NB/T 10214-2019Anchor bolt assembly for wind turbine generator system (English PDF)

3.1 Terms and definitions

3.1.1 Anchor bolt assembly

It is a structural component installed by a combination of anchor rods, nuts, washers, etc. and prestressed.

3.1.2 Anchor bolt

The two ends are processed into a threaded shape and a steel fastening connector with a large aspect ratio.

3.1.3 Shank diameter

The nominal diameter of the unthreaded section of the anchor rod product.

3.1.4 Anchor bolt assembly tensioning test

Axial tensile load is applied to both ends of the bolt and nut assembly to a certain set value and maintained for a period of time.

3.2 Symbols

The following symbols apply to this document.

As. Nominal stress cross-sectional area of thread, mm2 D. The basic major diameter of the thread (nominal diameter), mm d. Nominal diameter of thread, mm da. counterbore diameter, mm ds. the nominal diameter of the unthreaded section of the anchor rod product, mm dw. Major diameter of bearing surface, mm d2.Basic pitch diameter of external thread, mm d3.Small diameter of external thread, mm e. diagonal width of nut, mm H1.profile height of external thread of arc thread, mm H2.tooth profile height of arc thread internal thread, mm

L. length of anchor rod, mm

LK. The length of the anchor rod under the tensile force of K times the nominal specified plastic extension strength Rp0.2, mm L0.The anchor rod length under the tensile force of 10% of the nominal specified plastic extension strength Rp0.2, mm L1.Effective length of thread at the top of anchor rod, mm L2.Effective length of thread at the bottom of the anchor rod, mm m. height of nut or height of nut without effective torque, mm

P. Thread pitch, mm

R. 10.9 level anchor rod arc thread bottom radius, mm

Rd. short for arc thread Rp0.2.Nominal specified plastic extension strength, N/mm2 R1.8.8 level anchor rod arc thread crest radius, mm R2.8.8 level anchor rod arc thread bottom radius, mm R3.Bottom radius of arc thread internal thread, mm s. width across the nut, mm

Sp. Guaranteed stress, N/mm2 beta. Chamfer, ° theta. countersunk head angle, ° theta1:Circular thread profile angle,° theta2:Circular thread profile angle,° delta. Residual elongation of anchor rod,%

4.1 Product composition

Anchor rod components are generally composed of anchor rods, nuts, thin nuts and washers, as shown in Figure 1. Ordinary nuts can be used instead of thin nuts.

4.2 Performance level

4.2.1 The marking system for the performance level of anchor rods shall comply with the provisions of GB/T 3098.1, and the levels 8.8 and 10.9 can be selected.

4.2.2 The marking system of nut performance grades should comply with the requirements of GB/T 3098.2, and grades 6, 8 and 10 can be selected.

4.3 Product specifications

4.3.1 Anchor

The structure of the anchor rod is shown in Figure 2, which is generally a structure of threaded at both ends and polished rod in the middle.

4.3.3 Thin nuts

The type and specifications of the circular arc threaded thin nut are shown in Figure 4, Table 6, and Table 7. Among them, the type I thin nut and the 8.8 circular arc thread and the II type thin screw The female is used in combination with the 10.9 grade arc threaded anchor rod. For circular thread profile structure, profile dimensions and tolerances, please refer to Appendix B.

4.3.4 Washers

4.3.5 The type and size of the washer are shown in Figure 5 and Table 9. When customers have special requirements, flat chamfered washers can also be used.

5.1 Anchor material

5.1.1 Anchor rod material (bar material) should be alloy structural steel, and its recommended material grade should meet the requirements of Table 10, including phosphorus and sulfur content and The content of residual elements should meet the requirements of Table 11, and the allowable deviation of various chemical components should meet the requirements of GB/T 222. According to customer requirements Seeking to customize other grades and performance materials.

5.1.2 There should be no visible shrinkage cavities, bubbles, cracks, inclusions, peeling, whitening on the cross-section acid-immersed low-power structure test piece of the anchor material.

