Because specifying this requirement for each square

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may also be left in the bottoms of pits if the original surface is pitted." Because specifying this requirement for each square inch is impractically restrictive, AISC recommends that this requirement be applied instead to the total surface area.
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PAGE 21 APPENDIX When SSPC-SP10 surface preparation is specified, what acceptance criteria should be applied ? As stated in SSPC-SP10 (near-white blast cleaning) Section 2.2, "staining shall be limited to no more than 5 per- cent of each square inch of surface area and may consist of light shadows, slight streaks, or minor discolorations caused by stains of rust, stains of mill scale or stains of previously applied paint." Because specifying this require- ment for each square inch is impractically restrictive, AISC recommends that this requirement be applied instead to the total surface area. Field Touch-up and Repair How should contract documents address the problem of job-site mill-scale flaking ? When SSPC-SP2 (hand tool cleaning) or SSPC-SP3 (power tool cleaning) surface preparation is specified and a short-exposure-life prime coat is subsequently applied, tight mill scale generally remains on the surface prior to shop painting. Likewise, tight mill scale may remain with SSPC-SP7 (brush-off blast cleaning) surface prepara- tion. Depending upon the time of exposure, job-site conditions, and type of prime coast, some of this tight mill scale may loosen, resulting in mill-scale flaking. When required, provision should be made in the contract doc- uments for an appropriate field touch-up and repair program. Traditionally, this work has been delegated to the painting contractor. Is the fabricator/erector responsible to clean steel after it has been erected ? No. Shop-painted steel that is stored in the field pending erection should be kept free of the ground and so posi- tioned as to minimize water-holding pockets, dust, mud, and other contamination of the paint film. However, because site conditions are frequently muddy, sandy, dusty, or a combination of all three, it may be impossible to store and handle the steel in such a way as to completely avoid accumulation of mud, dirt, or sand on the surface of the steel. When required, provision should be made in the contract documents for an appropriate cleaning program. Is the fabricator/erector responsible for field touch-up to the repair of blemishes and abrasions that result during handling and storage after painting ? No. During storage, loading, transport, unloading, and erection, blemishes and abrasions caused by slings, chains, blocking, tie-downs, etc. occur in varying degrees and should be expected. Responsibility for field touch- up should be assigned in the contract documents. Traditionally, this work has been delegated to the painting con- tractor. Other General Information When welded surfaces are to be painted, what considerations are required ?
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  • Fall '19
  • Structural steel

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