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Sspc- [2nv8oj7p5dlk].sspc-pa1 paint application specification no. 1
Some gages can the first 1O0 mz 1,ft2 shall be measured as stated in Section be adjusted to read accurately in a given range. Adjust the gage 5. Then check the gage on increment thereof, one 10 m2 f t 2 area shall be randomly standards of higher and lower thicknesses to establish the range selected and measured.
Notes see Sections 5. If a the magnetic surface of the steel and the small rounded tip of the maximum thickness value is not explicitly specified, the speci- magnet or probe that restson the top surface of the coating. This fied thickness shall be the minimum. Such correction measurements for each 10 m2 ft2 area shall not be less is described in Section 4. No single spot measure- instructions for Type 2 gages. Any gagereading may under-run 8.
If the average of the spot measurements nism to measure the force needed to pull a small permanent for a given 1O m2 1O0 ft2 area meets or exceeds the specified magnetfrom the surface of thecoated steel.
See Appendix 1. Internal balancing 5. Nosingle spot measure- recalibrate when changing orientation. Any gage reading may over-run sures the force necessaryto pull the permanent magnet from the by a greater amount. If the average of the spot measurements surface. Because of gravitational effects, these gages must be for a given 1O m2 1O0 ft2 area meets or falls below the specified recalibrated when the orientation of the surface changes; e.
Some gages have three measurements may be made to define the non-conforming separate indicators which compensate for horizontal, vertical area. Type 1B gages are generally not as if higher maximum thickness readings are allowable under precise as Type 1A gages. Normally, Type 1 gages are not adjusted or reset for each new series of measurements.
Such shims are usually fairly rigid and curved and do not lie perfectly 6. Accuracy flat, even on a smooth steel test surface. Near the pull-off point 6. Forthicknesses less than 25 pm frequently springs back from the steel surface, raising the 1 mil , the gage must have an accuracy at least within e. Some Type 2 gages use a 7. Disclaimer permanent magnet. Whenthe magnet is brought near steel, the 7. By information furnished in SSPC standards and specifications is measuring this change in flux density,which varies inversely to as accurate, complete and useful as possible, SSPC cannot the distance between the magnet and the steel substrate, the assume responsibility nor incur any obligation resulting from the coating thickness can be determined.
Hall elements and mag- use of any materials, coatings or methods specified therein, or net resistance elements are the most common ways to measure of the specification or standard itself. However, the response of these ele- ments is temperature dependent, so temperature compensation is required. A coil containing a soft iron rod is energized with an 8. As with a permanent magnet, the magnetic flux density the presence of another mass of steel close to the body of the within the rod increases when the probe is brought near the steel gage.
This effect may extend as much as three inches 7. This change is easy to detect by using a second coil. The output of the second coil isrelated to coating thickness and this relationship can be determined experimentally. If the curvature 8. Repeated gage readings on a rough surface, even at points very close 8. Also, residual either a rough or a smooth uncoated steel surface.
If the steel is roughened, as by blast cleaning, positions be averaged. With a correctly calibrated and 8. Somegagesfunction well at much highertemperatures. Most electronic gages compensate for coating and the probe of the gage must be free from dust, grease temperature differences among the gage, probe and surface.
When is tacky or excessively soft. Any gage reading may under-run by a greater amount. See Appendix 1. Any gage reading may overrun by agreater amount. Ifthe average of the spot measurements for a given 10 m? Accuracy 5. Disclaimer 7. Notes Notes are not a requirement of this standard.
This measured distance, from the top surtsee of the coating, must be corrected forthe thickness cof any extrangous films or otherinterfering conditions on the surlece of the steel. Such correction is described in Section 4.
Because of gravitational effects, these gages must be recalibrated when the orientation of the surface changes; e. Such shims are usually fairy rigid and eurved and. Some Type 2 gages Use apermanent magnet. With acocectly calitrated and adjusted Type 2 gage, the reading abtained indicates the coating thickness above this imaginary plane. Ia Type t gage is used, the coating thickress is obtained by subtracting the base metal reading. Unusually soft lms may be dented by the prassure of the probe, Soft or tacky fms ean sometimes be mea: sured satisfactorily by pulling a shim on the film, measuring total thickness of coating plus shim and subtracting shim thickness, 8.
