Frequently Asked Questions

The key difference is molybdenum content. 316/316L contains 2-3% molybdenum, which significantly improves pitting corrosion resistance in chloride-containing environments. 304/304L has no intentional molybdenum addition. For chemical processing, offshore, and coastal applications where chlorides are present, 316L is the minimum recommended grade. 304L is suitable for general industrial, food processing, and architectural applications with low chloride exposure.

NACE MR0175/ISO 15156 specifies material requirements for equipment used in H₂S-containing (sour) environments in oil and gas production. For austenitic stainless steel pipe, NACE compliance means: maximum hardness HRC 22, solution-annealed condition, carbon ≤ 0.03% for L-grades, and no cold work that could increase hardness. TOKO TECH verifies NACE compliance with hardness testing and PMI per tube.

Seamless pipe is required for: high-pressure service (above Class 600), critical safety applications, small diameters below 2 inch where weld quality inspection is challenging, and applications requiring superior surface finish (Ra ≤ 0.8 μm). Welded pipe is suitable for: large-diameter applications (above 12 inch), low to medium-pressure service, cost-sensitive projects — offering 30-50% savings over seamless. Both must meet ASTM A312 requirements.

PREN (Pitting Resistance Equivalent Number) = %Cr + 3.3×%Mo + 16×%N. It quantifies a stainless steel's resistance to pitting corrosion in chloride environments. 304 (PREN ~19) — low chloride only. 316L (PREN ~26) — moderate chloride. 2205 Duplex (PREN ~35) — seawater service. Super Duplex 2507 (PREN ~42) — hot seawater. 904L (PREN ~43) — mixed acids. Hastelloy C-276 (PREN ~65+) — universal corrosion resistance. Select PREN +5 above your environment's minimum requirement for safety margin.

ASTM A312 governs seamless and welded austenitic stainless steel pipe for general process service. ASTM A790 covers duplex stainless steel pipe. ASTM A358 covers electric-fusion-welded pipe for high-temperature service. ASTM A269 covers seamless and welded austenitic tubing for general service. ASTM A270 covers sanitary tubing. For specific industries: ASME B31.3 (process piping), ASME BPVC (boiler/pressure vessel), NACE MR0175 (sour service), API 5LC (line pipe for corrosive service).

TOKO TECH performs 100% hydrostatic testing (1.5× design pressure), eddy current or ultrasonic testing per ASTM E213/E426, and positive material identification (PMI) on every pipe. Additional tests include: intergranular corrosion test (ASTM A262 Practice E for 304L/316L), ferrite content measurement for duplex grades (ASTM A923 Method C), hardness testing for NACE compliance, and dimensional inspection per ASTM A999/A1016.

Standard sizes in 304L/316L from inventory typically ship within 7-14 days. Non-stock sizes and alloy grades (duplex, nickel alloy) typically 4-8 weeks depending on specification. For urgent project requirements, we offer expedited production with partial shipments to support construction schedules. Contact our sales team with your specifications for a confirmed delivery schedule.

304/304L: -196°C to 800°C (continuous). 316/316L: -196°C to 800°C, with better creep resistance above 500°C. 321/321H: up to 900°C (titanium-stabilized). 310S: up to 1,100°C (high chromium). Alloy 800H: up to 1,100°C in oxidizing atmospheres. Inconel 625: up to 980°C. For sub-zero/cryogenic service: 304L and 316L maintain excellent toughness down to -196°C (LNG temperature).

Yes. We regularly work with SGS, TÜV, Bureau Veritas, Lloyd's Register, and DNV for third-party inspection. The inspector typically witnesses hydrostatic testing, reviews MTRs, verifies PMI results, and performs dimensional checks at our facility. We can also accommodate customer-appointed inspectors. EN 10204 3.2 certification with third-party validation is available on request.

Yes. Every shipment includes EN 10204 Type 3.1 Material Test Reports showing: chemical composition (heat analysis), mechanical properties (tensile, yield, elongation), hydrostatic test results, NDE results (eddy current/ultrasonic), and PMI verification. Reports are traceable to heat numbers marked on each pipe. Electronic MTRs are available for digital documentation systems.

For stock sizes and common grades (304L/316L), there is no strict minimum order quantity — we supply single pieces for urgent requirements. For production-order non-stock items, minimum quantities are typically one production lot per size/grade combination. Contact us with your requirements and we will provide the most cost-effective ordering option.

Every pipe is laser-marked with heat number, material grade, size, and standard at the manufacturing stage. The heat number traces back to the original mill heat with the chemical composition and mechanical test results recorded in the MTR. Our electronic MTR system maintains full digital traceability from mill certificate to individual pipe, supporting project documentation requirements for oil & gas, nuclear, and aerospace applications.

