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

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.


Mr. Manfred Meinig, inventor of the 4-bolts system

Original 4-Bolts METU Patent dated 1969