COMPREHENSIVE TECHNICAL ANALYSIS AND DATASHEET OF ASTM A194 GRADE 8LN NUTS
ASTM A194 Grade 8LN specifies premium austenitic stainless steel nuts manufactured from AISI Type 304LN. This advanced alloy is engineered with an exceptionally low carbon profile (Max 0.030%) to prevent sensitization (chromium carbide precipitation) during high-temperature service or heavy welding processes.
To compensate for the mechanical yield strength that is naturally lost when reducing carbon levels, Grade 8LN utilizes the intentional metallurgical addition of Nitrogen. Nitrogen acts as a powerful solid-solution strengthening agent, stabilizing the austenitic matrix, enhancing localized pitting resistance, and ensuring the material maintains exceptional toughness even in severe cryogenic applications.
■ Product Overview & Specifications
| Material Classification | Nitrogen-Strengthened Austenitic Stainless Steel (Type 304LN) |
|---|---|
| UNS Designation | S30453 |
| Microstructure | Austenitic (Low-Carbon, Nitrogen-Stabilized) |
| Magnetic State | Non-Magnetic (May exhibit slight magnetism from cold-working) |
| Density | ~8.00 g/cm³ (0.289 lb/in³) |
| Size Range | Metric: M6 to M100 | Imperial: 1/4" to 4" |
| Strengthening Method | Nitrogen Solid-Solution Strengthening |
■ Proprietary Datasheet Download (GATED)
ASTM A194 Grade 8LN — Complete Technical Datasheet
Contains detailed proof load thresholds, dimensional tolerances for ASME B18.2.2 standard and heavy hex profiles, and precise galling-prevention torque values for A193 B8LN assemblies.
⬇ DOWNLOAD DATASHEET■ MTC Integration Section
Material traceability is the backbone of safety in high-pressure environments. Every lot shipped by Ananka is accompanied by fully authenticated documentation mapping back to raw steel mill certificates.
- EN 10204 Type 3.1: Issued by our independent quality department, providing specific heat-traceable test results (actual chemical analysis, mechanical test results, hardness, and proof load tests).
- EN 10204 Type 3.2: For critical commercial, offshore, or chemical applications, we facilitate third-party witness testing.
■ Chemical Composition
| Carbon (C) | Manganese (Mn) | Chromium (Cr) | Nickel (Ni) | Phosphorus (P) | Sulfur (S) | Silicon (Si) |
|---|---|---|---|---|---|---|
| 0.030 Max | 2.00 Max | 18.0 – 20.0 | 8.0 – 11.0 | 0.045 Max | 0.030 Max | 1.00 Max |
■ Mechanical Properties
| Mechanical Property | Grade 8LN Limits |
|---|---|
| Hardness Limit (Rockwell) | 32 HRC Maximum |
| Proof Load | Dependent on Size |
■ Equivalent Grades & Designations
| Standard / System | Designation |
|---|---|
| ASME Standard | SA194 Grade 8LN |
| Common Trade Name | Type 304LN Stainless Nuts, Nitrogen-Strengthened 18-8 |
| European Equivalent | EN 1.4311 / X2CrNiN18-10 |
■ Applications & Industries
- Cryogenic Engineering: LNG (Liquefied Natural Gas) terminals and liquid oxygen systems where Nitrogen alloying maintains incredibly high toughness and prevents embrittlement at sub-zero temperatures.
- Chemical & Petrochemical Processing: Pressure vessels and transfer lines handling aggressive chemicals where low carbon is required to prevent sensitization near welds.
- Power Generation: Structural fastening in high-heat zones requiring high yield strength and extreme metallurgical stability.
■ Compatible Fastener Assemblies
| Internal Threads (A194 Gr 8LN) | Mating Bolts (A193 Gr B8LN) | Mating Studs (A193 Gr B8LN) |
|---|---|---|
| Grade 8LN Heavy Hex Nuts | ASTM A193 Grade B8LN Hex Bolts | A193 Grade B8LN Fully Threaded Studs |
■ Torque & Installation Guidelines
Due to the fully austenitic nature of 8LN, severe thread galling is a major risk under high clamping loads. Premium high-performance anti-seize lubrication is absolutely mandatory for safe installation and future unbolting.
| Nominal Diameter | Threads Per Inch (UNC) | Target Torque — Lubricated (ft-lbs) |
|---|---|---|
| 1/2" | 13 | 30 |
| 5/8" | 11 | 60 |
| 3/4" | 10 | 100 |
| 1" | 8 | 250 |
■ Frequently Asked Questions
1. What does the "LN" designation mean?
The letters indicate the precise metallurgical profile of the steel: L indicates Low Carbon (Max 0.030%) to prevent sensitization and intergranular corrosion. N indicates a precise Nitrogen addition, which powerfully strengthens the steel matrix from within to compensate for the lower carbon content.
2. How is Grade 8LN different from standard Grade 8 (Type 304)?
Standard Grade 8 (Type 304) has a higher allowable carbon limit, making it susceptible to chromium carbide precipitation if exposed to temperatures between 800°F–1500°F. Grade 8LN lowers the carbon to solve this problem, but adds Nitrogen so the nut retains the high mechanical yield strength required for heavy pressure piping systems.
3. Why specify Grade 8LN for Cryogenics?
Unlike standard carbon steel which becomes brittle and shatters at ultra-low temperatures, austenitic stainless steels remain ductile. The addition of Nitrogen in Type 304LN (Grade 8LN) specifically enhances microstructural stability, ensuring the fasteners maintain immense impact toughness in environments like liquid nitrogen (-320°F) or LNG processing.
