NAPF Section 500

Coatings and Linings

NAPF 500-03

SURFACE PREPARATION STANDARD FOR DUCTILE IRON PIPE

AND FITTINGS IN EXPOSED LOCATIONS RECEIVING SPECIAL
EXTERNAL COATINGS AND/OR SPECIAL INTERNAL LININGS

As approved by the
NAPF Board of Directors
Effective March 1, 2000
Revised 2/14/2006

National Association of Pipe Fabricators, Inc.

1901 N.W. 161st Street
Edmond, OK 73013
Phone: 888-798-1924
Fax: 800-860-5700
http://www.napf.com/
Copyright 2006 - National Association of Pipe Fabricators, Inc.
This publication may not be copied, transcribed or reproduced,
in whole or in part, in any manner without the full knowledge
and express written consent of the publisher.

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 Board Of Directors
The NAPF Board of Directors, which reviewed and approved this standard, had
the following personnel at the time of approval:
Ted B. Wright, President
Willard D. Goodman, Board Chairman
Ted J. Muntz, Standards Chairman
M Coryn, Utility Equipment Co., Bettendorf, IA
C. Comins, Custom Fab, Orlando FL
W. Goodman, Plant & Flanged Equipment Co., Minneapolis, MN
K. Kempf, Griffin Pipe Products Company, Council Bluffs, IA
M. Knust, Davis K, Inc., Amherst, VA
T. Muntz, Fab Pipe, Inc., Rogers, MN
D. Page, B&R Pipe Fabrication, Roanoke, TX
D. Wertz, Pipe Works, Inc., Santa Fe Springs, CA
T. Wright, National Association of Pipe Fabricators, Oklahoma City, OK

Committee Personnel
The NAPF Coatings and Linings Committee, which developed this standard, had
the following personnel at the time of development:
Donald L. McCage, P.E., Chairman
C. Comins, Custom Fab, Orlando FL
A. Horton, U.S. Pipe & Foundry Company, Birmingham, AL
D. McCage, Techno Coatings, Inc., Anaheim, CA
T. Muntz, Fab Pipe, Inc., Rogers, MN
J. O'Nan, Star Pipe Products, Houston, TX
D. Page, B&R Pipe Fabrication, Roanoke, TX
G. Washburn, Victaulic Co. of America, Allentown, PA
H. Wilson, Griffin Pipe Products Co., Lynchburg, VA
T. Wright, National Association of Pipe Fabricators, Oklahoma City, OK

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 Associated Personnel
The development of this standard was advanced through the advice, consultation
and technical support of the following personnel:
S. Arnold, Strand Associates, Inc., Madison, WI
V. Bauman, Bauman Coatings, Inc., Bessemer, AL
A. Colgin, Colgin & Associates, Birmingham, AL
L. Dornbusch, Sherwin Williams Company, Minneapolis, MN
G. Gardner, Sherwin Williams Company, Chicago, IL
B. Hanks, Tnemec Company Incorporated, Kansas City, MO
J. Hemming, Bonestroo Rosene Anderlik & Assoc., St. Paul, MN
K. Henderson, Malcolm Pirnie, Inc., White Plains, NY
H. Kennedy, Madison Coatings International, Toronto, Canada
G. Miller, Black and Veatch, Kansas City, MO
G. Mills, Ph.D., George Mills & Associates International, Humble, TX
T. Satchell, Jacobsen Helgoth Consultants, Lakewood, CO
R. Tubesing, Earth Tech, Inc., Plymouth, MN
D. Zienty, Short Elliott Hendrickson, Inc., St. Paul, MN

STANDARD
National Association of Pipe Fabricators
This document is a standard and as such constitutes a model developed to
establish acceptable standards for the water and wastewater industry. The
standard describes basic criteria and minimum requirements and contains
several options, which must be evaluated by the user. It does not contain
information normally included in a specification and therefore should not be
considered one. The NAPF does not endorse any material or application method
nor does it test, approve or certify their use. The standard has been developed
under pressures by the NAPF Standards Council and may be revised or
withdrawn at any time. Notice of such action will be posted in THE PIPELINE,
the official newsletter of the association, and will become effective the first day of
the month following publication.

