In order to protect
structural steel from corroding, it is necessary to apply a protective coating
system. The coating system consists of
three coats. On existing steel, all
three coats are applied in the field. On
new steel, inorganic zinc primer is normally applied in the fabrication shop
and the remaining two coats are applied in the field.
When applying coating
systems, it is very important for the Contractor to constantly monitor the
quality of the work. Due to his many
duties and responsibilities, the foreman is not able to properly monitor the
quality of the work. Therefore, the
Contractor is required to assign one person the duties of a Quality Control
Specialist (QCS). If there is no QCS on the project, the Contractor is not
allowed to proceed with any production work.
This person must be formally
trained as a QCS. Prior to allowing the QCS to begin work, the Engineer should
confirm that the QCS appears on the approved list maintained by the Office of
Construction Administration (OCA). This list can be viewed on their website.
The QCS is only to be
involved in quality control work while production work is going on. He is not
to be a foreman or a member of the Contractor’s production staff. He is not allowed to abrasive blast, apply
coating, recover spent abrasive, mix paint, run errands, set up or maintain the
traffic control, run or work on the equipment, etc. It is imperative that the QCS does not
perform supervisory duties on the production staff. If the QCS is not performing his duties or is
involved in any work other than quality control while production work is
proceeding, the violation should be documented and remedied. It should then be determined, based on the
disqualification guidelines in the specification, if the violation(s) warrants
disqualification of the QCS. If the
project staff feels that the criteria for disqualification have been met, all
documentation of the violation(s) is then sent to the Office of Construction
Administration for review. The QCS
should be allowed to continue work during this review process. If the Office of Construction Administration
determines violations are substantiated, the QCS will be permanently
disqualified from their duties as the QCS.
The Office of Construction Administration will inform the project staff
of the disqualification and the QCS should then be relieved of his duties as
the QCS.
The Quality Control
Specialist must be properly equipped with all the necessary testing equipment
and be able to climb to all parts of the structural steel. He has the authority
to stop the Contractor’s work if necessary and to inform the foreman of all
work that does not meet the requirement of the specifications.
The purpose of the quality
control points is to mandate points in the surface preparation and painting
process where the work can be inspected to ensure compliance with the
specifications. It is important that the
QCS signs off at all QCPs to verify that the work
being inspected has been checked and is in complete compliance with the
specifications. This sign-off puts the
accountability for quality on the QCS.
Only after receiving the QCS sign-off should the formal joint inspection
begin. The Contractor’s Quality Control
Specialist (QCS) and the owners’ Inspector (QA) must make independent checks
and document the work at the Quality Control Points.
The testing equipment listed
in the specification must always be available for use by the Inspector. If the equipment is not available or not in
good working order, all production work should be halted. Electric equipment must have batteries and
bulbs to be considered in good working order.
The tables and visual standards must be legible. There must also be film or photographic
printing equipment available.
The list in the specification
indicates the testing equipment that must be supplied by the Contractor, but it
in no way limits the means by which the Inspector may inspect the work. This may include, but is not limited to,
mirrors and larger lights. Note:
Magnification is not allowed to be used for the determination of SSPC-SP10
blast condition.
Abrasive blasting and
painting is to be done between April 1 and October 31. The Contractor should plan his work to ensure
that he is at an acceptable stopping point on October 31. This date is not to be waived without
concurrence from the Office of Construction Administration.
Paint, except for inorganic
zinc, must be applied when the temperature of the air within the enclosure,
steel surface, or paint is 50 °F (10 °C) or higher and is expected to remain
above 50 °F (10 °C) for the times noted in the table shown in 514.06.A. It should be noted that the times shown in
the table are not recoat times. They
simply dictate the required time a particular temperature must be maintained
after the coating is applied. At lower
temperatures the paint will not cure, and in some cases, the paint may not
resume curing when the temperatures warm up.
It is important to pay close attention to the temperature in the early
spring and the late fall. During the
early spring and the late fall, the temperatures will be above 50 °F (10 °C)
during the day, but the temperature will drop during the early evening hours
before the paint has had enough time to properly cure.
The surface temperature of
the steel should be taken in the area that is the coldest. This is not always the same on every
structure (i.e., the fascia beam bottom flange). If you cannot tell where the coldest area is
by running your hand over the steel, then it may be necessary to take readings
in multiple areas.
For inorganic zinc, apply
when the air, steel surface, and paint is 40 °F (4 °C) or higher.
