347H Seamless Pipe
2. Standard: ASTM A312, ASTM A376, ASME SA312, engineered for critical power generation services
3. Process: 100% solid-billet hot extrusion with strict ultrasonic and eddy current defect testing
4. Size Range: Standard and heavy-wall specifications (Sch 40S, 80S, 160) matching ASME B36.19M codes
5. Heat Treatment: High-temperature solution annealing above 1040°C to guarantee optimal creep behavior
6. Surface Finish: Uniformly pickled inside and out, thoroughly descaled for high-heat performance
7. Application: Ultra-supercritical boiler tubes, chemical synthesis towers, and refinery piping lines
8. Service Advantage: Sourced from tier-one international steel mills, full technical MTC reports provided
9. Packaging: Individual pipe wrapping with heavy woven sleeves or crated in robust plywood boxes
10. Key Advantage: Superior creep-rupture strength and high allowable stress values under long-term thermal pressure
347H Seamless Pipe for High-Temperature Industrial Systems – Niobium-Stabilized Creep Strength Solutions
Hebei All Trust Steel Co., Ltd manufactures premium-grade 347H Seamless Pipe engineered for extreme thermal environments where conventional austenitic steels fail. Our niobium stabilised high carbon seamless pipes have good creep-rupture strength and intergranular corrosion resistance at operating temperatures up to 815°C. Annual manufacturing capacity of over 15,000 tons 100% hydraulically tested Code compliance product built to ASTM A312, ASME SA312 and ASTM A213 requirements. Each lot is solution annealed above 1040°C, volumetrically ultrasonically scanned and microstructure checked for grain size to assure structural integrity in ultra-supercritical boilers, refinery hydrocracking units and chemical synthesis towers.
Why 347H Seamless Pipe Outperforms Standard Austenitic Grades
Conventional stainless steels have a quick deterioration in the presence of extended heat cycling and sensitisation zones.
This device addresses this key industrial difficulty with superior metallurgical design. The "H" designation signifies a regulated high carbon content (0.04-0.10%) combined with strategic niobium stabilization-minimum 8× carbon concentration, capped at 1.10%. This chemistry inhibits chromium carbide from precipitating at the grain boundaries during welding or prolonged exposure to high temperatures.
The seamless technique removes longitudinal weld seams that are susceptible to thermal fatigue and stress corrosion cracking. Hot-extrusion piercing mills provide a continuous and uniform cylindrical structure that can resist high steam pressure cycles without local failure sites.
Your petrochemical operations demand piping that won't fail during multi-decade service life. Our product maintains superior allowable stress values at elevated temperatures, surpassing 304H and standard 347 grades in creep strength retention.
Technical Specifications & Material Properties
| Property | Specification |
|---|---|
| Material Grade | 347H (UNS S34709 / 1.4912) |
| Manufacturing Standards | ASTM A312, ASME SA312, ASTM A213, ASTM A376, EN 10216-5 |
| Process Type | Hot Finished / Cold Drawn / Cold Rolled / Solution Annealed |
| Outer Diameter Range | 1/4" – 24" (13.7 mm – 609.6 mm) |
| Wall Thickness | SCH 5S / 10S / 40S / 80S / 160 / XXS (0.5 mm – 50 mm) |
| Standard Lengths | 5.8 m / 6 m / 11.8 m / 12 m / Custom Cut |
| Heat Treatment | Solution Annealing ≥1040°C + Rapid Quench |
| Surface Finish | Pickled & Descaled / Bright Annealed (BA) / Polished |
| End Configuration | Plain End (PE) / Beveled End (BE) / Custom ASME B16.25 |
| Chemical Composition | Cr: 17-19% / Ni: 9-13% / C: 0.04-0.10% / Nb: 8×C min., 1.10% max. |
| Density | 7.96 g/cm³ |
| Melting Range | 1398–1425°C |
| Maximum Service Temperature | 815°C (1500°F) for oxidation resistance |
Comprehensive Quality Testing & Certification
You need to have a verified record that all pipes fulfil international norms for high risk installations.
