Illustrated example: NPS 2 XXS equal tee, marked WP316/316L. Verify the specification against the order and material certificate.
Specify branch connections by pipe size, wall thickness and material grade. Explore ASME B16.9 dimensions, the illustrated equal tee and technical downloads for your next project inquiry.
Butt-weld connections · Equal & reducing tees · Dimensional references
Prepare Your Inquiry View Drawing & Size Chart Drawing Download
Butt-Weld Tees for Pipeline Branch Connections
A butt-weld tee creates a branch connection in a piping system, with the outlet typically positioned at 90° to the run. Equal tees connect a branch of the same nominal size; reducing tees connect a smaller branch. A complete specification identifies the pipe sizes, end wall thicknesses, material grade and applicable standards.
This page covers stainless steel tees, duplex stainless steel tees, super duplex stainless steel tees and nickel alloy tees. It includes dimensional references for equal and reducing tees, plus an illustrated NPS 2 XXS equal tee marked ASTM A403 WP316/316L. Other materials and sizes require order-specific confirmation.
Materials: Stainless Steel, Duplex, Super Duplex and Nickel Alloys
The following grades are selection references for an inquiry. They do not establish stock availability or verified supply capability for every combination. The product photograph represents the marked 316/316L example.
| Material family | Grade references | Fitting material specification | Selection notes |
|---|---|---|---|
| Stainless steel tees | 304/304L, 316/316L | ASTM A403/A403M | Specify the required grade and verify it against the material certificate. Dual-grade designation requires compliance with both grades. |
| Duplex stainless steel tees | UNS S31803, S32205 (2205) | ASTM A815/A815M | State the UNS grade explicitly. S31803 and S32205 should not be treated as interchangeable solely because both may be described as 2205. |
| Super duplex stainless steel tees | UNS S32750, S32760 | ASTM A815/A815M | Confirm the UNS grade, heat-treatment condition and project inspection requirements. |
| Nickel alloy tees | Alloy 625 (N06625), Alloy 825 (N08825), Alloy C-276 (N10276) | ASTM B366/B366M | Select the specific alloy for the service conditions and confirm availability for the requested size and wall thickness. |
ASME B16.9 addresses fitting dimensions and related requirements. ASTM material specifications address the relevant materials and manufacturing requirements. Material suitability must be assessed for the actual fluid, temperature and pressure.
NPS 2 XXS Equal Tee: Nominal Specifications
| Parameter | Illustrated specification |
|---|---|
| Fitting type | Butt-weld equal tee |
| Nominal pipe size | NPS 2 × 2 × 2 |
| Material marking | ASTM A403 WP316/316L |
| Outside diameter at all three ends | 60.3 mm |
| Nominal wall thickness | 11.07 mm (XXS) |
| Calculated nominal inside diameter | 38.16 mm (OD − 2t) |
| Run center-to-end, C | 64 mm at both ends |
| Outlet center-to-end, M | 64 mm |
| Overall run length, 2C | 128 mm |
| Dimensional reference | ASME B16.9-2024, SI table values |
| End preparation for this example | ASME B16.25-2022: 37.5° ± 2.5° bevel; 1.6 ± 0.8 mm root face |
These values are based on standard tables and readable product markings, rather than a measurement report. Confirm actual dimensions, fitting-body thickness distribution, manufacturing class and dual-grade qualification through inspection records and the material certificate.
Equal Tee Dimensions
C is the center-to-end distance along the run. M is the distance from the run centerline to the outlet end. The following SI dimensions cover the sizes listed in the supplied drawing; this reference range is not a confirmed production or inventory range.
| NPS | OD at bevel (mm) | C (mm) | M (mm) |
|---|---|---|---|
| 1/2 | 21.3 | 25 | 25 |
| 3/4 | 26.7 | 29 | 29 |
| 1 | 33.4 | 38 | 38 |
| 1 1/4 | 42.2 | 48 | 48 |
| 1 1/2 | 48.3 | 57 | 57 |
| 2 | 60.3 | 64 | 64 |
| 2 1/2 | 73 | 76 | 76 |
| 3 | 88.9 | 86 | 86 |
| 3 1/2 | 101.6 | 95 | 95 |
| 4 | 114.3 | 105 | 105 |
| 5 | 141.3 | 124 | 124 |
| 6 | 168.3 | 143 | 143 |
| 8 | 219.1 | 178 | 178 |
| 10 | 273 | 216 | 216 |
| 12 | 323.8 | 254 | 254 |
| 14 | 355.6 | 279 | 279 |
| 16 | 406.4 | 305 | 305 |
| 18 | 457 | 343 | 343 |
| 20 | 508 | 381 | 381 |
| 24 | 610 | 432 | 432 |
Reducing Tee Dimensions and Wall Thicknesses
The downloadable spreadsheet retains the 56 run/outlet combinations in the supplied file. T1 is the nominal matching-pipe wall thickness at the run; T2 is the nominal matching-pipe wall thickness at the outlet. Schedule 5S, 10S, 40S and 80S values were checked against the ASME B36.19-2022 base edition. Agree on the applicable edition and errata in the purchase order.
