ASTM A325 Large hexagonal screws Heavy Duty hexagonal head hot-dip galvanized bolts

American thread (NPT/ NPS)：The United States National Standard pipe thread standard is the United States national thread technical standard used on threaded pipes and pipe fittings. Its standard includes conical and parallel teeth for a variety of uses, including rigidity, pressure sealing, or both. Because of its use, there are various subdivision types of abbreviation, the common NPT, that is, the abbreviation of the United States taper teeth, and the other United States parallel teeth are referred to as NPS.Mainly used in North America. The thread Angle (the Angle between the side of the thread and the vertical face of the bolt axis) is 60 degrees. The spiral peak/spiral valley (the most prominent top of the thread is called the spiral peak, and the low point of the most concave thread is called the spiral valley) presents an acute Angle.

Inch thread (BSPT, R/ BSPP, G)：British Standard Pipe (BSP) is a thread standard (tooth gauge) widely used in the world, including the combination of external and internal threads (female teeth). As well as the NPT standard, it has often been used as a dental gauge standard for pipes and pipe fittings. The thread Angle is 55 degrees. Spiral peaks/valleys show rounded corners.

Middle carbon 35K,45K, or alloy steel 40Cr

G5