Stainless steel pipe is a hollow cylindrical metal product made of corrosion‑resistant alloy steel, widely used in industrial piping, fluid transport and structural applications. With excellent corrosion resistance, high strength and long service life, it meets strict requirements across chemical, food, medical, petroleum and construction fields. Understanding its classification, sizes, grades, weight standards and industry specifications helps engineers and buyers select the right pipe for safety, compatibility and cost‑effective projects.
Stainless steel pipe is a hollow cylindrical steel product extensively applied in industrial piping systems and mechanical components across petroleum, chemical, medical, food, light industry and instrumentation industries. Featuring low weight while retaining excellent bending and torsional strength, it is also widely utilized for manufacturing mechanical parts and constructing engineering structures.
Stainless steel pipes are mainly produced in two types: seamless and welded. Seamless pipes include hot-rolled, cold-rolled, cold-drawn, and extruded types, with cold drawing and cold rolling used as secondary processing methods. Welded pipes are divided into straight seam welded and spiral welded types.
Stainless steel pipes are classified by cross-sectional shape into round and special-shaped types. Special-shaped pipes include rectangular, elliptical, hexagonal, and other non-round forms. They are widely used in structural parts and machinery. Compared with round pipes, special-shaped pipes offer greater bending and torsional strength, helping reduce structural weight and save material.
Stainless steel pipes are classified by longitudinal cross-section into uniform and variable types. Variable cross-sectional pipes include tapered, stepped, and periodic shapes.
Application classification: Based on their application, they can be categorized into oil well pipes (casing pipe, tubing, and drill pipe, etc.), line pipes, boiler pipes, mechanical structure pipes, hydraulic prop pipes, gas cylinder pipes, geological pipes, chemical pipes (high-pressure fertilizer pipes, oil cracking pipes), and ship pipes.
Octal supply range for the stainless steel pipe and tube:
Standards: ASTM A321, ASTM A213, ASTM A269, ASME SB677
Duplex stainless steel pipe standards: ASTM A789/ ASME SA 789. ASTM A790/ ASME SA 790
Material: AISI 304, 304L, 316, 316L
Outer Diameter: 5.8 – 508mm,
Wall Thickness: 0.3 – 50mm
Stainless steel pipe dimensions and weights adhere to international standards such as ASTM A312 and JIS G3459. Core parameters include outer diameter, wall thickness, and theoretical weight. Specifications vary for different cross-sectional shapes (round, square, and rectangular). The following table lists commonly used specifications for industrial and residential applications. Weights are calculated based on 304 stainless steel (density 7.93 g/cm³).
|
Nominal diameter (inches) |
Outside diameter (OD) |
Wall thickness (WT) |
Inner diameter (ID) |
Theoretical weight (kg/m) |
|
1/4" |
13.72mm |
1.65mm |
10.42mm |
0.53 |
|
1/2" |
21.34mm |
2.77mm |
15.80mm |
1.28 |
|
3/4" |
26.67mm |
2.87mm |
20.93mm |
1.70 |
|
1" |
33.40mm |
3.38mm |
26.64mm |
2.53 |
|
1 1/2" |
48.26mm |
3.68mm |
40.90mm |
4.10 |
|
2" |
60.33mm |
3.91mm |
52.51mm |
5.51 |
|
3" |
88.90mm |
5.49mm |
77.92mm |
11.44 |
|
4" |
114.30mm |
6.02mm |
102.26mm |
16.10 |
|
Cross-sectional dimensions (mm x mm) |
Wall thickness (mm) |
Theoretical weight (kg/m) |
Implementation standards |
Applicable Scenarios |
|
15×15 |
1.0 |
0.45 |
ASTM A554 |
Decorative bracket |
|
25×25 |
1.5 |
1.13 |
ASTM A554 |
Furniture structure |
|
30×30 |
2.0 |
1.81 |
ASTM A554 |
Guardrail frame |
|
50×50 |
2.0 |
3.08 |
JIS G3446 |
Building keel |
|
80×80 |
3.0 |
7.30 |
JIS G3446 |
Mechanical support |
|
100×100 |
4.0 |
12.00 |
JIS G3446 |
Large steel structures |
Round tube: W = π × (OD - WT) × WT × 7.93 × 10⁻³ (W is weight, OD is outer diameter, WT is wall thickness);
Square/rectangular tube: W = (perimeter - 4 × WT) × WT × 7.93 × 10⁻³ (perimeter is the outer circumference of the cross section).
Meaning of pipe number: Sch 40s represents thin-wall/regular-wall thickness grades. The larger the number, the thicker the wall thickness, which is suitable for high-pressure scenarios.
Length specifications: Regular length of welded pipe is 6m, seamless pipe is 5-7m, and can be customized.
Note: The data in the table are theoretical values. The actual weight may have a deviation of ±3% due to production tolerance. The selection should be based on the pressure level and medium characteristics.
Stainless steel pipe dimensions and weight calculations follow unified international industrial standards to ensure global compatibility and interchangeability. The most widely recognized specifications include:
ASME B36.19: Standard specification for stainless steel pipe dimensions, covering nominal sizes, outer diameter tolerances and schedule wall thicknesses
ASTM A312 / A240: Core material standards for stainless steel seamless and welded pipes
ANSI/ASME B36.10M: General dimensional standard for seamless and welded steel pipes
These standards unify key parameters including nominal pipe size (NPS), outer diameter (OD), wall thickness (WT), schedule grade and theoretical weight, supporting standardized installation and engineering design worldwide.
Thin-wall pipes (SCH 5S / SCH 10S): Suitable for low-pressure fluid transmission, food processing pipelines, medical equipment piping and municipal water supply systems.
Medium-wall pipes (SCH 40S): Widely used in general chemical pipelines, heat exchange systems and conventional industrial process piping.
Thick-wall pipes (SCH 80S / SCH 160S): Applied in high-pressure, high-temperature and corrosive working conditions such as petrochemical refining, energy engineering and pressure vessel supporting pipelines.
Q1: What are the main types of stainless steel pipe?
A1: Mainly seamless and welded pipes; also available as round tube and square tube for different uses.
Q2: What are common stainless steel grades for pipes?
A2: 304, 304L, 316 and 316L are the most widely used for corrosion resistance and general industrial service.
Q3: What is the difference between pipe and tube?
A3: Pipe follows NPS and schedule standards for pressure piping; tube uses exact OD/WT sizes for precision and structural applications.
Q4: What does ASME B36.19 specify?
A4: It defines standard dimensions, schedules and weight charts for stainless steel pipes, ensuring global compatibility.
Permanent Steel Manufacturing Co.,Ltd (PMC) is a professional and experienced supplier of seamless steel pipes with rich industry experience, strict quality control and complete international certifications. We provide high-quality products and professional services for global customers. For any inquiries or cooperation, please feel free to contact us.
