UNS S31500 stainless steel pipe, also known as Alloy 315 SS pipe,
is a versatile austenitic-ferritic duplex stainless steel product
designed to balance the advantages of both austenitic and ferritic
stainless steels. It is widely recognized for its excellent
corrosion resistance, moderate strength, and good weldability,
making it suitable for various industrial applications. Below is a
detailed introduction covering its parameters, standards,
specifications, similar grades, characteristics, and applications.
Key Parameters
Standards Compliance
Alloy 315 stainless steel pipes are primarily manufactured in
accordance with ASTM A790, a standard specification for seamless
and welded duplex stainless steel pipe. This standard ensures
consistent quality, dimensional accuracy, and performance across
different production batches. Additional standards may apply based
on specific industry requirements, such as ASME BPVC (for pressure
vessel applications) or ISO 1127 (for general stainless steel pipe
specifications).
Specifications
- Type: Seamless pipe, welded pipe (ERW, TIG, or LASER welded)
- Outer Diameter (OD): Typically ranges from 1/8 inch (3.18 mm) to 24
inches (609.6 mm), with custom sizes available.
- Wall Thickness (WT): From SCH 5S to SCH 160, including standard,
extra-strong (XS), and double extra-strong (XXS) schedules; custom
thicknesses are offered for specific needs.
- Length: Standard lengths include 6 meters (20 feet), 12 meters (40
feet), or cut-to-length as per customer requirements (custom
cutting in length is available for precise project needs).
- Surface Finish: Annealed and pickled (AP), polished (BA, 2B, or
4K), or sandblasted, depending on application demands for corrosion
resistance or aesthetics.
Equal Grade of Alloy 315
UNS S31500/Alloy 315 is comparable to other duplex or austenitic
stainless steels with similar chemical and mechanical properties,
including:
- UNS S31803/S32205 (Alloy 2205): A widely used duplex stainless
steel with higher chromium and molybdenum content, offering
superior corrosion resistance in harsh environments.
- UNS S32750 (Alloy 2507): A super duplex stainless steel with
enhanced strength and corrosion resistance, suitable for extreme
conditions (e.g., offshore oil and gas).
- UNS S30400 (304 Stainless Steel): An austenitic stainless steel
with lower strength but excellent formability; often considered
where moderate corrosion resistance is sufficient.
Characteristics
- Balanced Microstructure: Combines austenitic and ferritic phases
(typically 50-50%), providing a good balance of strength and
toughness.
- Corrosion Resistance: Resistant to general corrosion, pitting, and
crevice corrosion in mild to moderate environments, such as
freshwater, atmospheric conditions, and dilute acids.
- Weldability: Compatible with common welding processes (TIG, MIG,
SMAW) with minimal risk of sensitization, though post-weld
annealing may be recommended for critical applications.
- Cost-Effectiveness: Offers better strength than austenitic
stainless steels (e.g., 304) at a relatively lower cost compared to
super duplex grades, making it a cost-efficient choice for many
industries.
Applications
Alloy 315 stainless steel pipes are utilized in various industries
due to their versatile performance:
- Chemical Processing: For transporting mild acids, alkalis, and
chemical solutions.
- Water Treatment: In pipelines for water distribution, wastewater
treatment, and desalination plants.
- Oil and Gas: For non-critical onshore pipeline systems and storage
facilities.
- Food and Beverage: In processing equipment and piping where hygiene
and corrosion resistance are required.
- Construction: For structural piping, architectural components, and
marine environments (mildly corrosive seawater conditions).
In summary, UNS S31500 (Alloy 315) stainless steel pipe under ASTM
A790 standard is a reliable choice for applications requiring a
balance of corrosion resistance, strength, and affordability, with
the flexibility of custom cutting to meet specific project lengths.
