ASTM-A780/A780M-09 2015 Standard Practice for Repair of Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings.pdf

Designation:A780/A780M -09 (Reapproved 2015) INTERNATIONAL StandardPracticefor RepairofDamagedandUncoatedAreasofHot-Dip GalvanizedCoatings This standard is isued under the fised designation A780VA780M; the number immediately following the designaticn indicates the year of original adption or in th case of revisin the year f last revis. A nmber n prentheses indicates the year of last rapprl. A superscript epsiloe (e) indicates an editorial change since the last revisice or reapproval. This standondl hasr beem approved for ase bry agencier ef the U.S. Depermenr ef Defense. 1. Scope 2.Referenced Documents 1.1 This practice describes methods that may be used to 2.1 ASTM Srandards:2 q uspaadpopspea A902 Terminology Relating to Metallic Coated Steel Prod- structural shapes and other products fabricated prior to hot-dip D520 Specification for Zinc Dust Pigment ucts galvanizing and uncoated areas remaining after initial hot-dip galvanizing. The damage may be the result of welding or 2.2 Society for Protective Coatings (SSPC) Documents:3 cutting (flame) in which case the coating will be damaged SSPC-PA2 Measurement of Dry Paint Thickness with Mag- predominantly by burming. This practice can also be used to netic Gages repair hot-dip galvanized coatings damaged by excessively SSPC-SP2 Hand Tool Cleaning rough handling during shipping or erection. Requirements SSPC-SP5/NACE No.I White Metal Blast Cleaning concerning the renovation of uncoated areas remaining after SSPC-SP10/NACE No.2 Near-White Blast Cleaning initial hot-dip galvanizing are contained within the applicable SSPC-SP11 Power Tool Cleaning to Bare Metal material specification. 3. Terminology 1.2 This practice describes the use of low melting point zinc alloy repair rods or powders made specifically for this purpose 3.1 Definitions-For definitions of terms used in this the use of paints containing zinc dust and the use of sprayed practice refer to Terminology A902. zinc (metallizing). 4.Materials 1.3 The extent of repair shall be limited to an area mutually agreeable to the contracting parties. Similarly contracting 4.1 PropertiesThe material used for repairs shall have the parties shall agree to the repair method to be used. following characteristics: 4.1.1One application of the material shall provide a coating 1.4 This specification is applicable to orders in either thickness of at least 2.0 mils (50.8 μm). inch-pound units (as A780) or in SI units (as A780M). 4.1.2 The applied coating shall provide barrier protection Inch-pound units and SI units are not necessarily exact s o e oq d s pe equivalents. Within the text of this specification and where 4.1.3 Application of the coating material shall be possible appropriate SI units are shown in brackets. Each system shall under shop or field conditions. be used independently of the other without bining values in 4.2 TypesThere are three types of material that possess the any way. required properties and may be used to repair damaged 1.5 This stondard does not purpor to address the sofey galvanized coatings as follows: problems if any associated with its use. It is the responsibiliry 4.2.1 Zinc-Based SoldersZinc alloy solders are to be used of the user of this standord to establish appropriate sofery cnd for repairs. The most mon types of solders are zinc- health practrices and determine the applicabiliry of reguxlatory cadmium zinc-tin-lead and zinc-tin-copper alloys. Zinc- limitations prior to use. cadmium and zinc-tin-lead alloys have liquidus temperatures in the ranges from 518 to 527°F (270 to 275°C) and 446 to 500°F This peactice is under the jurisdiction of ASTM Committee A05 on Metallc- For referenced ASTM standards visit the ASTM website .astm.org or Coated Iron and Steel Products and is the direct responsibility of Submitee A05.13 on Structural Shapes and Hardware Specifications. Standrds volume information refer to the standard’s Document Summary page on contact ASTM Customer Service at service@astm.org. For Annal Book af ASTM Ourret edition aprned May 1. 2015. Published May 2015. Originaly approved in 1980. Last previous edition approred in 2009 as A780 09. DOI: 10.1520/A0780_A0780M-09R15. Ptsburgh PA 15222-466 htp//ww.spc.g Available frm Society foe Protective Ccotings SSPC) 40 24th St 6th Floot Cogytt ASTMlstemafonl No ngrducloe r otgpmd wad lrse m M Prodty PE Me lce ASTM Nt: far Resale 97/18.2018 13:20:58 MDT Uivesity of Meboum5912e5001 UerZARATE ANDREA
