Page 14 - Donaldson - Exhaust product guide for medium and heavy-duty vehicles and equipment

Shoptalk
General Exhaust Facts, Maintenance Tips and Product Features

SHOPTALK Exhaust Product Materials than aluminized but exhibits cosmetic problems at

There are a number of materials found in diesel exhaust
applications. Some of the materials are appropriate exhaust system temperature. At first exposure to
for heavy-duty applications and have the mechanical high temperature it discolors. Over time it develops
properties to provide good service life. a nondestructive coating of surface rust. After an
extended time in the field a 409 product will display
Since materials vary in strength, corrosion resistance, external discoloration and look worse than a similar part
and price, a particular material may be preferred in made from aluminized steel, but will last much longer.
individual applications and components. Some of the
most common materials, their qualities and their typical Another choice is 409 stainless steel with an aluminum
uses are listed in the following table. coating. Aluminized 409 is used on diesel catalytic
converter mufflers due to its excellent high temperature
Materials* Used in Qualities resistance and the corrosion protection of the
Aluminized Mild Mufflers - Good Corrosion aluminized coating. Aluminized 409 is found primarily
Steel Resistance
Exhaust Components on emission products or high temperature gasoline
Stainless Steel Flexible Tubing - Stronger applications.
(with and without - Excellent Corrosion
aluminized coating) Mufflers Resistance Series 300 stainless steels are also utlized in exhaust
Exhaust Components - Temperature Limit
1500°F systems. The most common material is Type 304. This
Emissions Products
material has excellent corrosion resistance and very
Chrome Accessories - Bright Mirror Finish good high temperature strength and is used in some
Galvanized Flexible Tubing - Low Material Cost muffler applications where very high stresses occur.
- Temperature Limit This is a premium material and is also used in many
600°F
gasoline applications. The most prevalent use of the
Cold Rolled Accessories - Poor Corrosion material in heavy-duty diesel applications is for flex pipe.
Resistance
- Low Cost Flex pipe produced from light gauge 304 stainless steel
is an excellent choice considering all the factors of cost,
Aluminized steel is the preferred material for traditional durability and service life.
diesel exhaust applications. Aluminized steel is a low
carbon steel with a thin layer of aluminum alloyed Often chrome plated cold rolled steel parts are found
to the surface. The aluminum provides a barrier for on exhaust system parts. This material is a reasonable
protection of the base material. Aluminized steel choice for cosmetic applications where a bright mirror
parts have an ultimate service temperature of 1500°F finish is desired. Corrosion from the inside of the product
with a continuous duty temperature limit of 1000°F. can still occur. Chrome parts may be very challenging to
This material closely matches the expected service produce. It is important to produce the parts with a high
temperatures of diesel engine applications and has level of quality because surface irregularities are very
excellent corrosion resistance to acidic diesel exhaust visible to the end user.
gases. Aluminized steel parts provide good field life at a
reasonable cost. Paint adhesion issues could occur with An alternate choice for chrome parts is bright annealed
aluminized steel parts if operating conditions produce stainless steel. This material provides a bright mirror-like
continued surface temperatures that exceed 850°F. finish with excellent exhaust service life. Bright stainless
steel is typically used for muffler heat shields and
Series 400 stainless steels are used for many extended generally is an expensive material choice.
service life diesel applications and often in gasoline
applications due to their higher operating temperatures.
This material family provides slightly better strength at
exhaust system temperatures than aluminized steel.

Type 409 is the most common 400 series stainless steel
used in exhaust applications. Type 409 is stronger

12 • Exhaust Product Guide donaldsonfilters.com