310moLN Stainless Steel Pipe (UNS S31050 / ASTM A213)
Product Introduction
310MoLN stainless steel pipe is a top-tier heat- and corrosion-resistant alloy. It exhibits excellent oxidation resistance, carburization resistance, and ultra-high strength in high-temperature environments (up to 1100℃) and highly corrosive conditions (especially in sulfur-containing atmospheres). It is an expert-grade material that solves the dual challenges of insufficient high-temperature strength and high-temperature corrosion. It is an upgraded version of the classic 310S (25Cr-20Ni) heat-resistant stainless steel, developed by adding molybdenum (Mo) and nitrogen (N) elements.
Its price is 2-3 times that of ordinary 310S pipe and more than 5 times that of 304H pipe. You pay for "high temperature strength" and "resistance to complex corrosion". In practical applications, these pipes are used in leading petrochemical plants (elliptical tubes, pigtail tubes, and converter tubes in ethylene cracking furnaces). Some customers also use them on furnace rollers and muffle tanks in high-temperature annealing furnaces and carburizing furnaces. They are also commonly found in high-temperature converter tubes and superheater tubes in waste incinerators.
We will provide the material's MTR (Mean Transmission Report), high-temperature performance data sheet, heat treatment record, and non-destructive testing report based on your needs and the final product.
Procurement Specifications and Industry Standards
Your request for quotation must be as precise as a technical document.
1. Clearly Define Material Standards and Grades:
The standard for 310MoLN stainless steel tubing is ASTM A213/A312 (boiler tubes/seamless welded tubes) or ASTM A789/A790 (duplex stainless steel, although 310MoLN can also refer to this standard). We also refer to it as the unified grade: UNS S31050. This is the only reliable identifier; vague descriptions using only "310MoLN" are strictly prohibited.
2. Detailed Specifications and Delivery Conditions (Lifeline Terms):
Based on market material feedback and past customer needs, we maintain a comprehensive inventory of 310MoLN tubing. Common specifications are: outside diameter: 6mm - 1219mm; thickness: 0.5mm - 100mm. You can provide the outside diameter (OD), wall thickness (WT), and length to meet your requirements. Eccentric reducers are commonly used for boiler tubes; detailed drawings are required.
Delivery Condition: Must specify "Solution Annealed, typically water-quenched at 1050-1150°C".
3. Core Performance Requirements (Core of the Technical Agreement):
Must be locked in: "The supplier must provide high-temperature short-time yield strength data for this steel grade at 950°C and 1050°C, as well as creep rupture life estimation curves or data under stresses of XXX°C and XX MPa."
Composition Control: "Nitrogen (N) content must be ≥ 0.12%, Molybdenum (Mo) content must be ≥ 2.2%."
4. Special Requirements (Additional Fee, but Necessary):
Non-destructive Testing: 100% eddy current (ET) + ultrasonic (UT) testing, or hydrostatic testing according to ASTM A450.
Inner Wall Smoothness: To prevent coking, ethylene cracking furnace tubes often require the inner wall to be sandblasted or acid-washed to a specific roughness (e.g., Ra ≤ 1.6μm).
Dimensional accuracy: Extremely high requirements are placed on. the uniformity of wall thickness (eccentricity).
Processing difficulty and key points
(Understanding the reason for the exorbitant price)
310 moLN stainless steel pipes are extremely difficult to manufacture. The high alloy content results in poor hot working plasticity, making piercing and rolling difficult and leading to a low yield. This is one of the main reasons for its high cost
Welding is the biggest challenge:
Ultra-high matching welding consumables must be used, with nickel-based alloy welding consumables (such as Inconel 625/82 welding wire) being the preferred choice.
Strict welding procedure qualification (WPS/PQR) procedures must be established, extremely low interpass temperatures must be controlled, and argon purging of the inner wall is essential.
Post-weld solution heat treatment is mandatory to restore the corrosion resistance and high-temperature performance of the heat-affected zone. On-site post-weld heat treatment is a major technical challenge.
Hot bending is required for pipe bending:
Cold bending is highly prone to cracking; induction heating bending must be used, and the heating temperature range must be strictly controlled.
One-stop procurement golden rule:
Never just buy "bare pipes"! For projects such as pyrolysis furnace tubes, it is essential to find a professional petrochemical pipe fitting manufacturer or furnace tube supplier with full-process capabilities of "pipe manufacturing + bending + welding + heat treatment." They control materials, forming, and heat treatment as a whole, ensuring that you are purchasing "qualified furnace tube modules," not just raw materials. This is the only reliable way to control project risks.
For more information, please contact:
Email: susan@lorkgroup.com
WhatsApp: +86 19937075488
Chemical Composition
(based on UNS S31050, etc.)
| Weight% | Typical value |
| Ni | 20.0 - 22.0% |
| Cr | 24.0 - 26.0% |
| Mo | 2.0 - 3.0% |
| N | 0.10 - 0.18% |
| Fe | Bal |
Mechanical Properties
| Material | (solid solution state) |
| Tensile Strength | ≥ 650 MPa |
| Yield Strength (0.2%) | ≥ 300 MPa |
| Elongation | ≥ 12% |
| Hardness | HB ≤ 220 |
High-Temperature Performance (Data Must Be Requested During Procurement):
- High-Temperature Yield Strength (Rp0.2): For example, ≥ 35 MPa at 1100°C.
- 100,000-Hour Creep Tension Strength: Data at 950-1000°C; this is the direct basis for designing furnace tube wall thickness. Reputable suppliers should be able to provide such long-term performance curves or data sheets.
Quality Inspection
We typically conduct physical inspections on 310MoLN Stainless Steel Pipes after production. This is a necessary process to ensure material quality:
1. Chemical Composition Verification (PMI - The Dead End): Upon arrival, each pipe/batch must undergo PMI testing. The primary goal is to confirm the presence and content of Mo and N. This is a fatal blow to prevent the substitution of cheap 310S (Mo- and N-free) pipes.
2. Dimensional and Wall Thickness Measurement: Especially for wall thickness uniformity, multi-point inspection is performed using an ultrasonic thickness gauge.
3. Endoscopic Inspection: The inner wall is inspected for deep scratches, cracks, or residual oxide scale.
Quality inspection photos and videos are recorded and sent to the customer for confirmation.
If you are not confident in the testing we arrange and need to have it confirmed by a third-party testing agency and require a report, we can also arrange for the materials to undergo third-party destructive testing (mandatory for new suppliers): cutting pipe section samples and sending them to a national-level materials testing center or an authoritative petrochemical industry institution for high-temperature tensile testing, metallographic analysis (checking grain size and precipitates), and full composition analysis.
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