Alloy 254 SMO™ (6-moly) Tubing
Alloy 254 SMO™ (6-moly) Tubing
Alloy 6MO tubing is a high-alloy austenitic stainless steel designed for maximum resistance to pitting and crevice corrosion. The high levels of chromium, molybdenum, and nitrogen make 254 SMO (6-moly) suitable for high chloride environments such as brackish water, seawater, pulp mill, bleach plants, and other high chloride process streams. Since alloy 6MO is compatible with the common austenitic stainless steels, it is often used as a replacement in critical components of larger constructions where type 316L or 317L has failed by pitting, crevice attack, or chloride stress corrosion cracking. Though alloy 6MO is substantially stronger than the common austenitic grades, it is also characterized by high ductility and impact strength.
Product Specifications
ASTM A213, A269 / ASME SA213 / NORSOK M650 / NACE MR0175
Size Range
Outside Diameter (OD) | Wall Thickness |
.250”–.750” | .035″–.065″ |
Chemical Requirements
Alloy 6MO (UNS S31254)
Composition %
C | Mn | P | S | Si | Cr Chromium | Ni Nickel | Mo | N | Cu |
0.020 max | 1.00 max | 0.030 max | 0.015 max | 0.80 max | 19.5–20.5 | 17.5–18.5 | 6.0–6.5 | 0.18–0.22 | 0.50–1.00 |
Chemical Requirements
Alloy 6MO (UNS S31254)
Composition %
C | Mn | P | S | Si | Cr | Ni | Mo | N | Cu |
0.020 max | 1.00 max | 0.030 max | 0.015 max | 0.80 max | 19.5–20.5 | 17.5–18.5 | 6.0–6.5 | 0.18–0.22 | 0.50–1.00 |
Dimensional Tolerances
OD | OD Tolerance | Wall Tolerance |
≤ .500″ | ± .005” | ± 15% |
.500″–.750″ | ± .005” | ± 10% |
Mechanical Properties
Yield Strength: | 45 ksi min |
Tensile Strength: | 98 ksi min |
Elongation (min 2"): | 35% |
Hardness (Rockwell B Scale): | 96 HRB max |
Fabrication
Alloy 254 SMO™ (6-moly) has excellent weldability in addition to excellent formability which permits cold bending to very tight bending radii.
Industry Applications
Chemical Process
With a chemistry optimized for use in seawater and aggressive chloride-bearing media, alloy 254 SMO is often found in systems handling and processing chemicals with high halide contents.
Fabrication
Alloy 254 SMO (6-Moly) has excellent weldability and formability, which permits cold bending to very tight bending radii for specific fabrication applications. This is useful for making seawater handling equipment and pulp mill bleach systems.
Food & Beverage
Alloy 254 SMO tubing is chosen for pickling and brining steps during food processing due to its resistance to chloride pitting.
Marine
Used in the marine industry, alloy 254 SMO was specifically designed for equipment for handling of seawater, such as, seawater cooling, cooling water pipes, and ballast water systems.
Oil & Gas
Whether offshore with seawater systems or onshore when in contact with produced water, 254 SMO is offering the needed corrosion resistance in these high-chloride environments and is ensuring safe and continued operations of systems in the oil and gas industry.
Pulp & Paper
Pulp mill bleach system equipment uses Alloy 254 SMO because of its high resistance to stress corrosion cracking.
Power Generation
With a PRE of ≥42.5, alloy 254 SMO holds up well against pitting and crevice corrosion in tanks and pipelines for chemicals with high halide contents and is also reliable for components in gas cleaning systems. See power generation for more information.
Renewable Energy
In the renewable energy sector, alloy 254 SMO tubing is used in gas cleaning systems.
