Product Description
Seamless Tube Size: Outside Diameter: 6.0mm-127mm (1/8"-5"), Wall Thickness: 0.5mm-12.7mm, Length: 6m, 12m or as required
Standard & Grade of Seamless Tube: ASTM A213/ASME SA213 Grade TP347H (UNS S34709, Werkstoff 1.4912, X7CrNiNb18-10, SUS 347H TB); Also available TP304H, TP321H, TP316H, TP347HFG
Usage of Seamless Tube: Superheater tubes, reheater tubes, high-temperature headers, boiler water wall tubes, heat exchanger tubes, power generation, petrochemical processing, refinery heaters, furnace tubes, waste heat recovery boilers, subcritical and supercritical pressure boiler components
Womic Steel offering high quality & competitive prices of ASTM A213 TP347H stainless steel seamless boiler tubes, superheater tubes, pipe fittings. Mill certificate, hydro test, UT/ET inspection, flaring/flattening test, beveled end available. Fast delivery and best service.
Womic Steel: Manufacturing Capabilities & Company Strength
Womic Steel Group is a premier manufacturer and global exporter with over 20 years of expertise in producing carbon, alloy, and stainless steel tubular products. Our state-of-the-art seamless tube production facility specializes in niobium-stabilized high temperature stainless steel boiler tubes for power generation and petrochemical applications.
Production Size Range for ASTM A213 TP347H Seamless Tube: Outside diameter from 6.0mm to 127mm (1/8 inch to 5 inch) with wall thickness from 0.5mm to 12.7mm . Single random lengths of 6m, double random lengths of 12m, or custom lengths up to 18m as required.
Quality Certifications & Regulatory Compliance:
ISO 9001:2015 Certified: Quality management system ensuring consistent product quality across all operations.
ASTM A213 / ASME SA213 Compliance: Full compliance with ASTM A213/A213M and ASME SA213 Standard Specification for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes .
PED 2014/68/EU (CE Marking): Compliance with European Pressure Equipment Directive. CE marking available upon request.
ASME Boiler and Pressure Vessel Code: Section II materials certification available for ASME Code applications.
EN 10204 3.2 Certification: Inspection Certificate 3.2 validated by TÜV, LR, BV, or SGS for critical applications requiring full material traceability.
Third-Party Inspection (TPI) Approvals: Products and processes approved by SGS, BV, ABS, LR, DNV, GL, and TÜV.
Global Recognition: Womic Steel is a trusted supplier to boiler manufacturers, power plants, and petrochemical facilities serving over 80 countries worldwide.
ASTM A213 TP347H Stainless Steel Seamless Tube: Material Composition & Performance Characteristics
ASTM A213 TP347H is a niobium (columbium)-stabilized austenitic stainless steel seamless tube specifically designed for high temperature boiler and superheater service. The "H" designation indicates controlled carbon content (0.04-0.10%) for improved creep strength and stress rupture properties at elevated temperatures .
TP347H contains niobium as a stabilizing element (8×C min to 1.10% max), which combines with carbon to form niobium carbides (NbC) instead of chromium carbides at grain boundaries . This stabilization provides superior resistance to intergranular corrosion and sensitization, even after prolonged exposure to temperatures in the chromium carbide precipitation range (425-850°C).
Compared to TP304H and TP321H, TP347H offers better creep strength and oxidation resistance at temperatures up to 700°C, making it the preferred choice for supercritical boiler superheaters and reheaters where prolonged high temperature service is required .
ASTM A213 TP347H Stainless Steel Chemical Composition (Ladle Analysis, % by mass):
| Element | TP347H Requirement |
| Carbon (C) | 0.04 - 0.10 |
| Manganese (Mn) | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
| Silicon (Si) | ≤ 1.00 |
| Chromium (Cr) | 17.0 - 19.0 |
| Nickel (Ni) | 9.0 - 13.0 |
| Niobium (Nb) | 8×C min - 1.10 |
Note: The niobium addition stabilizes the material by forming niobium carbides (NbC) rather than chromium carbides at grain boundaries, preventing sensitization and maintaining corrosion resistance even after welding or high temperature exposure .
