Seamless tees from the manufacturer – Type A & Type B to EN 10253-2
Equal and reducing tees manufactured in-house in Unna, Germany – cold formed, hot formed or produced by hydroforming (IHU), to EN 10253-2/-4 and ASME B16.9, with inspection certificate 3.1 or 3.2.
up to
up to and beyond
(150 – 1,500 t)
to EN 10204
Type A or Type B – what is the difference?
In short: Type B has increased minimum wall thicknesses at the most highly stressed points – at the crown of the branch (Ts dimension) and at the base of the branch (Tb dimension). This provides additional safety margins at high pressure and high temperature.
Type B requires thicker starting material and specially designed dies – not every manufacturer can supply it. Compliance with the Ts and Tb dimensions is verified during quality inspection and fully documented.
Type A
- Wall thicknessstandard wall thickness to the standard
- Verificationstandard tests
- Applicationgeneral industrial piping
Type B
- Wall thicknessincreased minimum wall thicknesses Ts (crown of the branch) and Tb (base of the branch), thicker starting material, dedicated dies
- Verificationdocumented Ts / Tb verification
- Applicationhigh pressure and high temperature, power plants, nuclear technology, plants to AD 2000 or ASME
Tees at a glance
- Standards
- EN 10253-2/-4 (Type A and B), ASME B16.9 · Codes: EN 13480, AD 2000, ASME B31.1 / B31.3 / B31.12, NORSOK M-630, KTA 3201 / RCC-M
- Designs
- equal tees, reducing tees, special designs to drawing
- Dimensions
- outside diameter up to 610 mm, wall thicknesses up to 50 mm and beyond (e.g. 323.9 × 50 mm in P91)
- Manufacturing
- cold and hot forming, hydroforming (IHU), hydraulic presses 150 – 1,500 t, heat treatment in our own furnace
- Materials
- carbon steel, low-temperature, creep-resistant incl. P91 / P92, stainless steel, duplex / super duplex, nickel alloys, CuNi
- Testing
- NDT (UT, RT, PT, MT), PMI, hardness, ferrite for duplex, Ts / Tb verification for Type B
- Certificates
- EN 10204 3.1, 3.2 on request · quality management system to ISO 9001 and AD 2000
- Special designs
- extended run or branch, special diameter combinations, asymmetrical tees
Designs & special versions
To EN 10253 and ASME B16.9 – every design as Type A or Type B. We manufacture special versions to drawing.
- D = d
Equal tee
Branch with the same diameter as the run
- D > d
Reducing tee
Branch with a smaller diameter than the run
- L+
Extended run
Run ends extended to customer specification
- H+
Extended branch
Branch extended to drawing
- 50 mm
Ultra heavy-wall
e.g. 323.9 × 50 mm in P91 – also asymmetrical and in special combinations
Manufacturing & properties
From seamless or welded pipes – hot or cold formed depending on material, dimension and requirements, by hydroforming (IHU) or from pipe sections. Specially designed forming processes ensure uniform transitions, an optimised wall thickness distribution and high dimensional accuracy.
- Cold and hot forming
- Hydroforming (IHU – internal high-pressure forming)
- Hydraulic presses 150 – 1,500 t
- Heat treatment in our own furnace
- Optimised wall thickness at the transition
Materials
All common material groups – matched to temperature, pressure and corrosion, manufactured to EN 10253-2, ASME B16.9, AD 2000 and PED 2014/68/EU. Further materials on request.
