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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.

Chlorine corrosionAlloy 625 overlayWith certificate
400 – 450 °C
typical live steam temperature
2 – 3 mm
Alloy 625 overlay
below 5 %
iron content in the overlay
3.1 / 3.2
Certificate to EN 10204
Materials

Typical materials

The grade follows medium, temperature and pressure. The list below is a selection, not a limitation – we supply the grade that design and specification call for. A data sheet exists for every grade.

Codes

Standards and codes

Standards and codes
AreaCode
Pressure equipmentEN 12952 for water-tube boilers, PED 2014/68/EU
WeldingEN ISO 3834, procedure qualification to EN ISO 15614-1 / EN ISO 15614-7
Weld overlaylayer thickness and iron content to customer specification
MaterialsEN 10216-2 for creep-resistant boiler tube, EN 10028-7 for stainless plate
AcceptanceEN 10204: 3.1 certificate, 3.2 where third-party inspection is required
Non-destructiveEN ISO 17636 radiography, EN ISO 17640 ultrasonics
Focus

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.

FAQ

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.

Enquiry

Send your drawing – we will clarify the rest together

A drawing, bill of materials or short description is enough to get started. If already available, the following details help us prepare your quotation quickly.

  • Drawing or isometric; for membrane walls the panel size and pitch
  • Material, or operating data: flue gas and tube wall temperature, HCl content
  • Weld overlay: layer thickness and Fe content, if required
  • Quantity, assemblies and outage date
  • Certificate 3.1 or 3.2, scope of testing and delivery address

Waste incineration supply

Tell us what it is about – plant, medium, temperature. We come back with a proposal, a price and a date.