Point and intercrystalline cracks. Ingot segregation, center porosity, and general porosity are not more than level 2, and there should be no general spot segregation and edge spot segregation.

5.1.3 There should be no visible cracks, scars, folds and inclusions on the surface of the anchor material. If any of the above defects should be removed, the depth of removal is from The actual size of the steel rod should not exceed 1/2 of the tolerance of the steel rod size, and the removal width shall not be less than 5 times the depth, and the maximum removal of the same section The depth should not be more than 1 point. The cut surfaces of the ends of the raw materials of the anchor rod are smooth and free of burrs, scars, and flat tails.

5.1.4 The qualified level of non-metallic inclusions of anchor rod materials should meet the requirements of Table 12.

5.1.5 The band structure grade of the bolt material shall not be greater than 3.

5.2 Nut and thin nut material

5.2.1 The material of the nut and thin nut should be low alloy steel or alloy structural steel, and the material designation and chemical composition should meet the requirements of Table 13.

5.2.2 Nuts and thin nuts should be forged blanks.

5.3 Gasket material

5.3.1 The raw material of the gasket should be carbon structural steel, and its material designation and chemical composition should meet the requirements of GB/T 699.

5.3.2 Washers should be cut or stamped.

6.1 Anchor rod size deviation

6.1.1 The allowable deviation of the diameter of the bolt body shall meet the requirements of Group 1 in GB/T 702, as shown in Table 14.

6.1.2 The out-of-roundness of the anchor rod body shall meet the requirements of Table 15. Anchor rod out-of-roundness refers to the maximum diameter and minimum diameter of the same cross section of the rod body difference.

6.1.3 The curvature of the anchor rod shall not exceed 2.5 mm per meter, and the total curvature shall not exceed 0.25% of the total length.

6.1.4 The allowable deviation of the length of the anchor rod should meet the requirements of Table 16.

6.2 Size deviation of nuts and thin nuts

The dimensional deviation of the circular arc threaded nut and the circular arc threaded thin nut shall meet the requirements in Table 3, Table 4, Table 6, and Table 7.

The dimensional deviation of through thread thin nuts should meet the requirements in Table 5 and Table 8.

6.3 Dimensional deviation of washer

The size deviation of the washer should meet the requirements of Table 9.

7.1 Appearance quality requirements

7.1.1 The thread surface is smooth, and there should be no processed scales and oxide layers; grooves are allowed in the peaks of the effective thread length of the arc thread of the anchor rod. Its width should not be greater than 2 mm.

7.1.2 After the nut and thin nut threads are processed, impurities such as iron filings and burrs should be removed, and there should be no flash on both ends.

7.1.3 There should be no cracks, burrs, floating rust, dents or scratches on the surface of the gasket.

7.1.4 The anti-corrosion coating on the surface of the bolt components shall be continuous, and there shall be no defects such as missing coating, bubbles, cracks, dripping, agglomeration and inclusions. Coating thickness There is no local over-thickness and no obvious chromatic aberration.

7.2 Non-destructive testing of anchor rods

7.2.1 Non-destructive testing of anchor rods

When conducting non-destructive testing of internal defects before the heat treatment of anchor rods, ultrasonic non-destructive testing shall be used;

In the non-destructive testing of surface and near-surface defects, methods such as eddy current, magnetic particle, and magnetic flux leakage should be selected. Requirements are as follows.

a) Ultrasonic non-destructive testing of anchor rods should meet the requirements of Class A of GB/T 4162;

b) The non-destructive testing of anchor rods with eddy current flaw detection shall meet the requirements of level 6 of GB/T 11260;

c) The magnetic particle non-destructive testing of anchor rods shall meet the I level of NB/T 47013.4;

d) The magnetic flux leakage non-destructive test of the anchor rod shall meet the level 3 regulations of GB/T 32547.

7.2.2 Non-destructive testing of finished anchor rods

Penetration testing can be carried out on the thread or rod body at both ends of the finished anchor rod according to the needs of the customer, and it shall meet the level III regulations of NB/T 47013.5.

