Rectangular Connections

METU-SYSTEM Rectangular Duct Connections

The METU 4-bolt connection system for the easy and fast and assembly of rectangular ductwork was one of METU's main innovations which rapidly became a worldwide industry standard. Our profiles and corner pieces are still considered today to be one of the sturdiest in the market.

Four criteria affect the performance of your air-ducts, as not all rectangular connections are created equal:


Any leaks increase the energy consumption, the generation of noises
and influence negatively the air-quality.

The METU solution: a prominent edge in the corner area (1)
and a metal to metal sealing-lip (2)

Weak Profiles

The profile deflection influences the the efficiency and integrity of the system,
its applications range and the appearance of the installation.

The METU Solution: a hollow triangular profile (3)

Weak Corner Pieces

The corner piece strength influences the air-tightness of the assembly, the required number of clamps and the required number of supports.

The METU Solution: deeply press-formed corners (4) and the support leg of the profile (5)

Torsional Strength

A gap between the profiles influences the air-tightness of the connections,
the appearance of the installation and the required number of clamps.

The METU Solution: the supporting leg (5) offers a important resistance against torsion.



Corner Pieces


Original 4-Bolts Patent (1969)