A780/A780M-09(2015) (230 to 260°C) respectively. (The liquidus temperature is that resistance and service performance are very dependent on the temperature above which an alloy is pletely molten.) The properties of the paint system the extent of surface zinc-tin-copper alloys have a liquidus temperature in the range preparation and skills of individual applicators. Annex A2 from 660 to 670°F (349 to 354°C) but they are applied while D520 describes the zinc dust ponent of these paints. describes the use of paints containing zinc dust. Specification in a semisolid state in the preferred application temperature range from 480 to 570°F (250 to 300°C). The solders can be 4.2.3 Sprryed ZincThis method involves the application used in rod form or as powders. Annex A1 describes the use of of a zinc coating by spraying the surface to be repaired with zinc-based solders. process. Annex A3 describes the use of speayed zinc. droplets of molten metal using wire or ribbon or powder 4.2.2 Painzs Containing Zinc DusrThese are usually based on organic binders pre-mixed and formulated specifically for 4.3 For further information reference may be made to the use on steel surfaces. Paints containing zinc dust with concen- papers procedures and specifications in Refs. (1) through (2) trations of zinc dust in the range of 65 to 69 % or above 92 % (see list of references at the end of this practice). in the dried film are considered qually effective for the repair of damaged galvanized coatings. The repair paint to be used 5. Keywords shall be selected by the galvanizer unless the purchaser 5.1 coatings-zinc; galvanized coating repair; galvanized specifies a particular concentration or paint system. Corrosion coatings; touch-up: zinc coating repair; zinc coatings ANNEXES (Mandatory Information) A1. REPAIR USING ZINC-BASED ALLOYS A1.1 Clean the surface to be reconditioned using a wire A1.4 Rub the cleaned preheated area with the repair stick to brush a light grinding action or mild blasting. To ensure that deposit an evenly distributed layer of the zinc alloy. When a smooth reconditioned coating can be effected surface prepa- ration shall extend into the surrounding undamaged galva- powdered zinc alloys are used sprinkle the powder on the cleaned preheated surface and spread out with a spatula or nized coating. similar tool. The thickness of the applied coating shall be as A1.2 If the area to be reconditioned includes welds first agreed upon between the contracting parties. remove all weld flux residue and weld spatter (of a size that cannot be removed by wire brushing or blast cleaning) by A1.5 When the repair has been effected remove flux residue mechanical means such as chipping. grinding. or power by rinsing with water or wiping with a damp cloth. scaling etc. A1.6 Take thickness measurements with either a magnetic A1.3 Preheat the cleaned area to be reconditioned to at least electromagnetic or eddy-current gage to ensure that the 600°F (315°C). Do not overheat the surface beyond 750°F applied coating is as specified. (400°C) nor allow the surrounding galvanized coating to be bumed. Wire brush the surface to be reconditioned during preheating. Pre-flux if necessary. A2. REPAIR USING PAINTS CONTAINING ZINC DUST A2.1 Preparation of the damaged surface will be influenced A2.1.1 Surfaces to be reconditioned with paints containing by the type of paint selected and the anticipated service zinc dust shall be clean dry and free of oil grease preexisting conditions. Experience shows that in general organic zinc-rich paint and corrosion by-products. systems are tolerant of marginal surface preparation. Most organic paints containing zinc dust are not critical of climatic A2.1.2 Where anticipated field service conditions include or atmospheric conditions for curing. The following general immersion blast clean the surface in accordance with SSPC- guidelines shall apply: SP10/NACE No. 2 near white metal. For less critical field Coytt ASTMmafonl No nepauclce or nortitgpmied wlhad lerse m Mt ebyPEMhASTM No tr Resilte 9/82018 1329:58 MDT Univeriy of Melboume/S12895001 User=ZARATE ANDREA
