SSPC AB3 : 2000

SSPC: The Society for Protective Coatings

SSPC-AB 3Ferrous Metallic Abrasive

1ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959; http://www.astm.org

1

SSPC-AB 3February 1, 2003

1. Scope

1.1 This specification covers the requirements for fer-rous metallic abrasive for the removal of rust, mill scale,paint, or other surface coating system by blast cleaning.

1.2 This specification covers previously unused abra-sive material. It does not address cleanliness of recycledabrasive processed through field or shop abrasive blastcleaning units. Requirements for recycled ferrous metallicabrasive is covered in SSPC-AB 2.

2. Description and Use

2.1 Ferrous metallic abrasive can have two basic par-ticle shapes: (1) spherical or round for shot; and (2) angularor irregular for grit, as defined in Sections 4.1.3.1 and4.1.3.2.

2.2 The size designations and specifications for shotand grit are given in Tables 1 and 2 (see Note 7.2).

2.3 ABRASIVE CLASS: Ferrous metallic abrasive isdivided into two classes.

2.3.1 Class 1 – Steel Abrasive: Steel abrasive ischaracterized by low carbon content. Steel abrasive is notas hard as iron abrasive, and hence is more durable.

2.3.2 Class 2 – Iron Abrasive: Iron abrasive is charac-terized by high carbon content and hardness typically over55 Rc. The particle shape requirements for iron grit are lessstringent than those for steel grit.

2.4 ABRASIVE SELECTION: The owner/specificationwriter may define the abrasive class, shape, size, andhardness to meet the job requirements.

3. Referenced Standards

3.1 The latest issue, revision, or amendment of thereferenced standards in effect at the time of the bid solicita-tion shall govern, unless otherwise specified.

3.2 If there is a conflict between the requirements of anyof the cited reference standards and this specification, therequirements of this specification shall prevail.

3.3 SSPC STANDARD

AB 2 Cleanliness of Recycled Ferrous MetallicAbrasive

3.4 ASTM INTERNATIONAL STANDARDS1

C 128 Test Method for Specific Gravity andAbsorption of Fine Aggregate

C 136 Test Method for Sieve Analysis of Fineand Coarse Aggregates

D 4940 Test Method for Conductimetric Analysisof Water-Soluble Ionic Contamination ofBlasting Abrasive

E 11 Specification for Wire-Cloth Sieves forTesting Purposes

E 350 Test Methods for Chemical Analysis ofCarbon Steel, Low-Alloy Steel, SiliconElectrical Steel, Ingot Iron, and WroughtIron

E 384 Test Method for Microhardness ofMaterials

E 1019 Test Methods for Determination ofCarbon, Sulfur, Nitrogen, and Oxygen inSteel and in Iron, Nickel, and CobaltAlloys

Copyright The Society for Protective Coatings Provided by IHS under license with SSPC

Not for ResaleNo reproduction or networking permitted without license from IHS

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2

TA

BL

E 1

Steel S

ho

t Size S

pecificatio

ns

*S

creen opening sizes and screen numbers w

ith maxim

um and m

inimum

culmulative percentages allow

ed on corresponding screens. NO

TE

: These sizes correspond to those

in SA

E J444 C

ast Shot and G

rit Size S

pecifications for Peening and C

leaning.**

All percentages refer to w

eight percent.

70.1110

2.80all pass

——

——

——

——

——

80.0937

2.36—

all pass—

——

——

——

——

100.0787

2.0085%

min.**

—all pass

all pass—

——

——

——

120.0661

1.7097%

min

85% m

in.—

5% m

ax.all pass

——

——

——

140.0555

1.40—

97% m

in.85%

min

—5%

max.

all pass—

——

——

160.0469

1.18—

—97%

min

85% m

in.—

5% m

ax.all pass

——

——

180.0394

1.00—

——

96% m

in.85%

min.

—5%

max.

all pass—

——

200.0331

0.850—

——

—96%

min.

85% m

in.—

10% m

ax.all pass

——

250.0278

0.710—

——

——

96% m

in.85%

min.

—10%

max.

——

300.0234

0.600—

——

——

—96%

min.

85% m

in.—

all pass—

350.0197

0.500—

——

——

——

97% m

in.—

10% m

ax.—

400.0165

0.425—

——

——

——

—85%

min.

