High strength anchor bolt assembly components-Nut,washer technical requirements _—— LT

1.SCOPE 

This standard specified the technical and test regulations for high duty anchor bolts components- nuts and washers, and technical requirements for marking, packaging, transportation, storage, production process and quality assurance control.

This standard is applicable to the external processing and acceptance of nuts and washers for high strength anchor bolt systems.

2 . NORMATIVE REFERENCES

The following normative documents are indispensable for this standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. For undated references, the latest edition of the normative document referred to applies.

  GB/T 699-1999 Quality carbon structural steels 优质碳素结构钢

 GB/T 3077-2015 Alloy structure steels 合金结构钢

GB/T 230.1-2009 Metallic materials-Rockwell hardness test-Part 1: Test method 金属材料 洛氏硬度试验 第一部分：试验方法

GB/T 231.1-2009 Metallic materials-Brinell hardness test-Part 1: Test method 金属材料  布氏硬度试验 第一部分：试验方法

GB/T 4340.1-2009 Metallic materials-Vickers hardness test-Part 1: Test method 金属材料 维氏硬度试验 第一部分：试验方法

GB/T 16823.1-1997 Stress area and bearing area for threaded fasteners 螺纹紧固件应力截面积和承载面积

    GB/T 97.1-2002  Plain washers-Product grade A 平垫圈A级

GB/T 3098.1-2010 Mechanical properties of fasteners-Bolts,screws and studs紧固件机械性能 螺栓、螺钉和螺柱

GB/T 3098.2-2000 Mechanical properties of fasteners-Nuts-Coarse thread 紧固件机械性能 螺母 粗牙螺纹

GB/T 3103.1-2002 Tolerances for fasteners-Bolts,screws,studs and nuts紧固件公差 螺栓、螺钉、螺柱和螺母

GB/T 3103.3-2000 Tolerances for fasteners-Plain washers 紧固件公差 平垫圈

GB/T 5779.2-2000 Fasteners-Surface discontinuities-Nuts 紧固件表面缺陷 螺母

GB/T 196-2003  General purpose metric screw threads-Basic dimensions 普通螺纹 基本尺寸

GB/T 197-2003   General purpose metric screw threads-Tolerances 普通螺纹 公差

GB/T 90.1-2002  Fasteners-Acceptance inspection 紧固件 验收检查

GB/T 90.2-2002  Fasteners-Marking and packaging 紧固件 标志与包装

GB/T 6170-2000  Hexagon nuts, style 1        1型六角螺母

3.TECHNICAL REQUIREMENT 

3.1 Enrironmental requirement 

    WTGS(wind turbine generator system) foundation anchor bolt operating temperature range -40℃～50℃, relative humidity≤ 95%      

Outdoor weather conditions for WTGS foundation anchor bolts include air humidity, salinity and  dust bowl area.    

3.2 Apperance

3.2.1 Nuts 

Visual inspection and rule measurement shall be used to inspect nuts apperance, ensure that products conform to GB/T5779.2-2000 “Fasteners-Surface discontinuities-Nuts”， satidfying table 1.

 TABLE 1. SURFACE DISCONTINUITIES ON NUTS 

D——norminal thread diameter 

3.2.2 Washer 

    Cracks,burrs,rust, dents and scratches are not allowed on washers.

3.3 Dimension 

3.3.1  Dimensions and tolerances of nuts 

Dimensions and tolerances of nuts shall conform to GB/T6170-2000 “Hexagon nuts,style 1” regulations. According to GB/T6170-2000, the nut’s thickness m    shall be selected 1.2-1.3 times the value of m in the TABLE 1 “Preferred threads”.Specific values are shown in TABLE 2.

                               TABLE 2 Thickness of nuts 

unit：mm

3.3.2 Dimensions and tolerances of washers 

Dimensions and tolerances of washers shall be accoding to GB/T3103.3-2000. Cracks,burrs,rust, dents and scratches are not allowed on washers.

Washers with norminal diameter more than 30mm, dimensions and tolerances shall conform to TABLE 3.