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 NAPF 500-03
Surface Preparation Standard for Ductile Iron Pipe and Cast Ductile
Iron Fittings In Exposed Locations Receiving Special
External Coatings And/Or Special Internal Linings
Effective March 1, 2000
Revised 2/14/2006

FOREWARD
Introduction
Ductile iron has been used in the manufacture of pipe and fittings and is
recognized as the industry standard for water and wastewater systems due to its
strength, durability and reliability for the transportation of raw and potable water,
sewage, slurries and process chemicals.
Generally, ductile iron pipe and fittings are furnished from the manufacturer with
an external asphaltic coating and internal cement lining. This coating and lining is
well suited for most underground distribution service requirements.
For external corrosion protection the ductile iron pipe industry recommends
polyethylene encasement to protect buried ductile iron pipe and fittings in the
vast majority of installations where aggressive soil conditions are a concern.
This method of external corrosion protection, which has been extensively
researched and used to successfully protect millions of feet of iron pipe since
1951, has proven effective in a broad range of soil conditions.
In some cases, however, either due to installation factors or to the environment
to which the pipeline may be exposed, special bonded external coatings or
internal linings may be required or specified in lieu of these two standard
methods of protection. Appropriate surface preparation for these external
coatings or internal linings must be observed.
This standard is not intended for use as the basis for surface preparation
scenarios for bonded coatings for buried pipe applications. The conditions
of exposure are substantially different. Moreover, no research was
conducted by NAPF or others engaged in the standards publication to
support any such use.
Inapplicable Surface Preparation Standards Currently In Use
Several publications and standards exist for surface preparation of steel
surfaces. They include, but are not limited to Steel Structures Painting Council
(SSPC), National Association of Corrosion Engineers (NACE) Standards, and
Swedish Surface Preparation Standards. Although ductile iron and carbon steel
are both ferrous metals, there are inherent metallurgical, manufacturing and
processing differences between the two metals that preclude certain parts of the
SSPC, NACE and other surface preparation standards, written specifically for
steel surfaces, from being applied to ductile iron pipe and fittings.

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Attempts to apply steel surface preparation specifications to ductile iron is
inappropriate and may actually result in damage to the pipe surface with
subsequent reduced coating effectiveness and life expectancy.
Steel versus Ductile Iron Surfaces
Inherent manufacturing differences between ductile iron pipe and carbon steel
necessitate differences in surface preparation requirements. Examples of some
of these differences are as follows:
Rolled steel in "mill condition" will normally require (1) blast removal of mill
scale, rust or other surface contaminates, and (2) the establishment of an
anchor pattern to the normally smooth surface of steel through abrasive
blasting. Generally, ductile iron pipe will not require the same degree of
blast to achieve equivalent surface cleanliness. Also, ductile iron pipe has
a higher anchor profile as cast than can be achieved with steel by
abrasive blasting.
The chemistry and metallurgy of ductile iron pipe and fittings versus that of
carbon steel result in a surface that has a different texture and color from
that of steel. Additionally, the texture and color of ductile iron pipe and
fittings also may vary due to the differences in manufacturing processes.
1. Ductile iron pipe manufactured using the deLavaud centrifugally cast
process with dry spray on peen pattern metal molds will have an
annealing oxide on the exterior surface. This annealing oxide is different
than mill scales typically found on steel surfaces. It is significantly more
tenacious, adherent and more difficult to remove by abrasive blasting than
mill scale on steel surfaces. Testing by pipe manufacturers, the Ductile
Iron Pipe Research Association (DIPRA) and established coating
manufacturers have determined that tightly adherent annealing oxide on
ductile iron pipe acts as a very corrosion resistant protective layer on the
surface of the ductile iron.
2. For these reasons, narrative visual descriptions and/or visual standards
prepared for steel surfaces are not applicable for ductile iron surfaces (i.e.:
terns such as white metal abrasive blast and near white metal abrasive
blast do not apply). To illustrate, SSPC standards describe the visual
appearance changes to steel as abrasive blasting is applied. The surface
changes from a dull black/gray (SP 7) to gray (SP 6) to near white (SP 10)
to bright white (SP 5). However, ductile iron pipe changes from the "as
cast" medium gray to a bluish gray color when abrasive blasting (not
recommended by these standards) eventually may produce an uneven
black to a mottled dull gray/white surface color. However this activity
frequently results in damage to some ductile iron surfaces.

