Sihe Steel
Sihe Steel
Discover our primary range of precision-engineered, corrosion-resistant coiled tubes, seamless pipes, and custom connectives sourced globally for subsea and deepwater deployments.
Understanding the structural necessity of Columbium (Niobium) stabilization in high-temperature, high-pressure environments.
ASTM A312 TP347 (UNS S34700) is a stabilized austenitic stainless steel alloy featuring addition of Columbium (Niobium) and Tantalum. This unique chemical composition is specifically engineered to mitigate the risk of intergranular corrosion (IGC) within the chromium carbide precipitation sensitization temperature range—typically between 800°F (427°C) and 1500°F (816°C).
Because Columbium has a stronger chemical affinity for carbon than chromium does, it preferentially reacts with carbon to form stable columbium carbides. This prevents chromium depletion in regions immediately adjacent to the grain boundaries, preserving the overall passive layer of the pipe and preventing localized intergranular attacks.
For chemical and energy engineering applications, the mechanical integrity of ASTM A312 347 under intense operating pressures is critical. Below are the verified metrics according to the standard specification:
| Mechanical Properties | Value Metric (Imperial/SI) |
|---|---|
| Tensile Strength, min | 75 ksi (515 MPa) |
| Yield Strength (0.2% Offset), min | 30 ksi (205 MPa) |
| Elongation in 2 in. or 50mm, min | 35% (Longitudinal) |
| Brinell Hardness, max | 219 HBW |
Note: Elevated carbon levels in TP347H optimize the material's long-term creep limits and rupture strength at operating temperatures exceeding 1000°F (538°C).
A premier Chinese manufacturing base with specialized online bright annealing and processing lines supplying global projects.
Liaocheng Sihe Stainless Steel Material LTD is a leading expert based in China in the advanced field of stainless steel coiled tubing, stainless steel polishing tubes, and seamless coiled piping networks. Operating under strict adherence to global standards—including GB, ASTM, ASME, JIS, and EN—the enterprise maintains six fully automated, high-precision production lines to guarantee consistent product delivery.
With over a decade of processing experience and specialized production setups, the factory has deployed the world’s leading bright hydrogen annealing systems. This setup permits continuous, online solution annealing at temperatures exceeding 1040°C, removing mechanical stresses without compromising surface finish or dimensions.
Sihe’s comprehensive range of materials covers standard austenitic grades as well as high-performance duplexes, super duplexes, and nickel-base superalloys for ultra-corrosive service conditions.
Production Lines
Max Continuous Length
Global Export Rate
Countries Served
Liaocheng Sihe offers extensive sizing flexibility for seamless coiled tubing designed to eliminate structural leak paths in complex hydraulic loops and subsea umbilical bundles:
Outer Diameters range from 0.125 inch (3.175 mm) to 1.0 inch (25.4 mm). Wall thickness capacities span up to 0.165 inch (3.0 mm) depending on grade limits.
Continuous spool lengths up to 32,800 feet (10,000 meters) are available. This reduces the need for orbital welds in subsea applications, improving line reliability.
304/304L, 316L, 321, 317L, 309S, 310S, INCOLOY 800, Duplex 2205, Super Duplex 2507, Incoloy 825, and Inconel 625 series.
Deploying high-performance stabilized alloys in harsh environments where corrosion control and thermal limits are paramount.
We provide full-spectrum engineering customization to ensure our stainless steel tubing integrates seamlessly into your plant systems:
As offshore exploration transitions into deepwater sectors, subsea pipelines are subjected to high pressures and corrosive fluids. Using stabilized corrosion-resistant materials for coiled umbilical tubing helps maintain the safety and reliability of long-distance hydraulic transmission loops.
Providing flexible configurations, precise dimensional tolerances, and high structural reliability across our entire specialty product line.
Duplex 2205 containing austenitic and ferritic structures, optimized for corrosion resistance and strength.
1/2" OD stainless steel coiled tubing refers to a continuous coil used in umbilical and instrument lines.
Manufactured for high-temperature service environments like furnace tubes and heat-treating systems.
Rigorous mechanical, structural, and pressure testing frameworks to secure global operating approvals.
Liaocheng Sihe conducts extensive in-house and third-party inspection processes to verify the mechanical integrity of every production run. Testing protocols conform strictly to ASTM A312, ASTM A269, and European EN standards, ensuring reliable performance in safety-critical projects.
Our quality assurance pipeline includes:
We implement specialized export packing, including heavy-duty wooden spools, reinforced steel frames, and airtight polymer wrapping. For temperature-sensitive materials or corrosive marine transport, specialized hazard wrapping is applied to protect critical surfaces from salt spray and physical damage.
Addressing future requirements for high-temperature structural systems and green energy transition networks.
As the hydrogen economy expands, pipelines must resist hydrogen embrittlement. Micro-stabilized TP347 and nickel-alloy coiled lines are engineered to mitigate this mechanism under high-pressure gas conditions.
Next-generation thermal reactors require materials that withstand elevated temperatures. TP347H, with its controlled carbon range, provides the high creep resistance required for high-efficiency power plant boilers.
Offshore exploration is pushing into deeper waters with higher concentrations of H2S and chlorides. High-alloy coiled tubing, including Duplex 2205 and Incoloy 825, helps prevent stress corrosion cracking (SCC) in marine environments.
A reference guide to commercial sourcing, material surcharges, and order variables for procurement managers.
The unit price of ASTM A312 347 / 347H pipelines depends on several commercial and chemical variables. Stabilizing elements like Columbium (Niobium) and Tantalum carry raw material surcharges that cause fluctuations in base pricing. Procurement managers should review the following factors:
Sihe Steel updates pricing structures regularly in response to raw material markets. For project estimates, please supply our technical sales team with the following details:
Addressing technical, logistics, and quality control inquiries for international procurement.
Both are stabilized austenitic alloys, but TP321 is stabilized with titanium, whereas TP347 is stabilized with columbium (niobium) and tantalum. TP347 exhibits higher thermal resistance and creep strength than TP321 in temperatures exceeding 1000°F (538°C). Additionally, columbium carbides are more stable and less prone to loss during welding compared to titanium carbides.
Our pricing fluctuates based on raw material costs and current market conditions. Please contact us with your specifications, and we will send an updated price sheet based on your project requirements.
Yes, all international shipments require an ongoing MOQ. If you are a distributor looking for smaller initial quantities, please contact our team to discuss available stock options.
Yes, we supply most required documentation, including Certificates of Analysis/Conformance, Mill Test Reports (MTR) to EN 10204 3.1, export compliance documents, and cargo insurance certifications.
For standard samples, the lead time is approximately 7 days. For mass production, the lead time ranges from 20 to 30 days after receipt of the deposit. Lead times are calculated from the date we receive your deposit and final design sign-off. We work to align production runs with client construction deadlines.
Payments can be made to our bank account via wire transfer, Western Union, or PayPal: 30% deposit in advance, and the remaining 70% balance against the copy of the Bill of Lading (B/L).
We warrant our materials and workmanship. Our commitment is to resolve any product issues to ensure customer satisfaction, regardless of the warranty period.
Shipping costs depend on the delivery method selected. Air express is the fastest but most expensive, while sea freight is the standard option for volume orders. Exact freight rates are calculated based on shipment dimensions, weight, and destination port. Contact us for a detailed freight estimate.
Browse our selection of specialized high-nickel alloys, heat exchanger tubing, and duplex steel spools.
