Case Overview
A district-heating power plant operating a subcritical boiler at 540°C steam conditions needed to replace two superheater tube banks during its planned annual shutdown. A previous tube order had arrived with incomplete quality documentation, forcing the plant to conduct life-assessment studies on unverifiable material. The shutdown window allowed no repeat mistake. DZX was commissioned to supply replacement tubes with complete certificates and matching thermocouple materials for monitoring after replacement.
All tube batches were delivered within the 60-day window, with certificates covering chemistry, mechanical properties and NDT records. The plant’s remaining-life file was completed during commissioning without a single material query.
This case summarizes the application requirements, materials supplied by DZX and delivery value. For case-specific technical data, please contact our engineering team.
| Item | Details |
|---|---|
| Client Profile | District-heating power plant (subcritical, 540°C steam) |
| Project Scale | Two superheater tube banks, planned annual shutdown |
| Application | Superheater and reheater tubes; metal-temperature monitoring |
| Materials Supplied | TP304H, TP347H, Incoloy 800H and Type K/N thermocouples |
| Supply Forms | Tube, wire and mineral-insulated cable |
| Lead Time | All tube supply completed within the 60-day shutdown window |
| Project Country | Germany |
| Project Year | 2024 |
Our Solution
The replacement project had to close three gaps that had undermined confidence in remaining-life planning:
- Verifiable creep-service material: superheater tubes at 540°C steam operated near creep limits. The plant’s life-assessment method required verifiable chemistry, heat treatment and mechanical properties for every tube batch.
- Grades matched by section: the hottest outlet sections needed Incoloy 800H for oxidation and creep resistance, while TP304H/TP347H covered cooler inlet sections. One supplier had to coordinate them without batch mixing.
- Post-replacement monitoring: the plant wanted metal-temperature measurement on the new tube banks for ongoing remaining-life tracking, requiring thermocouple supply within the same delivery.
DZX coordinated supply as one project:
TP304H and TP347H boiler tubes were supplied to ASTM A213 with controlled chemistry and heat treatment; Incoloy 800H covered the hottest outlet sections. Grade segregation and heat identification were managed throughout to prevent site material mixing. Type K and N thermocouple wire and mineral-insulated cable were delivered together, verified to IEC 60584-1. Each tube batch included certificates covering chemistry, mechanical properties and NDT records, formatted for the plant’s remaining-life file.
| Material | Representative Grades | Key Properties | Available Forms |
|---|---|---|---|
| Stainless steel | TP304H、TP347H | Creep strength and fireside corrosion resistance | Tube (ASTM A213) |
| Incoloy alloys | 800H | High-temperature outlet sections | Tube and fittings |
| Thermocouple alloys | K、N | Metal and flue-gas temperature monitoring | Wire and mineral-insulated cable |
View Stainless Steel Alloys → | View Incoloy Alloys → | View Thermocouple Alloys →
Superheater and reheater tubes
High-temperature pressure tubing
Type K / N furnace and tube-wall temperature measurement
Technical Specifications
Key technical parameters agreed before production. Contact us for grade-specific datasheets and tolerance-verification reports.
| Parameter | Agreed Specification | Verification Method |
|---|---|---|
| Tube dimensions (typical) | 38 mm OD × 4 mm wall (to drawing) | Micrometer + ultrasonic thickness measurement |
| Wall-thickness tolerance | ±0.4 mm(ASTM A213) | Ultrasonic testing, batch NDT |
| Grade by section | Inlet: TP304H/TP347H; outlet: Incoloy 800H | Factory heat segregation + identification |
| Steam conditions | 540°C subcritical operation | Chemistry + creep-related properties |
| Monitoring materials supplied together | Type K/N wire and mineral-insulated cable, IEC 60584-1 | Batch calibration reports |
Each supplied batch includes a quality inspection certificate with chemical analysis, meeting the applicable standard for each grade.
| Material | Applicable Standards |
|---|---|
| Boiler tubes | ASTM A213、GB/T 5310 |
| Incoloy 800H | ASTM B407 |
| Thermocouple alloys | IEC 60584-1 |
| Quality System | Quality certificate including chemical analysis and mechanical properties |
Delivery and Quality Support
- Fast delivery: Sample and production lead times follow the project schedule; standard grades and sizes can be dispatched promptly from stock.
- Quality traceability: Every batch includes material certificates and inspection reports, with full heat and batch traceability.
- Technical support: Responsive support covers pre-sale material selection, drawing review and post-sale processing advice.
- Ongoing service: Regular follow-up after delivery tracks performance and addresses feedback promptly.
Customer Feedback
- Delivery within the window: all tubes supplied during the 60-day shutdown with zero site delays
- Remaining-life file completed: chemistry, properties and NDT certificates accepted without queries
- Zero batch mixing: grades segregated and identified from factory to site
- Monitoring in place: Type K/N thermocouple supply verified to IEC 60584-1 for post-replacement life tracking
- One project owner: tubes and instrumentation coordinated in one delivery under one quality system
- Reusable framework: the plant reused the documentation format for its next planned replacement
Our Capabilities
Jiangsu DZX Technology Co., Ltd. (Changzhou DLX Alloy) was founded in 2016. Its core team has worked in the field since 2002, with 24 years of precision-alloy R&D and production experience, operating a self-owned 12,000-square-meter modern factory with an ISO9001 system covering three inspection stages. Annual alloy output exceeds 1,200 tonnes, serving 1500+ business customers worldwide. The company operates integrated melting, drawing, annealing and precision-machining workshops, supporting volume customization of strip, wire, tube and bar. Every batch includes a chemical analysis report (MTC) for full delivery-quality traceability.
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