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Footnote: Test results are proprietary and available from the ductile iron pipe
manufacturers.
Unlike steel surfaces, it is possible to "overblast" the external surface of
ductile iron pipe. High nozzle velocities and/or excessive blast times can
cause "blistering" and "slivering" of some external deLavaud pipe surfaces
resulting in a surface which is unsuitable for coating with any material.
This overblasting normally occurs when attempts are made to remove the
tenacious, tightly adherent annealing oxide from the external surface of
deLavaud dry spray pipe with a peen pattern surface. Damage to the pipe
surface due to overblasting normally does not occur on internal surfaces.
Manufacturing Variability of Ductile Iron Surfaces
Not only are ductile iron pipe surfaces different from steel surfaces, but they may
also vary significantly with respect to each other depending on such variables as
the pipe manufacturer, the manufacturing process, pipe size, pipe thickness, iron
chemistry, iron cooling/solidifying rates and whether the surface to be coated is
internal or external. For example, some types of external ductile iron surfaces
with totally different appearances and coating characteristics include 1) small
peen pattern dry spray deLavaud process pipe, 2) large peen pattern dry spray
deLavaud process pipe, 3) chill free dual spray process large diameter pipe and
4) sand cast fitting surfaces.
In general, 1) large diameter, thicker pipe which solidify slower will have a
rougher interior surface than thinner, small diameter pipe; 2) higher carbon
content pipe will have a rougher internal surface than lower carbon content pipe.
Cast Fitting surfaces will be smoother than centrifugally cast ductile iron pipe
surfaces. Also, dual spray process large diameter pipe do not have annealing
oxides as do dry spray process deLavaud pipe, but rather will have a residue
layer of diatomaceous silica mold coating on the exterior surface.
Previously Painted Surfaces
1. Ductile Iron Pipe - The standard internal and external coating furnished by
the manufacturer is an asphaltic cutback paint. The NAPF does not
recommend the application of special coatings over asphaltic pipe
coatings due to the incompatibility of most such coatings and asphalt.
Asphaltic coatings are difficult to remove from centrifugally cast ductile
iron pipe surfaces. Therefore, uncoated pipe is recommended when
special coatings are required, unless otherwise recommended by the
coating manufacturer.

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 2. Cast Ductile Iron Fittings - Some cast ductile iron fittings may be furnished
by the manufacturer with an asphaltic cutback paint. The NAPF does not
recommend the application of special coatings over asphaltic coatings due
to the incompatibility of special coatings over asphaltic coatings due to the
incompatibility of most such coatings and asphalt. However, unlike
centrifugally cast ductile iron pipe surfaces, static cast ductile iron fitting
surfaces are smoother, thus affording a greater opportunity for the
removal of the previously applied asphaltic coatings. Although the NAPF
recommends uncoated fittings when special coatings are required, it may
be necessary to remove existing asphaltic paint through the use of more
arduous methods. Therefore, this standard provides definitive procedures
for both uncoated and previously coated cast ductile iron fittings.
Recommended Surface Preparation for Ductile Iron Pipe and Fittings
Most coating manufacturers require some type of surface preparation as a
condition of warranty. Since their recommendation for surface preparation will
vary depending on the type of coating and on the ultimate service environment,
the coating/lining manufacturer's technical data sheet should be consulted each
time a special coating/lining is used. Normally, recommendations given on
coating/lining manufacturer's technical data sheets are for carbon steel and may
not apply to ductile iron pipe and fittings. Therefore, the pipe or fitting
manufacturer or NAPF pipe fabricator should also be consulted regarding the
type of coating, method of application, and type of surface preparation to be
used.
The standards given on the following pages for surface preparation of ductile iron
pipe and fittings have been developed based on considerations discussed in the
preceding paragraphs.
These standards are described as:
NAPF 500-03-01 Solvent Cleaning
NAPF 500-03-02 Hand Tool Cleaning
NAPF 500-03-03 Power Tool Cleaning
NAPF 500-03-04 Abrasive Blast Cleaning
for Ductile Iron Pipe
NAPF 500-03-05 Abrasive Blast Cleaning
for Cast Ductile Iron
Fittings

