Instructions for sending high-strength bolts for inspection
1. Introduction of high strength bolts
High strength bolted coupling pair
2. The test parameters and sampling frequency of the bolt to be detected: (According to GB/T1231-2006, the technical conditions of high-strength hexagonal head bolts, large hexagonal nuts and gaskets for < steel structures >
1. Factory testing and frequency:
Factory inspections are carried out in batches. Same performance class, material, furnace number, thread specification, length (length when bolt length ≤ 100 mm
Phase difference ≤15 mm; When the bolt length > 100 mm, the length difference is ≤20 mm, which can be regarded as the same length), machining, heat treatment process, table
The bolts of the surface treatment process are the same batch; Same - - performance grade, material, furnace number, thread specifications, machining, heat treatment process, surface treatment process of the nut for the same batch; Gaskets of the same performance class, material, furnace number, specification, machining, heat treatment process, and surface treatment process are in the same batch. The connection pairs composed of the same batch of bolts, nuts and washers are the same batch of connection pairs.
The maximum number of high-strength bolted pairs in the same batch is 3 000 sets.
The test of the torque coefficient of the connecting pair is drawn in batches of 8 sets, and the average torque coefficient and standard deviation of the 8 sets of connecting pairs should conform to 3.3.1
stipulate.
Bolted wedge load. The nut guarantee load, nut hardness and washer hardness are tested in batches, and the sample size is n=8, and the number of qualified judgments is obtained
Ac=0。 ，
5.4 The sampling scheme for the inspection of bolts, nuts and washers for size, appearance and surface defects shall be in accordance with the provisions of GB/T 90.1.
3. Test method:
Bolt test method:
Nut test method