products with varying degrees of compatibility.However, there is potential
dangeroffailure if the list is viewed only from the standpoint of the products
approved for service.I fm ore than one of these materials listed as being
compatible with the liningistobeused, consideration must be given to the
sequence of use in which the chemicals or solvents willbestored or carried
in the tank. This is particularly critical when the cargo is water miscible,
for examplem ethanol or cellosolve, and is followed by aw ater ballast.
As equence such as this creates excessive softening of the film and makes
recovery of the liningfi lm more difficult and thus prone to early failure.
Certain tank coating systems may have excellentr esistance to specific
chemicals for agiven period after which they must be cleanedand allowed
to recover for adesignated period of time to return to their original resistance
level.T hirty days is ac ommon period of time for this process between
chemicals such as acrylonitrile and solventss uch as methanol.
When case histories are unavailable, or manufacturers are unabletomake
arecommendation, it will be necessary to conduct tests. This can occur in the
case of ap roprietary material beingh andled or if as olutionm ight contain
unknown chemicals. Sample panels of several coating systems should be
testedf or am inimumo f9 0d ays,w ith a6month test beingp referable.
Because of time requirements,90d aysiss tandard.
The test must be conducted at the maximum operating temperature to
which the lining will be subjected and should simulate operating conditions,
including washing cycles,coldw all, and the effects of insulation.
Otherf actors to consider in linings election includes ervice life,
maintenance cycles,o perating cycles,a nd the reliability of the lining.
Different protective linings provide different degrees of protection for various
periods of time, at avariety of costs. Allowable downtime of the facility for
inspection and maintenancem usta lso be considered in terms of frequency
and length of time.
After the coating system has been selected, recommendations from the
manufacturer for ac ompetent applicator should be requested and contact
should made with previous customers.
4.5L iningA pplication
In lining av essel, the primary concerni st od eposit av oid-free film of the
specified thickness on the surface. Any area that is considerably less than the
specified thickness may have anoncontinuous film. In addition, pinholes in
the coating may cause premature failure.
If the film is toot hick, there is always the danger of solvents being
entrapped, which can lead to bad adhesion, excessive brittleness, improper
cure, and subsequent poorperformance. Dry spraying of the coating should
be avoided because it causes the coating to be porous. Poor film formation
may be caused if thinners other than those recommended by the coating
Corrosion of Linings and Coatings
80
CAT8247—CHAPTER 4—17/10/2006—14:33—SRIDHAR—XML MODEL B–pp. 69–174
dangeroffailure if the list is viewed only from the standpoint of the products
approved for service.I fm ore than one of these materials listed as being
compatible with the liningistobeused, consideration must be given to the
sequence of use in which the chemicals or solvents willbestored or carried
in the tank. This is particularly critical when the cargo is water miscible,
for examplem ethanol or cellosolve, and is followed by aw ater ballast.
As equence such as this creates excessive softening of the film and makes
recovery of the liningfi lm more difficult and thus prone to early failure.
Certain tank coating systems may have excellentr esistance to specific
chemicals for agiven period after which they must be cleanedand allowed
to recover for adesignated period of time to return to their original resistance
level.T hirty days is ac ommon period of time for this process between
chemicals such as acrylonitrile and solventss uch as methanol.
When case histories are unavailable, or manufacturers are unabletomake
arecommendation, it will be necessary to conduct tests. This can occur in the
case of ap roprietary material beingh andled or if as olutionm ight contain
unknown chemicals. Sample panels of several coating systems should be
testedf or am inimumo f9 0d ays,w ith a6month test beingp referable.
Because of time requirements,90d aysiss tandard.
The test must be conducted at the maximum operating temperature to
which the lining will be subjected and should simulate operating conditions,
including washing cycles,coldw all, and the effects of insulation.
Otherf actors to consider in linings election includes ervice life,
maintenance cycles,o perating cycles,a nd the reliability of the lining.
Different protective linings provide different degrees of protection for various
periods of time, at avariety of costs. Allowable downtime of the facility for
inspection and maintenancem usta lso be considered in terms of frequency
and length of time.
After the coating system has been selected, recommendations from the
manufacturer for ac ompetent applicator should be requested and contact
should made with previous customers.
4.5L iningA pplication
In lining av essel, the primary concerni st od eposit av oid-free film of the
specified thickness on the surface. Any area that is considerably less than the
specified thickness may have anoncontinuous film. In addition, pinholes in
the coating may cause premature failure.
If the film is toot hick, there is always the danger of solvents being
entrapped, which can lead to bad adhesion, excessive brittleness, improper
cure, and subsequent poorperformance. Dry spraying of the coating should
be avoided because it causes the coating to be porous. Poor film formation
may be caused if thinners other than those recommended by the coating
Corrosion of Linings and Coatings
80
CAT8247—CHAPTER 4—17/10/2006—14:33—SRIDHAR—XML MODEL B–pp. 69–174