A dual-walled exhaust system significantly reduces the risk of engine fires. Dual-wall pipes are insulated with a central silica layer to reduce external surface temperatures. Lowering the temperature of the outer wall below the fuel flashpoint improves safety and eliminates the need to cover engine pipes with blankets.
In part three of our Heavy-Duty Exhaust essentials series, let's double down with dual-wall exhausts.
What is a Dual-Wall Exhaust?
- Dual-wall exhausts feature an inner and outer pipe layer
- A central silica layer provides additional insulation and assists with MDG 151 compliance (150°C external surface temperature)
- Dual-walls are resistant to fuels and oil infiltration
- These systems connect directly to OEM turbo outlets?
- A dual-wall exhaust should follow the OEM path where possible, but custom brackets and upgraded hardware are necessary for installation
Dual-Wall exhaust design features
- Reinforced components such as solid machined flanges
- Flanges, clamps and mounts designed for minimal heat transfer
- Strategically located vent ports help prevent inner wall failure
- Flexible elements absorb stresses caused by the heat differential between the inner and outer exhaust wall (i.e. different rates of expansion and contraction)
- Silica insulation provides superior temperature reduction compared to dual-walls with airgaps (non-insulated between the walls)
- Central layer options include thermal (insulated), acoustic (perforated) and non-insulated
Fire Mitigation – a robust setup
A dual-wall exhaust system separates fuel and heat sources and reduces outer wall surface temperatures for less ignition risk. Adding an insulated silica layer between the two pipe walls can significantly lower external surface temperatures. Using dual-wall insulated engine pipes eliminates the need for thermal blankets on engine pipes while achieving MDG 151 compliance.
Install thermal blankets on turbos, manifolds, and junctions for comprehensive fire mitigation.
An Aletek dual-wall system can provide you with the following strategic advantages:
- Superior fire strategy – a purpose-engineered solution for ongoing fire mitigation
- Endurance – by improving on OEM designs, there is less risk of premature component failure and unplanned downtime
- Integrated insulation solution – a longer lifespan for the insulated pipe setup (no need to replace blankets on engine pipes)
- Simplified maintenance – no engine pipe blankets remove the need to inspect lagging and the risk of non-reinstallation after servicing
Dual-wall exhaust strategy – considerations?
Reliability Engineers and maintenance crews should consider the following factors before implementing a dual-wall system.
Design considerations
- Check machine availability – dual-wall systems are only available for select assets
- Longterm investment – increased upfront cost compared to a direct-fit and blankets setup; TCO2 should factor in blanket replacement costs
- Space constraints – assess each asset's clearances to determine whether larger dual-wall pipes (and exhaust bend radiuses) will fit; space may limit design options
- OEM integration – due to space limitations, it may not be possible to follow the OEM exhaust path for all assets. The availability of replacement parts is imperative when commissioning a custom solution.
Implementation considerations
- Additional weight – dual-wall engine pipes are significantly heavier than single-wall and blanket setups but supported by reinforced clamps and bracketry
- Bracket and clamp replacement – dual-walls require new hardware to accommodate the larger pipe diameter (Aletek supplies custom hardware with full kit setups)
- Initial installation – new installs require experienced fitters; Aletek can assist
Update your onsite fire mitigation plan to include dual-wall exhausts, don't forget blankets for turbos, manifolds and junctions.
Dual-walls excel for drill rigs, large equipment & sound
Experience has shown that dual-wall exhausts are an excellent consideration for the following applications:
Rotary Blasthole Drills
- Robust upgrades that remove the need for blankets on mufflers and engine pipes
- Protection for workers from exposed mufflers and exhaust pipes
- Enhanced fire mitigation and asset protection?
- Popular solutions: (Atlas Copco) Epiroc DML60, PV235 & PV275?
Large equipment (Ultra Class Trucks & Excavators)
- Purpose-built systems for increased uptime and maximum productivity?
- Extreme durability and added protection against engine-related fires (when coupled with turbo, manifold and junction blankets)
- Less ongoing service requirements, no blanket-related maintenance on engine pipes
- Popular solutions: Cat 6040, 6060 & 794AC, Komatsu 830E-AC, Liebherr T282 & R996B, Terex RH340B?
Sound Suppression solutions
- Dual-wall utilised for engine pipes, silencers, tailpipes, etc
- Custom dual-wall systems help realise acoustic benefits
- Options for central thermal insulation (MDG 151 compliance) or an acoustic-lined inner wall (perforated for sound purposes)
- Custom solutions include: Cat 785B/C & 793D, Komatsu 830E-AC, Liebherr T282
Your next steps
Contact our experts if you're ready to double down and discover the benefits of a dual-wall exhaust setup for select assets. We engineer our Australian-made products to the highest standards to meet the most demanding operational conditions.
In our next instalment, we'll share a final breakdown and recap to wrap up our Exhausts Essentials series.
2 TCO: Total Ownership Costs?