Paint must be applied when
the temperature of the steel is at least 5 °F (3 °C) above the dew point. Applying paint to steel at temperatures below
5 °F (3 °C) above the dew point could result in condensation on the surface of
the steel. The dew point is to be
determined by using the psychrometer and the psychrometric tables or comparable electronic or digital
equipment for the measurement of dew point, accurate within 2 ºF and within one
percent relative humidity. The psychrometer should be used in the area to be painted or
blasted (i.e., in containment near the beams).
Note: If the barometric pressure is unknown when using the psychrometric tables, it is acceptable to assume a
barometric pressure equal to 30 inches.
Abrasive blasting must be
performed when the steel is at least 5 °F (3 °C) above the dew point. This is due to the possibility of
condensation. The Contractor will be
required to re-blast the steel if this requirement is not met.
Heated enclosures may be used
to maintain the temperatures above the minimum specified temperatures. If combustion type heating units are used,
the exhaust fumes must not be permitted in the enclosure, but should be vented
away from the enclosure. If exhaust fumes are not properly vented, they can
leave a deposit on the surface that could affect the ability of remaining coats
of paint to properly bond to the steel or the previous coats of paint. These
exhaust deposits could contaminate the freshly applied paint.
A recording thermometer
should be used to ensure that the minimum temperature is maintained until the
coating has cured. The thermometer
should be placed close to the perimeter of the enclosure since this is the area
subject to cooler temperatures. The
paper graph generated by the recording thermometer should be copied and filed
as part of the QCP documentation.
Special note should be made
to address the handling storage and disposal of hazardous materials used during
construction. Handling, storage, and
disposal of any volatile products are of particular concern. These would normally include thinners,
reducers, and solvents. Common types of
volatile used in a painting operation may include methyl ethyl ketone (MEK), xylene, and toluene based materials.
When these types of items are
on-site, it is important that the Contractor (1) submit MSDS sheets for each
product, (2) maintain a current inventory sheet as to the quantity of each
product (3) properly label usable product and hazardous waste created by the
use of these products, (4) properly containerize and store these products and
wastes so as to not create a health and safety hazard or exposure to the
environment, and (5) waste containers must be managed in such a way that
hazardous waste and non-hazardous waste are properly stored and kept separate.
Proper inspection cannot be
accomplished unless the Inspector has access and proper lighting to see every
surface to be painted.
To accomplish this, the
Contractor is required to provide, erect, and move scaffolding and all other
equipment necessary to provide the Inspector access to closely inspect the
work. On bridges with tall girders,
placing scaffolding only under the girders is not adequate to provide proper
access to the work. The Inspector should not climb around on the structural
steel to inspect the work. If the
Contractor fails to provide proper access to inspect the work, he should not be
allowed to continue since proper inspection cannot be performed.
All scaffolding of any width,
whether it is supported by a wire rope, mounted on the back of a truck, or
supported by any other means, that is at least 21 inches (533 mm) or more below
the surface to be painted, must have guard rail placed on all sides. It is not necessary for scaffolding that is
less than 21 inches (533 mm) below the surface to be painted to have guardrail
on the two sides bounded by the structural steel, but in this case, the
scaffolding must be at least 28 inches (711 mm) wide.
One row of guardrail is
required to be placed around the scaffolding when it is at least 21 inches (533
mm), but less than 43 inches (1092 mm) below the surface to be painted. Two rows of guardrail are required when the
scaffolding is placed 43 inches (1092 mm) or more below the surface to be
painted.
Remember you should never
utilize a means of inspection access that you do not foresee as being safe.
Prior to production blasting,
it is imperative that a test section be blasted and the job site visual
standards be agreed upon and documented.
A comparison to these standards will be utilized for the rest of the
project to accept the surface preparation of the steel. The test section allows the Contractor to
adjust his grit size/blast pressure combination to maximize his production
while producing work that is within the specifications.
Note: In the event of a
dispute, SSPC-VIS 1 will govern.
Document the work with
photographs, especially at Quality Control Points 3, 4, and 11.
One of the most important
items of work is surface preparation. It
is the most labor intensive and expensive phase of the work.
Prior to abrasive blasting,
areas that contain asphalt cement, oil, grease, diesel fuel deposits, or other
petroleum products and contaminants must be solvent cleaned. It is not necessary for the Contractor to
solvent clean the entire surface of the steel to be coated, but only those
areas that contain these contaminants.
