AB-1/2/3 Media Standards and Special Substrates

AB-1/2/3 Media Standards and Special Substrates

Quick Answer: SSPC-AB 1 sets requirements for mineral and slag abrasives. SSPC-AB 2 addresses cleanliness of recycled ferrous metallic abrasives. SSPC-AB 3 covers ferrous metallic abrasive as manufactured/supplied for blasting. CIP Level 2 uses these documents (when invoked) plus field verification—oil, water-soluble contaminants, and sieve/size awareness—to keep media from contaminating the work. Special substrates (nonferrous, stainless, galvanized, aluminum, and other non-carbon-steel surfaces) require standards and media choices that prevent ferrous embedding, wrong profile, and chemical contamination.

Two more Domain 5 Standards blueprint lines close the equipment-and-standards cluster: media standards with field verification, and standards for special substrates.

Why Media Standards Exist

Surface preparation standards (SP and WJ series) define the workpiece. AB standards define the consumable that hits the workpiece. Contaminated or wrong-size media is a root cause of:

• Oil contamination and coating cratering
• Ionic contamination under linings
• Profile outside specification
• Embedded particles that rust or create galvanic cells
• Failure to reach the specified cleanliness grade

Level 2 inspectors who never look at abrasive quality only inspect half the process.

SSPC-AB 1 — Mineral and Slag Abrasives

SSPC-AB 1 is the standard for mineral and slag abrasives used in blast cleaning (for example coal slag, copper slag, garnet, and other mineral/slag products within the standard’s scope).

What AB 1 is about (inspector-level)

Mineral/slag media are often expendable in field work (limited recycle). Contaminants in virgin bags still occur—storage on bare ground, open tops in rain, and mixed waste in hoppers are field failure modes.

Level 2 field habits for AB 1 media

1. Verify product name, size grade, and lot against the approved blast procedure.
2. Reject media with visible trash, clay balls, organics, or free oil.
3. Keep bags elevated and covered; transfer cleanly into pots.
4. When profile drifts, check whether a different mesh lot was substituted.
5. For immersion or high-risk work, support soluble salt / conductivity checks on media extract if the ITP requires.

SSPC-AB 2 — Cleanliness of Recycled Ferrous Metallic Abrasives

SSPC-AB 2 focuses on the cleanliness of recycled ferrous metallic abrasives—the steel shot/grit (and similar ferrous metallic media) circulating in reclaim systems after use.

This standard matters because recycle loops accumulate:

• Oils from equipment, compressors, or oily workpieces
• Water-soluble salts from marine work or contaminated steel
• Dust and non-metallic trash
• Paint and mill scale fines that overload separators

Inspector-level intent of AB 2

Shop centrifugal lines and field metallic recyclers are primary AB 2 application spaces. A polished, dark, greasy look on blasted steel with “correct” SP lighting is a classic oily-media symptom.

SSPC-AB 3 — Ferrous Metallic Abrasive

SSPC-AB 3 addresses ferrous metallic abrasive requirements for media supplied for blast cleaning—the manufactured/new metallic abrasive side of the story (shot, grit, and related ferrous metallic products within scope), including property and quality expectations that support consistent cleaning and profile.

How AB 3 differs from AB 2 in practice

Projects may invoke AB 3 for purchasing and receiving inspection, and AB 2 for ongoing recycle cleanliness—Level 2 should know which claim a contractor is making when they say “media meets AB.”

AB Comparison Table

Memory hook: AB 1 = mineral/slag, AB 2 = recycled metallic cleanliness, AB 3 = ferrous metallic product.

Field Verification Methods

Standards define limits and laboratory/referee methods; jobs also use practical field checks. CIP Level 2 should be fluent in the concepts below and apply the exact methods the project/ITP names.

1) Oil content

Purpose: Detect hydrophobic contamination in media that will transfer to steel.

