# INSTRUCTIONS FOR USE

## **MINNESOTA CONSTRUCTION SPECIFICATION 82*---**Painting Metalwork**** *

**1. Applicability **

Construction Specification MN-82 is applicable to the painting of
metalwork including structural metal, water control gates, piping,
pumps, and other metal equipment and machinery.

The durability of paint films on metal depends upon the exposure
condition, the types of paints used, the thickness of the coating, and
the method of preparing the metal surface before the application of
primers and paint. To a large extent the type of paint required is
dictated by the exposure condition, and the required surface preparation
is dictated by the type of paint to be applied. Each paint system
specifies the type and quality of paint, the number of coats or minimum
paint film thickness required, and the finish (gloss, semigloss, flat).

The paint systems are not equivalent optional methods. Each paint system
is designed to provide protection for a particular exposure condition or
to produce a particular finished appearance or both. The criteria for
selection of the appropriate paint system and surface preparations for
that finish are summarized in table 82--1 of these instructions.

Where a minor amount of painting is to be performed and it is not
required for protection, use a simple note on the drawings rather than
Construction Specification MN-82.

**2. Material specifications **

Material Specification 583, Coal Tar-Epoxy Paint, complements
Construction Specification MN-82 when Paint System F is specified.
References to the Steel Structures Paint Council (SSPC) for surface
preparation are summarized. Refer to SSPC for full text as appropriate.
No other material specifications complement this specification.

Any material requirements are to be specified in section 9.

**3. Included items **

Items to be included in contract specifications and drawings follow:

a.  Indicate by notes on the drawings, the surfaces and items to be
    painted.

b.  Designate the paint system (by letter) to be used for painting each
    indicated item. If all metalwork is to be painted by the same paint
    system, one standard note to that effect is sufficient.

c.  Waiver of the requirement that the contractor furnish a plan and
    material list if the plan is not necessary.

d.  Provide color requirements, finish (gloss, semigloss, flat) and any
    special requirements as appropriate.

e.  Instructions for painting, surface preparation, or other special
    conditions or methods not covered by the standard specification.

f.  Surface preparation for needed maintenance painting may be limited
    to those spots or areas having loss of protection by corrosion
    and/or wearing surfaces. A clean, sound paint surface provides a
    good base for added layers.

g.  Provide tinting requirements as appropriate. Various coatings have a
    unique tolerance for pigmentation. Under- or over-pigmentation can
    produce poor cover quality (hide) and less than desirable
    performance.

h.  Note in section 9 if the contractor is to provide paint
    specification information to the engineer that is to be shared with
    the owners to use for their responsibility for operation and
    maintenance.

**4. Methods **

Select the method or methods for surface preparation that is appropriate
for the durability and length of service required. Refer to table 82--1
for surface preparation recommendations. The quality of surface
preparation diminishes as the method number increases, and the expected
surface life is reduced accordingly. The small cost increase in
selecting a higher quality preparation can significantly reduce
operation and maintenance costs and untimely coating failure.

**5. Construction details **

In section 9 of construction specification MN-82, prepare and outline
job specific \"Construction Details\" (CD) in accordance with these
instructions. For ease of utilization, the use of recyclable color paper
for the CD should be considered.

[Table 82-1]{.underline} Paint systems for metalwork

  ----------------------------------- -------------------- ------------------------------------------ ------------------------ ---------------------
  Paint                               Type of paint        Description and conditions for use         Example applications     Surface preparation
                                                                                                                               
  system                              material                                                                                 
                                                                                                                               
  A                                   Alkyd primer         A good interior and exterior system.       Interior and exterior    Method 2 or 3,
                                                                                                                               
                                      (type 1)             It is not intended for humid or damp       surfaces of buildings,   commercial
                                      Alkyd enamel         environments. System A should not          piping, pumps, and       blast or brush-
                                      (type 2)             be applied to a surface that constantly    machinery above          off blast.
                                      Gloss or             sweats or is immersed in water. It         operating floors,        
                                      semigloss            chalks or oxidizes when subjected          doors, frames, tanks.    
                                      (type 3)             to sunlight.                                                        
                                                                                                                               
                                                                                                                               
  B                                   Single package       Similar to the qualities of system A.      Exterior or interior     Method 2 or 3,
                                                                                                                               
                                      moisture cured       Urethane primer allows system to be        surfaces of buildings,   commercial
                                      urethane primer      applied over poorly prepared surfaces      piping, pumps, and       blast or brush-
                                      (type 9)             particularly in areas where proper         machinery above          off blast.
                                      Alkyd enamel         preparation is difficult or impractical.   operating level. Good    
                                      (type 2)             It is a good system for repainting         rehabilitation system    
                                      Gloss or semigloss   over old existing paint for                when preparation is      
                                      (type 3)             rehabilitation.                            minimal.                 
                                                                                                                               
                                                                                                                               
  C                                   Epoxy                An excellent system for constant or        Trash racks and          Method 1, near
                                                                                                                               
                                      polyamide            intermittent immersion in salt or fresh    guards or flap gates,    white blast.
                                      (type 4)             water. Excellent for surfaces exposed      stop logs and guides,    
                                                           to constant humidity and sweating.         pumps, piping,           
                                      Epoxy                Excellent chemical resistance and          machinery, and storage   
                                      polyamide            available in almost all colors. Will       tanks.                   
                                      (type 5)             chalk or oxidize when exposed to                                    
                                                                                                                               
                                      sunlight.                                                                                
                                                                                                                               
  *See footnotes at end of table. *                                                                                            
                                                                                                                               
  ----------------------------------- -------------------- ------------------------------------------ ------------------------ ---------------------

