The English name for a saddle bolt is U-bolt, which is a non-standard component with a U-shaped shape and is also known as a U-bolt. It has threads on both ends that can be combined with a nut, and is mainly used to fix tubular objects such as water pipes or sheet objects such as the plate springs of cars. Due to its fixed object like a person riding on a horse, it is called a saddle bolt. Divided into two types based on thread length: full thread and non full thread.
According to the thread profile, it is divided into two types: coarse and fine. The coarse profile is not displayed in the bolt marking. Bolts are classified into eight grades based on their performance levels: 3.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, and 12.9. Bolts above grade 8.8 (including grade 8.8) are made of low-carbon alloy steel or medium carbon steel and undergo heat treatment (quenching+tempering), commonly known as high-strength bolts. Bolts below grade 8.8 (excluding grade 8.8) are commonly known as ordinary bolts.
Ordinary bolts can be divided into three grades based on production accuracy: A, B, and C. Grade A and B are refined bolts, while grade C is rough bolts. For connecting bolts used in steel structures, unless otherwise specified, they are generally ordinary rough C-grade bolts. There are differences in the processing methods for different levels, and the corresponding processing methods are usually as follows: ① The bolt rods of grade A and B bolts are machined by lathes, with smooth surfaces and precise dimensions. Their material performance level is 8.8, and the production and installation are complex, expensive, and rarely used; ② C-grade bolts are made of unprocessed round steel with imprecise dimensions, and their material performance level is 4.6 or 4.8. The deformation is large during shear connection, but it is easy to install and has low production costs. It is mostly used for tensile connection or temporary fixation during installation.