SS Seamless Tube Size Chart
Marine piping systems are the core components of ship propulsion, water supply and drainage, hydraulic, and fire protection systems. Compared to ordinary industrial pipes, marine-grade stainless steel seamless pipes have stringent requirements for corrosion resistance, pressure resistance, dimensional accuracy, and adaptability. Precise selection of dimensions directly determines the operational stability and service life of the ship's piping.
The selection of ss seamless tubes revolves around three core parameters: outer diameter, wall thickness, and length. These three parameters are mutually matched, determining the pipe's interface, pressure resistance, and installation compatibility, respectively. They are also core indicators for ship piping acceptance and design drawings.
1. Outer Diameter (OD): The Core Foundation for Pipeline Adaptation
International marine stainless steel seamless pipes adopt a dual standard of ISO metric series and ANSI inch series for outer diameter. This serves as the core basis for matching flanges, fittings, and valves worldwide and is also the universally accepted size in overseas shipbuilding markets such as Europe, America, Southeast Asia, and the Middle East.
The international shipbuilding industry strictly prohibits the use of non-standard outer diameter pipes, uniformly adhering to stringent dimensional tolerance standards. Compared to domestic conventional pipes, the precision requirements are higher, perfectly adapting to various imported ship equipment and eliminating installation misalignment and sealing leakage problems.
The standard marine pipe diameter range is 6mm-630mm, subdivided to adapt to different ship systems: 6-42mm small diameter pipes are mainly used for instrumentation and control, hydraulic circuits, and small water supply and drainage branches; 48-219mm medium diameter pipes are the main specifications, suitable for ship main water supply, drainage, fire protection, and cooling systems; 273-630mm large diameter pipes are mainly used for main water and oil pipelines of large cargo ships and ocean-going vessels.
In accordance with ASTM A312, ISO 6594, and IACS marine standards, the outer diameter tolerances for seamless marine pipes are standardized internationally: for pipes with an outer diameter ≤ 60.3 mm (2 inches and below), the allowable deviation is ±0.25 mm; for pipes with an outer diameter > 60.3 mm, the allowable deviation is ≤ ±0.5 mm.
This fully meets the acceptance requirements of major global classification societies such as LR, DNV, ABS, and CCS, and is suitable for the harsh service environment of ocean-going vessels with high salt spray and high humidity.
2. Wall Thickness (WT): A Key Guarantee for Pressure Resistance and Corrosion Protection
Wall thickness is a core pressure-bearing indicator for international ship piping selection. Overseas ship projects uniformly adopt the Sch standard wall thickness series (Sch40, Sch80, Sch160) instead of the domestic standard millimeter wall thickness designation, accurately matching international pipeline pressure ratings. Ships operate under conditions of long-term seawater corrosion, high-pressure transmission, and wave impact.
Therefore, wall thickness selection must strictly conform to international pressure standards. Insufficient selection can easily lead to pipeline damage and leakage, while excessive wall thickness will increase the ship's weight and increase energy consumption, failing to meet international lightweight ship design requirements.
Internationally, the standard wall thickness range for seamless stainless steel pipes used in marine applications is 0.5mm-20mm, corresponding to international standard Sch grades for precise adaptation to different operating conditions: the Sch40 thin-walled series is suitable for normal pressure ventilation and freshwater supply and drainage systems; the Sch80 medium-thick-walled series is suitable for conventional high-pressure cooling, fire fighting, and fuel delivery systems; the Sch160 thick-walled series is specifically designed for ocean-going vessel power systems, deep-sea high-pressure pipelines, and hydraulic core circuits, capable of withstanding high-intensity corrosion and high-pressure impacts.
The mainstream materials used are internationally recognized TP304 and TP316L stainless steel, conforming to ASTM A240 material specifications, ensuring excellent compatibility with overseas vessels.
Furthermore, the wall thickness of marine pipes is produced using a uniform standard, eliminating localized thickness deviations. Wall thickness tolerances strictly adhere to ship standards, ensuring consistent pressure resistance throughout the pipe and adaptability to complex marine operating conditions. The primary materials are 304 and 316L stainless steel, combined with standard wall thicknesses, effectively resisting corrosion from seawater salt spray and acid/alkali media.
3. Length: Installation and Construction Compatibility Standards
International market marine stainless steel seamless pipes are categorized into three lengths: international standard fixed length, variable length, and custom length. These are fully compatible with the standardized construction systems of European, American, and Southeast Asian ship cabins. Unlike domestically cut specifications, the length dimensions are uniformly aligned with global shipbuilding industry standards, meeting the construction requirements of neat pipeline layouts, minimal welding, and high sealing in overseas vessels.
Internationally common fixed lengths are 6000mm, 9000mm, and 12000mm (compatible with 20FT, 30FT, and 40FT ocean freight containers). These are the most commonly used specifications in global shipbuilding projects, perfectly matching international ocean freight container transport dimensions, reducing logistics costs, and minimizing on-site welding joints, while complying with international ship construction and acceptance standards. International variable lengths are uniformly no shorter than 2000mm, suitable for the installation of scattered branch pipelines on small vessels.