**[Table 82]{.underline}[--]{.underline}[1]{.underline} **Paint systems
for metalwork---Continued

  --------------------------------- ------------------- ------------------------------------------- ----------------------------- ---------------------
  Paint                             Type of paint       Description and conditions for use          Example applications          Surface preparation
                                                                                                                                  
  system                            material                                                                                      
                                                                                                                                  
  D                                 Epoxy polyamide     Same as system C except is topcoated        Exterior surfaces of          Method 2 or 3,
                                                                                                                                  
                                    primer (type 4)     with acrylic polyurethane. Not              buildings, such as drains,    commercial
                                    Epoxy polyamide     recommended for immersed metals.            overflows, gutters, and       blast or brush-
                                    (type 5)            Excellent interior or exterior in humid     piping exposed to either      off blast.
                                    Acrylic             or arid environment. High abrasion          humid or arid conditions.     
                                    polyurethane        resistance. Excellent color and gloss       Any metal items that          
                                    gloss (type 6)      retention (15 times greater than            gather condensation           
                                                                                                                                  
                                    or semigloss        systems A, B, or C). Excellent on steel     and/or have high exposure     
                                                                                                                                  
                                    (type 7)            that sweats. Available in either gloss or   to sunlight. Interior sur-    
                                                        semi-gloss. Should be considered for        faces, such as walls,         
                                                        long-term exposure to sunlight or when      ceilings, structural steel,   
                                                        esthetics are a factor.                     equipment, and piping.        
                                                                                                                                  
  E                                 Single package      Good system for dry or humid                Structural steel, siding,     Method 2 or 3,
                                    moisture cured      environments. Excellent color and           doors, frames, piping,        commercial or
                                                                                                                                  
                                    Urethane primer     gloss retention. Cannot be used for         machinery, and storage        brush-off blast.
                                                                                                                                  
                                    (type 9)            coating immersed metals and is not          tanks.                        
                                    Acrylic polyure-    as good as system D in constant                                           
                                    thane gloss         moisture. Excellent long-term                                             
                                    (type 6)            esthetics.                                                                
                                    or semigloss                                                                                  
                                    (type 7)                                                                                      
                                                                                                                                  
  F                                 Coal tar            Excellent in constant or intermittent       Trash guards, water           Method 1, near
                                    epoxy               immersion in salt or fresh water.           control gates, pipes,         white blast.
                                    (type 10)           Excellent also for buried steel surfaces.   steel piling, stop logs       
                                                        Available in black only; changes to         and guides, water tanks,      
                                                        brown when exposed to sunlight, but         and flumes.                   
                                                        sunlight does not adversely effect                                        
                                                        performance. Excellent chemical                                           
                                                        resistance and dependability exhibited                                    
                                                        in extensive use throughout the water                                     
                                                                                                                                  
                                                        and wastewater treatment industry.                                        
                                                                                                                                  
                                                        **Note:** Galvanized surfaces require a                                   
                                                        pretreatment vinyl acid wash primer                                       
                                                        before applying paint, as noted in type 8                                 
                                                        paints. Sandblasting or aged galvanized                                   
                                                        surfaces do not require a vinyl wash                                      
                                                        treatment.                                                                
                                                                                                                                  
  G                                 Epoxy polyamide     Excellent system for repair of damaged      Trash guards, CMP,            Method 4 or 5,
                                    primer (type 4)     galvanized metal in humid or arid           stop logs and guides,         hand tool or
                                    Single package      environments. Provides protection           and other galvanized          solvent clean.
                                    moisture cured      for surfaces exposed to constant            metalwork.                    
                                    urethane (type 9)   humidity and sweating.                                                    
                                                                                                                                  
                                                                                                                                  
  *See footnotes at end of table*                                                                                                 
                                                                                                                                  
  --------------------------------- ------------------- ------------------------------------------- ----------------------------- ---------------------

**Table 82--1 **Paint systems for metalwork---Continued

  -------- ---------------- ------------------------------------ ----------------------- ---------------------
  Paint    Type of paint    Description and conditions for use   Example applications    Surface preparation
                                                                                         
  system   material                                                                      
                                                                                         
  H        Vinyl acid       For use as a pretreatment wash for   Trash guards, CMP,      Steam clean
                                                                                         
           wash treatment   galvanized and nonferrous metals     stop logs and guides,   with TSP, or
           (type 8)         that require painting.               gutters, downspouts,    solvent clean,
                                                                 and other galvanized    regularly chang­
                                                                                         
                                                                 or nonferrous metals.   ing rags.
                                                                                         
  -------- ---------------- ------------------------------------ ----------------------- ---------------------

Footnotes:

a.  All surface preparation referred to herein shall be performed in
    accordance with SSPC (Steel Structures Painting Council).

b.  All painting and coating shall be performed per SSPC Good Painting
    Practices and paint manufacturer\'s recommendations.

c.  Coated steel subjected to potable water service shall be coated in
    accordance with American Water Works Association (AWWA) provisions
    and directions. Said coatings shall meet United States National
    Sanitation Foundation (US-NSF) requirements.

d.  When special protective coatings or other specific painting
    recommendations are necessary, refer to the Paint Manual, United
    States Department of Interior (USDI), Bureau of Reclamation, or
    paint manufacturer\'s data.

e.  Surface preparation indicated is the method that will provide
    coating quality appropriate for exposure conditions. Methods that
    produce a greater or a lesser quality can be chosen to produce the
    quality of work that is necessary. Hand tool cleaning (method 4) and
    solvent cleaning (method 5) are applicable for field applications,
    small areas requiring coating, or in making repairs to factory
    coatings.