How to select ASME bolt and nut standards

The ASME/ANSI codes for pressure vessels and piping specify that when American-standard fasteners are used, the nuts shall be from the Heavy hex series specified in B18.2.2 – heavy hex nuts. It was said by an industry expert.

When selecting ASME (American Society of Mechanical Engineers) standards for studs and nuts, the following factors should be considered: 1. Application area: Determine the application area and working environment of your project in order to choose materials and coatings suitable for that environment. 2. Dimensions and tolerances: Select the appropriate thread size and grade based on the dimensions of the components to be connected and the required tightening force. 3. Load requirements: Analyze the pre-tension required and the loads under operating conditions to ensure that the selected studs and nuts can withstand the corresponding forces. 4. Materials and grades: Select appropriate materials and mechanical property grades based on the working environment, such as stainless steel, alloy steel, or carbon steel, as well as their corrosion resistance. 5. Specific requirements of standards: Understand the specific requirements of each standard, such as thread type, tolerances, mechanical properties, size ranges, etc. Below are brief descriptions and application ranges of some common ASME standards: - ASME B18.2.1-2012: This standard specifies the size ranges and thread specifications for hex head bolts and screws. - ASME B18.2.3.1M-1999 (R2011): Defines hex head bolts and screws in metric sizes. - ASME B18.2.4.1M-2002: Specifies the dimensions and tolerances for metric studs. - ASME B18.22M-1981 (R2017): The standard for metric flat washers. - ASME B18.31.2-2014 (R2019): This is the standard for screws, specifying requirements such as diameter, length, and tolerances. - ASME B18.2.2-2022: Covers the requirements for hex nuts and other types of nuts, including dimensions and tolerances. - ASME B18.2.6M-2012: Standard specifically for high-strength metric hex head bolts used in steel structures. When selecting criteria, you need to consider your specific application and design requirements, and take into account the contents of the various criteria mentioned above to determine which one is best suited to your needs. If you’re not sure how to choose, you can consult professional engineers or technical experts. In addition, local regulations and engineering practice standards must also be followed. .

This post was last edited by *nchen on 2023-11-22 at 13:34. What are the considerations when choosing studs for pressure vessels, such as stud nuts for pipe flanges and equipment flanges?

Appendix 3 (Introduction to ASME/ASTM Steels) in \"Design Methods, Problems, and Key Points for Chemical Process Pressure Vessels (2nd Edition)\") provides a detailed explanation.