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Historic Preservation - Technical Procedures

Spectitle:

Repairing Damaged Or Missing Ornamental Metal

Procedure code:

0570001R

Source:

National Capitol Region Specifications - Old Executive Off

Division:

Metals

Section:

Ornamental Metalwork

Last Modified:

02/24/2012

Details:

Repairing Damaged Or Missing Ornamental Metal



REPAIRING DAMAGED OR MISSING ORNAMENTAL METAL


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on repairing existing
         ornamental metal work by removing, repairing and
         reinstalling existing pieces, or if too damaged,
         installing new ornamental metal to match.

    B.   See 01100-07-S for general project guidelines to be
         reviewed along with this procedure. These guidelines
         cover the following sections:

         1.   Safety Precautions

         2.   Historic Structures Precautions

         3.   Submittals

         4.   Quality Assurance

         5.   Delivery, Storage and Handling

         6.   Project/Site Conditions

         7.   Sequencing and Scheduling

         8.   General Protection (Surface and Surrounding)

         These guidelines should be reviewed prior to performing
         this procedure and should be followed, when applicable,
         along with recommendations from the Regional Historic
         Preservation Officer (RHPO).  

1.02 REFERENCES

    A.   American Society for Testing and Materials (ASTM), 100
         Barr Drive, West Conshohocken, PA 19428, (610) 832-9585
         or FAX (610) 832-9555.

    B.   American Welding Society (AWS), P.O. Box 351040, 550 Le
         Jeune Road, NW, Miami, FL 33135.

    C.   National Association of Architectural Metal Manufacturers
         (NAAMM), 221 N. LaSalle Street, Chicago, IL 60601.

    D.   Steel Structures Painting Council (SSPC), 4400 Fifth
         Avenue, Pittsburgh, PA 15213.

1.03 SUBMITTALS

    A.   Product Data: Submit manufacturer's fabricator's and
         finisher's specifications and installation instructions
         for products used in ornamental metal work, including
         finishing materials and methods.

    B.   Submit manufacturer's technical data for each product
         indicated including chemical analysis and recommendations
         for their application and use. Include test reports and
         certifications substantiating that products comply with
         requirements.

    C.   Shop Drawings: Submit shop drawings for fabrication and
         installation or ornamental metal work. Include plans,
         elevation and detail sections. Indicate materials,
         methods, finishes and types of joinery, fasteners,
         anchorages and accessory items; specify finishes. Provide
         setting diagrams and templates for anchorages, sleeves
         and bolts installed by others.  Fabricated parts and
         fasteners to be of the same metal as historic to avoid
         galvanic corrosion.

    D.   Samples: Submit samples, 6" square, of each metal and
         finish required. Prepare samples on metal of same alloy
         and thickness to be used for the work. Where normal color
         and texture variations are to be expected, include 2 or
         more units in each set of samples showing the limits of
         such variations. Full-size samples will be prepared and
         submitted for the architect's approval for each article.

    E.   Model: Provide model of castings made as directed until
         the model conforms to the  Contract drawings or to
         subsequent directions until approval of the model is
         obtained.

    F.   Restoration Program: Submit written program for each
         phase of restoration process including protection of
         surrounding materials on building and site during
         operations. Describe in detail materials, methods and
         equipment to be used for each phase of restoration work.

1.04 SYSTEM DESCRIPTION

    A.   Design Requirements:

         1.   Design components to allow for expansion and
              contraction for a minimum ambient temperature range
              of 100 F (37.8 C) without causing buckling,
              excessive opening of joint or over stressing of
              welds and fasteners.

         2.   Form ornamental metal work to the required shapes
              and sizes, with true curves, lines and angles.
              Provide necessary rebates, lugs and brackets for
              assembly of units. Use concealed fasteners wherever
              possible.

         3.   Comply with AWS for recommended practices in shop
              welding. Provide welds behind finished surfaces
              without distortion or discoloration of the exposed
              side. Clean exposed welded joints of all welding
              flux, and dress on all exposed and contact
              surfaces.

         4.   Mill joints to a tight, hairline fit. Cope or miter
              corner joints. Form joints exposed to weather to
              exclude water penetration.

         5.   Provide castings that are sound and free of warp or
              defects which impair strength and appearance. Mill
              joints to a close fit and finish exposed surfaces
              to smooth, sharp, well-defined lines and arises.

         6.   Comply with NAAMM "Metal Finishes Manual" for
              finish designations and application
              recommendations.

         7.   Match color, direction, and texture of existing
              ornamental metal work for new and replacement
              pieces.

1.05 QUALITY ASSURANCE

    A.   Mock-ups: Prepare sample panels for each type of
         ornamental metal material indicated to be repaired or
         replaced.