ASTM A213 TP347H Stainless Steel Mechanical Properties (Room Temperature):
| Property | TP347H Requirement |
| Tensile Strength (min) | 515 MPa (75,000 psi) |
| Yield Strength (min, 0.2% offset) | 205 MPa (30,000 psi) |
| Elongation (min, 2" gauge) | 35% |
| Hardness (max) | 192 HB / 90 HRB / 200 HV |
ASTM A213 TP347H Stainless Steel Physical Properties:
| Property | Value |
| Density | 7.9 g/cm³ |
| Melting Point | 1390-1430°C |
| Modulus of Elasticity | 193 GPa |
| Thermal Conductivity (100°C) | 16.3 W/m·K |
| Coefficient of Thermal Expansion (20-200°C) | 16.7 μm/m·K |
High Temperature Creep and Stress Rupture Properties:
TP347H is specifically designed for elevated temperature service with superior creep resistance compared to TP304H and TP321H. The material maintains useful strength up to 650-700°C for superheater and reheater applications .
TP347H vs TP304H vs TP321H Comparison:
| Grade | Stabilizer | Carbon | Max Service Temp | Creep Strength | Oxidation Resistance |
| TP304H | None (unstabilized) | 0.04-0.10 | 600°C | Good | Fair |
| TP321H | Titanium (Ti) | 0.04-0.10 | 650°C | Better | Good |
| TP347H | Niobium (Nb) | 0.04-0.10 | 700°C | Best | Excellent |
Note: TP347H offers the best combination of creep strength and oxidation resistance for high temperature service. The niobium stabilization provides superior resistance to intergranular corrosion and sensitization compared to TP321H .
Stabilization and Intergranular Corrosion Resistance:
TP347H contains niobium (columbium) as a stabilizing element. Niobium has a stronger affinity for carbon than chromium. When the material is heated in the carbide precipitation range (425-850°C), niobium preferentially forms niobium carbides (NbC) instead of allowing chromium carbides to form at grain boundaries. This prevents chromium depletion and maintains corrosion resistance. The higher carbon content (0.04-0.10%) combined with niobium stabilization provides both excellent creep strength and intergranular corrosion resistance .
Microstructure and Aging Characteristics:
During high temperature service, TP347H develops a stable microstructure with fine niobium carbide precipitates that provide strengthening. However, prolonged exposure can lead to sigma phase formation and carbide coarsening. Studies have shown that proper solution annealing (1040-1120°C) is critical for optimizing properties and preventing premature failure .
Internal Oxidation and Oxide Scale Characteristics:
TP347H forms a protective chromium oxide scale at high temperatures. However, in supercritical boilers, oxide exfoliation can occur. Shot peening (SB) treatment of the inner surface is recommended to enhance fine grain structure and reduce oxide spallation .
ASTM A213 TP347H Stainless Steel Seamless Tube Dimensional Range & Standards Compliance
Womic Steel supplies ASTM A213 TP347H seamless tubes across a wide dimensional spectrum, fully compliant with ASTM A213/A213M and ASME SA213 standards.
| Item | Specification |
| Standard | ASTM A213/A213M, ASME SA213 (Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes) |
| Grade | TP347H (UNS S34709, 1.4912, X7CrNiNb18-10, SUS 347H TB) |
| Manufacturing Process | Seamless - Cold Drawn / Cold Rolled / Cold Pilgered |
| Outside Diameter Range | 6.0mm – 127mm (1/8" – 5") |
| Wall Thickness Range | 0.5mm – 12.7mm (0.015" – 0.500") |
| Length | 6m (SR), 12m (DR), or custom lengths up to 18m |
| Delivery Condition | Solution Annealed (1040-1120°C) + Water Quenched |
| End Finish | Plain End (PE) / Beveled End (BE) |
| Surface Finish | Annealed & Pickled / Bright Annealed / Shot Peened (SB) |
| Special Tests | Flaring Test / Flattening Test / Hydrostatic Test / Eddy Current Test |
Dimensional Tolerances per ASTM A213:
| Characteristic | Tolerance |
| OD < 25mm (1") | ±0.13mm (±0.005") |
| OD 25-50mm (1"-2") | ±0.25mm (±0.010") |
| OD 50-100mm (2"-4") | ±0.38mm (±0.015") |
| OD 100-127mm (4"-5") | ±0.50mm (±0.020") |
| Wall Thickness (WT) | ±12.5% for WT > 1.65mm / ±15% for WT ≤ 1.65mm |
| Length | +50mm, -0mm (mill length) |
Manufacturing Process – Stainless Steel Seamless Tube
Womic Steel produces ASTM A213 TP321 stainless steel seamless tubes using advanced cold drawing and cold rolling processes, ensuring precise dimensional tolerances and superior surface finish.