7.3 Performance requirements

7.3.1 Mechanical properties

7.3.1.1 Mechanical properties of bolts

a The minimum hardness is only mandatory for heat-treated nuts or nuts whose specifications are too large to carry out a guaranteed load test; it is not mandatory for other nuts Sexual is instructive. For nuts that have not been quenched and tempered and can meet the guaranteed load test, the minimum hardness shall not be used as a basis for rejection.

7.3.1.3 Mechanical properties of washers

The hardness of the washers ranges from 35 HRC to 45 HRC (329 HV30 to 436 HV30).

7.3.2 Low temperature impact performance

7.3.2.1 Anchor rod material without quenching and tempering is made into a standard Charpy V-notch impact test piece with a notch depth of 2 mm. The brittleness transition temperature shall not be higher than -40°C.

7.3.2.2 The quenched and tempered bolt material is made into a standard Charpy V-notch impact test piece with a notch depth of 2 mm.

For impact test, the average value of impact absorption energy KV2 should not be less than 27 J, and the KV2 value of a single sample should not be less than 19 J.

7.3.3 Decarburization depth of thread

The depth of the thread decarburization layer shall be implemented in accordance with the provisions of GB/T 3098.1. The tooth bottom shall not have a complete decarburization layer, and the depth of the partial decarburization layer shall not exceed 0.05 mm.

7.3.4 Tensile performance of anchor rod assembly

The combination of anchor rod and nut should be able to withstand the axial tensile load of K times the nominal plastic extension strength of the anchor rod (if relevant technical regulations If the K value is not specified for the parts, the K value should generally not be less than 0.7), and the nut should be able to be unscrewed smoothly after unloading. The anchor rod is 0.7 times the nominal specified plastic extension strength Tensile loads of degrees are shown in Table 19 and Table 20 respectively. The tensile load of the anchor rod shall be calculated according to formula (1).

7.3.5 Tensile test of finished anchor rod

The minimum tensile load of arc threaded anchor rods shall meet the requirements of Table 21, and the minimum tensile load of ordinary threaded anchor rods shall meet the requirements of Table 22.anchor When the rod is broken under the ultimate tensile load, the anchor rod should break within the length of the unthreaded thread or the unthreaded rod.

7.3.6 Stress relaxation performance

The anchor rod assembly is under the initial prestress load of K times the nominal plastic extension strength of the anchor rod (if the relevant technical conditions do not specify K Value, the K value should generally not be less than 0.7), the stress relaxation rate of the anchor rod assembly for 10 hours should not be greater than 1.5%, and the stress relaxation rate for 1000 hours should not be Greater than 3%. The initial prestress load of the anchor rod 0.7 times the nominal specified plastic extension strength is shown in Table 19 and Table 20, respectively.

7.3.7 Fatigue performance

7.3.7.1 Fatigue performance of bolt material

The maximum stress of the fatigue specimen of the anchor material is 80% of the nominal specified plastic extension strength Rp0.2, the fatigue stress amplitude (the maximum stress and the minimum stress)

Half of the force algebra difference) under the condition of not less than 100 MPa, after at least 10 million cyclic loads, the fatigue specimen should not be fatigued. The surface condition is intact.

7.3.7.2 Fatigue performance of bolt components

The connection pair composed of the anchor rod and the nut shall meet the fatigue performance test of at least 2 million cycles of cyclic load. After being subjected to 2 million cycles of load, The anchor rod and nut should not be damaged by fatigue, and the surface condition is intact.

When the bolt is a heat-treated rod, the maximum stress of the test should generally be 65% of the nominal tensile strength of the bolt material, and the fatigue stress amplitude shall not be less than 40 MPa. When the project has special needs, the maximum stress and fatigue stress amplitude of the test shall be selected according to specific requirements.

When the bolt is steel with obvious yield steps, the maximum stress in the test is 80% of the nominal tensile strength of the bolt material, and the fatigue stress amplitude is appropriate Take 40 MPa.

7.4 Guaranteed load of nut

The guaranteed load of the nut shall meet the requirements of Table 23, Table 24 and Table 25. The stress area of the nut is carried out according to Table 1 and Table 2, respectively.