Solvent cleaning per SSPC-SP1
requires the removal of foreign material prior to solvent cleaning. This can be done by one or a combination of
the following: wire brushes, abrade, scrape, or clean with solutions of
appropriate cleaners followed by a fresh water rinse.
Make sure that all solvent
brought on-site are accompanied by a current MSDS for that product.
All solvent cleaning should
be completed prior to the start of the abrasive blasting operation. If this is not accomplished, the abrasive
blasting operation will not remove the asphalt cement, oil, grease, diesel fuel
deposits or other petroleum products and contaminants but drive them into the
steel.
In order to remove all
residual solvent, asphalt cement, oil, grease, or diesel fuel deposits after
the solvent cleaning, all solvent-cleaned areas are to be washed with water at
a pressure of at least 1,000 psi (7 Mpa). In order to be effective, the nozzle must be
held no further than 12 inches (300 mm) from the surface being washed.
The specification requires
that bottom flange edges of all beams are to be rounded to a radius of 1/8 ±
1/16 inch. This includes both rolled
beams and girders. It is impossible for
an edge to be given a radius with one straight pass of a grinder. It requires multiple straight passes or a
rounding motion.
The radius is necessary to
allow the application of the proper coating thickness. The sharp edge splits the spray of paint
which results in only a thin coating of paint being deposited along that edge.
The prime coat contains zinc
that protects the steel by reacting chemically with the surface of the
steel. It is important to remove all
foreign material from the surface of the steel to allow the zinc particles to
come in contact with the bare steel. It
is also important to roughen up or produce a profile on the surface of the steel. The profile aids the coating in adhering to
the surface of the steel.
Steel surfaces to be painted
are to be abrasively blasted to a near white metal, SSPC-SP10. SSPC-SP10 is generically defined as white
metal with an allowable 5 percent staining.
This allowable staining is a discoloration. It does not have any volume or noticeable
thickness. It should be noted that
SSPC-SP10 does not allow magnification for this determination. During inspection, pay special attention to
areas that are more difficult to blast or areas that might be difficult to
inspect. These areas include under
cross-frames, around bolt heads and nuts, end dams, cross-frames next to or
close to back walls, and any other areas of limited access. After the steel is blasted, it must be
maintained in that condition until it is painted. The backside of cross-frame assemblies that
are 3 inches (75 mm) or closer to backwalls may be
commercial blast cleaned according to SSPC-SP6.
SSPC-SP6 in generically defined as white metal with an allowable 33
percent staining. Again, this staining
does not have any noticeable thickness.
It is not a residue or film.
The abrasive used in the
field must be steel grit or a recyclable natural mineral, low dusting abrasive.
Do not use silica sands, mineral slags, and other types of non-metallic
abrasives that contain more than 0.5 percent free silica by weight, have a chloride content more than 25 ppm, and contain any organic
material. The Contractor needs to supply material data sheets proofing that the
mineral meets these requirements. The
abrasive must be recycled to minimize the volume of waste material placed into
landfills. The size or gradation of the
grit is not specified, but must provide a profile of 1.5 mils to 3.5 mils. G40 and G50 size steel grits are commonly
used by contractors for abrasive blasting in the field. The profile should be continuously monitored
during the blasting operation since the size of the abrasive can be reduced due
to being recycled, which can in turn reduce the size of the profile. The size of the profile can also be reduced
if the air pressure at the blasting nozzle is reduced. The profile should be monitored by the use of
extra-course replica tape and a spring micrometer. Make sure the replica tape is extra-course as
this is the appropriate tape to measure our specified profile range of 1.5 mils
to 3.5 mils. It is necessary to account
for the 2.0 mil adjustment required for the thickness of the replica tape. This adjustment can be subtracted from every
reading or the micrometer can be zeroed to -2.0 mils which results in a direct
reading being taken from the micrometer.
Some abrasives, when received
by the Contractor, can be contaminated with oil. Abrasives should be checked to ensure that
they are free of oil. This check should
be made by placing a small amount of abrasives in a jar with tap water. The abrasives and water should then be
stirred or shook up. The top of the
water should then be checked for signs of oil.
If oil is detected, the abrasives should not be used.
Apply a prime coat to the
steel that is blast cleaned in the field within 12 hours of the beginning of
abrasive blasting. This requires that
the time and location the blasting was started is accurately documented. This requirement is extended to 24 hours for
shop blasted steel as it is a more controlled environment.
