TP304 TP316 Stainless Steel Seamless Pipe For High Pressure Corrosion Resistant Service
ASTM A312 seamless stainless steel pipe is manufactured in accordance with ASTM A312 / ASME SA312, specifically designed for high-pressure and corrosion-resistant applications. The seamless construction eliminates the weld line, providing uniform strength, superior reliability, and excellent performance in demanding environments.
This product is available in TP304 and TP316 grades, offering a balance of cost-effectiveness and enhanced corrosion resistance. It is widely used in oil & gas transmission, chemical processing, power generation, marine engineering, and high-temperature industrial systems.
Key Specifications
| Parameter | Range / Details |
|---|---|
| Standard | ASTM A312 / ASME SA312 |
| Manufacturing Type | Seamless (SMLS) – no weld seam |
| Material Grades | TP304, TP304L, TP316, TP316L |
| Outer Diameter (OD) | 10.3mm – 609.6mm (1/8″ – 24″) |
| Wall Thickness (WT) | 0.2mm – 60mm (SCH 5S, 10S, 40S, 80S, 160, XXS) |
| Length | 5 – 12 meters, or custom cut |
| End Finish | Plain / Beveled / Threaded |
| Surface Condition | Annealed & pickled / Bright annealed / Passivated / Polished |
| Testing | Hydrostatic test, PMI, UT, Eddy current, Third-party (SGS/BV) |
| Certification | ISO 9001, MTC EN 10204 3.1, RoHS |
| Delivery Condition | Solution annealed, cold drawn or hot rolled |
Chemical Composition (wt%, max unless noted)
| Grade | C | Mn | P | S | Si | 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 | 8.0–13.0 | — |
| TP316 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 16.0–18.0 | 11.0–14.0 | 2.00–3.00 |
| TP316L | 0.035 | 2.00 | 0.045 | 0.030 | 1.00 | 16.0–18.0 | 10.0–14.0 | 2.00–3.00 |
Key Advantage of TP316/316L: The addition of molybdenum (Mo) provides superior resistance to chloride-induced pitting, crevice corrosion, and stress corrosion cracking, making it ideal for marine, chemical, and high-chloride environments.
Mechanical Properties (Solution Annealed Condition)
| Grade | Tensile Strength (MPa) min | Yield Strength (MPa) min | Elongation % min |
|---|---|---|---|
| TP304 | 515 | 205 | 35 |
| TP304L | 485 | 170 | 35 |
| TP316 | 515 | 205 | 35 |
| TP316L | 485 | 170 | 35 |
Heat Treatment: Solution annealed at 1900°F (1040°C) minimum, followed by rapid cooling.
Service Temperature Range: Cryogenic to 870°C (depending on grade). TP304/316 is suitable for continuous service up to 800°C in oxidizing atmospheres.
Dimensional Tolerances (ASTM A312 – Seamless Pipe)
Outside Diameter (OD) Tolerance
| NPS (inch) | Positive Tolerance (in / mm) | Negative Tolerance (in / mm) |
|---|---|---|
| 1/8 – 1½ | +0.015" / 0.4mm | -0.031" / 0.8mm |
| >1½ – 4 | +0.031" / 0.8mm | -0.031" / 0.8mm |
| >4 – 8 | +0.062" / 1.6mm | -0.031" / 0.8mm |
| >8 – 18 | +0.093" / 2.4mm | -0.031" / 0.8mm |
| >18 – 26 | +0.125" / 3.2mm | -0.031" / 0.8mm |
Wall Thickness Tolerance (Seamless Pipe)
| NPS | Condition | Positive Tolerance | Negative Tolerance |
|---|---|---|---|
| 1/8 – 2½ | All | +20.0% | -12.5% |
| 3 – 18 | t/D ≤ 5% | +22.5% | -12.5% |
| 3 – 18 | t/D > 5% | +15.0% | -12.5% |
| ≥20 | t/D ≤ 5% | +22.5% | -12.5% |
| ≥20 | t/D > 5% | +15.0% | -12.5% |
t/D = ratio of wall thickness to outside diameter
Why Choose Seamless Construction?