Production Workflow (Cold Drawn / Cold Rolled Seamless Tube Process):
Raw Material Inspection (Billet): Incoming stainless steel round billets (typically 50-200mm diameter) are verified for chemical composition per ASTM A213 TP321 requirements (17-19% Cr, 9-12% Ni, Ti ≥ 5×C). Each billet is assigned a unique heat number for full material traceability throughout production.
Billet Heating & Piercing: Billets are heated to forging temperature (1150-1250°C) in rotary hearth furnaces and pierced via cross-roll piercing mill (Mannesmann process) to form hollow tube shells (hollow blooms).
Extrusion or Rolling: The pierced hollow shells undergo further hot rolling or extrusion to reduce diameter and wall thickness. For TP321, careful temperature control prevents titanium carbide precipitation during hot working.
Annealing (Intermediate): After hot working, tubes are solution annealed at 1040-1120°C followed by rapid cooling (water quenching or air cooling) to dissolve carbides and restore corrosion resistance.
Pickling & Descaling: Scale formed during annealing is removed by pickling in acid baths (nitric-hydrofluoric acid mixture), revealing a clean, uniform surface.
Cold Drawing (Single or Multiple Passes): Tubes undergo single or multiple cold drawing passes through precision dies and over mandrels to achieve required OD, WT, and dimensional tolerances. Typical reduction per pass: 20-40%.
Cold Rolling (Pilgering - Optional): For greater wall thickness reduction or improved surface finish, tubes are processed through cold pilger mills. This process is particularly effective for thin-wall and precision tubes.
Intermediate Annealing: Between drawing or rolling passes, tubes undergo intermediate annealing (1040-1120°C) to relieve work hardening and restore ductility for subsequent processing.
Final Heat Treatment (Solution Annealing): Tubes receive final solution annealing at 1040-1120°C followed by rapid cooling to achieve specified mechanical properties, corrosion resistance, and grain structure. This is critical for TP321 to ensure titanium carbides are properly dissolved and reprecipitated.
Straightening & Cutting: Precision straightening to meet standard straightness tolerances (0.15% of total length), followed by cutting to exact ordered lengths with clean, burr-free ends.
Finishing & Surface Inspection: Visual examination to ensure freedom from surface defects such as cracks, folds, laps, and scabs. Pickling or bright annealing applied as final surface finish.
End Finishing: Plain ends (square cut), beveled ends (30-35° bevel angle with 1.6mm ±0.8mm landing), or threaded ends as per customer specification.
