Additive manufacturing · Metal and steel

Additive manufacturing in metal and steel: what is technically possible for flange, fitting, pipe, valve and spare part

The question “can this be printed?” has its own technical answer for every component class in piping. It depends on geometry, size, material and on what the part has to do – and on the honest calculation against the forged, rolled or cast standard part. This page goes through the component classes, gives traffic light, reason and route per process, explains the technical reasons behind the traffic lights and shows why repair by build-up welding is the simplest case. What the rules say about it is on the neighbouring page.

Standard parts: Flange, elbow, tee, reducer, pipe: technically possible, economically pointless
Worthwhile: Valve bodies and trims, impellers, special parts with internal channels
Repair: Laser or arc deposition on the existing part
Technical reasons: Porosity, anisotropy, residual stresses, surface, build volume, inspectability, cost
Inspection: Computed tomography where ultrasonic testing fails on the surface
Zickwolff: supplies the standard part – from stock or to order

Flanges, elbows, tees, reducers, pipes: technically possible – and still not worthwhile

A DN 50 flange fits into any powder bed. It is built, stress-relieved, cut from the plate, the sealing face and the bolt holes are machined – and at the end you hold a part that has cost a multiple of the forged flange, whose internal tightness only a computed tomography scan can prove, and that no product standard knows. That is the situation for all standard parts: elbows and tees are hot-formed from pipe or pressed from plate and welded, reducers turned or drawn, pipes rolled or longitudinally welded by the metre. Each of these processes is denser, faster and cheaper by orders of magnitude than layer-by-layer building. Technically “yellow” then – it works –, in practice never the choice. The one exception is special branches and manifolds with internal channels that cannot be drilled: that is where the benefit begins, and where the standard part range ends.

Laser powder bed fusion (PBF-LB/M): technical and normative assessment per component class
Component	Technical	Reason	Normative	Reason	Our recommendation
flange	with restrictions / only with individual appraisal	possible up to about DN 100 in the build volume, sealing face must be machined – forged flange is far cheaper	not worthwhile / no standard part, no approval	EN 1092-1 refers to forgings, castings and plate as product forms – an additively built flange is not a flange to the standard even with the right dimensions and material number – as a pressure part it needs an individual material appraisal under the PED	standard flange from stock – forged, certified, available in every size
elbow	with restrictions / only with individual appraisal	buildable up to the volume limit, wall thickness and inner surface to verify – no gain over a bent or hot-formed elbow	not worthwhile / no standard part, no approval	EN 10253 fittings are made from pipe or plate – a printed elbow is outside the product standard and, in a pressure line, outside EN 13480 without an appraisal	seamless or welded elbow to EN 10253 from stock
tee	with restrictions / only with individual appraisal	the one useful case: branch pieces and manifolds with internal channels that cannot be drilled	with restrictions / only with individual appraisal	as for the elbow: no product standard covers the additively built form – branch outlets with internal geometry are the one case where a print adds value – as a special part with appraisal	tee to EN 10253 from stock – special branches as forged or welded special part
reducer	not worthwhile / no standard part, no approval	rotationally symmetric part – turning from bar is faster, cheaper and fully dense	not worthwhile / no standard part, no approval	as for the elbow – the reducer is a standard part in every combination we stock	reducer to EN 10253 from stock
pipe	not worthwhile / no standard part, no approval	long, thin-walled, in lengths – neither build volume nor economics	not worthwhile / no standard part, no approval	pipe standards define rolled or welded tube in lengths – additive manufacturing has no product form here at all	pipe to EN 10216/10217 from stock, short special pieces machined from bar or welded
valve body	possible / permitted	small and medium bodies with internal flow paths – the process of the TÜV-certified pressure parts	with restrictions / only with individual appraisal	valve bodies are cast or forged to EN 1503 – a printed body is possible as a special or spare part with an individual appraisal and the manufacturer's qualification – certified manufacturers exist	spare part from the valve manufacturer (KSB prints certified pressure parts), otherwise standard valve from stock
valve trim	possible / permitted	cones, cages, seats and noise-reduction trims with internal channels – established	possible / permitted	trims are manufacturer parts without a product standard – the manufacturer's qualification decides, not a norm – not pressure retaining, so no PED material appraisal	spare part from the manufacturer, additively made where the manufacturer offers it
impeller	possible / permitted	closed impellers with curved channels – the reference application	possible / permitted	the textbook case: manufacturer part, not pressure retaining, geometry that casting struggles with – qualified additively by KSB for years	spare impeller from the pump manufacturer
special fitting or manifold	possible / permitted	manifolds, adapters, heat-exchanger cores with internal channels – where the process pays off	with restrictions / only with individual appraisal	no product standard applies anyway – the part is an individual design – under the PED it needs a material appraisal and, from category I upwards, conformity assessment with the pressure equipment it belongs to	additive manufacturing with individual appraisal – or conventional special fabrication (forged, machined, welded) where the geometry allows
repair by build-up	not worthwhile / no standard part, no approval	powder bed cannot build onto an existing part	not worthwhile / no standard part, no approval	build-up welding on an existing part is additive manufacturing under the rules of welding – qualified procedure, qualified welder or operator, NDT of the deposit – the oldest and best-regulated form	repair by a qualified welding shop – or replacement by the standard part from stock