—all pass

450.0139

0.355—

——

——

——

—97%

min.

—10%

max.

500.0117

0.300—

——

——

——

——

80% m

in.—

800.0070

0.180—

——

——

——

——

90% m

in.80%

min.

1200.0049

0.125—

——

——

——

——

—90%

min.

Screen N

oA

ST

M E

11

Screen

Opening

(inch

es)*

Screen

Opening(m

m)*

SH

OT

SIZ

E

230660

550460

390280

170110

703

30

780



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3


3.5 SOCIETY OF AUTOMOTIVE ENGINEERS (SAE)STANDARD2

J444 Cast Shot and Grit Size Specifications forPeening and Cleaning

4. Requirements

4.1 PHYSICAL PROPERTIES

4.1.1 Size Classification: The abrasive shall be testedin accordance with Section 5.2.1 and shall meet the sizerequirements for each size specified as defined in Table 1 forshot or Table 2 for grit.

4.1.2 Hardness: Abrasive hardness shall be tested inaccordance with Section 5.2.4 and shall meet the specifiedhardness requirements (see Notes 7.2 and 7.3).

4.1.3 Particle Shape (see Note 7.4)

4.1.3.1 Shot: Using 10X magnification, shot shall bepredominantly rounded particles with no more than 10%

elongated particles for steel abrasive and no more than30% elongated particles for iron abrasive. (An elongatedparticle is one with a length more than twice its diameter.)Also see Note 7.4

4.1.3.2 Grit: Using 10X magnification, grit shall beirregular or angular shaped particles with no more than 10%round or half-round particles for steel abrasive and no morethan 25% round or half-round particles for iron abrasive(also see Note 7.4).

4.1.4 Specific Gravity: When tested in accordancewith Section 5.2.2, the specific gravity of the abrasive shallbe no less than 7.0 for steel abrasive and no less than 6.8for iron abrasive.

4.1.5 Durability: Metallic abrasive is tested for durabil-ity in accordance with Section 5.2.5.

4.1.5.1 Steel: After 100 cycles in the durability test, nomore than 20% by weight of a steel abrasive shall passthrough the appropriate take-out screen as defined in Table3 for grit or in Table 4 for shot (see Note 7.5).

TABLE 2METALLIC GRIT SIZE SPECIFICATIONS

8 0.0937 2.36 all pass — — — — — — — —10 0.0787 2.00 — all pass — — — — — — —12 0.0661 1.70 80%** — all pass — — — — — —14 0.0555 1.40 90% 80%** — all pass — — — — —16 0.0469 1.18 — 90% 75% — all pass — — — —18 0.0394 1.00 — — 85% 75% — all pass — — —25 0.0278 0.710 — — — 85% 70% — all pass — —40 0.0165 0.425 — — — — 80% 70% — all pass —50 0.0117 0.300 — — — — — 80% 65% — all pass80 0.0070 0.180 — — — — — — 75% 65% —120 0.0049 0.125 — — — — — — — 75% 60%200 0.0029 0.075 — — — — — — — — 70%

ScreenOpening

ASTM E 11

ScreenOpening(inches)*

ScreenOpening(mm)* G 12 G14 G16 G18 G25 G40 G50 G80 G120

Grit Size

* Screen opening sizes and screen numbers with maximum and minimum culmulative percentages allowed on corresponding screens.NOTE: These sizes correspond to those in SAE J444.

** All percentages refer to weight percent.

2 Society of Automotive Engineers, 400 Commonwealth Drive, Warrentdale PA 15096-0001; http://www.sae.org



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TABLE 3Steel Grit Take-Out Screens

TABLE 4Steel Shot Take-Out Screens

TABLE 5Abrasive Chemistry

ElementSteel

Percent by Weight*Iron

Percent by Weight

* Percentages only reflect two significant figures.

CarbonManganesePhosphorus

1.5%, maximum1.2%, maximum

0.05%, maximum

1.6%, minimumN/AN/A

4.1.5.2 Iron: After 50 cycles in the durability test, nomore than 50% by weight of an iron abrasive shall passthrough the appropriate take-out screen as defined in Table3 for grit or in Table 4 for shot (see Note 7.5).

4.2 PROPERTIES

4.2.1 Chemistry: When tested in accordance with Sec-tion 5.2.3, the chemical composition of the abrasive shallconform to the requirements in Table 5.