After abrasive blasting is
complete, all abrasive and dust must be removed from the surface to be
painted. Dust and abrasive must be
removed from any adjacent painted surface or any adjacent structure. Dust and abrasive should be removed as soon
as possible to prevent rust staining of adjacent surfaces. Rust stains can be
very difficult to remove.
Occasionally the compressed
air used to propel the abrasive can become contaminated with oil or water from
the compressor. This oil or water, if
deposited on the surface of the steel to be painted, can be detrimental to the
coating system. To prevent this problem,
the Quality Control Specialist must blow air from a nozzle for 30 seconds onto
a white cloth or blotter held in a rigid frame.
This testing must be done at the start of each shift and at 4 hour
intervals. If any oil, water, or other
contaminates are present on the cloth or blotter, the blasting operation must
be suspended until the problem is corrected.
After the operation is corrected, and before the blasting operation is
permitted to proceed, another test should be made to ensure that the problem
has been corrected.
The Contractor must comply
with all federal, state, and local laws, rules, regulations, and ordinances.
Due to the possibility of the
existing coating containing lead , chromium, cadmium,
or arsenic, which are considered hazardous substances over regulatory
concentrations, the Contractor is required to erect an enclosure to completely
surround the area where the existing coating will be removed. Not only should the enclosure be placed
vertically around the sides of the blasting operation, it should be placed on
the ground under the blasting operation. In addition to containing potentially
hazardous debris, the enclosure prevents fugitive dust from escaping into the
environment.
The enclosure must be
constructed of materials that are free of tears, cuts, or holes to prevent dust
and lead from escaping into the environment.
Holes, cuts, or tears that do occur should be repaired immediately. The perimeter of the enclosure should extend
up between the beams to the bottom of the concrete deck. All seams should be fastened or lapped in a
manner that ensures a seal and does not allow any openings between the screens
or materials of the enclosure. The area where workers enter and exit the
enclosure should be sealed.
In addition to placing an
enclosure around the blasting operations, the Contractor must place ground
covers under all equipment. This ground
cover must be placed under the equipment for its entire length, not just a
portion of its length. If the ground is
not properly covered, there is the possibility that it could become
contaminated. These ground covers are
intended to reduce the impact of equipment leaking oil, fuel, or hydraulic
fluid.
All abrasive blasting debris
is to be picked up at the end of the day and must be stored in steel containers
that have lids which lock. The
Contractor will store the debris in 55 gallon drums with lids. The lids have a ring around them that are
capable of being locked. Normally, the
Contractor will lock the lids by means of a bolt. This method is acceptable as long as there is
a nut placed on the bolt and tightened by the use of a wrench. Many times the
lids are not properly locked at the end of the day. They should be checked at the end of the day
or the first thing in the morning to ensure that the Contractor is properly
locking the lids. The use of tie wire,
zip ties, or duct tape are not acceptable as a means for locking the lids. If the Contractor chooses to use a large
roll-off container to store abrasive blasting debris, the requirement for
providing a means to lock the lid of the container must still be enforced.
Within the first week of
production blasting, the Contractor must sample the abrasive blasting debris
and have it sent out for testing. If the
samples come back with lead, chromium, cadmium, or arsenic contents higher than
the limits shown in the table in Section 514.13.D.1
of the Construction and Material Specifications, the abrasive blasting debris
is considered hazardous. Note that parts
per million for these items is equivalent to mg/L. The Contractor must dispose of the abrasive
blasting debris within 60 days after it is generated. The 60 days starts as soon as the Contractor
generates the debris, not after the completion of the abrasive blasting
operation. If the debris remains on the
project site over 90 days, the state and the Contractor could be cited by the
Environmental Protection Agency. On
smaller structures, the debris can be removed in one operation. On larger structures where the abrasive
blasting operation extends over a period of several months, it will be necessary
to make several trips in order to comply with the 60 day limit. If after 60 days, the Contractor has not
properly disposed of the debris, all abrasive blasting and painting of the
structural steel on the project must immediately cease until the waste is
properly disposed. At this time, the
Department must cease processing all pay estimates and send notification to the
Contractor’s surety that he has breached the Contract.
Note that the date of
manufacture does not show up on all container labels. Some manufacturers show a code number in lieu
of a date of manufacture. You will need
to call the manufacturer and give them this code number and they will in turn
give you the date of manufacture.
