Table of Contents
- ASTM A194 Grade 2H Nuts Overview
- ASTM A194 Grade 2H Specifications
- What are ASTM A194 Grade 2H Nuts?
- Technical Properties & Composition
- Comparison: Grade 2H vs. Grade 2HM
- Why High-Pressure Industries Prefer ASTM A194 Grade 2H Nuts
- Key Technical Advantages
- Key Applications of Grade 2H Nuts
- Quality Assurance & Mechanical Testing
- Global Export Markets
- Frequently Asked Questions
- Contact Aurum Overseas
ASTM A194 Grade 2H Nuts Suppliers & Exporters
Aurum Overseas is a globally recognized ASTM A194 Grade 2H Nuts Supplier and ASTM A194 Grade 2H Nuts Exporter, stockholding high-strength quenched and tempered carbon steel fasteners engineered for high-pressure boilers, refinery pressure vessels, valve bonnets, and pipeline flanges.
Formulated to maintain structural preload integrity under extreme thermal cycling, these heavy hex fasteners pair seamlessly with ASTM A193 Grade B7 stud bolts to prevent joint relaxation and gasket blowout.
As an international ASTM A194 Grade 2H Nuts Exporter, Aurum Overseas supplies fully certified bolting to major engineering EPC contractors across North America, Europe, the Middle East, and Asia-Pacific.
ASTM A194 Grade 2H Specifications
| Parameter | Technical Specification / Range |
|---|---|
| Material Standard | ASTM A194 / ASME SA194 Grade 2H |
| Manufacturing Scope | Quenched & Tempered Medium Carbon Steel |
| Size Range | 1/4" to 4" (UNC, UNF, 8UN) | M6 to M100 Metric |
| Dimensional Standards | ASME B18.2.2 (Heavy Hex), ASME B18.2.4.6M |
| Proof Load Stress | 175 ksi (1/4" to 1-1/2") | 150 ksi (Over 1-1/2" to 4") |
| Hardness Range | Rockwell C24 to C38 (Brinell 248 to 327 BHN) |
| Minimum Tempering Temp. | 1000°F (538°C) |
| Surface Finishes | Plain Black Oil, Hot-Dip Galvanized (HDG), Zinc Plated, Cadmium, PTFE / Xylan Coated |
| Certification | EN 10204 3.1, NACE MR0175 / ISO 15156 (Upon Request) |
What are ASTM A194 Grade 2H Nuts?
ASTM A194 Grade 2H nuts are high-strength, quenched, and tempered carbon steel fasteners engineered for extreme pressure and high-temperature flange applications. Built in a Heavy Hex profile (ASME B18.2.2), they withstand proof loads up to 175 ksi while eliminating thread stripping and thermal creep.
As a leading ASTM A194 Grade 2H Nuts Supplier, Aurum Overseas delivers precision-machined nuts designed to seamlessly pair with ASTM A193 Grade B7 stud bolts, guaranteeing zero-leakage performance in critical refineries, power plants, and chemical pipelines.
Technical Properties & Composition
Chemical Composition (%)
| Element | ASTM A194 Grade 2H Requirements |
|---|---|
| Carbon (C) | 0.40% min (0.15% min base standard) |
| Manganese (Mn) | 1.00% max |
| Silicon (Si) | 0.40% max |
| Phosphorus (P) | 0.040% max |
| Sulfur (S) | 0.050% max |
Mechanical Properties & Hardness Limits
| Size Category | Proof Load Stress | Rockwell Hardness (Completed Nut) | Brinell Hardness (BHN) |
|---|---|---|---|
| 1/4" to 1-1/2" Inclusive | 175 ksi | HRC 24 to 35 | 248 – 327 BHN |
| Over 1-1/2" to 4" | 150 ksi | HRC 35 max (HRB 95 min) | 212 – 327 BHN |
Comparison: Grade 2H vs. Grade 2HM
| Parameter / Feature | ASTM A194 Grade 2H | ASTM A194 Grade 2HM |
|---|---|---|
| Material & Heat Treatment | Quenched and tempered medium carbon steel | Quenched and specially stress-relieved medium carbon steel |
| Primary Design Intent | High-pressure, elevated-temperature standard flange bolting | Sour gas (H₂S) environment resistance per NACE MR0175 |
| Hardness Limits | HRC 24 to 35 (Brinell 248 – 327 BHN) | Strictly capped at HRC 22 max (235 HBW max) |
| Proof Load Strength | Maximum tensile strength (175 ksi up to 1-1/2") | Slightly reduced proof stress due to higher tempering temperatures |
| Crack Resistance Mechanism | High mechanical load retention under heat | Prevents Sulfide Stress Corrosion Cracking (SSC) |
| Typical Industry Usage | Steam boilers, power plants, standard oil refining | Sour crude refineries, offshore oil & gas processing, H₂S lines |
Why High-Pressure Industries Prefer ASTM A194 Grade 2H Nuts
Plant maintenance engineers and piping designers select Grade 2H heavy hex nuts because they match the mechanical yield strength of ASTM A193 Grade B7 stud bolts. This equal strength distribution prevents thread stripping under heavy torquing loads.
