Stainless Steel Seamless Pipe

 

GNEE stainless steel adopts a standardized seamless steel pipe production process, from round steel billet inspection, 1200℃ high-temperature piercing, hot rolling, cold drawing finishing, solution heat treatment to pickling and passivation and final inspection. It strictly controls dimensional accuracy and surface quality, and ensures that the products meet the requirements of international standards such as ASTM A312 and A213 through PMI, UT and hydrostatic tests.

 

Standard	Product Type	Main Application
ASTM A312 / ASME SA312	Austenitic Stainless Steel Seamless Pipe	Chemical processing, pressure piping, general corrosion service
ASTM A213 / ASME SA213	Seamless Stainless Steel Tube	Heat exchanger, boiler, high-temperature service
ASTM A269	Precision Seamless Tube	Instrumentation, control systems, sanitary applications
ASTM A790 / ASME SA790	Duplex & Super Duplex Seamless Pipe	Offshore, marine, chloride environments
EN 10216-5	Stainless Steel Seamless Tube/Pipe	European industrial pressure applications
JIS G3459	Stainless Steel Pipe	Japanese industrial piping systems
ASME B36.19	Pipe Dimension Standard	Stainless steel pipe dimensions and schedules

 

 

Manufacturing Standard & Material Grades

Category	Specifications
Standard Specifications	ASTM A312, ASME SA312, ASTM A213, ASTM A269, DIN 17456, EN 10216-5
Austenitic Grades	304, 304L, 316, 316L, 321, 321H, 310S, 317L, 347, 347H
Super Austenitic	904L, S31254 (254SMO)
Duplex / Super Duplex	S31803 (2205), S32205, S32750 (2507), S32760

 

Dimensional Range (per ASME B36.19 / B36.10)

Item	Metric (mm)	Imperial (inch)
Size / Nominal Diameter	6 mm – 762 mm	NPS 1/8" to 30"
Wall Thickness (Schedule)	1.0 mm – 50 mm	SCH 5S, 10S, 40S, 80S, 160, XXS
Standard Length	5.8m, 6.0m, 11.8m, 12.0m	20ft, 40ft (or Random Lengths)

 

 Chemical Composition 

Grade	C (Max)	Mn (Max)	P (Max)	S (Max)	Si (Max)	Cr	Ni	Mo
TP304	0.08	2.00	0.045	0.030	1.00	18.0-20.0	8.0-11.0	-
TP304L	0.035	2.00	0.045	0.030	1.00	18.0-20.0	8.0-12.0	-
TP316	0.08	2.00	0.045	0.030	1.00	16.0-18.0	11.0-14.0	2.0-3.0
TP316L	0.035	2.00	0.045	0.030	1.00	16.0-18.0	10.0-14.0	2.0-3.0
TP321	0.08	2.00	0.045	0.030	1.00	17.0-19.0	9.0-12.0	Ti: 5x(C+N) min

 

Mechanical Properties

Grade	Tensile Strength (min)	Yield Strength (min)	Elongation (min)	Hardness (max)
304 / 316	515 MPa (75 ksi)	205 MPa (30 ksi)	35%	192 HBW / 90 HRB
304L / 316L	485 MPa (70 ksi)	170 MPa (25 ksi)	35%	192 HBW / 90 HRB
Duplex 2205	655 MPa (95 ksi)	450 MPa (65 ksi)	25%	293 HBW / 31 HRC

 

Dimensional Tolerances 

Nominal Pipe Size (NPS)	Over Tolerance (OD)	Under Tolerance (OD)	Wall Thickness (WT)
1/8" to 1-1/2"	+0.4 mm (1/64")	-0.8 mm (1/32")	-12.5%
>1-1/2" to 4"	+0.8 mm (1/32")	-0.8 mm (1/32")	-12.5%
>4" to 8"	+1.6 mm (1/16")	-0.8 mm (1/32")	-12.5%
>8" to 18"	+2.4 mm (3/32")	-0.8 mm (1/32")	-12.5%

 

Surface Condition & Finishing

Solution Annealing: All pipes are heat treated and quenched to restore corrosion resistance.

Pickling (AP): Acid treatment to remove scale and ensure passivated surface.

Polished: Outside Diameter (OD) and/or Inside Diameter (ID) polished to Grit 180, 240, 320, 400, 600.

Ends: Plain ends, Beveled ends (for welding), or Threaded ends.

 

Oil & Gas: Refineries, offshore platforms, and pipelines.

Chemical Processing: Transport of corrosive acids and chemicals.

Power Generation: Heat exchangers and high-pressure steam lines.

Food & Pharmaceutical: Clean-service transport lines (typically polished).

Water Treatment: Desalination plants and wastewater systems.

 

Test Method	Description
Hydrostatic Test	Each pipe tested at pressure to ensure no leaks (per ASTM A999).
Eddy Current / UT	100% Non-destructive electric test for internal/external flaws.
Flattening Test	Sample flattened to specified distance without cracking.
Flaring Test	Sample flared to a specified diameter without cracks (for tubes/small pipes).
PMI Test	Positive Material Identification to verify chemical elements.
Visual/Dimensional	Verification of surface quality, OD, WT, and Straightness.