Prior to applying paint, it
is necessary to thoroughly mix all the ingredients together. This is to be accomplished with a high shear
mixer. Paddle mixers are not allowed
since they will not adequately mix the different ingredients together. Do not use compressed air to cause a stream
of bubbles in the paint and paint shakers since it will not properly mix the
ingredients.
During the application of the
primer, it is important that it be continuously mixed. If it is not
continuously mixed, the zinc particles in the primer will settle to the bottom
of the container and will not be applied to the structural steel. To ensure that the mixing process is not
interrupted, it is important that the mixer be an automated mixer, not a hand
held mixer.
Thinning of the paint is
typically not required. However, if the
Contractor elects to thin the paint, it is important that it be thinned with
the correct type and volume of thinner. To ensure that the Contractor is using the proper type of thinner,
only use thinner recommended and supplied by the paint manufacturer. The maximum rate of thinner is to be as per
the manufacturer’s printed instructions.
If the paint manufacturer’s printed instructions do not list a maximum
proportion of thinner, the manufacturer should be contacted to obtain their
recommendation. Note: The manufacturer
may recommend different thinners based on humidity or temperature. All thinning should be done in the presence
of the Engineer or Inspector.
In an effort to ensure that
the thinner the Contractor is using is the thinner recommended and supplied by
the manufacturer, only use thinner that has been supplied to the project in
unopened containers with the labels intact.
The amount of thinner used from each container should be monitored to
prevent refilling of the container with other types of thinner.
The above restrictions do not
apply to the thinners that the Contractor uses to clean his equipment. Be aware that methyl ethyl ketone (MEK) is sometimes used as both a reducer and a cleaner.
Paint is applied to provide
the specified coating thickness by the use of brush or spray methods. Rollers can cause bubbling and other
irregularities in the coating. Use daubers, small diameter rollers, or
sheepskins to paint the following areas of difficult access: (1) where
cross-frame angles are located within 2 inches (50 mm) of the bottom flanges,
(2) where end cross-frames are within 6 inches (150 mm) of the backwall, (3) where there is less than 6 inches (150 mm)
between the bottom of the bottom flange and the beam seat, and (4) other areas
as determined by the Engineer.
The specification states that
each spray operator shall demonstrate to the Engineer or Inspector the ability to
apply the paint as specified. This
allows the project staff to remove a painter that is unable or unwilling to
produce work within the specification requirements.
All surfaces to be painted
shall be free of dust, dirt, and moisture.
If these or other contaminants are left on the surface they can cause
multiple types of defects, including adhesion failures and accelerated
rusting. Simply blowing down with
compressed air is not always sufficient.
It is sometimes necessary to wipe the surface down, use a vacuum system,
or some other means to adequately prepare the surface to receive paint. This cleanliness requirement includes both
the blasted steel surface as well as previously applied coats of paint.
Apply a prime coat to steel
that is blast cleaned in the field within 12 hours of beginning abrasive blasting. This requires that the time and location the
blasting started is accurately documented.
This requirement is extended to 24 hours for shop blasted steel as it is
a more controlled environment.
The maximum elapsed time
allowed between the application of any portion of the prime coat and the
application of the intermediate coat is 30 days. The maximum elapsed time allowed between the
application of any portion of the intermediate coat and the application of the
finish coat is 13 days. The maximum
recoat times shall not exceed the maximum recommended times by the
manufacturer. Extending the time beyond
the above mentioned time could adversely affect the bond of the coating. No additional time is allowed due to weather
related delays. Any coat that has been
allowed to cure more than the above listed time is to be removed and the steel
re-blasted to SSPC S-P10.
During spray application of
the paint, the operation is to be totally enclosed. The enclosure must be identical to the
enclosure used during the abrasive blasting operation. Failure to properly utilize the enclosure
could result in overspray damage to private property, including automobiles,
the ground, public property, vegetation, streams, lakes, etc. The enclosure is not required if the paint is
being applied by brush or roller.
Each coat of paint is to be
applied as a continuous film of uniform thickness. It is to be free of all defects, such as
holidays, pinholes, mud cracking, checking, runs, sags, etc.
Many time holidays in the
form of pinholes are difficult to detect.
The best way to view pinholes is with the aid of a flashlight. The flashlight should be placed to shine a
beam of light parallel to the painted surface.
If pinholes are present in the top coat, they will appear as small white
specs about the size of the end of a needle.
If they are present in the intermediate coat, they will appear as small
dark specs.