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 NAPF 500-03-01
Surface Preparations Standard for
"Solvent Cleaning"
1.0 Scope:
This standard covers the requirements for the solvent cleaning of
previously uncoated ductile iron pipe and fitting surfaces.
2.0 Definition:
2.1
Solvent cleansing is a method which shall result in the surface being free of
all oil, small deposits of asphalt paint, grease, soil, drawing and cutting
compounds and other soluble contaminants from iron surfaces

2.2
It is intended that solvent cleaning, when necessary, be used prior to the
application of special coating/lining and in conjunction with surface
preparation methods specified for the removal of rust, annealing oxide, or
mold coating

3.0 Surface Preparation Before and After Solvent Cleaning:

3.1
Prior to solvent cleaning, remove foreign matter (other than grease and oil)
by one or a combination of the following: brush with stiff fiber or wire
brushes, abrade, scrape or clean with solutions of appropriate cleaners
provided such cleaners are followed by a fresh water rinse.

3.2
After solvent cleaning, remove dirt, dust and other contaminants from the
surface prior to coating/lining application. Acceptable methods include
brushing, blowing off with clean, dry air, or vacuum cleaning.

4.0 Methods of Solvent Cleaning:

4.1

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Remove heavy oil or grease first by scraper. Then remove remaining oil or
grease by any of the following methods:

4.1.1
Wipe or scrub the surface with rags or brushes wetted with solvent. Use
clean solvent and clean rags or brushes for the final wiping.

4.1.2
Spray the surface with solvent. Use clean solvent for the final spraying.

4.1.3
Vapor degrease using stabilized chlorinated hydrocarbon solvents.

4.1.4
Immerse completely in a tank or tanks of solvent. For the last immersion,
use solvent which contains no detrimental amounts of contaminant.

4.1.5
Emulsion of alkaline cleaners may be used in place of the methods
described. After treatment, wash the surfaces with fresh water or steam to
remove detrimental residues.

4.1.6
Steam clean, using detergents or cleaners and follow by steam or fresh
wash to remove detrimental residues.

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5.0 Inspection:
5.1
All work and materials supplied under this standard shall be subject to
timely inspection by the purchaser or its authorized representative.

5.2
The procurement documents covering work or purchase should establish
the responsibility for testing and for any required affidavit certifying full
compliance with the standard.

6.0 Safety:
6.1
All safety requirements stated in this standard and its component parts
apply in addition to any applicable federal, state and local rules and
requirements and shall be in accordance with instructions and
requirements of insurance underwriters.

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 NAPF 500-03-02
Surface Preparations Standard for
"Hand Tool Cleaning"
1.0 Scope:
This standard covers the requirements for the hand tool cleaning of ductile
iron pipe and fitting surfaces.
2.0 Definition:
2.1
Hand tool cleaning is a method of preparing iron surfaces by the use of
non-power hand tools which shall result in the surface being free of all
loose annealing oxide, loose rust, loose mold coating and other loose
detrimental foreign matter. It is not intended that adherent annealing oxide,
mold coating and rust be removed by this process. Annealing oxide, mold
coating, and rust are considered adherent if they cannot be removed by
lifting with a dull putty knife. All asphalt paint must be removed prior to
hand tool cleaning.

2.2
Visual standards of surface preparation agreed upon by the contracting
parties may be used to further define the surface.

3.0 Surface Preparation Before and After Hand Tool Cleaning:

3.1
Before hand tool cleaning, remove oil, small deposits of asphalt paint,
grease, soluble welding residues, and salts by the methods outlined in the
Standard for Solvent Cleaning or other agreed upon methods. (See NAPF
500-03-01).

3.2
After hand tool cleaning and prior to coating, remove dirt, dust or similar
contaminants from the surface. Acceptable methods include brushing,
blowing off with clean, dry air, or vacuum cleaning.

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4.0 Methods of Hand Tool Cleaning:
4.1
Use hand tools to remove stratified rust (rust scale).

4.2
Use hand tools to remove all weld slag.

4.3
Use hand wire brushing, hand abrading, hand scraping or other similar
non-impact methods to remove all loose annealing oxide, and all loose or
non-adherent rust.

5.0 Inspection:
5.1
All work and materials supplied under this standard shall be subject to
timely inspection by the purchaser or its authorized representative.