A780/A780M - 09 (2015) exposure conditions clean the surface to bare metal in A2.1.4 Spray or brush-apply the paints containing zinc dust accordance with SSPC-SP11 as a minimum. Where circum- stances do not allow blast or power tool cleaning it is to the prepared area. Apply the paint as in accordance with the permissible to hand tool areas clean in accordance with manufacturer's printed instructions in a single application SSPC-SP2. To cnsure that a smooth reconditioned coating can employing multiple passes to achieve a dry film thickness to be be effected surface preparation shall extend into the undam- agreed upon between the contracting parties. Allow adequate curing time before subjecting repaired items to service condi- aged galvanized coating. The method and extent of surface preparation shall be mutually agreeable to the contracting tions in accordance with the manufacturer’s printed instruc- parties. tions. A2.1.3 If the area to be reconditioned includes welds first A2.1.5 Take thickness measurements with either a remove all weld flux residue and weld spatter (of a size that magnetic electromagnetic or edy-current gage to ensure that cannot be removed by wire brushing or blast cleaning) by the applied coating is as specified in accordance with mechanical means such as chipping. grinding. or power SSPC-PA2. scaling etc. A3. REPAIR USING SPRAYED ZINC (METALLIZING) A3.1 Surfaces to be reconditioned by zinc metallizing shall A3.6 The surface of the sprayed coating shall be of uniform be clean dry and free of oil grease and corrosion products. texture free of lumps coarse areas and loosely adherent A3.2 If the area to be reconditioned includes welds first particles. remove all fux residue and weld spatter of a size or type that A3.7 The nominal thickness of the sprayed zinc coating cannot be removed by blast cleaning by mechanical means shall be previously agreed upon between the contracting that is chipping etc. parties. A3.3 Blast clean the surface to be reconditioned in accor- dance with SSPC-SP5/NACE No. 1 white metal. A3.8 Take thickness measurements with either a magnetic electromagnetic or eddy-current gage to ensure that the A3.4 To ensure that a smooth reconditioned coating can be applied coating is as specified. effected surface preparation shall be extended into the sur- Sueoo pozqueae3 poleepun Supunou A3.5 Apply the coating to the clean and dry surface by means of metal-spraying pistols fed with either zinc wire or zinc powder. Apply the sprayed coating as soon as possible after surface preparation and before visible deterioration of the surface has occurred. REFERENCES (1) Van Eijnsbergen J F. H. et al Reconditioning Damaged Galvanized e oa g .es (3) SSPC-Paint-20 Zinc Rich Coatings. Type I Inorganic Type II Organic Steel Structures Painting Council 4400 Fifth Ave. (2) *Remended Practices for Fused Thermal Sprayed Deposits Interlaken June 1961 pp. 128141. Pitsburgh PA 15213 1979. (4) MIL-P-21035 (Ships) Military Specification * Paint High Zinc Dust American Welding Society Inc 550 N.W. LeJeune Rd. Miami FL Content Galvanizing Repair Amendment 1 U.S. Govermment 33135 1975. Printing Office Washington DC 1970. Coyt ATMlol No nepauclce or neortitgpomied wlhad lerse m 3t ty PEMe whASTM Not tr Resilte 9/82018 13:2F:58 MDT ogUveity of Meboum9125001 UerZARATE ANDREA
A780/A780M-09 (2015) in s standard Uers ofts standar are exssy aedhatdtmiaton ofte vay ofanysuch patnt rhs ane ASTM Intemationa/ takes no poition respecting the varldity of any paent rights asserted in connection with any item mentioned of infringement of such rights are entirely their own responsibity. rviffs This standard is subject fo revslon at any time by the responsible technical mttee ang must be reviewed every five years and and should be adtressed to ASTM Intemationa/ Headguarters. Your ments w receive carefuf consideration at a meeting of the responsible fehicaf mifee wich youmay at f you feef tht your mets hve no eceived a fairherng you shud make your views known to the ASTM Commitee on Standards at the aadress shown below: United States. Indivdual reprints (single or mufiple copies) of this standard may be obtained by contacting ASTM ar the above This standard is copyrighted by ASTM Intermationsl 100 Barr Harbor Drive PO Box C700 West Conshohocken PA 19428-2959 (amw.asdm.org) Pemission rights Io photocopy she standar may aso be secured from the Copyright Ciarance Centr 222 adtress or ar 610-832-9585 (phone) 610-832-9555 (fax) or service @astm.org (e-mai): or through the ASTM website Rosewood Drive Danvers MA 01923 Tel: (978) 646-2600; hfgp:/.copyright./ Prodnty PE Mai ner Icere wth ASTM Coytgt ASTMistaratona SH w44 uao Feg pigudDeou 0 grpude aN Not for Resile 47/182018 13.29:55 MDT ogUveity of Meoum9121 UerZARATE ANDREA