Roxul Industrial Insulation Process - Manual (Page 119)

2.2 Product properties & test methods
2.2.4 Water leachable chloride content
ASTM C795
“Standard Specification for Thermal Insulation for
Use in Contact with Austenitic Stainless Steel”.
This specification covers non-metallic thermal
insulation for use in contact with austenitic
stainless steel piping and equipment. In addition
to meeting the requirements of this standard, the
insulation materials must pass the preproduction
test requirements of ASTM C692, for stress
corrosion effects on austenitic stainless steel, and
the confirming quality control, chemical require-
ments when tested according to ASTM C871.
ASTM C795 shows the results of ASTM C871 in a
graph to illustrate a range of acceptable chloride
concentrations in conjunction with sodium plus
silicate concen trations (see graph illustration
below).
2.2.5 Water repellency
The thermal conductivity and therefore the
insulating capacity of mineral wool insulation
materials are considerably impaired by the
penetration of moisture into the material. Wet
insulation material can also contribute to
corrosion. Therefore, insulation materials must be
dry and protected against moisture during
storage, construction and after being fitted. To
protect the material against the ingress of
moisture, mineral wool insulation materials are
offered with a hydrophobic treatment.
Hydrophobic treatment makes it difficult for water
to penetrate into the insulation and repels water
affecting the insulation from the outside. During
the mineral wool manufacturing process,
hydrophobic oil, which surrounds each fiber like a
protective film, is added. This provides effective
protection against moisture penetration across
the entire insulation thickness. Hydrophobic
treatment does not affect the water vapor
diffusion transmission. The effectiveness of the
hydrophobic treatment is temporary and depends
on the level of moisture. It decreases when
exposed to high temperatures. The primary
objective of the hydrophobic treatment is to
protect the insulation from short bursts of rainfall
during installation, for example. In principle, even
mineral wool insulation that has been hydrophobi-
cally treated must be protected against the
ingress of moisture during transport, storage and
application.
The water repellency of mineral wool insulation
can be tested in accordance with several
standards.
ASTM C795 acceptability of insulation material on the basis
of the plot points of the Cl - and the Na + an SiO
32-
analyses
10.000
1.000
Water-leachable content Sodium and Silicate
(Na + an SiO
32-
) (ppm)
Wa
ter-leachable content Chloride (C
l -
) (ppm)
100
10
1
10.000
100.000
1.000
100
10
1
Unacceptable analysis
Acceptable analysis
ROCKWOOL
mineral
wool
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