As a leading ASTM A194 Grade 2H Nuts Exporter, Aurum Overseas supplies nuts with wider across-flats dimensions. This expanded bearing face dissipates clamping loads over a broader gasket surface area, preventing flange face distortion and eliminating creep during thermal pressure surges.
Key Technical Advantages
High Proof Load Capacity
Capable of withstanding up to 175 ksi proof stress without permanent thread deformation or load loss.
Thermal Creep Stability
Holds pre-torqued clamping force across continuous operating temperatures up to 800°F (427°C).
Controlled Hardness Range
Quenched and tempered within strict HRC 24–35 bounds to eliminate brittle fracture vulnerabilities.
Uniform Thread Fit
Precision machined to UN Class 2B/3B and Metric 6H fit tolerances for rapid assembly without thread binding.
Coating Versatility
Suitable for Hot-Dip Galvanizing, Zinc-Nickel plating, or Fluoropolymer (PTFE/Xylan) coatings for aggressive marine or coastal atmospheres.
Key Applications of Grade 2H Nuts
| Industry Sector | Typical Equipment Application | Service Conditions |
|---|---|---|
| Petrochemical Refining | Catalytic crackers, hydrotreaters, pressure vessel bonnets | High thermal cycles, hydrocarbon pressures, and ambient temperature swings |
| Power Generation | Main steam lines, boiler feed pumps, turbine casings | High-pressure superheated steam, thermal expansion stress, continuous vibration |
| Oil & Gas Pipelines | Cross-country transmission manifolds, metering skids | High hydrostatic pressures, dynamic line surges, and external soil stresses |
| Chemical Synthesis | Heat exchanger shell-and-tube joints, autoclave closures | Corrosive process media, high clamping load demands, cyclic pressures |
Quality Assurance & Mechanical Testing
As a dedicated ASTM A194 Grade 2H Nuts Supplier and ASTM A194 Grade 2H Nuts Exporter, Aurum Overseas verifies every heat lot against ASTM specifications before shipment.
- Hardness Testing: Rockwell (HRC/HRB) and Brinell hardness testing across sliced cross-sections to verify core heat-treatment uniformity.
- Proof Load Verification: Full-scale hydraulic axial pull testing to confirm 175 ksi thread strength.
- Chemical Spectrometry: Optical Emission Spectroscopy (OES) to confirm carbon, manganese, and trace element percentages.
- Dimensional Inspection: Pitch diameter, thread angle, and height-across-flats check using calibrated Go/No-Go plug gauges.
- Traceable Documentation: Certified MTRs issued in strict compliance with EN 10204 Type 3.1.
Global Export Markets
As an established ASTM A194 Grade 2H Nuts Exporter, Aurum Overseas maintains expansive inventories and offers rapid air/sea freight logistics to industrial centers globally.
USA
Canada
Mexico
Germany
United Kingdom
France
Italy
Netherlands
Norway
UAE
Saudi Arabia
Qatar
Kuwait
Oman
Singapore
Malaysia
Australia
Frequently Asked Questions
ASTM A194 Grade 2H nuts are specifically produced, heat treated, and proof tested for high-temperature pressure vessel and piping applications, whereas ASTM A563 Grade DH nuts are intended primarily for structural steel bolting (e.g., pairing with A325 or A490 bolts).
Yes, Grade 2H nuts can be hot-dip galvanized. However, thread tapping must account for coating thickness, and heat-treated nuts must be monitored during baking to avoid hydrogen embrittlement.
Grade 2H nuts are most commonly paired with ASTM A193 Grade B7 stud bolts in elevated-temperature pressure service.
Grade 2H nuts are recommended for continuous operating temperatures up to 800°F (427°C). Above this range, alloy grades like Grade 7 or stainless grades like Grade 8 are required.
Yes, as a global ASTM A194 Grade 2H Nuts Exporter, Aurum Overseas ships fully certified heavy hex bolting across North America, Europe, the Middle East, and Asia-Pacific.
Contact Aurum Overseas
Aurum Overseas supplies high-performance ASTM A194 Grade 2H Nuts engineered for high-pressure piping, refining, and power generation systems with immediate export dispatch.
Contact our sales engineering team today to verify material test reports, request pricing, and confirm stock availability.