An exhaust pipe connector is not just a connector and few may know that the position of the connector in the exhaust system determines which of a total of three types should be used.
The exhaust pipe connector was originally developed to reduce the noise and vibrations which the exhaust system generates in a vehicle, and was mostly used between the exhaust manifold and the exhaust down pipe on vehicles with transverse engine and front wheel drive. "Gradually, the use of exhaust pipe connectors also spread to other parts of the exhaust system and in connection with turbochargers," says Jørgen Grand, Product Director at Triscan and continues: "It is exactly the diverse application that determines which of the total of three types of exhaust pipe connectors you should use. Basically you distinguish between the flex pipe to be used at temperatures up to 650 ° C, up to 800 ° C or above 800 ° C ".
Up to 650°C
For petrol engines you should use exhaust pipe connectors with a working range up to 650 ° C at the rear silencer. For diesel engines this type of exhaust pipe connector is used immediately after the particle filter. The pressure in this part of the exhaust system does not exceed 20 psi working pressure, and the exhaust pipe connector can therefore be designed in a simple two-layer construction as shown here.
2-layer construction for temperatures below 650°C and 20 psi. Outer layer: Braided hose. Inner layer: Piping in metal
Up to 800°C
Exhaust pipe connectors that can withstand temperatures up to 800 ° C are typically positioned at the start of the exhaust system. The pressure in this part of the exhaust system exceeds 20 psi, and the connector must therefore be designed in a three-layer construction as shown here
3-layer construction for temperatures below 800°C and over 20 psi. Outer layer: Braided hose in metal. Middle layer: Piping in metal. Inner layer: Braided hose in metal
Above 800°C
Exhaust pipe connectors are also in some cases used in connection with the wastegate in the turbo system - for example in the VW Touran - for the purpose of reducing vibration transmitted to the turbocharger. This type of connector requires a special three-layer structure as shown below.
3-layer construction for temperatures above 800°C og above 20 psi. Outer layer: Braided hose in metal. Middle layer: Piping in metal. Inner layer: Double-flange hose in metal
Triscan’s programme of exhaust pipe connectors
Triscan’s programme of exhaust pipe connectors comprises 41 references which are all manufactured in a sturdy 3-layer construction that ensures long durability and which can be used at temperatures below 800°C.
The flexible connectors, for welding, are in a superior quality stainless steel – SS 304 – and can be supplied with or without socket. "The price difference between the 2- and 3-layer versions is not very big, and because the number of references is already high, it will not be profitable for the garages, the wholesalers or Triscan to offer both types," says Jørgen Grand, adding "Flex connectors have an exposed existence and we have therefore chosen to manufacture our programme in superior and durable materials. The programme also includes a so-called uni flexible pipe which can be adapted to three different pipe diameters. In addition to flexible connectors, Triscan also offers a programme of 17 different pipe sockets.