Unalloyed and low-alloy steels
- P235GH / 1.0345
- P265GH / 1.0425
- P355GH / 1.0566
- L360 / 1.0582 / API 5L X52
- L415 / 1.8972 / API 5L X60
- WPB / A234 WPB / Carbon Steel
- WPHY70 / A860 WPHY70
Low-temperature steels
- WPL3 / A420 WPL3
- WPL6 / A420 WPL6
- LF2 / A350 LF2
- P355NL2
- P460NL2
- 10Ni14
- 12Ni14 / 1.5637
Creep-resistant steels
- 16Mo3 / 1.5415
- WP11 / P11 / 1.7335 / 13CrMo4-5
- WP22 / P22 / 1.7380 / 10CrMo9-10
- WP91 / P91 / 1.4903 / X10CrMoVNb9-1
- WP92 / P92 / 1.4901 / X10CrWMoVNb9-2
- X20 / 1.4922 / X20CrMoV11-1
- WB36 / 1.6368 / 15NiCuMoNb5
Austenitic stainless steels and super-austenitic grades
- 304 / 1.4301 / X5CrNi18-10 / V2A
- 304L / 1.4307 / X2CrNi18-9 / TP304L / WP304L
- 316L / 1.4404 / X2CrNiMo17-12-2 / TP316L / WP316L / V4A
- 316Ti / 1.4571 / X6CrNiMoTi17-12-2 / TP316Ti / WP316Ti
- 321 / 1.4541 / X6CrNiTi18-10 / TP321 / WP321
- 347H / 1.4912 / X7CrNiNb18-10 / TP347H / WP347H
- 310S / 1.4845 / X8CrNi25-21 / TP310S / WP310S
- 254SMO / 1.4547 / X1CrNiMoCuN20-18-7 / UNS S31254
- Alloy 926 / 1.4529 / X1NiCrMoCuN25-20-7 / UNS N08926
- 904L / 1.4539 / X1NiCrMoCu25-20-5 / UNS N08904 / 2RK65
Duplex and super duplex
- Duplex / 1.4462 / X2CrNiMoN22-5-3 / UNS S31803 / F51
- Super Duplex / 1.4410 / X2CrNiMoN25-7-4 / UNS S32750 / F53
- Super Duplex / 1.4501 / X2CrNiMoCuWN25-7-4 / UNS S32760 / F55
Nickel alloys
- Monel 400 / 2.4360 / UNS N04400
- Alloy 625 / 2.4856 / UNS N06625 / Inconel 625
- Alloy 825 / 2.4858 / UNS N08825 / Incoloy 825
- Alloy C-276 / 2.4819 / UNS N10276 / Hastelloy C-276
- Alloy 718 / 2.4668 / UNS N07718
- Alloy 800H / 1.4876H / UNS N08810
- Alloy C-22 / 2.4602 / UNS N06022 / Hastelloy C-22
Copper-nickel and special materials
- CuNi10Fe1,6Mn / C70600 / 90-10 CuNi
- CuNi70/30 / C71500
- Zirconium 702 / UNS R60702
Quality testing & documentation
Manufacturing and testing within our quality management system to ISO 9001 and AD 2000. Every test is documented with an inspection certificate to EN 10204 (3.1 / 3.2).
- Visual inspection
- Dimensional and wall thickness measurement
- UT · RT · PT · MT
- Ts / Tb verification (Type B)
- PMI
- Hardness testing
- Ferrite measurement (duplex)
- Third-party inspection: TÜV, BV, customer
- ITP with hold & witness points
In use worldwide
Thanks to their dimensional accuracy and strength, our tees are ideal for pressure, temperature and corrosive environments with the highest safety requirements.
Frequently asked questions about tees
What is the difference between Type A and Type B to EN 10253-2?
Type A is the design with standard wall thickness. Type B has increased minimum wall thicknesses at the crown of the branch (Ts dimension) and at the base of the branch (Tb dimension) – exactly where the tee is most highly stressed during forming. This requires thicker starting material and specially designed dies. Type B is mainly used in high-pressure and high-temperature piping, in power plants and in nuclear technology.
Which designs does Nirotec supply?
Equal tees and reducing tees to EN 10253 and ASME B16.9 as well as special designs: extended run ends, extended branch, special diameter combinations outside the standard and asymmetrical tees to drawing.
Up to what size and wall thickness do you manufacture tees?
Outside diameters up to 610 mm and wall thicknesses up to 50 mm and beyond – for example ultra heavy-wall tees 323.9 × 50 mm in P91.
How are the tees manufactured?
By cold and hot forming on hydraulic presses from 150 to 1,500 t, by hydroforming (IHU, internal high-pressure forming) for precise transition geometries, or from pipe sections. Heat treatment takes place in our own furnace.
Which inspection certificates do I receive?
Inspection certificates to EN 10204 3.1 or 3.2, for Type B with documented Ts / Tb verification. Third-party inspections by TÜV, Bureau Veritas or customer inspectors as well as project-specific ITPs with hold and witness points are possible on request.
What information do you need for a quotation?
Standard / design (e.g. EN 10253-2 Type B or ASME B16.9), version (equal or reducing), dimensions of run and branch (DN / NPS, wall thickness or schedule), material, quantity and requested delivery date as well as the required documentation (3.1 / 3.2, NDT, third-party inspection). Alternatively, simply send us your drawing or bill of materials.
Last updated: October 2026
Request tees
Standard, material, dimensions and quantity are enough – or simply send us your drawing or bill of materials. Heavy-wall designs and special materials too.