Note: If you are painting
over an inorganic zinc primer, you should play close attention to pinholes
appearing in the intermediate coat. The
inorganic zinc has an inherent characteristic of “outgassing” due to its porous
nature. The released gas pushes up
through the intermediate coat and causes the pinholes. To avoid the majority of pinholes in this
situation, the Contractor should properly apply one or multiple mist coats of
intermediate paint prior to the remaining full application.
Repairing pinholes can be
very difficult. Applying another coat of
paint over the pinholes will only result in the pinhole reflecting through the
additional coat of paint. It is the
Contractor’s responsibility to repair the pinholes. The best way to correct pinholes is by
removing the coating down to at least the prime coat of paint. If the prime coat is not removed,
measurements should be taken to ensure that the required minimum thickness of
prime paint is still present. If the
Contractor elects to leave the prime coat, he will probably remove the topcoats
with sand paper. If a large area needs
to be repaired, it will probably be more prudent for the Contractor to
abrasively blast the coating down to bare metal and reapply it.
Runs and sags are normally
prevalent around bolts and areas of limited access. This is sometimes due to the fact the
Contractor tries to paint these areas using only a spray gun (i.e., without the
use of a brush). These defects should be
corrected after each coat is applied. If
not, the defect will just translate into the next coat and the repair will be more
extensive.
This item is paid for by the
man-hour. The quantity of man-hours
eligible for payment should not include the superintendent or the QCS, but only
the personnel who actually perform the work.
All gaps
greater than 1/8 inch need to be caulked. Caulking is used to seal gaps
around the perimeter of adjacent steel plates and angles. This void is caused by rust forming between
the plates or angles and forcing them apart to the extent that it is not
possible to seal the void with paint.
Caulking materials appear on
the Qualified
Product List (QPL) maintained by the Office of
Material Management (OMM).
Prior to measuring coating
thickness, it is necessary to determine the effect of the blasted surface of
the steel on the paint gauge. Since the steel receives a profile of 1.5 to 3.5 mils (40 to 90 μm), the paint gauge will read high. To compensate for this additional height, it
will first be necessary to take a reading on the blasted surface immediately
prior to applying the prime coat. Preferably three or more readings should be
taken and averaged out. This average
reading should then be subtracted from all paint film thickness readings. As an alternate to subtracting the thickness
attributed to the surface profile from the paint film thickness, recalibrating
the paint gauge to read 0 mils on the blasted steel is also acceptable.
It is important to determine
the coating thickness by taking the average thickness in the manner specified
in the specifications. This involves
taking five spot readings for each type of member (e.g., webs, bottom of top
flange, top of bottom flange, bottom of bottom flange, cross-frames,
stiffeners, etc.) over an area of 100 square feet. A spot reading is comprised of the average of
three closely-spaced, individual readings. The average reading for this 100
square foot area may be used to represent up to 1,000 square feet of painted
steel surface. The number of 100 square
foot areas to be measured is determined by the area of steel painted. Form CA-S-2
should be used to tabulate the results.
The spot averages are to be
within 80 percent to 150 percent of specified minimum and maximum thicknesses,
respectively. The area averages must
fall within the actual specified minimum and maximum values.
There are provisions in the
specification for addressing areas with a film thickness greater than the
maximum specified. If a Contractor
chooses to have the certified testing done as described in the specification,
make sure the preparation of the panels mirrors the actual field installation
of the paint in question. This includes
paint thickness, multiple or mist coats, as well as type and quantity of thinner
used. The Painting Contractor and Paint
Manufacturer must submit certified test data and a written statement from the
paint manufacturer stating that the excessive thickness will not be detrimental
to the overall coating system to the Office of Construction Administration. If
they don’t submit this information, or the Office of Construction
Administration does not accept the excessive coating thickness, the painting
contractor must remove the coatings down to the bare steel per C&MS 514.22.
The purpose of the final
inspection is to ensure that the quality of surface preparation and coating
thickness are witnessed by a third party.
This third party could be the project engineer, area engineer, or other District
personnel.
The Engineer will select the
locations and take the dry film thickness (DFT)
readings. The Contractor will then
perform the removals. The 9 square
inches required by the specification is the minimum “clean” area of steel. It normally takes about a 6 inch by 6 inch
square to get 9 square inches of “clean” steel.
The Contractor will use Methylene Chloride and MEK
as a chemical stripper/solvent. These
chemicals are both corrosive and the safety precautions found on the MSDS
sheets and manufacturer’s literature need to be followed.
