ASTM A194/A194M-25 Standard Specification for Nuts (PDF)

Below is the complete ASTM A194/A194M-25 standard specification for carbon, alloy, and stainless steel nuts used in bolts for high-pressure or high-temperature service.

This specification covers chemical composition, mechanical properties, dimensional standards, manufacturing requirements, marking, and testing for nuts in Grades 1, 2, 2H, 2HM, 3, 4, 6, 6F, 7, 7M, 8, 8M, 8MA, 8C, 8T, 8R, 8N, 16, and related variants. The document is the authoritative reference for refinery, petrochemical, pressure-vessel, valve, flange, and high-temperature bolting applications.

Grades Covered by ASTM A194/A194M-25

The A194 standard PDF defines mechanical and chemical requirements for the following nut grades:

• Grade 2H: quenched & tempered carbon steel, the most widely used heavy hex nut grade.
• Grade 4: quenched & tempered carbon-alloy steel.
• Grade 7: quenched & tempered Cr-Mo alloy steel (AISI 4140).
• Grade 7M: sour-service Cr-Mo nuts per NACE MR0175 / ISO 15156.
• Grade 8: solution-treated Type 304 austenitic stainless steel.
• Grade 8M: solution-treated Type 316 molybdenum-bearing stainless.
• Grade 8MA: Class 1A solution-treated 316.
• Grade 8C: niobium-stabilised 347 stainless.
• Grade 8T: titanium-stabilised 321 stainless.

Dimensional Standards Referenced

Nuts manufactured to A194 are dimensioned per ASME B18.2.2 heavy hex, hex, heavy hex jam, hex jam, square, and B18.2.4.1M metric hex patterns. Metric equivalents are covered in ISO 4032, ISO 4033, and ISO 4035.

About this PDF

This is the official ASTM A194/A194M-25 specification document. TorqBolt distributes it as part of the TorqBolt fastener reference library to support engineers, procurement teams, and inspectors working with industrial bolting. For RFQ on any A194-grade nut, see TorqBolt contact.