picking up a yard-wide (meter-wide) roll of
the stuff about^3 / 8 -inch (9.5 mm) thick. We cut
it to shape with tin snips and nailed it to the
wall of our cabin behind the coal stove’s
chimney. No respirators, not even a face
mask. Indeed, look at any old text on plumb-
ing, furnaces, kilns, or fire protection, and as-
bestos will be the primary ingredient for all
high-temperature insulating needs. If you are
working on a boat over 30 years old, it may
well have asbestos lagging, possibly a lot of
it.Beware: we know now that inhaling or in-
gesting asbestos is a deadly health hazard.Lagging supplies and kits are often avail-
able from engine manufacturers and from
muffler manufacturers such as Nelson and
Silex. You can also purchase lagging material
independently.LAGGINGMATERIALS Without asbestos, the
most common lagging and insulation materials
for exhaust and fire installation are fiberglass,
calcium silicate, and mineral wool. Depending
on manufacturing details and secondary ingre-
dients, fiberglass insulation (Figure 9-20) is usu-
ally serviceable to temperatures of around
1,000°F to 1,200°F (540°C to 650°C) and cal-
cium silicate to about 1,800°F (980°C). Mineral
wool is used as the name for two different
products: slag wool from iron-ore blast-
furnace slag, and rock wool from—as you
would expect—rocks. They are good for maxi-
mum temperatures of about 1,500°F to 1,700°F
(800°C to 930°C). All insulation should meet
or exceed 46 CFR 164.009.
Calcium silicate, sometimes known un-
der the trade name Thermo-12/Blue, is in fact
hydrous calcium silicate. It is lightweight
with good structural strength. It makes excel-
lent insulation liners for pipe hangers and
clamps as well as insulation pads and boards.
Even-higher-temperature insulation can
be found in ceramic fiber boards, good for as
much as 2,300°F (1,250°C) continuous and
3,000°F (1,650°C) intermittent, and amor-
phous silica, which is good for 2,000°F
(1,100°C) continuous and 3,000°F (1,650°C)
intermittent.
For most standard exhaust and muffler
lagging, fiberglass insulation is quite adequate.
Catalytic converters (so far, not found onPART THREE:EXHAUST SYSTEMS
Figure 9-18.
Removable insula-
tion cover with
wire closure ties
and hooks
(Courtesy
Applegate
Industrial
Materials, Inc.)
Figure 9-19.
Muffler/silencer
insulation blanket
(Courtesy Nelson
Silencer/Fleetguard,
Inc.)