The inspector should also be involved in the selection of the applicator.
Because at ank lining requires nearly perfect application, ak nowledgeable
and conscientious contractor is required. Again,t he lowest bidder is not
necessarily the best choice.E valuate the applicator before awarding the
contract to assure that the tank liningcontractor is experienced in applying
the specifiedl ining. Before placingacontractor on the bidder’sl ist, review
his qualifications. Inquire as to what jobs he has done usingt he selected
liningmaterial and follow up with those particular applications. If possible,
visit his facilities and inspect his workmanship. An experienced inspector is
helpfuld uringt hise valuation.T aking theses teps will help ensure
installation of at ank liningt hat will provide the desired performance.
4.7C uring
Proper curing is essential if the lining is to provide the corrosion protection
for which it was selected. Each coat must be cured usingp roper air
circulation techniques. Fresh air over 508 F( 108 C) and havingarelative
humidity of less than 89% should be supplied to an opening at the topofthe
vessel with an exhaust at the bottom. The air flow should be fed by forced air
fansa nd should be downward because the solvents used in coatings are
usually heavier than air.B ecause of this, proper exhaustion can only be
obtained with downward flow.
To prevent solvent entrapment between coats and to ensure aproper final
cure, the curing time and temperature must be in accordance with the
manufacturer’s instructions for the specific coating material. Awarmforcedair cure between coats and as afi nal cure willp rovide ad ense film and
tighterc ross-linking, whichp rovides superior resistance to solventsa nd
moisture permeability.Before placingthe vessel in service, the lining should
be washed downwith water to remove anyloose overspray.
Linings must be allowed sufficienttime to obtain afull cure before being
placed in service. This usually requires 3–7 days. Do not skimponthis time.
When the tank is placed in service, operating instructionss hould be
prepared and should include the maximum temperature to be used. The
outsideofthe tank should be labeled; “Do not exceed X 8 F(X 8 C). This tank has
been lined with___________. It is to be used onlyfor ___________ service.”
4.8S afetyduringA pplication
Manyl ining formulations contain solvents, making it necessary to take
certain safety precautions. It is necessary that all liningmaterials and thinners
be kept away from any source of open flame.T his means that welding in
Corrosion of Linings and Coatings
82
CAT8247—CHAPTER 4—17/10/2006—14:33—SRIDHAR—XML MODEL B–pp. 69–174
Because at ank lining requires nearly perfect application, ak nowledgeable
and conscientious contractor is required. Again,t he lowest bidder is not
necessarily the best choice.E valuate the applicator before awarding the
contract to assure that the tank liningcontractor is experienced in applying
the specifiedl ining. Before placingacontractor on the bidder’sl ist, review
his qualifications. Inquire as to what jobs he has done usingt he selected
liningmaterial and follow up with those particular applications. If possible,
visit his facilities and inspect his workmanship. An experienced inspector is
helpfuld uringt hise valuation.T aking theses teps will help ensure
installation of at ank liningt hat will provide the desired performance.
4.7C uring
Proper curing is essential if the lining is to provide the corrosion protection
for which it was selected. Each coat must be cured usingp roper air
circulation techniques. Fresh air over 508 F( 108 C) and havingarelative
humidity of less than 89% should be supplied to an opening at the topofthe
vessel with an exhaust at the bottom. The air flow should be fed by forced air
fansa nd should be downward because the solvents used in coatings are
usually heavier than air.B ecause of this, proper exhaustion can only be
obtained with downward flow.
To prevent solvent entrapment between coats and to ensure aproper final
cure, the curing time and temperature must be in accordance with the
manufacturer’s instructions for the specific coating material. Awarmforcedair cure between coats and as afi nal cure willp rovide ad ense film and
tighterc ross-linking, whichp rovides superior resistance to solventsa nd
moisture permeability.Before placingthe vessel in service, the lining should
be washed downwith water to remove anyloose overspray.
Linings must be allowed sufficienttime to obtain afull cure before being
placed in service. This usually requires 3–7 days. Do not skimponthis time.
When the tank is placed in service, operating instructionss hould be
prepared and should include the maximum temperature to be used. The
outsideofthe tank should be labeled; “Do not exceed X 8 F(X 8 C). This tank has
been lined with___________. It is to be used onlyfor ___________ service.”
4.8S afetyduringA pplication
Manyl ining formulations contain solvents, making it necessary to take
certain safety precautions. It is necessary that all liningmaterials and thinners
be kept away from any source of open flame.T his means that welding in
Corrosion of Linings and Coatings
82
CAT8247—CHAPTER 4—17/10/2006—14:33—SRIDHAR—XML MODEL B–pp. 69–174