EN 12952 or EN 12953? Boiler standards and materials at a glance
Two standard series, two types of boiler: EN 12952 covers water-tube boilers, EN 12953 shell boilers. Anyone procuring tubes, bends or tubesheets for them needs to know which of the two applies – because material selection, scope of testing and documentation all follow from it.
Water-tube boiler or shell boiler?
The difference lies in what is inside the tube. In a water-tube boiler the water flows through the tubes and the flue gas passes around them. In a shell boiler it is the other way round: the flue gas runs through the tubes, which sit in the water space.
| Feature | Water-tube boiler | Shell boiler |
|---|---|---|
| Standard | EN 12952 | EN 12953 |
| Inside the tube | water or steam | flue gas |
| Typical pressure | high to very high | medium |
| Typical output | large, up to power plant scale | small to medium |
| Typical application | power plants, waste incineration, industrial boilers | process steam, district heating, heating plants |
| Critical components | superheater coils, membrane walls, headers | tubesheets, furnace tube, smoke tubes |
Both series are harmonised standards under the Pressure Equipment Directive 2014/68/EU. Building to them satisfies its essential safety requirements.
How the series are structured
Both series consist of several parts. For material procurement the first parts matter most.
| Part | EN 12952 (water-tube) | EN 12953 (shell) |
|---|---|---|
| Part 1 | General | General |
| Part 2 | Materials for pressure parts | Materials |
| Part 3 | Design and calculation | Design and calculation |
| Further parts | Workmanship, inspection during construction, equipment, feedwater quality, acceptance tests | Workmanship, inspection during construction, equipment, water quality, acceptance tests |
On the order a reference to the materials part is usually enough – EN 12952-2 or EN 12953-2 – together with the actual product standard of the tube.
The creep-resistant materials
The higher the steam temperature, the more alloying elements. The overview below shows the grades most common in boiler construction, each with the range in which they are typically used in continuous service.
| Material | Standard | Continuous service to approx. | Typical use |
|---|---|---|---|
| P235GH, P265GH | EN 10216-2 | 400 °C | feedwater, saturated steam, economiser |
| 16Mo3 | EN 10216-2 | 530 °C | evaporator, first superheater stages |
| 13CrMo4-5 | EN 10216-2 | 570 °C | superheaters, headers |
| X20CrMoV11-1 | EN 10216-2 | 580 °C | live steam lines in older plants |
| 10CrMo9-10 | EN 10216-2 | 600 °C | hot superheater stages, reheaters |
| P91 (X10CrMoVNb9-1) | EN 10216-2 | 620 °C | modern plants with high steam parameters |
Important: these values are guidance for continuous service, not design limits. The permissible design temperature follows from creep rupture strength, wall thickness and the required service life – it comes out of the calculation to Part 3, not out of a table.
Testing and documentation
Boiler components are almost always main pressure-bearing parts in a higher category. An inspection certificate 3.1 to EN 10204 is therefore the rule, 3.2 where a notified body witnesses. That usually comes with:
- Non-destructive testing – ultrasonic or eddy current on every tube, radiography on welds
- Heat treatment record – normalised or quenched and tempered, with a chart
- Traceability – heat and batch per item, marked on the part
- Dimensional check – especially on bent parts: wall thinning and ovality in the bend
For enquiries referencing the AD 2000 code the same applies in a different system – for tubes, data sheet W 4 governs there.
What we supply for this
We supply superheater coils, membrane walls and drilled tubesheets to drawing, plus creep-resistant tubes in fixed lengths, bends with special radii and flanges and fittings in matching grades. How superheater coils and tubesheets are made is described in Superheater coils and tubesheets; an overview of the grades is available under Materials.
Frequently Asked Questions
What is the difference between EN 12952 and EN 12953?
EN 12952 covers water-tube boilers, in which the water flows through the tubes and the flue gas passes around them. EN 12953 covers shell boilers, in which the flue gas runs through the tubes. Water-tube boilers reach higher pressures and outputs; shell boilers are typical for process steam and district heating.
Which materials are used in boiler construction?
Below roughly 400 °C, P235GH and P265GH are sufficient. Above that come creep-resistant grades: 16Mo3 to around 530 °C, 13CrMo4-5 to around 570 °C, 10CrMo9-10 to around 600 °C and P91 to around 620 °C. The actual design temperature follows from the calculation.
Are EN 12952 and EN 12953 harmonised standards?
Yes. Both series are harmonised standards under the Pressure Equipment Directive 2014/68/EU. Designing and manufacturing to them satisfies the essential safety requirements of the directive.
Which material certificate do I need for boiler tubes?
As a rule an inspection certificate 3.1 to EN 10204, because boiler components are almost always main pressure-bearing parts in a higher category. Where a notified body or the purchaser witnesses, it becomes a 3.2. Either must be agreed before manufacture.
What should be watched on bent boiler tubes?
Wall thinning on the outside of the bend and ovality within it. Both have to be accounted for in the calculation to Part 3 and should be named explicitly in the scope of testing on the order.
Do you need exactly these parts?
Grade, size, pressure rating and quantity are enough – you usually receive your quote the same day, with an inspection certificate 3.1 on request.
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