4.2.2 Conductivity: When tested in accordance withSection 5.2.7, the conductivity of the solution of water-soluble contaminants shall not exceed 1000 microsiemensper centimeter (µS/cm). (1 µS/cm = 1 µmho/cm)

4.2.3 Cleanliness: When tested in accordance withSection 5.2.6, the abrasive shall be free of dust, oil, grease,corrosion, and non-magnetic matter subject to the limita-tions in Sections 4.2.3.1 and 4.2.3.2, and other contami-nants. The presence of rust in excess of a slight red or blueoxidation of the abrasive particle shall be cause for rejec-tion.

4.2.3.1 Accept: If the sample has 0.2 percent or less byweight of non-magnetic matter and no oil film or slick on thesurface of the water, it is considered clean. Clouding ordiscoloration of the water is not grounds for rejection.

4.2.3.2 Reject: If the sample has more than 0.2 percentby weight of non-magnetic matter and/or has an oil film orslick on the surface of the water and sides of the container,it must be rejected.

5. Quality Assurance Test Methods

5.1 RESPONSIBILITIES FOR TESTING: Unless other-wise specified, the supplier is responsible for performingand documenting the preliminary acceptance tests andinspections called for in this specification. The procurementdocuments should establish the specific responsibilities forconformance testing.

5.2 TEST PARAMETERS: Unless otherwise specifiedin the contract or purchase order, the supplier shall beresponsible for compliance with the requirements for class,size, specific gravity, chemical composition, hardness, durabil-ity, cleanliness, and conductivity.

5.2.1 Size: The abrasive sizing shall be tested in accor-dance with ASTM C 136.

4

Grit SizeSteel Take-Out

Screen SizeIron Take-OutScreen Size

G12

G14

G16

G18

G25

G40

G50*

G80*

G120*

40 mesh

40 mesh

40 mesh

40 mesh

50 mesh

50 mesh

70 mesh

*

*

40 mesh

40 mesh

40 mesh

40 mesh

50 mesh

50 mesh

80 mesh

*

** Abrasive sizes G50, G80 and G120 cannot be accurately tested

due to limitations of the test apparatus in retaining fine abrasives.

Shot SizeSteel Take-Out

Screen SizeIron Take-OutScreen Size

S780

S660

S550

S460

S390

S330

S280

S230

S170

S110*

S70*

40 mesh

40 mesh

40 mesh

40 mesh

40 mesh

50 mesh

50 mesh

50 mesh

50 mesh

70 mesh

*

40 mesh

40 mesh

40 mesh

40 mesh

40 mesh

50 mesh

50 mesh

50 mesh

70 mesh

80 mesh

*

* Shot sizes S110 and S70 cannot be accurately tested due tolimitations of the test apparatus in retaining these sizes.



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5


3 Ervin Test Machines are available (for purchase or as loaners) from Ervin Industries, Inc. at 3893 Research Park Drive, Ann Arbor, MI48108; phone (800) 748-0055 or (734) 769-4600; fax (734) 663-0136; E-mail: [email protected]

5.2.2 Specific Gravity: Specific gravity shall be deter-mined in accordance with ASTM C 128.

5.2.3 Chemical Composition: Chemical compositionshall be determined in accordance with ASTM E 1019 forcarbon content and ASTM E 350 for manganese and phos-phorus content.

5.2.4 Hardness: Hardness values shall be obtainedand converted to Rockwell C equivalents in accordance withASTM E 384 utilizing a microhardness tester with a 500 gload.

5.2.4.1 Metallic abrasive sometimes contains internalshrinkage, voids, or inclusions, which remain undetectedbeneath the surface in a mounted and polished sample.These characteristics can cause a non-uniform hardnessreading and shall be ignored when testing for hardness.

5.2.5 Durability Test Procedure

5.2.5.1 Procedure1. Obtain a representative sample and weigh out

100 grams (± 0.1 g) of new abrasive.2. Place a 100 g sample in a calibrated standard

durability test machine (see Section 5.2.5.2) andrun a steel abrasive for 100 cycles and an ironabrasive for 50 cycles.

3. Remove the sample from the test machine andhand screen the sample on the appropriate take-out screen (see Table 3 for grit; Table 4 for shot).Record the weight of the sample remaining onthe screen after hand screening is completed.