For customized layouts of large ocean-going freighters, overseas engineering vessels, and special-purpose ships, we support international non-standard length customization, with length tolerances controlled within ±10mm. Dimensional accuracy meets the unified requirements of IACS (International Classification Society), adapting to customized installation scenarios on various ships worldwide.
II. Commonly Used Standard Dimensions for Marine Stainless Steel Seamless Tubes
Based on ASTM A312, ISO 6594, and IACS international marine standards, this table compiles specifications for marine stainless steel seamless tubes suitable for the global market. It includes newly added internationally recognized Sch wall thickness grades and metric/international operating condition adaptation instructions, covering major shipbuilding and ship repair projects in Europe, America, Southeast Asia, and the Middle East. If you look for a seamless tube manufacturer, welcome to contact us directly.
Commonly Used International Outer Diameters (mm/inch) | International Sch Thickness Grades/Wall Thickness (mm) | International Standard Length (mm) | International Applicable Ship Scenarios |
6-12mm (1/4"-3/8") | Sch40: 0.8-1.5mm | 3000, 6000 | International ship instrumentation and control, hydraulic branch lines, small ventilation ducts |
16-32mm (1/2"-1.25") | Sch40/Sch80: 1.2-2.5mm | 6000, 9000 | Overseas vessel water supply and drainage, light fire fighting, and cabin ventilation systems |
38-57mm (1.5"-2") | Sch80: 2.0-3.5mm | 6000, 9000, 12000 | Cooling systems, main water supply and drainage, and fuel oil pipelines for international ocean-going vessels |
76-133mm (2.5"-5") | Sch80/Sch160: 3.0-4.5mm | 9000, 12000 | Main fire protection, high-pressure cooling water, and lubricating oil pipelines for large overseas vessels |
159-219mm (6"-8") | Sch160: 4.0-6.0mm | 12000, 15000 | Main water, oil, and power system piping for medium-sized international ocean-going vessels |
Main water, oil, and power system piping for medium-sized international ocean-going vessels | Sch160: 6.0-10.0mm | 12000, 18000 | Main media transmission pipelines for large global cargo ships and ocean-going vessels |
530-630mm (20"-24") | Custom-made thickened sch: 10.0-14.0mm | 15000, 18000 (International Customization) | Core pipelines for overseas ultra-large engineering vessels and ocean-going transport ships |
Original source: https://www.marinesteelpipe.com/a/ss-seamless-tube-size-chart.html
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Marine piping systems are the core components of ship propulsion, water supply and drainage, hydraulic, and fire protection systems. Compared to ordinary industrial pipes, marine-grade stainless steel seamless pipes have stringent requirements for corrosion resistance, pressure resistance, dimensional accuracy, and adaptability. Precise selection of dimensions directly determines the operational stability and service life of the ship's piping.
The selection of ss seamless tubes revolves around three core parameters: outer diameter, wall thickness, and length. These three parameters are mutually matched, determining the pipe's interface, pressure resistance, and installation compatibility, respectively. They are also core indicators for ship piping acceptance and design drawings.
1. Outer Diameter (OD): The Core Foundation for Pipeline Adaptation
International marine stainless steel seamless pipes adopt a dual standard of ISO metric series and ANSI inch series for outer diameter. This serves as the core basis for matching flanges, fittings, and valves worldwide and is also the universally accepted size in overseas shipbuilding markets such as Europe, America, Southeast Asia, and the Middle East.
The international shipbuilding industry strictly prohibits the use of non-standard outer diameter pipes, uniformly adhering to stringent dimensional tolerance standards. Compared to domestic conventional pipes, the precision requirements are higher, perfectly adapting to various imported ship equipment and eliminating installation misalignment and sealing leakage problems.
The standard marine pipe diameter range is 6mm-630mm, subdivided to adapt to different ship systems: 6-42mm small diameter pipes are mainly used for instrumentation and control, hydraulic circuits, and small water supply and drainage branches; 48-219mm medium diameter pipes are the main specifications, suitable for ship main water supply, drainage, fire protection, and cooling systems; 273-630mm large diameter pipes are mainly used for main water and oil pipelines of large cargo ships and ocean-going vessels.
In accordance with ASTM A312, ISO 6594, and IACS marine standards, the outer diameter tolerances for seamless marine pipes are standardized internationally: for pipes with an outer diameter ≤ 60.3 mm (2 inches and below), the allowable deviation is ±0.25 mm; for pipes with an outer diameter > 60.3 mm, the allowable deviation is ≤ ±0.5 mm.
This fully meets the acceptance requirements of major global classification societies such as LR, DNV, ABS, and CCS, and is suitable for the harsh service environment of ocean-going vessels with high salt spray and high humidity.