Quality Control & Testing Procedures
| Stage | Inspection Method | Purpose |
| Raw Material (Billet) | Chemical Analysis (OES Spectrometer) | Verify compliance with ASTM A213 TP321 composition limits (Cr, Ni, Ti, C, etc.) |
| Raw Material (Billet) | Tensile Testing at Room Temperature | Verify base material strength before processing |
| Raw Material (Billet) | Ultrasonic Testing (UT) | Detect internal laminations and defects |
| In-Process | Dimensional Inspection (Micrometers, Calipers) | Monitor OD, WT during drawing and rolling |
| In-Process | Surface Visual Inspection | Detect surface defects (folds, laps, cracks) |
| Finished Tube | Solution Annealing Verification | Ensure proper heat treatment (1040-1120°C, rapid cooling) |
| Finished Tube | Tensile Testing (Room & High Temp) | Verify yield strength (min 205 MPa), tensile strength (min 515 MPa), elongation (min 35%) |
| Finished Tube | Hardness Test (HRB / HV) | Verify maximum hardness 92 HRB / 210 HV |
| Finished Tube | Flaring Test | Verify ductility and soundness (tube end expanded with tapered mandrel) |
| Finished Tube | Flattening Test | Verify ductility and soundness (tube flattened between parallel plates) |
| Finished Tube | Hydrostatic Testing | Each tube pressure tested to specified pressure (no leakage permitted) |
| Finished Tube | Eddy Current Testing (ET) | Continuous on-line inspection for surface and subsurface defects |
| Finished Tube | Ultrasonic Testing (UT) | Full body inspection for internal defects (supplementary requirement) |
| Finished Tube | Intergranular Corrosion Test (Optional) | Verify resistance to sensitization (per ASTM A262 Practice E) |
| Finished Tube | Dimensional & Visual Inspection | Verify OD, WT, length, straightness, surface quality |
| Finished Tube | Marking Verification | Ensure permanent marking per ASTM A213 (standard, grade, size, heat number) |
Supplementary Tests (Upon Request):
High Temperature Tensile Test
Creep and Stress Rupture Test
Charpy Impact Test (for low temperature applications)
Grain Size Measurement (per ASTM E112)
Intergranular Corrosion Test per ASTM A262 (Practice E - Strauss test)
Ferrite Content Measurement (for duplex stainless steel)
Quality Documentation:
Mill Test Certificate per EN 10204 Type 3.1 or 3.2
Hydrostatic Test Report (tube-by-tube)
ET / UT Inspection Report
Flaring / Flattening Test Report
Traceability from heat number to finished tube
NACE MR0175 certification (upon request)
Primary Applications – ASTM A213 TP321 Stainless Steel Seamless Tube
ASTM A213 TP321 stainless steel seamless tubes are essential components in high temperature and corrosive service environments across various industries:
Power Generation: Superheater tubes, reheater tubes, boiler water wall tubes, steam headers, and main steam pipelines in thermal power plants, combined cycle units, and nuclear power plants (non-core). TP321's high temperature strength up to 816°C makes it ideal for supercritical boiler applications.
Industrial Boilers: Steam generation systems, hot water boilers, waste heat recovery boilers (WHRB), and heat recovery steam generators (HRSG) for manufacturing facilities. The titanium stabilization prevents sensitization during welding and service.
Petrochemical & Refining: Heat exchangers, process heaters, cracking furnaces (ethylene crackers), reformer tubes, and high temperature fluid transfer lines in refineries and petrochemical plants. TP321 resists polythionic acid stress corrosion cracking in refinery service.
Chemical Processing: Reactors, reformers, high temperature piping systems handling corrosive gases and liquids, and equipment for nitric acid, sulfuric acid, and organic chemical production.
High Temperature Headers: Steam headers and manifold systems operating at temperatures between 400-800°C where creep resistance and thermal stability are critical.
Furnace Tubes: Radiant tubes, convection section tubes, and transfer lines in industrial furnaces, thermal oxidizers, and incinerators.
Heat Exchangers: Shell and tube heat exchangers, U-tube bundles, and condenser tubes for high temperature and corrosive service.
Aerospace & Defense: High temperature hydraulic lines, engine bleed air systems, and exhaust system components requiring oxidation resistance up to 800°C.
Pharmaceutical & Food Processing: High temperature steam lines and sterile processing equipment where corrosion resistance and cleanability are essential.
