SMLS pipes for fluids are seamless pipes specially used for transporting various fluids such as water, oil, natural gas, steam, chemical media, etc. With their characteristics of no welds and high strength, they have become the core pipe material in the fields of petrochemicals, municipal water supply and drainage, energy transportation, machinery manufacturing, etc.
Since fluid transportation places extremely high demands on the safety, sealing and durability of pipelines, such smls pipes must meet strict quality standards. These standards usually stipulate key technical requirements such as the material, dimensional tolerance, mechanical properties, chemical composition, surface quality, non-destructive testing methods and hydrostatic testing of steel pipes.
International standards
1. API SPEC 5L (American Petroleum Institute Standard 5L) - Linepipe Specification
Overview: As the most critical line pipe standard for the global oil and gas industry, it covers both seamless and welded steel pipes—all intended for pipelines that transport oil, gas, water, and other fluids.
Key Features:
PSL1 and PSL2: It defines two product specification levels. PSL2 has tighter rules for chemical composition, mechanical properties, non-destructive testing, and traceability, so it’s suited for more high-stakes applications.
Steel grades: Spanning from A to X (like B, X42, X52, X60, X70, X80), the number in each grade represents the minimum yield strength.
Low-temperature toughness: PSL2 grades come with mandatory requirements for low-temperature impact toughness.
Corrosion resistance: Many high-grade line pipes are engineered to resist sulfide stress corrosion cracking (called Sour Service) and carbon dioxide corrosion.
Applications: Long-distance oil and gas transmission pipelines, gathering pipelines, oilfield pipeline networks, urban gas pipeline networks, and similar setups.
2. ASTM A106 / ASME SA-106 - Seamless carbon steel pipe for high temperature service
Overview: Specifies seamless carbon steel pipe for high-temperature service.
Main grades: Grade A, Grade B (most commonly used), Grade C.
Features: Excellent high-temperature performance and pressure-bearing capacity.
Applications: Piping systems for transporting high-temperature, high-pressure fluids (such as steam, hot water, and oil products) in industries such as petroleum, natural gas, power generation, petrochemicals, and refineries.
3. ASTM A333 / ASME SA-333 - Seamless carbon and alloy steel pipe for low-temperature service
Overview: This standard lays out specifications for seamless carbon steel and alloy steel pipes, all made specifically for low-temperature working conditions.
Main Grades: It covers grades like Gr.1, Gr.3, and Gr.6—with Gr.6 being the most commonly used one among them.
Features: These pipes stand out for great low-temperature impact toughness; they don’t easily break in a brittle way when exposed to low temperatures.
Applications: They’re used in liquefied natural gas (LNG) transportation, cryogenic storage systems, refrigeration equipment, and also pipelines that operate in extremely cold regions.
4. ASTM A312 / ASME SA-312 - Seamless and welded austenitic stainless steel pipe
Main Grades: 304/304L, 316/316L, 321, 347, etc.
Features: Excellent corrosion resistance, along with good high-temperature strength and processability.
Applications: Fluid transportation systems that demand high corrosion resistance or hygiene standards, such as those in the chemical industry, food processing, pharmaceutical industry, seawater desalination, and medical equipment.
5. ISO 3183 - Petroleum and natural gas industries — Steel pipes for pipeline transportation systems
This is an international standard that is highly coordinated with API 5L and also specifies the technical requirements for steel pipes used in pipeline transportation systems in the oil and gas industry.
Chinese National Standard (GB/T)
1. GB/T 8163 - Seamless steel pipes for conveying fluids
Overview: This is the most commonly used seamless steel pipe standard for fluid transportation in China.
Main grades: 10#, 20# (most commonly used), Q345A/B/C/D/E, etc.
Features: Covers carbon steel and low-alloy steel, suitable for transporting general fluids (such as water, oil, and gas), with basic requirements for chemical composition, mechanical properties, and hydrostatic testing.
Applications: Industrial and civil construction, urban water supply and drainage, fire protection, HVAC, and general chemical fluid transportation.
2. GB/T 9711 - Petroleum and natural gas industries - Technical delivery conditions for steel pipes
Overview: Equivalent to or modified from API 5L and ISO 3183, this standard is a professional standard for domestic oil and gas line pipe.
Main grades: L245 (B), L290 (X42), L360 (X52), L415 (X60), L450 (X65), L485 (X70), etc. The number following the L indicates the minimum yield strength (in MPa).
Features: Also available in PSL1 and PSL2 grades, this standard has strict requirements for material properties, manufacturing, inspection, testing, and delivery of line pipe to ensure high safety.
Applications: Long-distance oil and gas pipelines.
3. GB/T 14976 - Stainless steel seamless pipes for fluid transportation
Overview: This standard specifies seamless stainless steel pipes for fluid transportation.
Main grades: 0Cr18Ni9 (304), 00Cr19Ni10 (304L), 0Cr17Ni12Mo2 (316), 00Cr17Ni14Mo2 (316L), etc.
Applications: Fluid transportation requiring corrosion resistance or high cleanliness in the chemical, pharmaceutical, food, and water industries.
Other relevant standards
GB/T 3087 - Seamless steel tubes for low and medium pressure boilers and GB/T 5310 - Seamless steel tubes for high pressure boilers: Although primarily used in boilers, their specified high temperature pressure resistance also allows them to be used in certain high pressure fluid transport applications (such as steam and hot water).
GB/T 6479 - Seamless steel pipes for high-pressure fertilizer equipment: specially designed for conveying high-pressure, high-temperature and highly corrosive media in the fertilizer industry.
GB/T 9948 - Seamless steel tubes for petroleum cracking: For use in furnace tubes, heat exchangers and pipelines in petroleum refineries.
Read more: Fluid Pipe, Seamless Steel Pipe for Fluid Transportation