Valves, impellers, special parts: where printing has its justification

Valve bodies with internal flow paths and trims – plugs, cages, seats, noise-reducing inserts with fine channels – are established in the powder bed; the manufacturers qualify their parts themselves, and KSB has been certified by TÜV SÜD since 2020 for the additive manufacturing of components under the Pressure Equipment Directive. Impellers with curved channels are the reference application, because casting manages the geometry only with cores and rework. Special fittings – manifolds, adapters, heat exchanger cores – are the case in which the process competes against nothing standardised: the part does not otherwise exist. And wire arc deposition builds large steel parts, nozzles and blanks that are subsequently fully machined, where a forging is missing or takes too long.

Wire arc additive manufacturing (DED-Arc, WAAM): technical and normative assessment per component class
Component	Technical	Reason	Normative	Reason	Our recommendation
flange	with restrictions / only with individual appraisal	large flanges buildable as blanks, then fully machined – economic only where no forging exists	not worthwhile / no standard part, no approval	EN 1092-1 refers to forgings, castings and plate as product forms – an additively built flange is not a flange to the standard even with the right dimensions and material number – as a pressure part it needs an individual material appraisal under the PED	standard flange from stock – forged, certified, available in every size
elbow	with restrictions / only with individual appraisal	large-diameter elbows buildable as thick shells with machining – niche for sizes without a standard elbow	not worthwhile / no standard part, no approval	EN 10253 fittings are made from pipe or plate – a printed elbow is outside the product standard and, in a pressure line, outside EN 13480 without an appraisal	seamless or welded elbow to EN 10253 from stock
tee	with restrictions / only with individual appraisal	thick-walled special tees as blanks, fully machined	with restrictions / only with individual appraisal	as for the elbow: no product standard covers the additively built form – branch outlets with internal geometry are the one case where a print adds value – as a special part with appraisal	tee to EN 10253 from stock – special branches as forged or welded special part
reducer	not worthwhile / no standard part, no approval	turning is the process	not worthwhile / no standard part, no approval	as for the elbow – the reducer is a standard part in every combination we stock	reducer to EN 10253 from stock
pipe	with restrictions / only with individual appraisal	short thick-walled special pieces and nozzles as blanks are buildable	not worthwhile / no standard part, no approval	pipe standards define rolled or welded tube in lengths – additive manufacturing has no product form here at all	pipe to EN 10216/10217 from stock, short special pieces machined from bar or welded
valve body	with restrictions / only with individual appraisal	large bodies as blanks with full machining	with restrictions / only with individual appraisal	valve bodies are cast or forged to EN 1503 – a printed body is possible as a special or spare part with an individual appraisal and the manufacturer's qualification – certified manufacturers exist	spare part from the valve manufacturer (KSB prints certified pressure parts), otherwise standard valve from stock
valve trim	with restrictions / only with individual appraisal	coarse – only for large blanks	possible / permitted	trims are manufacturer parts without a product standard – the manufacturer's qualification decides, not a norm – not pressure retaining, so no PED material appraisal	spare part from the manufacturer, additively made where the manufacturer offers it
impeller	with restrictions / only with individual appraisal	large open impellers as blanks	possible / permitted	the textbook case: manufacturer part, not pressure retaining, geometry that casting struggles with – qualified additively by KSB for years	spare impeller from the pump manufacturer
special fitting or manifold	possible / permitted	large special parts, nozzles and blanks in steel at low material cost	with restrictions / only with individual appraisal	no product standard applies anyway – the part is an individual design – under the PED it needs a material appraisal and, from category I upwards, conformity assessment with the pressure equipment it belongs to	additive manufacturing with individual appraisal – or conventional special fabrication (forged, machined, welded) where the geometry allows
repair by build-up	possible / permitted	classic build-up welding – large volumes, on site if needed	possible / permitted	build-up welding on an existing part is additive manufacturing under the rules of welding – qualified procedure, qualified welder or operator, NDT of the deposit – the oldest and best-regulated form	repair by a qualified welding shop – or replacement by the standard part from stock

