What Is Grade 2H Hardware?

Grade 2H refers to a high-strength carbon steel fastener grade used mainly for heavy-duty bolting in oil and gas flange connections. Most commonly, it applies to heavy hex nuts that pair with high-strength studs such as ASTM A193 B7.

Material and Strength

Manufacturers produce 2H nuts from medium carbon steel and then heat treat them to achieve higher strength and hardness. As a result, 2H hardware provides strong resistance to high bolt loads in pressure-containing joints.

Relevant Specifications

• ASTM A194 Grade 2H: Governs heavy hex nuts used in high-pressure service.
• Common pairing: ASTM A193 Grade B7 studs or bolts.

How It Works in Flanged Joints

Technicians install 2H nuts on threaded studs (often B7). Then they tighten the
nuts to apply preload to the flange joint. This clamping force compresses the
gasket and creates a pressure-tight seal. Because 2H nuts match high-strength
studs, the assembly handles high-pressure and high-temperature service.

Typical Applications

• Oil and gas pipeline flanges
• Refinery and petrochemical piping systems
• Pressure vessels and heat exchangers
• High-pressure valve and equipment connections

Advantages

• It provides high strength for demanding bolted joints
• It pairs well with high-strength studs like B7
• It performs reliably under high pressure and temperature
• It resists deformation under heavy torque loads

Limitations

• It requires proper lubrication and torque control during installation
• It can gall if mismatched with incompatible stud materials
• It offers less corrosion resistance than stainless options

Summary

Grade 2H refers to a high-strength ASTM A194 nut used in oil and gas bolting applications. When paired with ASTM A193 B7 studs, it creates a reliable, high-load bolting system for critical flange connections.