| Feature | Benefit |
|---|---|
| No weld seam | Eliminates weak points; uniform mechanical properties |
| Higher pressure rating | Suitable for high-pressure hydraulic and steam systems |
| Better fatigue resistance | Ideal for cyclic pressure and vibration applications |
| Superior corrosion resistance | No weld-affected zone susceptible to preferential attack |
| Wider temperature range | Performs reliably from cryogenic to high temperatures |
Typical Applications – High-Pressure & Corrosive Service
| Industry | Specific Uses | Recommended Grade |
|---|---|---|
| Oil & Gas | Downhole tubing, flow lines, offshore platforms | TP316 / 316L |
| Chemical Processing | Reactors, heat exchangers, transfer lines for acids/alkalis | TP316L |
| Power Generation | Boiler tubes, superheater lines, high-pressure steam | TP304H / TP316H |
| Marine Engineering | Seawater cooling lines, shipbuilding, and desalination plants | TP316 / 316L |
| Pharmaceutical & Biotech | High-purity systems, sanitary piping | TP304L / 316L (electropolished) |
| Hydrogen & Alternative Energy | High-pressure hydrogen transport, fuel cell systems | TP316 / 316L |
| Hydraulic & Instrumentation | Precision seamless tubing for control systems | TP304 / 316 |
Available Surface Finishes for Seamless Pipe
| Finish | Description | Typical Application |
|---|---|---|
| Mill Finish (Annealed & Pickled) | Oxide scale removed by acid pickling | General industrial piping |
| Bright Annealed (BA) | Bright, reflective surface; no scaling | Clean systems, food/dairy |
| Polished (No.4 / 180-600 grit) | Uniform brushed finish | Architectural, sanitary |
| Mirror Polish (#8) | Highly reflective | Decorative, ultra-clean |
| Electropolished | Smooth, passive surface | Pharmaceutical, semiconductor |
Quality Control & Testing – Seamless Pipe
All seamless pipes are subject to rigorous quality assurance:
-
PMI (Positive Material Identification) – 100% material verification
-
Hydrostatic Test – Per ASTM A312 requirements
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Ultrasonic Testing (UT) – Optional, for critical applications
-
Eddy Current Test (ET) – For surface defect detection
-
Mechanical Testing – Tensile, hardness, flattening, flaring
-
Third-party Inspection – SGS, BV, TUV available upon request
Certifications Provided:
-
Mill Test Certificate (EN 10204 3.1)
-
ISO 9001:2015 compliance
-
NACE MR0175 / MR0103 (for sour service, upon request)
Packaging & Logistics
-
Standard Export Packaging: Wooden cases or seaworthy bundles
-
End Protection: Plastic caps (plain ends) or thread protectors (threaded ends)
-
Labeling: Grade, size, heat number, and standard are clearly marked
-
Shipping Terms: FOB, CFR, CIF, or as agreed
-
Lead Time: Typically 15–30 days based on quantity and specification
Frequently Asked Questions (FAQ) – Seamless Pipe
1. What is the difference between ASTM A312 seamless and welded pipe?
Seamless pipe is manufactured without a weld seam, offering uniform strength, higher pressure ratings, and better fatigue resistance. Welded pipe is generally more cost-effective for lower-pressure, large-diameter applications.
2. Why choose TP316 over TP304 for high-pressure service?
TP316 contains molybdenum (2–3%), which provides superior resistance to chloride pitting, crevice corrosion, and stress corrosion cracking – critical for marine, chemical, and high-chloride environments.
3. What is the maximum pressure rating for ASTM A312 seamless pipe?
Pressure rating depends on grade, wall thickness, and temperature. For example, a 2" SCH 40S TP316 seamless pipe at ambient temperature has a working pressure of approximately 1700 psi. Detailed calculations can be provided per ASME B31.3.
4. Can seamless pipe be used for cryogenic service?
Yes. Austenitic stainless steels like TP304 and TP316 retain excellent toughness at cryogenic temperatures (down to -196°C / -320°F), making them suitable for LNG and liquid nitrogen applications.
5. Is third-party inspection mandatory?
Not mandatory but highly recommended for critical projects. We can arrange SGS, BV, or TUV inspection at the buyer's cost.
6. What documents are provided with each shipment?
Standard documents include: Mill Test Certificate (EN 10204 3.1), Packing List, Commercial Invoice, and Certificate of Origin (if required). Heat treatment records and NDT reports are available upon request.
7. Do you offer custom lengths and sizes?
Yes. Custom OD, wall thickness, and cut lengths can be accommodated. Please provide your detailed requirements for a quotation.
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