1 Scope
This standard specifies a selection of tolerances for bolts, screws, studs and nuts with product grades A, B and C and for tapping screws with product grade A.
Note: The product grades refer to the size of the tolerances where grade A is the most precise and grade C is the least precise.
The tolerances, except tolerances for threads, are selected from GB/T 1800.2 and GB/T 1800.4. The tolerances for metric threads are taken from GB/T 2516. The tolerances for tapping screw threads are covered in GB/T 5280.
The tolerances of form and position shall be specified and indicated in accordance with GB/T 1182, GB/T 4249 and GB/T 16671.
The tolerances specified in this standard apply to fasteners prior to coating unless otherwise specified. See also GB/T 5267.1.
In cases where there is a difference between the tolerance requirements in this standard and the product standard, the product standard shall take precedence
It is recommended that these tolerances also be used for non-standard fasteners.
Dimensions and tolerances given in this standard are in millimetres.
2 Normative references
The following standards contain provisions which, through reference in this standard, constitute provisions of this standard. At time of publication, the editions indicated were valid. All the standards will be modified, however, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below.
GB/T 70.3-2000 Hexagon socket countersunk head screws (eqv ISO 10642: 1997)
GB/T 944.1-1985 Cross recesses for screws (eqv ISO 4757: 1983)
GB/T 1182-1996 Geometrical tolerancing - Generalities, definitions, synbiks, indications on drawings (eqv ISO 1101: 1996)
GB/T 1800.2-1998 Limits and fits – Bases - Part 2:Basic rules of tolerances, deviations and fits (eqv ISO 286-1: 1988)
GB/T 1800.4-1999 Limits and fits Tables of STANDARD tolerance grades and limit deviations for holes and shafts (egv ISO 286-2: 1988)
GB/T 2516-1981 Common screw thread deviation table (diameter: 1~355 mm)
GB/T 3105-2002 General purpose bolts and screws-Radii under the head (idt ISO 885: 2000)
GB/T 4249-1996 Tolerancing principle (eqv ISO 8015: 1985)
GB/T 5267.1-2002 Fasteners--Electroplated coatings (ISO 4042: 1999, IDT)
GB/T 5276-1985 Fasteners; Bolts, screws, studs and nuts; Symbols and designations of dimensions (eqv ISO 225: 1983)
GB/T 5279-1985 Countersunk head screws; Head configuration and gauging (idt ISO 7721: 1983)
GB/T 5280-2002 Tapping screws thread (idt ISO 1478: 1999)
GB/T 5285-1985 Hexagon head tapping screws (eqv SO 1479: 1983)
GB/T 6170-2000 Hexagon nuts, style 1 (eqv ISO 4032: 1999)
GB/T 6188-2000 Hexalobular internal driving feature for bolts and screws (idt ISO 10664: 1999)
GB/T 16671-1996 Geometrical tolerancing - Maximum material requirement, least material requirement and reciprocity requirement (eqv ISO 2692: 1996)
GB/T 16824.1-1997 Hexagon head tapping screws with collar (idt ISO 7053: 1992)
GB/T 16824.2-1997 Hexagon flange head tapping screws (idt ISO 10509: 1992)
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3 Tolerances for metric bolts, screws and studs
3.1 Dimensional tolerances
Symbols and designations of dimensions are specified in GB/T 5276.
Foreword I
ISO Foreword III
1 Scope
2 Normative references
3 Tolerances for metric bolts, screws and studs
4 Tolerances for metric nuts
5 Tolerances for tapping screws
Annex A (informative) Tolerances
Annex B (informative) Examples of dimensioned and toleranced fasteners
Annex C (informative) Examples of gauges and other measuring devices