5.2
The procurement documents covering work or purchase should establish
the responsibility for testing and for any required affidavit certifying full
compliance with the standard.

6.0 Safety:
6.1
All safety requirements stated in this standard and its component parts
apply in addition to any applicable federal, state and local rules and
requirements and shall be in accordance with instructions and
requirements of insurance underwriters.

NAPF 500-03-03

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 Surface Preparations Standard for
"Power Tool Cleaning"
1.0 Scope:
This standard covers the requirements for the power tool cleaning of
ductile iron pipe and fitting surfaces.
2.0 Definition:
2.1
Power tool cleaning is a method of preparing iron surfaces by the use of
power assisted hand tools which shall result in the surface being free of all
loose annealing oxide, loose rust, loose mold coating and other loose
detrimental foreign matter. It is not intended that adherent annealing oxide,
mold coating and rust be removed by this process. Annealing oxide, mold
coating, and rust are considered adherent if they cannot be removed by
lifting with a dull putty knife. All asphalt paint must be removed prior to
hand tool cleaning.

2.2
Visual standards of surface preparation agreed upon by the contracting
parties may be used to further define the surface.

3.0 Surface Preparation Before and After Power Tool Cleaning:

3.1
Before power tool cleaning, remove oil, small deposits of asphalt paint,
grease, soluble welding residues, and salts by the methods outlined in the
Standard for Solvent Cleaning or other agreed upon methods. (See NAPF
500-03-01).

3.2
After power tool cleaning and prior to coating, remove dirt, dust or similar
contaminants from the surface. Acceptable methods include brushing,
blowing off with clean, dry air, or vacuum cleaning.

4.0 Methods of Power Tool Cleaning:

4.1

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Use rotary or impact power tools to remove rust.

4.2
Use rotary or impact power tools to remove all weld slag.

4.3
Use power wire brushing, power abrading, power impact or other power
rotary tools to remove all loose annealing oxide, and all loose or non-
adherent rust. Do not burnish the surface.

4.4
Operate power tools in a manner that prevents the formation of burrs,
sharp ridges and sharp cuts.

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5.0 Inspection:
5.1
All work and materials supplied under this standard shall be subject to
timely inspection by the purchaser or its authorized representative.

5.2
The procurement documents covering work or purchase should establish
the responsibility for testing and for any required affidavit certifying full
compliance with the standard.

6.0 Safety:
6.1
All safety requirements stated in this standard and its component parts
apply in addition to any applicable federal, state and local rules and
requirements and shall be in accordance with instructions and
requirements of insurance underwriters.

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 NAPF 500-03-04
Surface Preparations Standard for
"Abrasive Blast Cleaning of Ductile Iron Pipe"
1.0 Scope:
This standard covers the requirements for the abrasive blast cleaning of
ductile iron pipe and fitting surfaces.
[CAUTION: Ductile iron pipe external surfaces, in some cases, can be
damaged by excessive abrasive blast cleaning beyond this standard. (See
Foreward)].
2.0 Definition:
2.1
Abrasive Blast Cleaning - External Pipe Surfaces is a method of preparing
the exterior of ductile iron pipe surfaces which, when viewed without
magnification, shall result in the surface being free of all visible dirt, dust,
loose annealing oxide, loose rust, loose mold coating and other foreign
matter. All oils, small deposits of asphalt paint and grease shall have been
removed by solvent cleaning (see NAPF 500-03-01). After the entire
surface to be coated is struck by the blast media, tightly adherent
annealing oxide, mold coating and rust staining may remain on the surface
provided they cannot be removed by lifting with a dull putty knife.

2.2
Abrasive Blast Cleaning - Internal Pipe Surfaces is a method of preparing
the interior of ductile iron pipe surfaces which, when viewed without
magnification, shall result in the surface being free of all visible dirt, dust,
loose annealing oxide, loose rust, loose mold coating and other foreign
matter. All oils, small deposits of asphalt paint and grease shall have been
removed by solvent cleaning (see NAPF 500-03-01). The entire surface to
be coated shall be struck by the blast media. Depending upon the type
of service for which the lined pipe is intended, and upon the type of
lining which is specified, different degrees of tightly adherent
annealing oxide and rust staining removal may be required. For some
lining materials, extra internal grinding prior to abrasive blasting may be
required. Internal pipe surface preparation requirements shall be specified
by the pipe manufacturer or pipe fabricator as well as the lining
manufacturer, and shall be based upon testing of a specific lining applied
to ductile iron pipe exposed to a specific environment.