5.2.5.2 Apparatus: Durability tests shall be performedusing an Ervin Test Machine3 or equivalent shot/grit testmachine, properly calibrated in accordance with themanufacturer’s instructions.

5.2.6 Abrasive Cleanliness1. Obtain a representative sample.2. Weigh out 100 grams ± 1 gram.3. Magnetically remove all magnetic material.4. Weigh remaining non-magnetic material and

record weight.5. Check magnetic material for rust in excess of

slight red or blue oxidation.6. Recombine magnetic and non-magnetic material

in a glass jar and cover with at least one inch ofpotable water.

7. Vigorously shake the jar containing water andrecombined material.

8. After shaking, observe water surface in jar asdescribed in Sections 4.2.3.1 and 4.2.3.2.

5.2.7 Conductivity: Conductivity tests shall be run inaccordance with ASTM D 4940.

6. Disclaimer

6.1 While every precaution is taken to ensure that allinformation furnished in SSPC standards and specificationsis as accurate, complete, and useful as possible, SSPCcannot assume responsibility nor incur any obligation result-ing from the use of any materials, coatings, or methodsspecified herein, or of the specification or standard itself.

6.2 This specification does not attempt to addressproblems concerning safety associated with its use. Theuser of this specification, as well as the user of all productsor practices described herein, is responsible for institutingappropriate health and safety practices and for ensuringcompliance with all governmental regulations.

7. Notes

Notes are not requirements of this specification.

7.1 ABRASIVE PRODUCTIVITY: For greatest produc-tivity, always use the finest size abrasive that will effectivelyclean the surface and produce the proper profile. Abrasiverecycling machines should be set to retain all usable abra-sive sizes in the working mix for maximum productivity andlowest abrasive consumption. Productivity is directly af-fected by such variables as particle size, shape, number ofparticles, velocity, distance, and angle of attack, and hard-ness of the surface being cleaned. There is a maximumabrasive flow rate that provides highest productivity. In-creasing the abrasive flow beyond the critical rate usuallyreduces productivity.

7.2 ABRASIVE HARDNESS: Abrasive hardness mayaffect the performance of ferrous metallic abrasive as fol-lows:

51 Rc and higher hardness• Increasing hardness increases the cutting rate com-

pared to abrasive with hardnesses below 51 Rc (hard-ness of 51 on the Rockwell C scale), particularly whenremoving live (i.e., soft, flexible) coating systems.



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• Increasing hardness increases the surface profile com-pared to abrasive with hardnesses below 51 Rc.

• Increasing hardness lowers the durability and increasesabrasive consumption compared to abrasive withhardnesses below 51 Rc .

RC 50 and lower hardness· Good cutting rate for new steel and most coating

systems· Lower profile compared to abrasive with hardnesses

of 51 Rc and higher.· Higher durability but greater tendency to rounding

compared to abrasive with hardnesses of 51 Rcandhigher.

7.3 ABRASIVE CHANGE WITH USE: With use, abra-sive hardness, particle size, and particle shape will varydepending on initial hardness, blasting velocity, and blast-ing method. Abrasive hardness may increase with continuedreuse. Abrasive size will decrease with continued reuse.Because of change in hardness, shape, and size, it is impor-tant that new abrasive is added to the work mix on a regularbasis to ensure quality and consistency of blast profile andcleanliness.

7.4 ABRASIVE SHAPE: Abrasive shape may affectthe profile produced for subsequent new coatings in thefollowing ways:


6

• Shot generally produces a rounded profile and iseffective in removing mill scale.

• Grit generally produces a deeper, angular profile andis more effective for the removal of existing coatingsystems and rust.

7.5 ABRASIVE DURABILITY: Abrasive durability isbased on laboratory conditions using test equipment. Actualresults under field conditions will vary. Hence, the durabilitytest described in Section 5.2.5 should not be used to quantita-tively compare the field efficiency of different abrasive.

7.7 ABRASIVE DISPOSAL: Disposal of spent abrasiveshould comply with all applicable federal, state, and localregulations. It should be noted that the spent abrasive maycontain hazardous paint and other foreign matter.

7.8 FOR MORE INFORMATION: SSPC's Volume 1,Good Painting Practice, and Volume 2, Systems and Speci-fications, provide additional information on abrasive types andselection.



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Engineering

SSPC AB3 : 2000