A common stripping procedure
is as follows:
1.
Spray surface with stripper.
2.
Wait 5 to10 minutes to allow the stripper
to work.
3.
Use a scraper or putty knife to remove
top coat and intermediate coat. It may take multiple applications of the
stripper to accomplish this.
4.
Spray the exposed primer with stripper
and allow time to work.
5.
Scrape off majority of primer. Be careful
not to damage the substrate.
6.
Repeatedly apply solvent or stripper and
rub with a rag until steel substrate is clean.
This process takes about 15
minutes for each stripped area. Work on other areas while the stripper
sits. It is imperative that the Engineer
observe the removal process as the stripper and a scraper can remove lead paint
as well as new paint.
The engineer will evaluate
the stripped area and document his findings on Form CA-S-18.
If the surface of the
stripped area is not found to be in complete conformance with the Contract
documents, additional locations may be tested.
Note: the Contractor is only paid for stripped areas that are found to
be in conformance with the Contract documents.
Once all the required tests
have been performed, and the progressive project data has been reviewed, the
Engineer should complete Form CA-S-19.
Destructive test locations
shall be repaired per 514.22.
If it is necessary to make
repairs, the repair should blend in with the surrounding area so that it is not
evident that a repair was made.
If the area to be repaired
does not cover a large area, abrasively blasting the surface may not be
advisable since it will damage the surrounding coating that does not need to be
removed. In place of using abrasives,
the Engineer may allow alternate methods of preparing the surface. This might include the use of power tools
with abrasive bits or hand tools.
Whatever method is used, it is still necessary to prepare the surface in
a manner that will give a surface profile of 1.5 to 3.5 mils (40 to 90 μm).
In order to produce a smooth
transition, it is necessary to feather the adjacent coatings. This cannot be accomplished through the use
of abrasives. The new coat of paint
should only be applied to the same coat that was feathered (i.e., the prime
coat should only be applied to the feathered prime coat, the intermediate coat
should only be applied to the feathered intermediate coat, and the finish coat
should only be applied to the feathered finish coat). Applying the finish coat to an existing
finish coat that has not been feathered, or in any other way abraded, will
result in finish with a dull, frosty appearance instead of a bright, glossy
finish.
All work limitation and
documentation requirements are in effect when surface preparation is performed
and paint is applied.
Material Data Sheets and TE 24’s for Inorganic Zinc
Silicate Primer Paint per 708.01.
Material
Data Sheets and TE 24’s for Organic Zinc Prime Coat,
Epoxy Intermediate Coat, Urethane Finish Coat per 708.02.
Material Data Sheets for
abrasives and thinners, if used.
Copy of the
Quality Control Specialist’s and Superintendent’s Work Type 26 – Structural
Steel Painting Course certificate, (Course taken within the last 4 years).
Material Data Sheets for
Caulk, single pack moisture cured polyurethane from OMM’s
QPL
In addition to the
requirements for the Contractor’s Quality Control Specialist, listed in the
Construction and Materials Specifications 514.04, the owner’s inspector is
responsible for performing Quality Assurance. The owner’s inspector makes
independent checks of the QCS’s readings and results.
Also provide signed documentation of inspection, testing, conditions, and
material information to the Engineer on the following ODOT forms or forms with
the equivalent information.
1.
Document Dry Film Paint Thicknesses on
Form CA-S-2.
2. Ensure the Quality Control Specialist fills out and
signs form CA-S-7
prior to all Quality Control Point inspections.
3.
Document the Quality Control Specialist’s
information and the Job Site Visual Standards on Form CA-S-11.
4.
Document Solvent Cleaning (QCP#1) and
Grinding of Flange Edges (QCP#2) on Form CA-S-12.
5.
Document Abrasive Blasting (QCP#3) on
Form CA-S-13.
6.
Document Waste Disposal (QCP#4) on Form CA-S-14.
7.
Document Prime Coat Application (QCP#5)
on Form CA-S-15.
8.
Document Grinding Fins and Slivers
(QCP#6) and Caulking (QCP#9) on Form CA-S-16.
9.
Document Intermediate Coat Application
(QCP#8) or Finish Coat Application (QCP#10) on Form CA-S-17.
10. Document the Final Destructive Tests on Form CA-S-18.
11. Document the Final Acceptance (QCP#11) on Form CA-S-19.