GNEE uses international export standards to package seamless stainless steel tubing, ensuring safe handling, moisture protection, and surface preservation during long-haul sea transport. Depending on tubing size, surface finish, and customer requirements, products are packaged using plastic end caps, waterproof packaging, woven bags, steel straps, wooden pallets, or sea-ready wooden crates. Each bundle of tubing is clearly marked with the material grade, specifications, furnace number, quantity, and order information for easy identification and traceability. For precision tubing, polished tubing, and high-value stainless steel materials such as 316L, 904L, and duplex 2205/2507, additional protective measures are available, including PE film, scratch-resistant materials, and individual packaging, to prevent surface damage, contamination, and deformation during loading, unloading, and transportation.

 

 

Q1: What is stainless steel seamless pipe?

Stainless steel seamless pipe is manufactured from solid steel billets through hot piercing, extrusion, cold drawing, and heat treatment processes without welding seams. It provides uniform structure, high pressure resistance, and excellent corrosion performance. GNEE supplies seamless pipes in 304/304L, 316/316L, 321, 310S, 904L, Duplex 2205 and Super Duplex 2507 grades for chemical, oil & gas, power generation, and industrial piping systems.

 

Q2: What is ASTM A312 stainless steel pipe?

ASTM A312 stainless steel pipe is an international specification covering seamless, welded, and heavily cold-worked austenitic stainless steel pipes for high-temperature and corrosive service. It is widely applied to TP304, TP304L, TP316, TP316L, TP321 and TP347 grades. GNEE provides ASTM A312 seamless pipes with PMI verification, hydrostatic testing, dimensional inspection, and EN 10204 3.1 material certificates.

 

Q3: What is the difference between seamless and welded pipe?

The main difference is the manufacturing process. Seamless pipes are produced from solid billets without welding joints, offering better pressure resistance and structural uniformity. Welded pipes are manufactured by rolling steel plates or coils and welding the seam, which provides cost advantages for large diameter applications. For high-pressure, high-temperature, or critical chemical services, seamless pipe is usually preferred.

 

Q4: Is 316L stainless steel pipe better than 304?

316L stainless steel pipe is generally better than 304 in environments containing chlorides, seawater, chemicals, or aggressive media because it contains 2–3% molybdenum (Mo), which improves pitting and crevice corrosion resistance. However, 304 remains a cost-effective choice for general applications such as water systems, food equipment, and indoor piping.

Grade	Main Advantage	Recommended Application
304/304L	Economical corrosion resistance	Food, water, general industry
316/316L	Higher chloride resistance	Marine, chemical, pharmaceutical

 

Q5: What size stainless steel seamless pipe can you supply?

GNEE supplies stainless steel seamless pipes in a wide range of dimensions, including outside diameter from 6 mm to 630 mm+, wall thickness from 0.5 mm to 50 mm, and standard lengths of 5.8 m, 6 m, and 12 m. Customized sizes, schedules, and special dimensions are available according to project requirements.

Parameter	Supply Range
OD	6 mm – 630 mm+
Wall Thickness	0.5 mm – 50 mm
Length	5.8 m / 6 m / 12 m
Schedule	SCH 5S – SCH XXS

 

Q6: What is SCH 40 stainless steel pipe?

SCH 40 (Schedule 40) stainless steel pipe refers to a standard wall thickness classification defined by ASME B36.19. It does not represent the pipe diameter but indicates the wall thickness suitable for specific pressure applications.

Example:

Size	OD	SCH 40 Wall Thickness
1"	33.4 mm	3.38 mm
2"	60.3 mm	3.91 mm
4"	114.3 mm	6.02 mm
6"	168.3 mm	7.11 mm

 

Q7: Can stainless steel seamless pipe be customized?

Yes. GNEE provides customized stainless steel seamless pipes according to customer requirements, including special diameters, wall thicknesses, lengths, surface finishes, material grades, and inspection standards.

Customization options include:

ASTM / ASME / EN / JIS standards

304, 316L, Duplex, Nickel alloy grades

Pickled, polished, BA surfaces

Cut-to-length service

Third-party inspection

 

Q8: What certificates are provided?

For international projects, GNEE provides complete quality documentation to ensure material traceability and compliance.

Available certificates include:

Certificate	Purpose
EN 10204 3.1 MTC	Chemical & mechanical traceability
PMI Report	Alloy grade verification
Hydrostatic Test Report	Pressure performance confirmation
Inspection Report	Quality confirmation
Certificate of Origin	Export documentation

 

Q9: How long is the delivery time?

The delivery time depends on material grade, dimensions, stock availability, and order quantity. For standard stainless steel seamless pipe sizes, GNEE typically offers delivery within 7–15 days. Customized production, special alloys, or large engineering projects require additional manufacturing time according to production schedules.

Order Type	Typical Delivery Time
Standard Stock Sizes	7–10 days
Customized Sizes	15–30 days
Large Project Orders	According to production plan

We're professional stainless steel seamless pipe manufacturers and suppliers in China, specialized in providing high quality customized service. Be free to wholesale stainless steel seamless pipe in stock here and get free sample from our factory. For price consultation, contact us.

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