1.06 PROJECT/SITE CONDITIONS

    A.   Protect surrounding surfaces of building from damage
         resulting from ornamental metal restoration work.


PART 2---PRODUCTS

2.01 MATERIALS

    A.   Provide materials which have been selected from their
         surface flatness, smoothness and freedom from surface
         blemishes where exposed to view in the finished unit.
         Exposed-to-view surfaces which exhibit pitting, seam
         marks, roller marks, "oil-canning" stains, discolorations
         or other imperfections on the finished units will not be
         acceptable.

    B.   Aluminum: Comply with the following standards for the
         forms and types of aluminum for the required items of
         work.

         1.   Aluminum Extrusions: Alloy and temper recommended
              by aluminum producer of finisher for type of use
              and finish indicated, and with not less than the
              strength and durability properties specified in
              ASTM B221 for 6063-T5.

         2.   Bars, Rods and Wire: ASTM B211.

         3.   Castings: ASTM B26 or B108; alloy 214 for natural
              anodized finish, and alloy 43 for color anodized or
              baked enamel finish.

         4.   Forgings: ASTM B247, alloy 6061-T6.

    C.   Stainless Steel: Comply with the following standards for
         the forms and types of stainless steel for the required
         items of work.

         1.   Type: AISI Type 302/304.

         2.   Bar Stock: ASTM A276.

         3.   Plate: ASTM A167.

         4.   Castings: ASTM A296, iron-chromium-nickel alloy.

    D.   Bronze: Comply with the following standards for the forms
         and type of bronze for the required items of work. Alloys
         listed refer to standards of the Copper Development
         Association.

         1.   Temper: Provide bronze materials in standard
              commercial tempers and hardness, as required for
              fabrication, strength and durability.

         2.   Extruded Shapes: ASTM B455; Alloy C38500,
              Architectural Bronze.

         3.   Plates and Bars: Alloy C28000 Muntz Metal.

         4.   Rod and Wire: ASTM B134, Alloy C23000.

         5.   Castings: ASTM B584; match color of other bronze.

    E.   Miscellaneous Materials:

         1.   Welding Electrodes and Filler Metal: Type and alloy
              of filler metal and electrodes as recommended by
              producer of the metal to be welded, and as required
              for color match, strength and compatibility in the
              fabricated items.

         2.   Fasteners: Furnish of same basic metal and alloy,
              matching finished color and texture as the metal
              being fastened. Provide Phillips flat-head screws
              for exposed fasteners, countersunk for flush
              fitting.

         3.   Anchors and Inserts: Furnish inserts to be set in
              concrete or masonry work, and provide other
              anchoring devices as required for the installation
              of ornamental metal items. Provide toothed steel or
              lead shield expansion bolt devices for drilled-in-
              place anchors. Provide galvanized or cadmium-coated
              anchors and inserts for exterior installations.

              a.   Provide units with exposed surfaces matching
                   the texture and finish of the metal item
                   anchored.

         4.   Bituminous Paint: SSPC-Paint 12 (cold-applied
              asphalt mastic).

         5.   Protective Lacquer: Clear non-yellowing for
              protection of the finished metal surface.


PART 3---EXECUTION

3.01 PREPARATION

    A.   Protection:  Protect mechanical finish on exposed
         surfaces from damage by application of strippable
         temporary protective covering prior to shipment.

    B.   Surface Preparation:  Coat concealed surface which will
         be in contact with concrete, masonry, wood, or dissimilar
         metals, in exterior work and work to be built into
         exterior and below grade  walls and decks, with a heavy
         coat of bituminous paint. Do not extend coating onto
         exposed surfaces.

3.02 ERECTION, INSTALLATION, APPLICATION

    A.   Coordinate and furnish anchorages and setting drawings,
         diagrams, templates, instructions and directions for the
         installation of items having integral anchors which are
         to be embedded in concrete or masonry construction.
         Coordinate delivery of such items to the project site.

    B.   Provide anchorage devices and fasteners where necessary
         for securing ornamental metal items to in-place
         construction; including, threaded fasteners for concrete
         and masonry inserts, toggle bolts, through-bolts, lag
         bolts, wood screws and other connectors as required.

    C.   Perform all cutting, drilling and fitting required for
         the installation of the ornamental metal items. Set the
         work accurately in location, alignment and elevation,
         plumb, level and true, measured from established lines
         and levels.

    D.   Form tight joints with exposed connections accurately
         fitted with uniform reveals and specs for sealants and
         joint fillers. Where cutting, welding and grinding are
         required for proper shop fitting and jointing of the
         work, restore finishes to eliminate any evidence of such
         corrective work.

    E.   Do not cut or abrade finishes which cannot be completely
         restored in the field. Return items with such finishes to
         the shop for required alterations, followed by complete
         refinishing or provide new units at Contractor's option.

    F.   For guidance on cleaning ornamental metal, see 05700-02-
         R.

                         END OF SECTION