The XXS example uses ASME B36.10-2022 separately. XXS must not be read from the spreadsheet’s Schedule 80S columns.
| Run NPS | Outlet NPS | Run OD | Outlet OD | C | M |
|---|---|---|---|---|---|
| 0.75 | 0.5 | 26.7 | 21.3 | 29 | 29 |
| 1 | 0.5 | 33.4 | 21.3 | 38 | 38 |
| 1 | 0.75 | 33.4 | 26.7 | 38 | 38 |
| 1.25 | 0.75 | 42.2 | 26.7 | 48 | 48 |
| 1.25 | 1 | 42.2 | 33.4 | 48 | 48 |
| 1.5 | 0.5 | 48.3 | 21.3 | 57 | 57 |
| 1.5 | 0.75 | 48.3 | 26.7 | 57 | 57 |
| 1.5 | 1 | 48.3 | 33.4 | 57 | 57 |
| 1.5 | 1.25 | 48.3 | 42.2 | 57 | 57 |
| 2 | 0.75 | 60.3 | 26.7 | 64 | 44 |
| 2 | 1 | 60.3 | 33.4 | 64 | 51 |
| 2 | 1.25 | 60.3 | 42.2 | 64 | 57 |
| 2 | 1.5 | 60.3 | 48.3 | 64 | 60 |
| 2.5 | 1.5 | 73 | 48.3 | 76 | 67 |
| 2.5 | 2 | 73 | 60.3 | 76 | 70 |
| 3 | 1.5 | 88.9 | 48.3 | 86 | 73 |
| 3 | 2 | 88.9 | 60.3 | 86 | 76 |
| 3 | 2.5 | 88.9 | 73 | 86 | 83 |
| 4 | 1.5 | 114.3 | 48.3 | 105 | 86 |
| 4 | 2 | 114.3 | 60.3 | 105 | 89 |
| 4 | 2.5 | 114.3 | 73 | 105 | 95 |
| 4 | 3 | 114.3 | 88.9 | 105 | 98 |
| 5 | 3 | 141.3 | 88.9 | 124 | 111 |
| 5 | 4 | 141.3 | 114.3 | 124 | 117 |
| 6 | 2.5 | 168.3 | 73 | 143 | 121 |
| 6 | 3 | 168.3 | 88.9 | 143 | 124 |
| 6 | 4 | 168.3 | 114.3 | 143 | 130 |
| 6 | 5 | 168.3 | 141.3 | 143 | 137 |
| 8 | 4 | 219.1 | 114.3 | 178 | 156 |
| 8 | 5 | 219.1 | 141.3 | 178 | 162 |
| 8 | 6 | 219.1 | 168.3 | 178 | 168 |
| 10 | 5 | 273 | 141.3 | 216 | 191 |
| 10 | 6 | 273 | 168.3 | 216 | 194 |
| 10 | 8 | 273 | 219.1 | 216 | 203 |
| 12 | 6 | 323.8 | 168.3 | 254 | 219 |
| 12 | 8 | 323.8 | 219.1 | 254 | 229 |
| 12 | 10 | 323.8 | 273 | 254 | 241 |
| 14 | 8 | 355.6 | 219.1 | 279 | 248 |
| 14 | 10 | 355.6 | 273 | 279 | 257 |
| 14 | 12 | 355.6 | 323.8 | 279 | 270 |
| 16 | 10 | 406.4 | 273 | 305 | 283 |
| 16 | 12 | 406.4 | 323.8 | 305 | 295 |
| 16 | 14 | 406.4 | 355.6 | 305 | 305 |
| 18 | 12 | 457 | 323.8 | 343 | 321 |
| 18 | 14 | 457 | 355.6 | 343 | 330 |
| 18 | 16 | 457 | 406.4 | 343 | 330 |
| 20 | 14 | 508 | 355.6 | 381 | 356 |
| 20 | 16 | 508 | 406.4 | 381 | 356 |
| 20 | 18 | 508 | 457 | 381 | 368 |
| 22 | 16 | 559 | 406.4 | 419 | 381 |
| 22 | 18 | 559 | 457 | 419 | 394 |
| 22 | 20 | 559 | 508 | 419 | 406 |
| 24 | 16 | 610 | 406.4 | 432 | 406 |
| 24 | 18 | 610 | 457 | 432 | 419 |
| 24 | 20 | 610 | 508 | 432 | 432 |
| 24 | 22 | 610 | 559 | 432 | 432 |
For reducing tees with run sizes NPS 26 and larger, M is a recommended dimension. The nominal pipe wall-thickness table does not specify a uniform fitting-body wall thickness or determine a fixed pressure rating.
