Ⅰ. Definition and size format
The mechanical teefitting is marked as: main pipe size × branch pipe outlet size (e.g., “4” × 2″ means it is suitable for a nominal 4-inch main pipe and has a 2-inch right-angle branch outlet).
The main pipe size refers to the standard nominal pipe diameter it is adapted to, and the shell inner diameter matches the actual pipe outer diameter (e.g., the actual outer diameter of a nominal 3″ pipe is about 3.5″).
The branch pipe outlet size is expressed as a nominal size, which is directly related to the required flow rate and is usually smaller than the main pipe size.
Ⅱ. Size selection principles
1. Pipeline specification matching
Determine the nominal size (NPS) and actual outer diameter of the main pipe and select a matching mechanical tee shell;
Ensure that the branch pipe size meets the design flow and pressure requirements.
2. Borehole size specification
The outlet size is different from the required borehole diameter. For example, a 1½″ nominal branch pipe (actual outer diameter is about 1.9″) usually requires a hole of about 2.7″. The specific size should be consulted with the manufacturer.
3. Interface type selection
Choose a threaded interface (NPT/BSP) or a grooved interface according to system needs.
Some styles of branch pipe interfaces are configured in a mixed manner. For example, the front two ends are grooved, and the middle is threaded.
III. Key factors affecting size
1. Flow and pressure drop
If the branch pipe is too small, it will limit the water flow and increase the pressure drop; if it is too large, it may cause system instability.
The inlet flow demand must be evaluated and matched with the branch pipe size.
2. System pressure and load capacity
When selecting the size, the maximum working pressure of the tee must be considered (commonly 300 psi ~ 20.7 bar, and some models can reach 500 psi).
3. Installation space and typical range
According to common product information:
Common optional sizes include 2″ × ½″, 2″ × 1″, 3″ × 1¼″, 4″ × 2″, 8″ × 4″ and other combinations;
The mainstream mechanical tee on the market is generally suitable for the main pipe size of 2″ ~ 8″ (DN50~DN200), and the branch pipe size is often between ½″ ~ 4″.
Before installation, be sure to refer to the detailed dimension drawing and aperture table provided by the manufacturer.
V. Installation precautions
When drilling, be sure to drill in the center line of the main pipe and ensure that there are no burrs or rust on the edge of the hole.
During installation, apply appropriate lubricant to lubricate the gasket, and the bolts should be tightened to the specified torque by alternating and evenly applying force.
Avoid over-tightening or uneven force to cause sealing failure or hardware damage.
VI. Yinuo product support and selection advantages
As a professional manufacturer with more than 20 years of industry experience, Yinuo provides a variety of specifications of mechanical tees, covering:
Bolted Mechanical Tee
We select ASTM A197 malleable cast iron or A536 ductile iron materials. The products have multiple certifications of UL, FM, ISO, and CE, and are widely applicable to fire protection, HVAC, gas, and building decoration systems. The standard factory model supports DN50 × DN32 to DN200 × DN100, adapting to different pipe diameter requirements to ensure structural stability and reliable sealing.
All mechanical tees pass water pressure testing and size inspection before leaving the factory, and are accompanied by installation aperture drawings and installation instructions, which can effectively reduce project construction risks and rework probability.
If you need to obtain a detailed model list or personalized engineering suggestions, please contact us: ☎[email protected]
Conclusion
The key to choosing the right mechanical tee size is:
Precisely match the pipe size
Strictly follow the drilling size
Adapt the interface method to the use environment
Comply with the system pressure and certification specifications
If the above factors are ignored, it will cause the system pressure loss to increase at best, and leakage, strength failure, and even safety accidents at worst. It is recommended to always choose brand products that meet international standards and have reliable performance, and comprehensively consider the size selection based on the actual project pipe diameter, flow demand, and layout conditions.