TABLE 3 Dimensions and geometric tolerances of washers ND＞30mm   

3.4 Materials 

3.4.1 Nuts and washers 

Materials recommendation for nuts and washers shall conform to TABLE 4. Other materials shall company with purchasers’ agreement.    

  TABLE 4 Anchor bolts, nuts, washers materials

3.4.2 Nuts and washers manufacturing methods 

 （1）Nuts are hot forged from hot-rolled steel round bars,internal threads screwed。  

 （2）Washers are punched from steel plates. 

3.5 Properties inspection 

3.5.1 Cone proof load test on nuts 

Cone proof load test on nuts shall be calculated by As(section area)×Sp(proof stress). Sp numerical value of grade 10 style 1 nuts shall be 1060N/mm².

3.5.2 Hardness of nuts 

   Hardness of nuts shall be according to TABLE 5 regulations, threads’section area and cone proof load shall be conform to TABLE 5.

                       table 5 Nut properties

3.6 Surface Treatment   

Before coating on nuts and washers, clean the surface, remove oxide scale, rust, oil stain, to guarantee grade Sa2.5 cleanliness.Surface treatment and formula shall be selected by producers. Grease corrossion protection method on nuts and washers is not included in this regulation.

 4. INSPECTION 

Inspection items and methods for nuts and washers shall conform to TABLE 6.

TABLE 6 Inspection item,sampling quantity and methods

4.1 Delivery inspection 

Co-processing manufacturer shall make delivery test according to TABLE 6 regulations. Products delivery shall be accompanied by quality assurance certificates signed and issued by quality inspection department.

4.2 Type inspection 

Type inspection should be carried our in one of the following cases:

a)Trial making and  type identification of new products 

b)Magnificant changes in design and production technology

c)Production resume after suspension for more than half a year

d)Significant difference between delivery inspection and latest type inspection

e)Request from national quality supervision organizations 

4.3 Acceptance inspection 

The authorizing party shall perform acceptance inspection and type inspection on the delivered products, according to technical requirements regulations.

4.4 Qualified determination

4.4.1 When each inspection item meets required specifications in this standard, the product is judged to be qialified; When there is one test result fail, double sample should be taken for re-test, and if re-test result fail as well, products of this batch shall be unqualified.

4.4.2 When authorizing party and subcontractor have objection on quality, negotiation first,or they will be arbitrated by a qualified third party.

5  MARKING, PACKAGING, TRANSPORTATION AND STORAGE

5.1 Marking

    Marking methods for nuts and washers shall perform according to regulations, including:

a)Identification of manufacturer

b)Property class

Figure 1 

5.2 Packaging

a)Packing box should be firm and moisture-prrof. Different batches must not be mixed.Specific packing methods shall be determined by subcontractor;

b)Manufacturer’s name, product’s name, standard, batch, specifications, quantity and gross weight shall be marked outside the packing box;

c)Essential thread protection should be taken, specific methods determined by subcontractor.

5.3 Transportation 

By road,railway and sea are acceptable transportation methods. Transportation requirements:

a)Barbarically loading or unloading are not allowed 

b)During transportation, according to specific conditions, products should be well covered to proof snow or dust. 

5.4 Storage

Storage requirements for nuts and washers: 

a)Do not place together with anything that are corrosive to steels, such as acids and alkalis; 

b)Soil, rain and snow corrossion should be prevented when products are stacked outdoors. 

c)Products should be stacked steadily, easy to hoist and transport. Same model products should be stacked together. 

6 QUALITY ASSURANCE 

6.1 GENERAL REQUEST 

Subcontractor should provide a complete quality assurance system, and ensure raw materials, producing process and product control performing in accordiance with this technical requirements. 

6.2 TEST 

6.2.1 Subcontractor shall provide products inspection regulations, test report and orignal quality assurances according to this technical requirements, and ensure inspection equipments and measuring instruments all in good condition. 

6.2.2 Authorizing party’s inspector shall conduct process supervision and product testing witness on a regular or irregular basis.