Common International Standards for Stainless Steel Seamless Tubes
| Standard | Full Standard Name | Applicable Grades | Typical Application |
| ASTM A213 | Standard Specification for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes | TP304, TP304L, TP304H, TP309, TP310, TP316, TP316L, TP316H, TP316Ti, TP321, TP321H, TP347, TP347H | Boiler tubes, superheater tubes, heat exchanger tubes |
| ASTM A312 | Standard Specification for Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes | TP304/L, TP316/L, TP321, TP347, TP904L | General service stainless steel pipes, pressure piping |
| ASTM A269 | Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubes for General Service | TP304/L, TP316/L, TP321, TP347 | General service tubing, instrumentation, mechanical applications |
| ASTM A789 | Standard Specification for Seamless and Welded Ferritic/Austenitic Stainless Steel Tubing for General Service | S31803 (2205), S32205, S32750 (2507), S32760 | Duplex stainless steel tubes, general service |
| ASTM A790 | Standard Specification for Seamless and Welded Ferritic/Austenitic Stainless Steel Pipe | S31803 (2205), S32205, S32750 (2507), S32760 | Duplex stainless steel pipes, pressure applications |
| EN 10216-5 | Seamless steel tubes for pressure purposes - Technical delivery conditions - Part 5: Stainless steel tubes | 1.4301 (304), 1.4307 (304L), 1.4401 (316), 1.4404 (316L), 1.4541 (321), 1.4878 (321H), 1.4550 (347) | Pressure purposes, European market |
| EN 10305-1 | Steel tubes for precision applications - Technical delivery conditions - Part 1: Seamless cold drawn tubes | E215, E235, E355 (carbon steel) | Precision applications, hydraulic cylinders |
| EN 10216-2 | Seamless steel tubes for pressure purposes - Non-alloy and alloy steel tubes with specified elevated temperature properties | P235GH, P265GH, P295GH, P355GH (carbon/alloy) | Pressure purposes, elevated temperature |
| JIS G3459 | Stainless steel pipes | SUS304TP, SUS304LTP, SUS316TP, SUS316LTP, SUS321TP, SUS347TP | Stainless steel pipes, Japanese market |
| JIS G3463 | Stainless steel boiler and heat exchanger tubes | SUS304TKA, SUS316TKA, SUS321TKA, SUS347TKA | Boiler and heat exchanger tubes, Japanese market |
| GB/T 14976 | Seamless stainless steel pipes for fluid transport | 0Cr18Ni9 (304), 00Cr17Ni14Mo2 (316L), 1Cr18Ni9Ti (321) | Fluid transport, Chinese market |
| GB/T 14975 | Seamless stainless steel pipes for structural purposes | 0Cr18Ni9 (304), 1Cr18Ni9Ti (321) | Structural purposes, Chinese market |
| GB 13296 | Seamless stainless steel tubes for boiler and heat exchanger | 0Cr18Ni9 (304), 0Cr17Ni12Mo2 (316), 1Cr18Ni9Ti (321) | Boiler and heat exchanger, Chinese market |
| ISO 1127 | Stainless steel tubes - Dimensions, tolerances and conventional masses per unit length | — | Dimensional standard for stainless steel tubes |
| NACE MR0175 / ISO 15156 | Petroleum and natural gas industries - Materials for use in H₂S-containing environments in oil and gas production | 304/L, 316/L, 321, 347, 2205, 2507 | Sour service, oil and gas production |
Packaging & Shipping
Packaging:
l Protective Covering: Individual plastic sleeves or spiral wrapping applied to each tube to prevent surface scratches and moisture contact.
l Bundling: Tubes bundled together and secured with steel straps (3-5 straps per bundle) with protective corner guards. Wooden dunnage or foam rings between layers prevents abrasion.
l End Caps: Plastic end caps (PE or PP) on both ends protect beveled/plain ends and threads from impact damage and debris ingress.
l Wooden Crates: For high-value or precision orders, tubes packed in sturdy wooden crates or plywood cases for enhanced protection.
l Desiccant Bags: Added for moisture-sensitive applications or long sea freight.
Shipping:
Mode of Transportation: Container vessels (20ft/40ft), bulk carriers (>500 tons), or air freight for sample shipments.
Containerization: Tubes loaded into standard containers. Max load: 20-25 tons per 20ft, 25-28 tons per 40ft.
Bulk Vessel Loading: Large orders loaded directly into bulk carriers with lifting beams, dunnage, and lashing to secure cargo.
Labeling & Documentation: Each bundle labeled with grade, standard, dimensions, heat number. Complete shipping documents (invoice, packing list, bill of lading, COO, MTC) prepared for customs clearance.
Secure Fastening: Bundles secured with steel strapping, dunnage bags, or timber bracing to prevent shifting during transit.
