manufacturer are used. Do not permit application to take place below the
temperature recommended by the manufacturer.
Duringa pplication, the film thickness should be checked. This can be
accomplished by use of an Elcometer or Nordsen wet film thickness gauge.
If the wet film thickness meets specifications, in all probability the dry film
will also be within specification limits.
All gauges used to measure dry film thickness must be calibrated before
use, followingt he manufacturer’s recommendedp rocedure. Readings
should be taken at random locations on af requent basis. Special attention
should be given to hard-to-coat areas.
4.6I nspection
Proper inspection requires that the inspector be involved with the job from
the beginning. An understanding of the design criteria of the vessel and the
reasons for the specificdesign configuration is helpful. The inspectorshould
participate in the prework meeting, prejob inspection, surfacep reparation
inspection, and coating application inspection. Daily inspection reports
should be prepared alongw ith afi nal acceptance report.
Before the coating is applied, the inspector should verify that the vessel
has been properly prepared for lining. Welds must be ground smooth with a
rounded contour. It is not necessary that they be ground flush.S harp
protrusions should be rounded and weld crevices manually opened so that
the coating can penetrate. If this is not possible, the projection should be
removed by grinding. Back-to-back angles, tape,orstitch welding cannot be
properly cleaned and coated. They should be sealed with caulkingtoprevent
crevice corrosion.
After the vessel has been sandblasted, the inspector should work quickly
so that the application of the coating to the surface is not delayed.
The inspector should examine coatings during and after application. It is
important to check for porosities. The first visual inspection is mandatory to
detectp inholing and provide recoat instructions. Visual inspections are
performed either with the unaided eye or by the use of amagnifying glass.
After repairs of visibledefects, inspection should be carried out usinglow
voltage (75 Vorl ess) holiday detectors that ring, buzz,o rl ight up to show
electrical contact through aporosity within the coating to the metal surface.
This check should be performed after the primer or second coat, so that these
areas can be touched up and made free of porosities before the final top coat.
These visual techniques permit the inspectortoidentify areas that have been
missed, damagedareas, or thin areas. In someinstances, white primers have
been used to spot areas of low film thickness or inadequate coverage of the
substrate.T he final test, employing instruments, will provide the inspector
with an accurate appraisal as to whether or not the proper film thickness has
been achieved.
Liquid-Applied Linings
81
CAT8247—CHAPTER 4—17/10/2006—14:33—SRIDHAR—XML MODEL B–pp. 69–174
temperature recommended by the manufacturer.
Duringa pplication, the film thickness should be checked. This can be
accomplished by use of an Elcometer or Nordsen wet film thickness gauge.
If the wet film thickness meets specifications, in all probability the dry film
will also be within specification limits.
All gauges used to measure dry film thickness must be calibrated before
use, followingt he manufacturer’s recommendedp rocedure. Readings
should be taken at random locations on af requent basis. Special attention
should be given to hard-to-coat areas.
4.6I nspection
Proper inspection requires that the inspector be involved with the job from
the beginning. An understanding of the design criteria of the vessel and the
reasons for the specificdesign configuration is helpful. The inspectorshould
participate in the prework meeting, prejob inspection, surfacep reparation
inspection, and coating application inspection. Daily inspection reports
should be prepared alongw ith afi nal acceptance report.
Before the coating is applied, the inspector should verify that the vessel
has been properly prepared for lining. Welds must be ground smooth with a
rounded contour. It is not necessary that they be ground flush.S harp
protrusions should be rounded and weld crevices manually opened so that
the coating can penetrate. If this is not possible, the projection should be
removed by grinding. Back-to-back angles, tape,orstitch welding cannot be
properly cleaned and coated. They should be sealed with caulkingtoprevent
crevice corrosion.
After the vessel has been sandblasted, the inspector should work quickly
so that the application of the coating to the surface is not delayed.
The inspector should examine coatings during and after application. It is
important to check for porosities. The first visual inspection is mandatory to
detectp inholing and provide recoat instructions. Visual inspections are
performed either with the unaided eye or by the use of amagnifying glass.
After repairs of visibledefects, inspection should be carried out usinglow
voltage (75 Vorl ess) holiday detectors that ring, buzz,o rl ight up to show
electrical contact through aporosity within the coating to the metal surface.
This check should be performed after the primer or second coat, so that these
areas can be touched up and made free of porosities before the final top coat.
These visual techniques permit the inspectortoidentify areas that have been
missed, damagedareas, or thin areas. In someinstances, white primers have
been used to spot areas of low film thickness or inadequate coverage of the
substrate.T he final test, employing instruments, will provide the inspector
with an accurate appraisal as to whether or not the proper film thickness has
been achieved.
Liquid-Applied Linings
81
CAT8247—CHAPTER 4—17/10/2006—14:33—SRIDHAR—XML MODEL B–pp. 69–174