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JB/T 6688-1993 English PDF (JBT6688-1993)

JB/T 6688-1993 English PDF (JBT6688-1993)

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JB/T 6688-1993: Specification for 12-spline Flange Nut and 12 point Flange Nut

This Standard applies to the manufacture and acceptance of 12-spline flange nut and 12 point flange nut (hereinafter referred to as bolt and nut respectively) that are used for gas turbine power plant.
JB/T 6688-1993
JB
INDUSTRY STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
J 13
Specification for 12-spline Flange Nut and 12
point Flange Nut
ISSUED ON. JUNE 01, 1993
IMPLEMENTED ON. JANUARY 01, 1994
Issued by. Ministry of Machinery Industry of PRC
Table of Contents
1 Scope ... 3
2 Normative references ... 3
3 Technical conditions ... 3
4 Inspection rules ... 8
5 Acceptance inspection, marking and packaging ... 9
Additional Information... 9
Specification for 12-spline Flange Nut and 12 point
Flange Nut
1 Scope
This Standard applies to the manufacture and acceptance of 12-spline flange nut and 12 point flange nut (hereinafter referred to as bolt and nut respectively) that are used for gas turbine power plant.
2 Normative??references
GB 3 Run-outs, undercuts and chamfers for general purpose metric screw
threads
GB 196 General purpose screw threads - Basic dimensions for diameter from 1 to 600mm
GB 197 General purpose screw threads - Tolerances and fits for diameter from 1 to 355mm
GB 228 Tensile testing of metallic materials
GB 3077 Technical requirements for alloy structure steels
GB 3098.1~3098.4 Mechanical properties of fasteners
GB 3099 Bolts, screws, nuts and accessories - terminology and nomenclature GB 3106 Bolts, screws and studs - Nominal lengths and thread lengths for general purpose bolts
GB 5276 Fasteners - Bolts, screws, studs and nuts - Symbols and designations of dimensions
GBn 177 Hot-rolled and forged heat-resisting super alloy bars for general force-bearing parts
3 Technical??conditions
3.1 Main indicators
3.1.3.1 Tolerance of screw thread
a. Tolerance of outer screw thread is 6g;
b. Tolerance of inner screw thread is 6H.
3.1.3.2 The biggest permissible value of surface roughness parameter for screw thread side Ra is 3.2??m.
3.1.4 When the material yield limit is not less than 932MPa, the wrenching force that the bolt can withstand shall not be less than the provisions in Table 5. Table 5
Thread specification
mm M6 M8 M10 M12 M14 M16 M18 M20 M22 M24
Wrenching force
N???m 8.14 18.1 29.9 58.3 93.5 127.1 183.3 223.5 331.8 485.6
Thread specification
mm M27 M0 M33 M36 M39 M42 M45 M48 M52
Wrenching force
N???m 543.0 880.8 1153 1564 1926 2407 2926 3845 3845
3.1.5 When the material yield limit is not less than 932MPa, the wrenching force that the bolt can withstand shall not be less than the provisions in Table 6. Table 6
Thread specification
mm M6 M8 M10 M12 M16 M20 M24
Wrenching force
N???m 9.75 21.7 32.5 68.7 165.0 326.1 540.1
Thread specification
mm M27 M30??3 M33??3 M36??3 M39??3 M42??3 M45??3
Wrenching force
N???m 777.5 1273 1593 2045 2544 3200 4076
3.1.6 Geometric tolerances of bolts and nuts shall be in accordance with the provisions in Table 7-1 ~ Table 7-3.
3.1.6.1 Coaxiality
4.7 Wrenching torque test of bolts. When torque reaches to the values in Table 5, 12-spline of bolts shall not produce the permanent deformation that influences the usage and sliding between wrenches. Accuracy of torque measuring device shall not be less than ??5%.
4.8 Wrenching torque test of nuts. When torque reaches to the values in Table 5, 12 point of nuts shall not produce the permanent deformation that influences the usage and sliding between wrenches. Accuracy of torque measuring device shall not be less than ??5%.
5 Acceptance??inspection,??marking??and??packaging
5.1 Bolts and nuts shall be submitted for inspection in batch. Each batch shall be made of materials with same type, same size and same furnace number. It shall conduct heat treatment according to the same specification.
5.2 Appearance of bolts and nuts shall be subject to 100% inspection.
5.3 As required, bolts and nuts can be subject to magnetic particle inspection or fluorescence detection.
5.4 Bolts shall be marked at the head-top by braille or concave characters. Nuts shall be marked at the supporting surface by concave characters. Marking symbol. 30CrMnSi and 40CrNiMoA use symbol ?€?D?€?; 40Cr2MoV use symbol ?€?Z?€?; GH2132 use symbol ?€?G?€?.
5.5 Other acceptance rules and packaging shall be in accordance with GB 90 ?€?Acceptance inspection, marking and packaging of fasteners?€?.
Additional??Information.
The Standard was proposed by Nanjing Institute of Gas Turbine.
This Standard shall be under the jurisdiction of Nanjing Institute of Gas Turbine. This standard is drafted by the following organizations. Nanjing Turbine and Electric Machinery (Group) Co., Ltd., Nanjing Institute of Gas Turbine, Harbin Steam Turbine Plant, and China Shipbuilding Industry Corporation 703 Research Institute.

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