The technical reasons behind the traffic lights

Residual porosity and tightness. Layer-by-layer solidification leaves pores behind; without hot isostatic pressing the tightness of a pressure-retaining part is a matter of testing, not of assumption.
Anisotropy. Strength and toughness depend on the build direction – a tensile test in one direction says nothing about the other; tests must record the direction.
Residual stresses and distortion. Each layer cools on the previous one; without stress-relief annealing the part distorts when cut from the plate, with arc deposition already during the build.
Surface. Powder bed Ra 5–20 µm, arc deposition wavy layer by layer – every sealing face, every fit, every thread is machined.
Support structures and build volume. Overhangs need supports that must be removed; the build volume limits powder bed parts to typically about 400 mm.
Inspectability. Ultrasonic testing fails on rough surfaces and complex geometry, radiography on thick sections – internal flaws are shown by computed tomography, test specimens per build job complement it (Test methods).
Effort. Powder, machine hour, post-processing and testing against catalogue goods: for a standard part the ratio is unambiguous – the order of magnitude per component class is in the following table.

Effort against stock part or conventional manufacture: order of magnitude per component class (single piece and small series)
Component	Order of magnitude	Why
flange	many times more expensive	forged flange from stock is mass production – the printed part carries powder, machine hours, heat treatment, re-machining of the sealing face and the material appraisal
elbow	many times more expensive	fitting from pipe is mass production – the printed part needs supports and internal re-work
tee	many times more expensive	slightly cheaper than the elbow because the interior is shorter – still far outside any economy
reducer	many times more expensive	as the elbow
pipe	not worthwhile	pipe by the metre against layer-by-layer production – printing appears with pipe only as repair by build-up welding
valve body	comparable	for single pieces the pattern and tooling for casting are not needed – this is why manufacturers print small quantities themselves
valve trim	often cheaper	complex trims with flow channels are often cheaper printed than milled – provided the manufacturer has qualified the part – lead time weeks instead of months according to the manufacturers
impeller	comparable	the classic manufacturer example – single piece without pattern – the advantage lies less in cost than in time – weeks instead of months according to the manufacturer
special fitting or manifold	often cheaper	where internal channels would conventionally need several parts and welds, printing is often cheaper – the one case in which printed can be the first choice
repair by build-up	often cheaper	hence the rule of thumb “repair yes, buy the standard part” – from about DN 200 the repair wins, at DN 50 the stock part

Orders of magnitude from freely accessible sources for single pieces and small series – no prices, no offer. Lead-time statements for impellers and trims are manufacturer information.