The certified stress is not less than 720 N/mm², the guaranteed stress of grade 8 nuts is not less than 920 N/mm², and the guaranteed stress of grade 10 nuts is not less than 1060 N/mm².

7.5 Anti-corrosion requirements

7.5.1 When bolts are coated with grease for anti-corrosion treatment, anti-corrosion grease or low-temperature lubricating anti-rust oil for unbonded prestressed tendons should be selected. Its performance complies with JG/T 430 or SH/T 0692 regulations.

7.5.2 When the anchor rod, nut, thin nut, and washer are treated with Dacromet for anti-corrosion treatment, the coating shall be silver-gray zinc-chromium coating, the coating grade Not lower than the level 4 specified in GB/T 18684.

7.5.3 When the nuts, thin nuts and washers are phosphated for anticorrosion treatment, low-zinc and manganese-containing phosphating film should be selected, and its performance conforms to GB/T 11376 Regulations.

7.5.4 When the nuts, thin nuts, and washers are blackened for anticorrosion treatment, their oxide film performance should meet the requirements of GB/T 15519.

7.5.5 When the anchor rod, nut, thin nut, and washer are treated with dacromet, organic anti-corrosion coating, or heavy-duty anti-corrosion coating, the coating body The system shall carry out a neutral salt spray test in accordance with the requirements of GB/T 10125, and the test time shall be 1000 h. After the test, the coating shall not blisters, peel off, rust, and Cracked.

7.5.6 If other anti-corrosion materials are needed, the specific requirements shall be agreed upon by the supplier and the buyer.

8.1 Material inspection

8.1.1 Chemical composition inspection

The sampling and sample preparation methods of the samples used for the determination of the chemical composition of the bolt component materials shall be implemented in accordance with the provisions of GB/T 20066, and the chemical composition shall be determined in accordance with GB/T 20123 and GB/T 20125 or GB/T 4336 should meet the requirements of 5.1.1, 5.2.1, and 5.3.1.

8.1.2 Microstructure inspection

The macrostructure inspection of anchor material shall be carried out in accordance with the provisions of GB/T 1979 and GB/T 226, and shall meet the requirements of 5.1.2.

8.1.3 Inspection of non-metallic inclusions

The detection of non-metallic inclusions in anchor material shall be carried out in accordance with the provisions of GB/T 10561 and shall meet the requirements of 5.1.4.

8.1.4 Band structure inspection

The ribbon structure inspection of bolt material shall be carried out in accordance with the provisions of GB/T 13298 and GB/T 13299, and shall meet the requirements of 5.1.5.

8.1.5 Mechanical performance inspection

The sampling location and sample preparation of the mechanical properties of anchor material shall be in accordance with the provisions of GB/T 2975, and the mechanical properties shall be in accordance with GB/T 228.1 It should meet the requirements of 7.3.1.1. The sample sampling locations are as follows.

When the major diameter of the thread is less than 39 mm, the center shall be sampled, and the diameter of the test piece shall be calculated as three-quarters (3/4 d) of the major diameter of the thread;

When the major diameter of the thread is greater than or equal to 39 mm, eccentric sampling, the sampling center position is at one-fourth (1/4 d) of the major diameter of the thread, the test piece The diameter is calculated as three-eighths (3/8 d) of the major diameter of the thread.

8.1.6 Hardness inspection

The anchor rod hardness test is carried out on a section with a major diameter equal to the thread from the end of the anchor rod, at a quarter of the thread diameter from the center of the section.

Measure 4 points at any time and take the average of the last 3 points. The test method is carried out in accordance with the provisions of GB/T 230.1 or GB/T 4340.1. Should meet the requirements of 7.3.1.1. To The Vickers hardness (HV30) test is an arbitration value.

The hardness test of nuts and washers is carried out at any 4 points on the surface of the part, and the average of the last 3 points is taken. Test method according to GB/T 230.1 or GB/T 4340.1 Provisions. It shall meet the requirements of 7.3.1.2 and 7.3.1.3. […]