2. Wall Thickness (WT): A Key Guarantee for Pressure Resistance and Corrosion Protection
Wall thickness is a core pressure-bearing indicator for international ship piping selection. Overseas ship projects uniformly adopt the Sch standard wall thickness series (Sch40, Sch80, Sch160) instead of the domestic standard millimeter wall thickness designation, accurately matching international pipeline pressure ratings. Ships operate under conditions of long-term seawater corrosion, high-pressure transmission, and wave impact.
Therefore, wall thickness selection must strictly conform to international pressure standards. Insufficient selection can easily lead to pipeline damage and leakage, while excessive wall thickness will increase the ship's weight and increase energy consumption, failing to meet international lightweight ship design requirements.
Internationally, the standard wall thickness range for seamless stainless steel pipes used in marine applications is 0.5mm-20mm, corresponding to international standard Sch grades for precise adaptation to different operating conditions: the Sch40 thin-walled series is suitable for normal pressure ventilation and freshwater supply and drainage systems; the Sch80 medium-thick-walled series is suitable for conventional high-pressure cooling, fire fighting, and fuel delivery systems; the Sch160 thick-walled series is specifically designed for ocean-going vessel power systems, deep-sea high-pressure pipelines, and hydraulic core circuits, capable of withstanding high-intensity corrosion and high-pressure impacts.
The mainstream materials used are internationally recognized TP304 and TP316L stainless steel, conforming to ASTM A240 material specifications, ensuring excellent compatibility with overseas vessels.
Furthermore, the wall thickness of marine pipes is produced using a uniform standard, eliminating localized thickness deviations. Wall thickness tolerances strictly adhere to ship standards, ensuring consistent pressure resistance throughout the pipe and adaptability to complex marine operating conditions. The primary materials are 304 and 316L stainless steel, combined with standard wall thicknesses, effectively resisting corrosion from seawater salt spray and acid/alkali media.
3. Length: Installation and Construction Compatibility Standards
International market marine stainless steel seamless pipes are categorized into three lengths: international standard fixed length, variable length, and custom length. These are fully compatible with the standardized construction systems of European, American, and Southeast Asian ship cabins. Unlike domestically cut specifications, the length dimensions are uniformly aligned with global shipbuilding industry standards, meeting the construction requirements of neat pipeline layouts, minimal welding, and high sealing in overseas vessels.
Internationally common fixed lengths are 6000mm, 9000mm, and 12000mm (compatible with 20FT, 30FT, and 40FT ocean freight containers). These are the most commonly used specifications in global shipbuilding projects, perfectly matching international ocean freight container transport dimensions, reducing logistics costs, and minimizing on-site welding joints, while complying with international ship construction and acceptance standards. International variable lengths are uniformly no shorter than 2000mm, suitable for the installation of scattered branch pipelines on small vessels.
For customized layouts of large ocean-going freighters, overseas engineering vessels, and special-purpose ships, we support international non-standard length customization, with length tolerances controlled within ±10mm. Dimensional accuracy meets the unified requirements of IACS (International Classification Society), adapting to customized installation scenarios on various ships worldwide.
II. Commonly Used Standard Dimensions for Marine Stainless Steel Seamless Tubes
Based on ASTM A312, ISO 6594, and IACS international marine standards, this table compiles specifications for marine stainless steel seamless tubes suitable for the global market. It includes newly added internationally recognized Sch wall thickness grades and metric/international operating condition adaptation instructions, covering major shipbuilding and ship repair projects in Europe, America, Southeast Asia, and the Middle East. If you look for a seamless tube manufacturer, welcome to contact us directly.
Commonly Used International Outer Diameters (mm/inch) | International Sch Thickness Grades/Wall Thickness (mm) | International Standard Length (mm) | International Applicable Ship Scenarios |
6-12mm (1/4"-3/8") | Sch40: 0.8-1.5mm | 3000, 6000 | International ship instrumentation and control, hydraulic branch lines, small ventilation ducts |
16-32mm (1/2"-1.25") | Sch40/Sch80: 1.2-2.5mm | 6000, 9000 | Overseas vessel water supply and drainage, light fire fighting, and cabin ventilation systems |
38-57mm (1.5"-2") | Sch80: 2.0-3.5mm | 6000, 9000, 12000 | Cooling systems, main water supply and drainage, and fuel oil pipelines for international ocean-going vessels |
76-133mm (2.5"-5") | Sch80/Sch160: 3.0-4.5mm | 9000, 12000 | Main fire protection, high-pressure cooling water, and lubricating oil pipelines for large overseas vessels |
159-219mm (6"-8") | Sch160: 4.0-6.0mm | 12000, 15000 | Main water, oil, and power system piping for medium-sized international ocean-going vessels |
Main water, oil, and power system piping for medium-sized international ocean-going vessels | Sch160: 6.0-10.0mm | 12000, 18000 | Main media transmission pipelines for large global cargo ships and ocean-going vessels |
530-630mm (20"-24") | Custom-made thickened sch: 10.0-14.0mm | 15000, 18000 (International Customization) | Core pipelines for overseas ultra-large engineering vessels and ocean-going transport ships |