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Copyright 2006 National Association of Pipe Fabricators - All Rights Reserved
3.0 Appearance of Completed Surfaces:
3.1
The surface shall be roughened to a degree suitable for the specified
coating system.

3.2
The entire surface shall be subjected to the abrasive blast. The remaining
annealing oxide, rust staining or mold coating shall be tight and the surface
sufficiently abraded to provide good adhesion and bonding of the specified
coating system.

3.3
The appearance of the surface may be affected by the particular blasting
abrasive used, the original surface condition and the pipe manufacturing
process.

3.4
Visual standards of surface preparation agreed upon by the contracting
parties may be used to further define the surface.

4.0 Surface Preparation Before and After Abrasive Blast Cleaning:

4.1
Before abrasive blast cleaning, deposits of oil or grease shall be removed
by the methods outlined in the Standard for Solvent Cleaning or other
agreed upon method.

4.2
After blast cleaning and prior to coating/lining, perform the following:

4.2.1
Remove deposits of oil, grease or other contaminants. (See NAPF 500-03-

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 01).

4.2.2
Remove dust and loose residues from dry abrasive blast cleaning.
Acceptable methods include brushing, blowing off with clean, dry air, or
vacuum cleaning. (When compressed air is used for blowing off, use and
maintain moisture and oil separators and traps to provide a clean and dry
air supply).

5.0 Blast Cleaning Methods and Operation:

5.1
Methods:

5.1.1
Dry abrasive blasting, using compressed air, blast nozzles and abrasive.

5.1.2
Dry abrasive blasting, using a closed cycle, recirculating abrasive system
with compressed air, blast nozzle and abrasive, with or without vacuum for
abrasive recovery.

5.1.3
Dry abrasive blasting, using a closed cycle, recirculating abrasive system
with centrifugal wheels and abrasive.

5.2
Operation:

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5.2.1
When compressed air is used for nozzle blasting, moisture and oil
separators and traps shall be used and maintained to provide a clean dry
air supply.

5.2.2
Blast cleaning operations shall be performed such that no damage is done
to partially or entirely completed portions of the work.

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6.0 Blast Cleaning Abrasives:
6.1
Abrasives shall conform to the following requirements:

6.1.1
The abrasive shall be free of corrosion producing contaminants and also
free of oil, grease, or other deleterious contaminants.

6.1.2
Selection of abrasive size and type shall be based on the surface condition
of the pipe to be cleaned and on the finished surface to be produced for
the subsequent coating/lining system.

6.1.3
The cleanliness and sizing of the abrasive shall be maintained to ensure
compliance.

7.0 Inspection:
7.1
All work and materials supplied under this standard shall be subject to
timely inspection by the purchaser or its authorized representative.

7.2
The procurement documents covering work or purchase should establish
the responsibility for testing and for any required affidavit certifying full
compliance with the standard.

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8.0 Safety:
8.1
All safety requirements stated in this standard and its component parts
apply in addition to any applicable federal, state and local rules and
requirements and shall be in accordance with instructions and
requirements of insurance underwriters.

Copyright 2006 National Association of Pipe Fabricators - All Rights Reserved

 NAPF 500-03-05
Surface Preparations Standard for
"Abrasive Blast Cleaning of Cast Ductile Iron Fittings"
1.0 Scope:
This standard covers the requirements for the abrasive blast cleaning of
cast ductile iron fitting surfaces.
2.0 Definition:
2.1
Abrasive Blast Cleaning - Cast Ductile Iron Fittings. Internal and External
Surfaces is a method of preparing the interior and exterior of cast ductile
iron fittings surfaces which, when viewed without magnification, shall result
in the surface being free of all visible dirt, dust, loose annealing oxide,
loose rust, loose mold coating and other foreign matter. All oils, small
deposits of asphalt paint and grease shall have been removed by solvent
cleaning (see NAPF 500-03-01). Four degrees of abrasive blast cleaning
for fittings are available, depending on the type of service for which the
fitting is intended and upon the type of coating/lining specified.