Tracking & Insurance: Container tracking numbers provided. Marine cargo insurance available upon request.
Packaging & Shipping
Packaging:
- Protective Covering: Individual plastic sleeves or spiral wrapping applied to each tube to prevent surface scratches and moisture contact.
- Bundling: Tubes bundled together and secured with steel straps (3-5 straps per bundle) with protective corner guards. Wooden dunnage or foam rings between layers prevents abrasion.
- End Caps: Plastic end caps (PE or PP) on both ends protect beveled/plain ends and threads from impact damage and debris ingress.
- Wooden Crates: For high-value or precision orders, tubes packed in sturdy wooden crates or plywood cases for enhanced protection.
- Desiccant Bags: Added for moisture-sensitive applications or long sea freight.
Shipping:
Mode of Transportation: Container vessels (20ft/40ft), bulk carriers (>500 tons), or air freight for sample shipments.
Containerization: Tubes loaded into standard containers. Max load: 20-25 tons per 20ft, 25-28 tons per 40ft.
Bulk Vessel Loading: Large orders loaded directly into bulk carriers with lifting beams, dunnage, and lashing to secure cargo.
Labeling & Documentation: Each bundle labeled with grade, standard, dimensions, heat number. Complete shipping documents (invoice, packing list, bill of lading, COO, MTC) prepared for customs clearance.
Secure Fastening: Bundles secured with steel strapping, dunnage bags, or timber bracing to prevent shifting during transit.
Tracking & Insurance: Container tracking numbers provided. Marine cargo insurance available upon request.
Common Industry Applications Summary
|
Industry |
Application |
Recommended Grade |
| Power Generation | Superheater tubes, reheater tubes, boiler water walls, steam headers | TP321, TP321H, TP347H |
| Petrochemical | Ethylene cracking furnace tubes, reformer tubes, heat exchangers | TP321, TP321H, TP347 |
| Oil & Gas | High temperature piping, heat exchanger bundles, process heaters | TP321, TP316/L, 2205 |
| Chemical Processing | Reactors, high temperature piping, corrosive service | TP321, TP316/L, 904L |
| Pharmaceutical | High purity steam lines, sterile processing equipment | TP304/L, TP316/L (BA finish) |
| Food & Beverage | Processing equipment, high temperature steam lines | TP304/L, TP316/L (BA finish) |
| Refining | Crude heaters, vacuum heaters, catalytic crackers | TP321H, TP347H |
| Aerospace | High temperature hydraulic lines, exhaust systems | TP321, 17-4PH |
| Desalination | High temperature brine heaters, evaporators | TP316/L, 2205, 2507 |
| Pulp & Paper | Digester tubes, bleach plant piping, recovery boilers | TP316/L, 2205, 904L |
Womic Steel Advantages & FAQ
Why Partner with Womic Steel for Stainless Steel Seamless Tubes?
Complete Range of Grades: Full portfolio of austenitic (304/304L, 316/316L, 321/321H, 347/347H, 310S), duplex (2205, 2507), and super austenitic (904L) stainless steel seamless tubes under one roof.
Multiple Standard Compliance: ASTM A213, A312, A269, A789, A790, EN 10216-5, EN 10305-1, GB/T 14976, JIS G3459, JIS G3463. One supplier for multiple market requirements.
Precision Manufacturing: Cold drawn and cold rolled (pilgered) processes ensuring tight dimensional tolerances (±0.05mm for precision tubes) and superior surface finish (BA, mirror, brushed).
Full Traceability: Each tube traceable from heat number to finished product with complete documentation.
Value-Added Services: End beveling (30-35°), plain end cutting, threading, plastic caps installation, and surface finishing (BA, pickled, polished, mirror) available in-house.
Quality Assurance: 100% hydrostatic testing, eddy current testing (ET), optional ultrasonic testing (UT), flaring and flattening tests performed on every tube.
Third-Party Inspection: Facilitation of inspections by DNV, BV, SGS, TÜV, ABS, LR. 3.2 certificates supplied upon request.
Global Logistics: Strategic partnership with freight forwarders for optimized container loading and cost-effective worldwide shipping.
