It is importantthat processing liquor is not directed against the side of the
vessel,b ut rather toward the center.O ther appurtenances inside the vessel
mustb el ocated for accessibility of the lining.H eating elements should be
placed with aminimum clearance of 6in. Baffels, agitatorbaseplates, pipes,
ladders, and other items can eitherbelined in place or detached and coated
before installation. The use of complex shapess ucha sa ngle channels and
I-beamss hould be avoided. Sharp edgess hould be ground smooth and
should be fully welded. Spotwelding or intermittent welding should not be
allowed.G ouges, hackles, deep scratches, slivered steel, or other surface
flaws should be ground smooth.
Concrete tanks should be located abovet he water table. They require
special liningsystems. Unless absolutely necessary,expansion jointsshould
be avoided. Small tanks do not normally requiree xpansionj oints. Larger
tanks can make use of ac hemically-resistant joint such as ap olyvinyl
chloride (PVC). Any concrete curing compound must be compatible with the
liningm aterial, or removed before application. Formj oints must be as
smooth as possible. Adequate steel reinforcement must be used in astrong,
densec oncretem ix to reduce movement andc racking. Thel ining
manufacturer should be consulted for special instructions. Concrete tanks
should be coated by al icensed applicator.
4.2V esselPreparation
For the liningmaterial to obtain maximum adhesion to the substrate surface,
it is essentialt hat the surface be absolutely clean. All steel surfaces to be
coatedm ust be abrasive-blastedt oawhite metal in accordance with SSPC
SpecificationSP5-63 or NACE Specification 1. Awhite metal blast is defined
as removing all rust, scales, paints, andsoon, to aclean white metal that has
au niform gray-white appearance. No streaks or stains of rusto ra ny other
contaminantsa re allowed. At times,anear-white, blast-cleaned surface
equal to SSPC SP-10 may be used. If this is permitted by the manufacturer of
the lining material it should be used as it is less expensive.
All dust and spentabrasive must be removed from the surface by vacuum
cleaning or brushing. After blasting, all workers coming into contactw ith
the clean surfaces hould wear clean, protective glovesa nd clothing to
prevent contaminationofthe cleaned surface. Anycontamination may cause
premature failure by osmotic blisteringoradhesion loss.The first coatmust
be applied before the surface starts to rust.
Concrete surfaces must be clean,dry,and properly cured before applying
the lining. All protrusions and form joints must be removed. All surfaces
mustb et oughened by sandblasting to remove all loose,w eak, or powdery
concrete to open all voids and provide the necessary profile for mechanical
adhesion of thec oating. Alld ustm ustb er emovedb yb rushingo r
Corrosion of Linings and Coatings
74
CAT8247—CHAPTER 4—17/10/2006—14:33—SRIDHAR—XML MODEL B–pp. 69–174
vessel,b ut rather toward the center.O ther appurtenances inside the vessel
mustb el ocated for accessibility of the lining.H eating elements should be
placed with aminimum clearance of 6in. Baffels, agitatorbaseplates, pipes,
ladders, and other items can eitherbelined in place or detached and coated
before installation. The use of complex shapess ucha sa ngle channels and
I-beamss hould be avoided. Sharp edgess hould be ground smooth and
should be fully welded. Spotwelding or intermittent welding should not be
allowed.G ouges, hackles, deep scratches, slivered steel, or other surface
flaws should be ground smooth.
Concrete tanks should be located abovet he water table. They require
special liningsystems. Unless absolutely necessary,expansion jointsshould
be avoided. Small tanks do not normally requiree xpansionj oints. Larger
tanks can make use of ac hemically-resistant joint such as ap olyvinyl
chloride (PVC). Any concrete curing compound must be compatible with the
liningm aterial, or removed before application. Formj oints must be as
smooth as possible. Adequate steel reinforcement must be used in astrong,
densec oncretem ix to reduce movement andc racking. Thel ining
manufacturer should be consulted for special instructions. Concrete tanks
should be coated by al icensed applicator.
4.2V esselPreparation
For the liningmaterial to obtain maximum adhesion to the substrate surface,
it is essentialt hat the surface be absolutely clean. All steel surfaces to be
coatedm ust be abrasive-blastedt oawhite metal in accordance with SSPC
SpecificationSP5-63 or NACE Specification 1. Awhite metal blast is defined
as removing all rust, scales, paints, andsoon, to aclean white metal that has
au niform gray-white appearance. No streaks or stains of rusto ra ny other
contaminantsa re allowed. At times,anear-white, blast-cleaned surface
equal to SSPC SP-10 may be used. If this is permitted by the manufacturer of
the lining material it should be used as it is less expensive.
All dust and spentabrasive must be removed from the surface by vacuum
cleaning or brushing. After blasting, all workers coming into contactw ith
the clean surfaces hould wear clean, protective glovesa nd clothing to
prevent contaminationofthe cleaned surface. Anycontamination may cause
premature failure by osmotic blisteringoradhesion loss.The first coatmust
be applied before the surface starts to rust.
Concrete surfaces must be clean,dry,and properly cured before applying
the lining. All protrusions and form joints must be removed. All surfaces
mustb et oughened by sandblasting to remove all loose,w eak, or powdery
concrete to open all voids and provide the necessary profile for mechanical
adhesion of thec oating. Alld ustm ustb er emovedb yb rushingo r
Corrosion of Linings and Coatings
74
CAT8247—CHAPTER 4—17/10/2006—14:33—SRIDHAR—XML MODEL B–pp. 69–174