Waste incineration
In a waste boiler it is not pressure that decides service life but the flue gas. Chlorine, sulphur and fly ash attack the tube wall from outside – which makes material selection matter more here than anywhere else.
Why waste boilers differ from coal boilers
Household waste and refuse-derived fuel contain chlorine, sulphur, zinc and lead. In the flue gas these form salts that deposit on the heating surfaces and attack the tube wall underneath the deposit – known as chlorine corrosion. It runs faster the higher the tube wall temperature is. That is why waste boilers are deliberately operated at lower steam parameters than coal boilers, and why the protective layer on the membrane wall is a trade of its own. Selecting by pressure rating alone means ordering short.
What we supply for it
Every part to your drawing, with material certificate and documentation.
The gas-tight wall of the furnace
Bent tube strings for the hottest part of the boiler
Bent tube runs that take up or give off heat
The plate in which the boiler tubes end
Boiler tubes rarely arrive on site in mill lengths. We supply them…
Headers collect and distribute steam or water in the boiler and in the…
Typical materials
The grade follows medium, temperature and pressure. A data sheet exists for every grade.
Standards and codes
| Area | Code |
|---|---|
| Pressure equipment | EN 12952 for water-tube boilers, PED 2014/68/EU |
| Welding | EN ISO 3834, procedure qualification to EN ISO 15614-1 |
| Weld overlay | layer thickness and iron content to customer specification |
| Materials | EN 10216-2 for creep-resistant boiler tube, EN 10028-7 for stainless plate |
| Acceptance | EN 10204: 3.1 certificate, 3.2 where third-party inspection is required |
| Non-destructive | EN ISO 17636 radiography, EN ISO 17640 ultrasonics |
Typical tasks
Membrane wall with protective layer
In the first pass the furnace wall carries an Alloy 625 weld overlay. Layer thickness, bonding and a low iron content are decisive – iron picked up from the base material dilutes the protection.
Superheater in the flue gas pass
The hottest point in the most aggressive environment. Heat-resisting grades or clad tubes are usual; the design deliberately keeps the tube wall temperature down.
Outage with a fixed shutdown window
The boiler is down for a few weeks only. Tube sets are supplied marked by item number so that nothing has to be sorted on site.
Replacement after a tube failure
In a leak shutdown availability is everything. We establish material and size from the old tube or the drawing and deliver at short notice.
Waste incineration – frequently asked questions
Why are waste boilers run at lower steam pressure?
Because corrosion depends on tube wall temperature, not on pressure alone. Higher steam parameters mean a hotter tube wall and markedly faster loss through chlorine corrosion. Efficiency is deliberately traded for service life.
What does the Alloy 625 overlay achieve?
It places a nickel-rich layer between flue gas and tube. Nickel and chromium withstand chloride attack far better than the ferritic base material. Layer thickness – usually 2 to 3 mm – and a low iron content in the overlay are what matter.
Why does the iron content in the overlay matter so much?
Welding mixes base material into the overlay. The more iron carried in, the less remains of the nickel alloy’s protection. Good specifications therefore set an upper limit, often below 5 per cent measured at the surface.
Can you supply from an old tube instead of a drawing?
Yes, on repairs that is the normal case. We need outside diameter, wall thickness, length and if possible the old material designation or an analysis. Without a reliable material designation we recommend testing the material before ordering.
What do you need for a quotation?
Plant and boiler type, position in the boiler, tube size and wall thickness, material grade, where applicable the overlay thickness and iron limit, quantity, date and the required certificate to EN 10204.
Waste incineration supply
Tell us what it is about – plant, medium, temperature. We come back with a proposal, a price and a date.