Superheater coils
Bent tube strings for the hottest part of the boiler – bent, welded and tested to drawing. We supply them in creep-resistant grades with defined bending radii, string spacing and verified remaining wall thickness in the bend.
What is a superheater coil?
A superheater coil is a bent tube string inside a boiler in which steam is heated beyond saturation temperature. It sits in the hottest zone and carries the full internal pressure at the same time – the hardest combination a tube material has to withstand.
Scope of supply & execution
| Item | Detail |
|---|---|
| Basis of manufacture | Drawing with bending plan, radii, string spacing and weld positions |
| Tube size | Outside diameter 25 to 133 mm, wall thickness as designed |
| Bending radius | 1.5 D to 5 D to drawing, tighter radii on request |
| Remaining wall thickness | verified and documented in the bend – that is where stress is highest |
| Materials | 16Mo3, 13CrMo4-5, 14MoV6-3, 10CrMo9-10, X20CrMoV11-1, P91 |
| Welding | butt welds to qualified procedures, preheating and PWHT to suit the material |
| Testing | radiographic or ultrasonic testing of the welds, pressure test, ball passage |
| Code | EN 12952 for water-tube boilers, AD 2000 leaflet W 4 for the tubes |
| Documentation | 3.1 or 3.2 certificate to EN 10204, bending and test report, WPQR |
Materials we supply for this
The grade follows from medium, temperature and pressure. Each grade has a data sheet with composition, properties and standards.
Typical fields of use
- Superheaters and reheaters in steam boilers
- Economiser bundles and feedwater preheaters
- Tube coils in heat recovery boilers behind gas turbines
- Waste incineration plants with a corrosive flue gas side
- Biomass and refuse-derived fuel boilers
- Replacement bundles for outages and damage cases
The records you receive
Inspection certificate 3.1 or 3.2 to EN 10204
Batch-related test results for every pressure-bearing item, countersigned on request.
Non-destructive testing
Visual, penetrant, magnetic particle, ultrasonic or radiographic testing of the welds as specified.
Pressure test
Hydrostatic test to the applicable code and drawing, with test report.
Traceability
Batch and heat number of every item remain traceable through the documentation.
From drawing to delivery
1. Drawing or sketch
Send us the drawing, isometric or bill of material – a hand sketch with dimensions is enough to start.
2. Agree material and code
We settle grade, standard, pressure rating and the required certificate with you.
3. Quotation
You receive a quotation with price, execution and a firm delivery date.
4. Delivery with documentation
The component arrives ready to install, with certificates and test reports.
Superheater coils – frequently asked questions
What matters most when bending?
The remaining wall thickness in the bend. Bending thins the outer side, and that is exactly where the stress is highest. The drawing sets the permissible minimum; we verify and document it.
Which material for which temperature?
Guide values for continuous service: 16Mo3 to around 530 °C, 13CrMo4-5 to 570 °C, 14MoV6-3 to 565 °C, 10CrMo9-10 to 600 °C, X20CrMoV11-1 to 580 °C and P91 to about 620 °C. The creep values of the standard and the design to the applicable code are decisive.
What is the difference between a superheater coil and a tube coil?
Tube coil is the general term for a bent tube string. The superheater coil is the tube coil in the superheater of a boiler – the application with the highest temperature and full internal pressure.
Which tests are usual?
Visual inspection of all welds, radiographic or ultrasonic testing of the butt welds, pressure test with report and a ball passage test to prove the free cross-section after bending.
What do you need for a quotation?
The drawing with bending plan, tube size, material grade, number of strings, design pressure and temperature and the required certificate to EN 10204. A dimensioned sketch with radii and number of strings is enough for a first calculation.
Superheater coils – request a quote
Drawing, material and quantity are enough – we come back with price and lead time.