 48 Replacing GB/T Dimensions, Shapes, Masses and Tolerances of Seamless Steel Tubes 无缝钢管尺寸 外形 重量及允许偏差 Issue on: May 13, 28 Implemented on: November 1, 28 Issued by: General Administration of Quality Supervision, Inspection and Quarantine of the People s Republic of China; Standardization Administration of the People s Republic of China. Page 1 of 37

2 Table of Contents Foreword Scope Outside diameter and wall thickness Length Shapes Masses Page 2 of 37

3 Foreword This Standard corresponds to ISO 42:1991 "Plain end steel tubes, welded and seamless - General tables of dimensions and masses per unit-length", ISO 5252:1991 "Steel tubes - Tolerance systems" and ISO 1127:1992 "Stainless steel tubes - Dimensions, tolerances and conventional masses per unit-length". This Standard is not equivalent to ISO 42:1991, ISO 5252:1991 and ISO 1127:1992. This Standard replaces GB/T "Dimensions shapes, masses and tolerances of seamless steel tubes". Compared with GB/T , the main changes of this Standard are as follows: Common steel pipe outside diameters 232, 267(267.4), 32, 318.5, 368, 419, 473, 699, 711, 72, 762, 788.5, 813, 864, 914, 965, 116 are added; Upper limit of wall thickness of common steel tube is modified; Unit-length theoretical weight in Table 1 and Table 2 is modified; In Table 3,.5,.6,.7,.8,.9 are added to the wall thickness for outside diameter of steel pipe whose; 15 Overall length tolerances mm level is added; "ellipticity" is changed into "noncircularity"; noncircularity" calculation formula is added; Upper limit of usual length is changed from 12mm" to 125mm"; Tolerances requirements between actual weight and theoretical weight are modified. This Standard was proposed by China Iron & Steel Association. This Standard shall be under the jurisdiction of China Steel Standardization Technical Committee Drafting organization of this Standard: Pangang steel Group, Chengtu steel Co., Ltd, and China Metallurgical Information Standardization Research Institute. Chief Drafting Staffs of this Standard: Yan Ru, Li Zhi, Huang Ying and Liqi. This Standard is first-time issued in May Page 3 of 37

4 Dimensions, Shapes, Masses and Tolerances of Seamless Steel Tubes 1 Scope This Standard specifies seamless steel tube size, shape, masses and tolerances. This Standard is applicable to selection of size, shape, masses and tolerances in formulating all kinds of flat-end seamless steel tube. 2 Outside diameter and wall thickness 2.1 Classification Outside diameter and wall thickness of steel tube can be divided into three classes: outside diameter and wall thickness of common steel tube (refer to Table 1); outside diameter and wall thickness of precision tube (refer to Table 2), and outside diameter and wall thickness of stainless steel tube (refer to Table 3). 2.2 Outside diameter Outside diameter of steel tube can be divided into three series: series 1, series 2 and series 3. Series 1 is the common series, belonging to the recommended adopted series; series 2 is not the common series; series 3 is the special series. Outside diameter of common steel tube can be divided into series 1, series 2 and series; outside diameter of precision tube can be divided into series 2 and series 3; outside diameter of stainless steel tube can be divided into series 1, series 2 and series Permissible tolerance Outside diameter and wall thickness tolerances selection For selection of permissible tolerance of outside diameter and wall thickness, steel tube application and technological equipment shall be taken into consideration Tolerances of outside diameter and wall thickness adopted in product standard shall be superior to standardized tolerances. According to customer requirements and product, non-standardized or other tolerances can be adopted Outside diameter tolerances Page 4 of 37

5 GB Table 7 Non-standardized wall thickness tolerances Unit: millimeter Tolerance grade Non-standardized wall thickness tolerances NS1 NS2 NS3 NS4 +15.%s -12.5%S +15.%S -1.%S +12.5%S -1.%S +12.5%s -7.5%S Note: S is the nominal wall thickness of steel tube Steel tube of special purpose and cold rolling (pull) Steel tube wall thickness tolerances may adopt absolute tolerance. 3 Length 3.1 Usual length Usual length of steel tube is 3 mm ~ 12 5mm. 3.2 Fixed-length and multiple-length Fixed-length and multiple-length shall be within usual length; overall length tolerances can be divided into four grades (refer to Table 8). Each multiple-length will reserve the kerf surplus according to the requirements below: a) For outside diameter 159 mm: 5 mm~1mm; b) For outside diameter >159mm: 1mm~15mm. Tolerance grade L1 L2 L3 L4 Table 8 Overall length tolerances Overall length tolerances Unit: millimeter 3.3 Steel tube length of special purposes For steel tubes of special purposes, such as stainless acid resistant ultra-steel thin wall Page 34 of 37

6 GB tuber, the length requirements for minor diameter steel tube can be stipulated otherwise. 4 Shapes 4.1 Degree of curvature Degree of curvature of steel tube can be divided into overall length degree of curvature and degree of curvature of each meter Degree of curvature of overall length Degree of curvature surveyed of the overall length of steel tube can be named as degree of curvature of overall length; degree of curvature of overall length can be divided into 5 classes (refer to Table 9). Table 9 Degree of curvature of overall length Unit: millimeter Grade of degree of curvature E1 E2 E3 E4 E5 Degree of curvature of overall length, not greater than.2%l.15%l.1%l.8%l.6%l Note: L is length of single steel tube Degree of curvature of each meter Degree of curvature surveyed is referred as the degree of curvature of each meter; degree of curvature of each meter can be divided into 5 classes (refer to Table 1). Table 1 Degree of curvature of each meter Unit: millimeter Grade of degree of curvature Degree of curvature of each meter, not greater than F1 3. F2 2. F3 1.5 F4 1. F Noncircularity Noncircularity of steel tube can be divided into 4 grades (refer to Table 11). Page 35 of 37

7 GB Table 11 Noncircularity Grades of noncircularity Noncircularity, no greater than outside diameter tolerance NR1 8% NR2 7% NR3 6% NR4 5% a Noncircularity calculation formula is: 2( D max Dmin ) 1%, Where: D max is the maximum value of cross D D max section s outside diameter., D min is the minimal value of cross section s outside diameter.. min 5 Masses 5.1 Delivery of steel tube can be carried out by referring to actual weight; theoretical weight can also be served as the standard. Actual weight delivery can be divided into single pipe masses or batch weight. 5.2 Refer to Formula (1) for the calculation of theoretical weight of the steel tube. W ( D S) S /1 (1) Where: W Theoretical weight of steel tube; the unit is kilogram/ meter (kg/m); ; Intensity of steel; unit is kilogram/ cubic decimeter (kg/dm 3 ); D nominal outside diameter of steel tube; unit: millimeter (mm); S nominal wall thickness of steel tube; unit: millimeter (mm). 5.3 As for steel tube delivered according to theoretical weight, tolerances between actual weight and theoretical weight can be stipulated. Tolerances between single steel tube actual weight and theoretical weight can be divided into 5 classes (refer to Table 12). Tolerances between theoretical weight and actual weight of each batch not less than 1 t can be ±7.5 or ±5%. Table 12 Permissible tolerances of masses Tolerance grade Tolerances masses of single steel tube W1 ±1% W2 ±7.5% W3 +1% -5% W4 +1% Page 36 of 37

8 GB % W5 +6.5% -3.5% END Page 37 of 37