Magnetic particles adher- Ing to the probe can be removed using an adhesive backed tape. For higher alloy steels, the gage rasponse should be checked, In any ever, the gage should be rezalibrated on the same steel over which the coating has oon appliod, 8.
Tho sensitivity to edge offacts and discontinuities varies from gage to gage. Measurements closer than 2,6 em 1 in from the discontinuity may not be valid unless, the gage is calibrated specifically for that location. This effect may extend as much as three inches 7. Ifthe curvature is appreciable, valid measurements may sill be oblained by calibrating or adjusting the gage on a similarly curved surface.
Also, residual magnetism in the steel substrate may alfect gage readings. With ficed probe two-pole gages in such cases, it i recommended that the readings before and after revers ing the pole positions be averaged. Other gages may require demagnelization of the steel 8. Some gages function well at much higher temperatures. Most elec tronic gages compensate for temperature differences among the gage, probe and surface. Two inspectors using the same gage will not necessarily record the exact same number for a given spot measurement using the same 4 om 1.
To allow for this natural fluctuation, an individual spot measurement is permitted to be below the specified minimum thickness astong as other spotsin the 10, rm? The chrome plated panes are fat smooth stee! Set of 4 48, ,, m 2, 5. This involves atleast 16 readings of the thickness gage. See Figure A1. These steps include 1 gage calibration, 2 verification of gage accuracy and 3 gage adjustment.
These steps are incorporated by reference in SSPC-PA 2 and are completed before obtaining coating thickness measurements to determine conformance to a specified coating thickness range. Verification of gage accuracy is typically performed using certified coated thickness standards for Type 1 or Type 2 gages or certified shims Type 2 gages.
Adjustment of Type 2 gages to compensate for substrate characteristics described later is typically performed using certified shims. Measured shims individually labeled with a stated thickness value commonly supplied with Type 2 gages can also be used for gage adjustment. Dry film thickness gages are calibrated by the equipment manufacturer, their authorized agent or an accredited calibration laboratory under controlled conditions.
A test certificate or other documentation showing traceability to a national metrology institution is required. While there is no standard time interval for re-calibration, an interval is usually established based upon experience and the work environment. A one-year calibration interval is a typical starting point suggested by gage manufacturers.
To guard against measuring with an inaccurate gage, SSPC-PA 2 requires that gage accuracy be verified at a minimum at the beginning and end of each work shift according to the procedures described in ASTM D If a large number of measurements is being obtained, the user may opt to verify gage accuracy during measurement acquisition e. If the gage is dropped or suspected of giving erroneous readings during the work shift, its accuracy should be rechecked. The accuracy of Type 1 magnetic pull-off gages is verified by placing the gage probe onto a certified coated thickness standard Figures 4 and 5.
Also, uncoated shims of flat plastic sheet with assigned values traceable to a national metrology institution. If a one-point verification procedure is adopted, the coated standard should be selected based on the intended range of use. For example, if the intended use is between 4 and 6 mils, then a 5-mil coated standard is appropriate.
Using the same example, if a two-point verification procedure is adopted, then a 2 -mil and an 8-mil set of coated standards slightly below and above the intended range of use is appropriate. Unless explicitly permitted by the gage manufacturer, shims certified or measured are not permitted for verification of accuracy of Type 1 gages. These readings represent themeasurement device. SSPC-PA 2 states that a minimum of 10 locations arbitrarily spaced should be measured one reading per location , then averaged.
This average base metal reading is then deducted from subsequent coating thickness measurements to remove any effect of the base metal surface and its conditions. For example, if a gage reads 5. However, since Type 1 gages are non-linear, one cannot assume a linear correction value across the full range of the gage. While the gage may be out of tolerance by 0. The accuracy of Type 2 electronic gages can be verified by placing the gage probe onto a certified coated thickness standard described for Type 1 gages or certified shims Figures 7 and 8.
The certified shim should be placed onto a smooth, uncoated metal surface to remove any effect of the surface roughness during this process.
A one-point or two point accuracy verification procedure can be performed as described for Type 1 gages. The final step in the process is to adjust the gage on the surface to which the coating will be applied.
The gage reading is adjusted to match the thickness of the shim, which effectively removes any influence from the underlying surface. First, once the surface is coated e. Secondly, some Type 2 gages cannot be adjusted. In this case, the user will need to obtain base metal readings BMR from the prepared, uncoated substrate described earlier for Type 1 gages.
