Lateral Tee / Y-Lateral - Butt-Weld Pipe Fitting
Our lateral tee (Y-lateral) creates a branch at a 45-degree angle rather than the 90-degree right angle of a standard tee. This gradually angled branch reduces flow turbulence and pressure loss at the junction, providing a smoother, more natural transition for the branching fluid and significantly lowering erosion risk at the branch crotch.
Each lateral tee is supplied with factory-prepared weld-end bevels conforming to BS EN 10253 or ASME B16.25, ready for full-penetration butt welding. Complete traceability from parent material through to finished fitting is maintained, with material test certificates and heat numbers issued with every delivery.
Standards & Materials
Lateral tees are manufactured to BS EN 10253-2 and ASME B16.9 in carbon steel ASTM A234 WPB and stainless steel grades 304/304L and 316/316L. Reducing-branch and custom-angle variants are available to order.
| Attribute | Specification |
|---|---|
| Manufacturing Standard | BS EN 10253-2 / ASME B16.9 |
| Carbon Steel | ASTM A234 WPB, A420 WPL6 (low-temp service) |
| Stainless Steel | ASTM A403 WP304/304L, WP316/316L |
| Special Grades | Duplex & Super Duplex (UNS S31803 / S32205 / S32750), Alloy 20, Inconel 625 / 825, Monel 400, Hastelloy C-276 - available on request |
| Fabrication | Butt-welded or wrought to standard tee geometry |
| Test Pressure | Hydrostatic testing per BS EN 10253-2 requirements |
| Branch Angle | 45 degrees (standard); other angles available on request |
Dimensions & Sizes
Lateral tees are available from 1/2" (DN15) to 24" (DN600) in schedules 10, 40 and 80. The table below shows typical run sizes with the corresponding run and branch centre-to-face dimensions.
| Run Size | DN | Run Centre-to-Face C (mm) | Branch Centre-to-Face M (mm) | Branch Angle |
|---|---|---|---|---|
| 1/2" | DN15 | 38 | 38 | 45° |
| 1" | DN25 | 51 | 51 | 45° |
| 2" | DN50 | 64 | 64 | 45° |
| 3" | DN80 | 76 | 76 | 45° |
| 4" | DN100 | 89 | 89 | 45° |
| 6" | DN150 | 108 | 108 | 45° |
| 8" | DN200 | 127 | 127 | 45° |
| 10" | DN250 | 146 | 146 | 45° |
| 12" | DN300 | 165 | 165 | 45° |
Performance & Benefits
The 45-degree branch angle of a lateral tee provides a markedly smoother flow path than a standard 90-degree tee. This translates to lower pressure loss across the fitting, reduced turbulence-induced vibration and significantly less erosion at the branch crotch — a common failure point in conventional tee installations handling abrasive or high-velocity fluids. The result is extended service life and reduced maintenance costs.
Typical Applications
Commonly used across the UK in wastewater treatment plants, drainage systems, pneumatic conveying lines, chemical process piping and slurry transport systems where a gradually angled branch improves flow characteristics and reduces wear at the junction point.
Quality Assurance & Traceability
Every fitting is manufactured to BS EN 10253-2 and ASME B16.9 and supplied with full material traceability and EN 10204 Type 3.1 test certificates. Heat numbers are recorded throughout production to support inspection, QA and UK project-compliance requirements.
Supply & Delivery
Stocked at our Sheffield, UK facility and delivered nationwide across England, Scotland and Wales. We offer fast dispatch from stock with tracked UK delivery to site, and next-day options for common sizes.
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Which sizes and schedules are available?
Available from 1/2" (DN15) to 24" (DN600) in schedule 10, 40 and 80, in both metric and imperial sizes to suit UK installations.
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Can you provide material certificates?
Yes. Material test certificates and full traceability documentation are available with every order, to project and quality-management requirements.
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What branch angle is standard on a lateral tee?
The standard branch angle is 45 degrees, which provides the optimal balance between flow efficiency and fitting compactness. This angle significantly reduces the turbulence and pressure loss associated with the 90-degree branch of a conventional tee. Custom branch angles can be manufactured to specification on request.
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Do you deliver across the UK?
We deliver nationwide throughout England, Scotland and Wales, with fast dispatch from stock and tracked deliveries to site.