Application Of Thermal Wrap.

Application of thermal wrap to exhaust piping and exhaust silencers

It is sometimes necessary to control heat radiation from power generation equipment in applications where the generator set is located inside an enclosure or engine room. Providing a safe environment to maintenance personnel is the main consideration for the use of thermal insulation for exhaust manifolds and exhaust piping. With the typical engine exhaust gas temperature ranging between 800F and 1000F for diesel engines (as much as 1200F for gas-fired engines), it is important to select the appropriate level of thermal insulation.

Most engine distributors can provide thermal insulation, whether it be silica-based (typically formed in place) or blanket-type thermal wraps, for generator set applications. For thermal wrap (blankets), typical thickness ranges between 1" to 3". Some exhaust silencer manufacturers also provide internally-insulated silencers, which do away with the need for external insulation.

How effective is this internal insulation? It depends on the material and thickness used, and other environmental conditions. Consider this sample application:

  1. a disk silencer
  2. operating on a sample 1000kW genset with engine exhaust gas flow of 8,475 ACFM
  3. and exhaust gas temperature of 950°F

If this genset were located in a sound enclosure, or engine room with approx 15mph cooling air flow (draft created by radiator fan), the approximate surface temperature of the silencer would be 145F. If the silencer had 1" internal insulation, the shell temperature may reach 190F. Without insulation, the temperature would be much higher (over 200F) and could cause severe injury to personnel.

Similarly, a flex connector with typical 1" thick thermal wrap on this same installation would have a surface temperature of 190F. Thermal blankets used on the engine's turbos and exhaust manifolds would have the highest heat load.

For a recommended specification, we suggest a minimum of 2"-thick thermal wrap for turbos and exhaust manifolds, and our standard Cool Series silencers (with 2" internal insulation). If using conventional silencers, we recommend 2"-thick external insulation on the silencer and related exhaust piping.

Davidson Sales Company represents Maxim in Florida, Georgia, South Carolina, North Carolina, Puerto Rico (USA), Caribbean, & US Virgin Islands. For questions regarding specialized applications of exhaust systems and thermal insulation, please contact Davidson Sales Company.