2.1.1
Ductile Iron Fitting Blast Clean #1 - No staining may remain on the surface
after abrasive blast cleaning. This is the only method recommended for
fittings previously coated with asphaltic paint.

2.1.2
Ductile Iron Fitting Blast Clean #2 - In addition to the above general
description, no more than 5% staining may remain on the surface after
abrasive blast cleaning. Staining may consist of light shadows, rust stains,
oxide stains or stains from previously applied coatings (provided the
coating is not asphaltic).

2.1.3
Ductile Iron Fitting Blast Clean #3 - In addition to the above general
description, no more than 33% staining may remain on the surface after
abrasive blast cleaning. Staining may consist of light shadows, rust stains,
oxide stains or stains from previously applied coatings (provided the
coating is not asphaltic).

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2.1.4
Ductile Iron Fitting Blast Clean #4 - In addition to the above general
description, no limit is placed on the staining which may remain on the
surface after abrasive blast cleaning provided it is tightly adherent. Staining
may consist of light shadows, rust stains, oxide stains or stains from
previously applied coatings (provided the coating is not asphaltic).

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3.0 Appearance of Completed Surfaces:
3.1
The surface shall be roughened to a degree suitable for the specified
coating system.

3.2
The entire surface shall be subjected to the abrasive blast. The remaining
annealing oxide, rust staining or mold coating shall be tight and the surface
sufficiently abraded to provide good adhesion and bonding of the specified
coating system.

3.3
The appearance of the surface may be affected by the particular blasting
abrasive used, the original surface condition and the pipe manufacturing
process.

3.4
Visual standards of surface preparation agreed upon by the contracting
parties may be used to further define the surface.

4.0 Surface Preparation Before and After Abrasive Blast Cleaning:

4.1
Before abrasive blast cleaning, deposits of oil or grease shall be removed
by the methods outlined in the Standard for Solvent Cleaning or other
agreed upon method.

4.2
After blast cleaning and prior to coating/lining, perform the following:

4.2.1
Remove deposits of oil, grease or other contaminants. (See NAPF 500-03-

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 01).

4.2.2
Remove dust and loose residues from dry abrasive blast cleaning.
Acceptable methods include brushing, blowing off with clean, dry air, or
vacuum cleaning. (When compressed air is used for blowing off, use and
maintain moisture and oil separators and traps to provide a clean and dry
air supply).

5.0 Blast Cleaning Methods and Operation:

5.1
Methods:

5.1.1
Dry abrasive blasting, using compressed air, blast nozzles and abrasive.

5.1.2
Dry abrasive blasting, using a closed cycle, recirculating abrasive system
with compressed air, blast nozzle and abrasive, with or without vacuum for
abrasive recovery.

5.1.3
Dry abrasive blasting, using a closed cycle, recirculating abrasive system
with centrifugal wheels and abrasive.

5.2
Operation:

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5.2.1
When compressed air is used for nozzle blasting, moisture and oil
separators and traps shall be used and maintained to provide a clean dry
air supply.

5.2.2
Blast cleaning operations shall be performed such that no damage is done
to partially or entirely completed portions of the work.

Copyright 2006 National Association of Pipe Fabricators - All Rights Reserved

6.0 Blast Cleaning Abrasives:
6.1
Abrasives shall conform to the following requirements:

6.1.1
The abrasive shall be free of corrosion producing contaminants and also
free of oil, grease, or other deleterious contaminants.

6.1.2
Selection of abrasive size and type shall be based on the surface condition
of the pipe to be cleaned and on the finished surface to be produced for
the subsequent coating/lining system.

6.1.3
The cleanliness and sizing of the abrasive shall be maintained to ensure
compliance.

7.0 Inspection:
7.1
All work and materials supplied under this standard shall be subject to
timely inspection by the purchaser or its authorized representative.

7.2
The procurement documents covering work or purchase should establish
the responsibility for testing and for any required affidavit certifying full
compliance with the standard.

Copyright 2006 National Association of Pipe Fabricators - All Rights Reserved

8.0 Safety:
8.1
All safety requirements stated in this standard and its component parts
apply in addition to any applicable federal, state and local rules and
requirements and shall be in accordance with instructions and
requirements of insurance underwriters.

Copyright 2006 National Association of Pipe Fabricators - All Rights Reserved