Repair by build-up welding: additive manufacturing that nobody calls that

Building up worn seats, restoring shafts and stems, cladding walls, compensating corrosion loss – this has been everyday maintenance work for decades and is technically nothing other than directed energy deposition (DED). The laser with powder works precisely and with low heat input, the arc with wire fast and coarse, on site if need be. The difference from all other component classes: here there is a body of rules that has stood for decades – welding procedure qualification, personnel qualification, non-destructive testing of the deposit. That is why repair is technically and normatively the simplest case.

Bridge to welding. Cladding, hardfacing and repair welding stand in the same standards as the weld seam: procedure qualification to EN ISO 15614, fabrication to EN 13480-4 and AD 2000 HP, testing under the rules of non-destructive testing. Whoever enters additive manufacturing from this side also understands the new rules faster: DIN/TS 17026 and EN 13445-14 transfer the idea of procedure qualification to the powder bed. A knowledge section of its own on welding is in preparation.

Spare part without drawing

The spare part for which no drawing exists any more comes about in three steps, however it is made in the end: measuring the old part, determining the material (stamp, certificate, if in doubt analysis), new drawing with tolerances and material condition. Only then is the decision made – turning, forging, casting, build-up welding or additive. For pump and valve parts the route leads to the manufacturer, who knows and has qualified his part; for everything that has a product standard, to the stock. What the stamp on the component reveals is explained on our pages on reading markings and identifying components.

Frequently asked questions on metal and steel

Up to what size can a flange be printed?

In the powder bed up to the build volume limit, in practice up to about DN 100; above that only as a blank in arc deposition with complete machining. Neither offers a technical or an economic advantage over the forged flange from stock.

Why is a printed part more porous than a forged one?

Because it solidifies layer by layer: gas inclusions and incompletely melted powder particles remain as pores. Forging compacts the material, printing builds it up. HIP closes the pores afterwards.

How is a printed part inspected for internal flaws?

With computed tomography, complemented by test specimens from the same build job (tensile test, impact test, microstructure). Ultrasonic testing and radiography can be used only to a limited extent on rough surfaces and complex geometries.

Can I have a valve body printed?

The manufacturer can – as a spare or special part with his qualification and, for pressure equipment, with a particular material appraisal. For standard valves the stock part is the route.

What about repair welding on a flange?

Building up sealing faces and re-machining them is permitted and common – under the rules of welding, with procedure qualification and testing of the deposit. Whether it pays off against the new flange from stock is decided by the size.

Flanges, fittings, pipes and valves from stock

Tell us component, standard, material and size – we supply forged, rolled or cast, certified to EN 10204, from stock or to order.

Send an inquiry

Your inquiry to Zickwolff

Send us what you have – designation, standard, quantity, date. We will clarify the rest with you.

One item or a question

Send inquiry

Not in stock? We procure it – single items too.

Designation, standard and quantity are enough.

Several items

Send bill of materials

200 items? One parts list is enough – we deliver complete.

Attach it as a file.

Helpful if already known: project and country, date needed, certificates, packaging and language of the packing lists. If anything is missing, we will ask.

It is urgent

Request express

When do you need it? Express delivery, to the site if required.

Tell us by when you need the material – we will tell you what is possible.

← Back to the additive manufacturing overview

Technical basis: ISO/ASTM 52900 (terminology), DIN/TS 17026:2020-10 and E DIN EN 13445-14:2025-01 (scopes), Directive 2014/68/EU Annex I No. 4, EN 1092-1, EN 10253, EN 10216/10217, EN 10204, ASME PTB-13-2021, API Std 20S (2025), DNV-ST-B203 (2025), UBA assessment basis for metallic materials (2026) – each from the freely accessible scopes and legal texts; manufacturer statement KSB on certified production (2020). Suitability assessments are ours; the binding assessment of a pressure-retaining part lies with the notified body and the manufacturer. No prices, no delivery promise. Information without guarantee.