Measurements to Determine Conformance to a Specification. Arguably the most critical section in the document, Section 8 describes how many areas to check, the size of the areas, the number of measurements to obtain in each area and what steps to take if spot or area measurements do not conform to the specification.
SSPC-PA 2 contains three definitions that are critical to understanding this next area of discussion. They include:. Acquisition of more than three gage readings within a spot is permitted.
Any unusually high or low gage readings that are not repeated consistently are discarded. For example, more than 20 minutes and less than eight hours after mixing are the pot life limits for some chemically cured coatings see Section 6.
Therefore only enough coating should be catalyzed for prompt use. Most mixed, catalyzed coatings cannot be stored, and unused portions of these shall be placed in proper storage containers for later appropriate disposal.
In all such cases, the temperature and moisture conditions of Sections 6. Where cover is required to achieve these conditions, the steel shall remain under cover or be protected until dry or weather conditions permit its exposure.
Coatings to be applied by brush will usually require no thinning. All thinning shall be done under supervision of a knowledgeable person acquainted with the correct amount and type of thinner to be added to the coating and familiar with pertinent regulations relating to solvent emissions.
Thinner should be at the same temperature as the coating material. At very low temperatures, thinners can shock sensitive coating materials, resulting in gelling.
Such striping shall extend a minimum of one inch 2 cm from the edge. The stripe coat shall set to touch before the full prime coat is applied.
However, the stripe coat shall not be permitted to dry for a period long enough to allow rusting of the unprimed steel. Alternatively, the stripe coat may be applied after a complete prime coat. Stripe coating of edges, corners, rivets, welds, etc.
To prevent removal of the stripe coat of coating by later application of the prime coat, the striped coating should be allowed to at least set to touch before application of the full prime coat; a longer drying period is advantageous, however. Where it is felt that a long drying period of stripe is necessary, but the precoated steel will deteriorate in the interval, the full prime coat of coating may be applied, allowed to dry, and the stripe coating then applied.
Tinting of the striping coating is advisable to promote contrast see Section 6. Stripe coating is most effective on edges that are rounded by grinding. Coating shall not be applied on frosted or ice-coated surfaces see Note All thin spots or areas missed in the application shall be recoated and permitted to dry before the next coat of coating is applied.
As indicated in Section 11, vinyls, lacquers, emulsions, high-build coatings, and bituminous coatings usually deviate from these thicknesses.
Consult the coating manufacturer for the appropriate time interval before recoating. Field tinting shall be done only with coatings of the same type from the same manufacturer. The tinting material shall be compatible with the coating and not detrimental to its service life. It is suggested that the coating be tinted by the manufacturer and appropriately labeled. Single component coatings to be blended for tinting shall be thoroughly mixed separately before combining and further mixing.
For multiple-components, it is necessary to blend similar components of the two different colors together before combining and mixing these blends. Also see Note If, for any reason, this time period is exceeded, the undercoat surface shall be specially treated as recommended by its manufacturer before topcoating.
Such treatments include mild abrasion, solvent treatment, and use of a fog coat. The equipment shall be maintained in proper working condition. Spray equipment shall meet the material transfer requirements of the local air pollution or air quality management district. Round or oval brushes are generally considered most suitable for rivets, bolts, irregular surfaces, and rough or pitted steel.
Any solvents left in the equipment shall be completely removed before using. During application, the gun shall be held perpendicular to the surface and at a distance which will ensure that a wet layer of coating is deposited on the surface. The trigger of the gun should be released at the end of each stroke. Their nap should be appropriate for the particular surface roughness. It may be necessary to use an approved different coating material or other equipment to resolve these problems.
Coating rollers shall be of a style and quality that will enable proper application of coating having the continuity and thickness required in Sections 6. Conversely, coatings formulated for application at ambient or low temperatures may not be suitable for application to hot surfaces. The traps or separators must be of adequate size and must be bled continuously or drained periodically during operations.
The air from the spray gun impinging against a clean surface shall show no condensed water or oil. ASTM D provides a test procedure for indicating the presence of oil or water in compressed air. PA 3 provides information on how to use airless spray equipment safely. Air-assisted airless spray shall be performed in accordance with all provisions of Sections 7.
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