Custom Titanium Marine Wet Exhaust Elbows
Your factory marine wet exhaust elbows failed again? Now is the time to try a titanium wet exhaust elbow. Titanium is a light, strong, corrosion-resistant metal. Titanium is the only material that can withstand seawater without corrosion damage. Titanium is not a new material but is relatively new, misunderstood, and underused in the Maritime sector. Carbon and stainless steel, copper-nickel (CuNi), and bronze are historical materials in marine construction. Each has one or more intrinsic weaknesses when it comes to providing a long service life. Corrosion, erosion, electrolysis, and heat oxidation are all failure paths in the machinery used at sea.
What is a marine wet exhaust system?
Failed stainless steel wet exhaust elbow after 2.5 years in service
Marine exhaust systems are an essential part of marine engines and are sometimes often overlooked. A wet exhaust mixes seawater with the exhaust before it can be routed out of the boat. The seawater is provided by a dedicated seawater pump which routes water through the engine lube oil cooler, gearbox cooker, and the main heat exchanger before being injected into the exhaust downstream of the exhaust manifold. Injecting seawater into the exhaust can dramatically lower the exhaust run’s temperature, reducing the risks of fire or being burned by an exhaust pipe.
The marine stainless steel wet exhaust elbow pictured on the side has failed after 2.5 years in service. Stainless steel cannot survive in the hot exhaust and chlorine-rich environments. When a marine wet exhaust elbow fails, the marine engine is at risk if seawater backflows into the cylinders.
If you are having continuous failures with your factory marine exhaust elbows, now is the time to try a titanium marine wet exhaust elbow. Titanium (Ti) is much lighter than stainless steel (SS), so it will not weigh as much. Titanium is stronger and more durable; therefore, it can withstand higher temperatures and corrosion. Titanium is a great conductor of heat; thus, the exhaust system runs cooler and more efficiently.
Titanium in Sea Water Service
“Unalloyed titanium welded tubing and piping has provided more than 40 years of outstanding service in seawater for the chemical, oil refining, desalination, and power industries. As a result of its immunity to ambient, natural seawater attack, titanium is considered to be the technically correct material for many critical marine applications, including many naval and offshore components.”
Ronald W. Schutz, RMI Titanium Company
Titanium Myths
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- Myth 1 – Too Costly: Titanium sits very close to stainless steel in price and well below the cost of copper. The phenomenal growth in offshore wind generators and electric vehicles exacerbates this.
- Myth 2 – Difficult to Weld: Titanium is a ‘reactive metal’ and must be welded in an oxygen-free, Argon shielded environment. But, with proper design and fabrication considerations taken into account, the custom marine wet exhaust elbows can be made cost-effectively. Welding titanium can be accomplished faster than welding some stainless steel with no pre-heat or post-heat treatment required (measured in inches per minute). The elimination of heat treating further reduces manpower, equipment, staging, and QA/QC costs. Automated welding machinery has greatly improved welding applications with a high success record.
- Myth 3 – Difficult to Machine: Machining titanium is very similar to machining carbon steel in terms of tooling, feed rates, and required cooling. As a material, it machines more like carbon steel when adequately lubricated and cooled. Taking the human element out of the machining process allows for consistent and high-speed cutting rates, reliable tool life, and tight tolerances. Machining titanium has come down in cost due to CNC, additive manufacturing, and advanced casting techniques.
- Myth 4 – Low Heat Transfer: “Q” is much more influenced by fluid velocity and tube wall thickness than by a material’s thermal conductivity “k”. Several variables drive heat transfer, all with various levels of influence in the overall equation. Q is a function of heat transfer coefficient, fluid flow velocities, fluid flow characteristics (laminar or turbulent), plate separation distance, and, most importantly, material thickness. Because titanium is so robust, it can accommodate high fluid velocities, small material thickness (no corrosion), and very high temps and delta temps (exhaust systems). These advantages overshadow the low heat transfer coefficient, leading to lighter, more efficient, and longer-lived heat exchangers and exhaust systems.
- Myth 5 – Product Availability: Titanium production continues to increase globally, keeping prices even. The global pandemic has negatively impacted aerospace consumption, so the supply and price of titanium have remained stable. This is not the case for Nickel and Copper alloys.
When considering materials for highly stressed, corrosive service, the current choices center around high nickel content alloys. Comparing technical specs for both super austenitic stainless steel and titanium show that pluses and minuses exist for each material. Consideration must be given not just to the particular material’s chemical resistance to the fluids to which it will be exposed but also to the design, construction, installation, and inevitable repairs required over the equipment’s life.
Nowhere is this more clearly illustrated than in the current activity surrounding marine exhaust gas scrubbers. Custom titanium marine wet exhaust elbows eliminate recurring failures, regulatory fines, and costly replacement scenarios by eliminating super austenitic stainless steel exhaust scrubbers.
Custom Titanium Diesel Exhaust Elbows
Titanium Wet Exhaust Elbow
Titanium provides significant cost, stability, and longevity advantages when used in manufacturing marine products. Titanium is longer-lived and less overall expensive, reducing total ownership costs and environmental risks. Titanium is a light, strong, corrosion-resistant metal. Titanium is the only material that can withstand seawater without corrosion damage. The long service life of the titanium wet exhaust elbows counters the higher price per unit mass of titanium. Systemic problems of corrosion, erosion, and heat damage are eliminated when titanium is used to supplant traditional but lesser alloys. Lower Total Cost of Ownership (TCO) argues strongly for using titanium in marine applications.
The wet exhaust nozzle pictured on the side is made of 100% titanium construction. This titanium wet exhaust elbow is sized for a 120 kW generator (Northern Lights – John Deere package). Titanium is unaffected by exhaust heat, sulfur, seawater, or chlorides.
Titanium is considered to be the technically correct material for many critical marine applications.
Now, the US Navy specifies titanium as the material of choice for machinery heat exchangers. This significantly reduces the annual replacement costs and helps maintain combat readiness. Your engines, gearboxes, hydraulic power units, comfort cooling systems, and wet exhaust elbows can be equally protected, providing service years longer than brass or copper units. Importantly, the operating costs for the ship are lowered, and vessel downtime is reduced.
Are you looking for a replacement marine exhaust system? All titanium exhaust risers and wet or dry elbows are custom-built. Contact us today with your exhaust drawings for pricing and availability.