We supply Inconel 625 (N06625), Incoloy 825 (N08825), Hastelloy C-276 (N10276), Hastelloy C-22 (N06022), Monel 400 (N04400), Alloy 600 (N06600), Alloy 601 (N06601), Alloy 800H/800HT (N08810/N08811), and Alloy 718 (N07718). Available as seamless pipe, tube, bar, and coil. Each grade is available with full MTR and optional third-party inspection to SGS/TÜV standards.

Choose duplex 2205 when: (1) chloride concentration exceeds 1,000 ppm and temperature is above 25°C; (2) design pressure requires wall thickness > SCH 80 in 316L — 2205's double yield strength allows thinner walls; (3) weight reduction is critical (offshore topsides); (4) chloride stress corrosion cracking is a known risk. The 30-50% material cost premium for 2205 is typically recovered through wall thickness savings and longer service life.

Standard finish: pickled and passivated (matte gray, Ra 3.2-6.3 μm). Bright annealed: Ra ≤ 0.8 μm for semiconductor, pharmaceutical, and food-grade applications. Mechanical polished: Ra 0.4-0.8 μm for cosmetic and sanitary requirements. Electro-polished: Ra ≤ 0.4 μm for ultra-high-purity gas and semiconductor applications. Bore-polished ID available for specific heat exchanger and instrumentation tubing requirements.

Yes. Standard pipe ends: plain cut, bevelled (30° bevel + 1.6mm root face per ASME B16.25), or threaded. Bevelled ends are standard for all pipes above 2 inch NB in wall thickness ≥ SCH 10S. We can also supply with plastic end caps to protect the bevel during transport. Custom end preparations (J-bevel, compound bevel) are available on request for specific welding procedure requirements.

ASTM A312 covers seamless and straight-seam welded austenitic stainless steel pipe for general corrosive and high-temperature service — the most common specification. ASTM A358 covers electric-fusion-welded pipe for high-temperature and general corrosive service, typically for larger diameters (above 8 inch) where seamless is not available. Both have similar chemistry and mechanical requirements, but A358 requires 100% radiographic examination of the weld seam.

Pipes are packed in seaworthy wooden crates or steel frames depending on size and weight. Small-diameter pipe (below 2 inch) is bundled with steel straps and end-protected. Large-diameter pipe is individually wrapped with end caps. All crates are fumigated per ISPM 15 for international shipping. We use container-optimized loading plans to maximize freight efficiency — typically 22-25 tons per 20ft container.

Rough cost multipliers (304L = 1.0 base): 316L ≈ 1.3-1.5× (molybdenum addition), duplex 2205 ≈ 2.0-2.5× (higher alloy content + manufacturing complexity), super duplex 2507 ≈ 3.0-3.5×, nickel alloys (625/C-276) ≈ 6-10×. However, duplex's double yield strength allows thinner walls — actual project cost difference vs 316L is often only 20-30% after accounting for wall thickness reduction.

We regularly ship to 50+ countries across Europe (UK, Germany, Italy, Netherlands, Spain), Middle East (UAE, Saudi Arabia, Qatar, Oman, Kuwait), Southeast Asia (Singapore, Malaysia, Indonesia, Thailand, Vietnam), Americas (USA, Canada, Brazil, Mexico, Chile), Africa (Nigeria, South Africa, Egypt, Algeria), and CIS (Russia, Kazakhstan, Uzbekistan). We handle all export documentation including certificates of origin, EUR.1, and legalized commercial invoices.

Yes. We cut pipe to your specified length (typically 6m standard, custom lengths available). Random lengths (5-7m) for container optimization, or fixed lengths (exact 6m or 12m) for project requirements. Cutting tolerance: ±3mm for standard, ±1mm for precision cutting. End finishing: plain, bevelled, or threaded. Cut ends are de-burred and protected. Minimum cutting charge may apply for small-quantity orders.

Standard payment terms: 30% T/T advance with order, 70% before shipment (or against copy documents). For established customers: net 30 days from B/L date available after credit review. Letter of Credit (L/C) at sight accepted from major international banks (subject to confirmation terms). We also accept D/P (documents against payment) for certain markets. All prices quoted FOB Shanghai or CIF destination port per Incoterms 2020.

We maintain buffer stock of common sizes in 304L, 316L, and duplex grades specifically for urgent project requirements. For stock items, we can ship within 24-48 hours of order confirmation. For production items, we offer expedited manufacturing schedules (subject to capacity) for a modest priority fee. Air freight is available for critical small-bore tube and instrumentation orders where lead time is the overriding priority.

For an accurate quotation, please provide: (1) Material grade (e.g., 316L, UNS S31603); (2) Pipe size — OD × wall thickness (or NPS + schedule); (3) Quantity — meters or pieces; (4) Specification/standard (ASTM A312, A790, B444, etc.); (5) End finish requirement; (6) Any special testing requirements (NACE, PMI, IGC); (7) Delivery port (for CIF pricing). Typical quotation turnaround: within 24 hours.