Hebei All Trust Steel has four levels of inspection before shipping, these are:
Non-Destructive Testing (NDT):
- 100% Ultrasonic Testing (UT) for volumetric defect detection
- Eddy Current Testing (ECT) for surface and near-surface flaws
- Radiographic Testing (RT) for critical heavy-wall applications
- Hydrostatic Pressure Testing at 1.5× design pressure
Mechanical & Metallurgical Validation:
- High-temperature tensile testing per ASTM E21
- Creep-rupture testing at service temperature simulation
- Intergranular corrosion testing (ASTM A262 Practice A/E)
- Grain size determination (ASTM E112)
- Positive Material Identification (PMI) for stabilization ratio verification
- Hardness testing (Rockwell B / Brinell)
Quality Documentation Provided:
- EN 10204 3.1 & 3.2 Mill Test Certificates (MTC)
- PMI spectroscopy reports with heat number traceability
- ISO 9001:2015 quality management certification
- CE / PED compliance certificates
- Third-party inspection reports (SGS / BV / TÜV / DNV)
Critical Industrial Applications
Ultra-Supercritical Power Generation:
Your boiler superheater and reheater tubes experience tremendous pressure and temperature cycling. This preserves the structural integrity of the product, while being subjected to constant temperature cycling, which prevents the tubes from rupturing and causing expensive unexpected downtime.
Petrochemical Refinery Systems:
Piping in hydrocracking and hydrotreating units is susceptible to sulphide stress corrosion in high-pressure hydrogen conditions. Niobium stabilisation provides resistance to polythionic acid cracking and failure due to sensitisation.
Chemical Processing Equipment
Organic production reactors and heat exchangers need materials resistant to intergranular assault in the ranges of sensitisation temperature. Seamless structure means no weld zone weaknesses like those seen in welded alternatives.
Radiant heater grates:
High temperature furnace tube must not lose its creep strength under prolonged heat stress. 347H Seamless Pipe is regulated to a higher carbon content, which gives better time-temperature-stress performance than the conventional 347 grades.
Manufacturing Excellence & Customization Capabilities
We partner with 15+ ISO-certified steel mills equipped with advanced heavy seamless piercing technology.
Value-Added Processing Services:
- Precision cutting to fixed or random lengths up to 12 meters
- Compound bevel edge preparation for thick-wall field welding per ASME B16.25
- Laser hole drilling and slot cutting for header integration
- Pipe bending with controlled radius specifications
- Threading and end beveling for flanged connections
- Surface polishing from pickled finish to 8K mirror polish
Inventory Availability:
We maintain 5,000+ tons of rolling stock, ensuring rapid fulfillment for urgent projects. Standard schedules (40S, 80S, 160) ship within 3–5 days from our warehouse facilities.
Custom Order Lead Times:
- Standard specifications: 15–20 days
- Heavy-wall or special schedules: 25–30 days
- Priority production scheduling available to reduce timelines by 35%
Protective Packaging & Global Logistics
Your pipes must arrive at remote project sites in pristine condition.
Export-Grade Packaging:
- Individual PVC sleeves with plastic end caps
- Heavy-duty woven fabric bundles or hexagonal strapping
- Fumigation-free plywood crates for maritime shipment
- Waterproof wrapping to prevent salt corrosion during transit
Flexible Shipping Terms:
We support FOB, CFR, CIF, and DDP delivery from Shanghai, Ningbo, Tianjin, Qingdao, and Shenzhen ports. Mixed container loading accommodates pipes, fittings, flanges, and valves to optimize freight costs.
FAQ
Q：What core stabilization chemistry allows this product to thrive in high-temperature utility systems?
A：This pipe utilizes a strategic niobium (columbium) stabilization formula combined with an optimized high carbon content, maximizing elevated-temperature creep rupture strength and resisting intergranular corrosion up to 815°C extremes.
Q：Why is a seamless structure critical for this high-carbon pressure piping asset?
A：The seamless piercing process provides a completely uniform, joint-free cylindrical wall profile, eliminating weld zone creep vulnerabilities and localized thermal stress fractures under severe steam power loops.
Q: What are the particular metallurgical audits that confirm the stabilisation and safety criteria of this high-temperature batch?
A：Strict grain size microstructural analysis of every production lot, obligatory intergranular corrosion validation and 100% volumetric ultrasonic testing (UT) for code-approved high-heat safety.
Q：Can this heavy-duty pipe be customized with specialized edge preparations for thick-walled field welding?
A：Yes, we support extensive custom fabrication options, offering precision compound angles and beveled endings according to ASME B16.25 codes alongside fixed random length structures up to 12 meters.
Q：In what specific high-stress energy infrastructures is this product universally deployed?
A：It is optimized for central station thermal power plants, main steam superheater headers, chemical process cracking units, and high-temperature radiant heater networks.
Contact Us
For technical specifications, custom sizing, or project quotations, contact our engineering team at info@hballtrust.com. We respond within one hour during business hours and deliver complete proposals within eight hours for the 347H Seamless Pipe.
