Sihe Steel
Sihe Steel
Explore our precision-engineered high alloy coiled and straight tubing solutions designed for hostile operating environments.
Alloy 625 (UNS N06625 / W.Nr. 2.4856) is a nickel-chromium-molybdenum alloy with an addition of niobium. The interaction of molybdenum and niobium within the alloy's matrix provides outstanding strength and toughness without requiring a precipitation-hardening heat treatment. The solid-solution matrix resists high levels of mechanical stress and thermal fatigue from cryogenic levels up to 1800°F (982°C). This makes the material highly desirable for downhole control lines, subsea umbilical systems, and aggressive chemical processing plants where component failure is not an option.
The high nickel content (minimum 58%) provides virtual immunity to chloride-induced stress corrosion cracking (SCC), which frequently plagues standard austenitic stainless steels like 304 and 316. Chromium (20-23%) and molybdenum (8-10%) deliver exceptional resistance to localized attacks such as pitting and crevice corrosion. Additionally, the alloy's niobium content (3.15-4.15%) stabilizes the material against intergranular precipitation during welding or thermal processing, ensuring the integrity of the heat-affected zone (HAZ) even in highly corrosive environments containing hydrogen sulfide (H2S), carbon dioxide (CO2), and elemental sulfur.
| Alloy Grade | Nickel (Ni) % | Chromium (Cr) % | Molybdenum (Mo) % | Niobium + Tantalum (Nb+Ta) % | Pitting Resistance Equivalent Number (PREN) |
|---|---|---|---|---|---|
| Alloy 625 | 58.0 min | 20.0 - 23.0 | 8.0 - 10.0 | 3.15 - 4.15 | > 45 (Highly Resistant) |
| Alloy 825 | 38.0 - 46.0 | 19.5 - 23.5 | 2.5 - 3.5 | 0.6 - 1.2 (Ti) | ~ 31 (Moderate) |
| Duplex 2205 | 4.5 - 6.5 | 22.0 - 23.0 | 3.0 - 3.5 | - | ~ 35 (High) |
| Super Duplex 2507 | 6.0 - 8.0 | 24.0 - 26.0 | 3.0 - 5.0 | - | > 40 (Very High) |
As onshore reserves deplete, global oil and gas extraction has moved into deep-water and ultra-deep-water basins. These extreme offshore environments demand corrosion-resistant alloys capable of withstanding external hydrostatic pressure and internal corrosive fluid exposure. High-integrity seamless coiled tubing made from Inconel 625 serves as control lines and hydraulic paths within subsea umbilicals, connecting topside floating production systems (FPSOs) to deep sea wells. The elimination of circumferential welds in continuous coils up to 32,800 feet (10,000 meters) minimizes potential leak paths, guaranteeing safe and reliable fluid transmission.
The global push towards clean energy and decarbonization has stimulated demand for hydrogen infrastructure. Hydrogen embrittlement is a critical risk for standard steels; however, Nickel Alloy 625 exhibits excellent resistance to hydrogen permeation and embrittlement, positioning it as a preferred material for high-pressure hydrogen storage and delivery systems. In parallel, aerospace and defense sectors utilize Alloy 625 coiled tubing for turbine engine fuel lines, exhaust systems, and hydraulic manifolds due to its high fatigue strength and resistance to scaling under extreme thermal cycling.
At Liaocheng Sihe Stainless Steel Material LTD, we integrate Industry 4.0 protocols into our cold-drawing and precision coiling lines. Our production processes feature real-time dimensional monitoring, ensuring laser-guided control of outer diameters (OD) from 0.125 inches (3.175 mm) to 1 inch (25.4 mm), and wall thickness up to 0.165 inches (3 mm). High-precision cold-drawing processes increase the tensile and yield strength of the tubing, while internal lubrication systems maintain a smooth inner surface, preventing micro-voids and contamination that could accelerate stress corrosion cracking.
Our facility utilizes state-of-the-art in-line bright annealing furnaces under a controlled high-purity hydrogen atmosphere. This process relieves internal stresses induced by cold-drawing, achieving a recrystallized austenitic structure with a bright, oxidation-free surface finish. Quality assurance is backed by a rigorous testing matrix: 100% pneumatic and hydrostatic testing, continuous eddy current examination, mechanical flaring and flattening tests, microstructural analysis, and hardness verification. Our certifications guarantee that each batch of Alloy 625 coiled tubing meets ASTM, ASME, EN, and JIS standards.
Established with a legacy of decade-long manufacturing excellence, Liaocheng Sihe Stainless Steel Material LTD operates six advanced production lines dedicated to the creation of premium stainless steel and nickel alloy coiled tubes, capillary tubing, and heat exchanger pipes. We execute rigorous standards under GB, ASTM, ASME, JIS, and EN guidelines. Our specialized metallurgical offerings encompass austenitic grades (304/304L, 316L, 321, 317L, 309S, 310S), Duplex/Super Duplex alloys (2205, 2507), and nickel-based superalloys (Incoloy 800, Incoloy 825, Inconel 625).
Our high-quality products are heavily integrated into defense, semiconductor manufacturing, biopharmaceutical engineering, precision hydraulics, oil and gas exploration, shipbuilding, and solar energy systems. Currently, 80% of our production volume is exported to over 30 countries and regions globally, including the United States, Germany, Spain, South America, Southeast Asia, the Middle East, and Eastern Europe.
As offshore operations transition into deeper waters and more hostile environments, the engineering demand for highly reliable corrosion-resistant alloys increases. Our goal is to assist clients in selecting the optimized material specification to maximize product lifespan and project safety. With continuous technical innovation, bright annealing treatments, and customized length capabilities up to 10,000 meters, we stand ready to resolve complex engineering challenges for our international client base.
Tailored solutions engineered to meet the stringent dimensional and material specifications of global industrial applications.
Full support for diverse alloy materials (304, 316L, 2205, 825, 625) and specialized dimensions ranging from 6.35 mm to 19 mm OD for flexible stainless steel coils.
High-precision spiral forming, drawing, and custom configurations specifically tailored for boiler heat exchangers, condensers, and micro-capillary systems.
Advanced mechanical cutting, flame cutting, and high-tolerance laser cutting services ensuring zero deformation on the tube ends for subsequent welding and connection.
In-house state-of-the-art mechanical polishing, electro-polishing (EP), and bright annealing (BA) technologies to achieve critical roughness profiles (Ra < 0.25µm).
Custom end-forming, expansion, flaring, and flanging processes widely implemented in automotive exhaust systems, chemical pipelines, and analytical instrument fittings.
Where performance and material integrity are non-negotiable under extreme thermal and chemical stresses.
Our production conforms to global regulatory norms. Below are our official system and product certificates.
Engineering and purchasing details for global projects.
Verify specific grades and click the links below for product detailed descriptions, dimensions, and catalogs.