Technical Drawing and Size Chart
The drawing describes an equal tee. The spreadsheet covers reducing tees. Use the document corresponding to the required fitting type. The supplied drawing retains bilingual technical labels.
Download the corrected reducing tee size chart (XLSX)
Manufacturing, Inspection and Service Selection
Tees are used in process piping, equipment connections, water-treatment systems and other pipework requiring a branch. Specify the material and wall thickness based on the fluid, temperature, pressure and project design requirements.
Review the material grade, heat identification, heat-treatment condition and dimensional inspection records. Define the manufacturing class, nondestructive examination, PMI, additional corrosion testing and any EN 10204 3.1 documentation in the order. ASME B16.9 does not itself require individual hydrostatic testing of every fitting; project-specific testing should be agreed separately.
Frequently Asked Questions
What is the difference between an equal tee and a reducing tee?
An equal tee has the same nominal pipe size at the run and outlet. A reducing tee has a smaller outlet than the run. Specify a reducing tee as run × run × outlet, for example NPS 2 × 2 × 1, with C = 64 mm and M = 51 mm under the SI table values used here.
What are the dimensions of a 2-inch equal tee?
For an NPS 2 equal tee, the ASME B16.9-2024 SI table gives C = M = 64 mm and an outside diameter of 60.3 mm. The overall run length is 128 mm.
Is XXS the same as Schedule 80 or Schedule 160?
No. For NPS 2, XXS has a nominal wall thickness of 11.07 mm, compared with 5.54 mm for Schedule 80 and 8.74 mm for Schedule 160. The illustrated tee is described according to its readable XXS marking; verify the actual specification against the order and material certificate.
How do I select a stainless steel, duplex, super duplex or nickel alloy tee?
Provide the fluid composition, chloride content, operating temperature, design pressure and corrosion allowance. Specify the material grade, manufacturing class and inspection requirements after evaluating the service conditions. A shared dimensional standard does not make different materials interchangeable.
Why are the NPS 22 Schedule 40S and 80S cells blank in the spreadsheet?
These thicknesses are not listed in the ASME B36.19-2022 base-edition table checked for this document. A blank means not listed, not zero thickness. Specify an agreed wall thickness and applicable standard in the purchase order.
Is outlet dimension M mandatory for every reducing tee?
ASME B16.9-2024 Table 6.1-8 states that M is recommended, rather than mandatory, for reducing tees with run sizes NPS 26 and larger. Agree on the required outlet dimension in the order.
What information is required for a tee quotation?
Provide the tee type, run and outlet NPS, material specification and grade, Schedule or nominal wall thickness at each end, standard edition, quantity, service conditions, inspection documents and delivery destination.
Prepare Your Tee Inquiry
Include the following details to support an accurate technical review and quotation:
- Fitting type: equal tee or reducing tee.
- Size: run × run × outlet NPS, plus the Schedule or nominal thickness at each end.
- Material: ASTM specification, WP or UNS grade, and required manufacturing class.
- Service conditions: fluid, temperature, design pressure and corrosion allowance.
- Order details: quantity, inspection and certification requirements, requested delivery date and destination.
Example: Butt-weld equal tee, NPS 2 × 2 × 2, XXS, ASTM A403 WP316/316L, dimensions to ASME B16.9-2024 SI values. Confirm the manufacturing class, inspection documents and quantity in the purchase specification.