Technical Support: Engineering team available for material selection, grade substitution, and application consulting.
Choose Womic Steel Group as your reliable partner for high-quality ASTM A213 TP321 stainless steel seamless tubes and unbeatable delivery performance for boiler, heat exchanger, and petrochemical projects worldwide. Welcome to inquire!
Website: www.womicsteel.com
Email: sales@womicsteel.com
Tel/WhatsApp/WeChat:
Victor: +86-15575100681
Jack: +86-18390957568
Frequently Asked Questions (FAQ)
Q: What is the difference between TP347H and TP304H?
A: TP347H is niobium-stabilized while TP304H is unstabilized. TP347H offers superior resistance to intergranular corrosion and sensitization after welding or high temperature exposure. TP347H also provides better creep strength and oxidation resistance at temperatures up to 700°C, making it preferred for superheater and reheater applications .
Q: What is the difference between TP347H and TP321H?
A: TP347H uses niobium (columbium) for stabilization, while TP321H uses titanium. TP347H offers better creep strength and oxidation resistance at higher temperatures. TP347H is also less prone to titanium nitride (TiN) inclusion issues. TP347H is the preferred grade for supercritical boiler applications .
Q: Why is TP347H used for superheaters and reheaters?
A: TP347H offers excellent creep strength, oxidation resistance, and intergranular corrosion resistance at elevated temperatures (up to 650-700°C). The niobium stabilization prevents sensitization during prolonged high temperature service, maintaining corrosion resistance and mechanical properties .
Q: What is the maximum operating temperature for TP347H?
A: TP347H is suitable for continuous service up to 700°C (1292°F) for superheater and reheater applications. For temperatures above 700°C, specialized alloys may be required. The material is widely used in subcritical and supercritical pressure boilers .
Q: What is shot peening (SB) treatment for TP347H tubes?
A: Shot peening (SB) is a surface treatment that bombards the inner surface of the tube with small shots to create a fine grain structure. This treatment enhances resistance to high temperature oxidation and reduces oxide scale exfoliation, which can cause tube blockage in supercritical boilers .
Q: Does TP347H require post-weld heat treatment?
A: No. Due to niobium stabilization, TP347H does not require post-weld heat treatment to restore corrosion resistance. However, proper welding procedures with appropriate filler metal (ER-347) and heat input control are essential .
Q: What welding consumables are recommended for TP347H?
A: For welding TP347H, use ER-347 filler wire for TIG/MIG welding or E347-15/E347-16 electrodes for SMAW (stick welding). When welding dissimilar materials (e.g., TP347H to ferritic steel), ERNiCr-3 or ENiCrFe-3 type consumables are recommended per ASME standards .
Q: What NDT is required for ASTM A213 TP347H boiler tubes?
A: Hydrostatic testing (each tube) or eddy current testing (ET) is mandatory. Optional tests include ultrasonic testing (UT), flaring test, and flattening test. For critical superheater applications, 100% UT or ET is often specified.
Q: What is the typical lead time for ASTM A213 TP347H seamless tubes?
A: Stock sizes: 20-30 days. Custom sizes: 35-50 days. Special requirements (3.2 certification, third-party inspection, shot peening treatment) add 10-15 days.
Q: What documentation do you provide for TP347H tube shipments?
A: Mill Test Certificate (EN 10204 Type 3.1 or 3.2), chemical composition report, tensile test report (room and high temperature), grain size report, hydrostatic test report, flaring/flattening test report, NDT report (UT/ET), dimensional report, packing list, invoice, bill of lading.
Q: Is TP347H suitable for ASME Code applications?
A: Yes. TP347H is approved under ASME Boiler and Pressure Vessel Code Section II as SA-213 TP347H. Code stamping and certification available upon request.
Q: What is the difference between TP347H and TP347HFG?
A: TP347HFG (Fine Grain) is a modification of TP347H with controlled fine grain size (ASTM No. 8-10) for improved steam oxidation resistance. TP347HFG is specifically designed for superheater and reheater tubes in ultra-supercritical boilers where superior oxidation resistance is required.
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