Field/awareness techniques:

• Visual sheen on media or on blasted steel
• Water-film / water-break style observations on blasted panels (oil causes beading or breaks in a continuous water film)
• Wash / flotation / extraction tests described in procedures or AB-related test practices when required
• Investigation of oil sources: compressor lubricators, leaking gearboxes on reclaim elevators, oily production steel mixed into the line

Response to failure: Remove contaminated media from service, clean or replace reclaim inventories, fix the oil source, re-blast affected work.

2) Water-soluble contaminants

Purpose: Detect ionic contamination (salts) in media that can deposit on the surface.

Awareness approach:

• Prepare an extract of media in deionized water per the specified method
• Measure conductivity or specific ions as the ITP requires
• Compare to project/AB limits
• Increase sampling when blasting marine structures or previously contaminated steel into a recycle loop

Soluble salts on steel may also be measured on the substrate (Bresle-type or other invoked methods)—media testing and surface testing are related but not identical hold points.

3) Sieve analysis awareness

Purpose: Confirm particle size distribution still matches the approved grade so profile and cleaning rate stay controlled.

Inspector use:

• Know the approved mesh/size for the job
• Recognize symptoms of mix failure: profile collapse (excess fines) or excessive roughness/embedding (wrong coarse fraction)
• Support laboratory or field sieve checks when profile troubleshooting or AB conformance is required
• For recycle systems, verify classifiers and scalping screens are working—sieve results diagnose separator problems

Verification program sketch (shop recycle example)

1. Receiving: metallic media lot checked to AB 3/PO requirements
2. In service: scheduled AB 2 cleanliness tests (oil + soluble contaminants)
3. Continuous: dust collector differential pressure, separator settings, new media addition rate
4. Correlation: profile + cleanliness inspections on production steel
5. Triggers: any coating adhesion anomaly or oily appearance → immediate media retest

Standards for Special Substrates

Carbon-steel SP grades and steel grit are not universal. Special substrates need methods and standards matched to metallurgy and coating systems.

Nonferrous metals and stainless steels

Inspectors should confirm media segregation (no shared steel-grit pots on aluminum jobs without decontamination plans), verify cleanliness grades appropriate to the metal, and avoid power tools that smear carbon steel onto stainless.

Galvanized steel

• Sweep blast / brush-off style prep and specific galvanizing surface standards/practices are often invoked rather than white-metal blast that removes zinc.
• Oil from chromate-free passivation treatments and wet storage stain need recognition.
• Over-blasting that strips zinc defeats the galvanizing system—follow the project’s galvanizing prep standard, not carbon-steel immersion SP 5 by default.

Concrete, wood, polymeric (link to multi-substrate prep)

• Concrete: SP 13 / NACE No. 6 and ICRI CSP language (previous section).
• Wood and polymeric substrates: manufacturer and project methods; aggressive mineral blast may destroy the substrate.
• Always read scope of any SP/AB document before forcing it onto a non-applicable substrate.

Special-substrate standards discipline

1. Identify substrate alloy/condition on the ITP.
2. List invoked prep standards specific to that substrate.
3. Approve media type compatible with the substrate.
4. Isolate equipment to prevent cross-contamination.
5. Adjust profile expectations—nonferrous profiles are often lower.
6. Document hold points separately from carbon-steel lots.

Integrated Scenario

A shop blasts carbon steel to SP 10 on a wheel line using recycled steel grit, then the same crew plans to blast aluminum handrail with the same grit “because AB 3 media is high quality.”

Level 2 response:

• AB 3 quality on ferrous metallic product does not make steel grit acceptable on aluminum if the specification bans ferrous media.
• Risk is ferrous embedding and coating failure/staining.
• Require approved non-metallic media (often under AB 1 mineral products or other approved specialty media), clean equipment, and the aluminum-specific prep standard/PDS requirements.
• For the carbon-steel line, continue AB 2 cleanliness monitoring of the recycled mix so SP 10 is not undermined by oil.

Common Traps

• Confusing AB 1 / AB 2 / AB 3 scopes on a multiple-choice item.
• Believing virgin media certificates prove recycled hopper cleanliness (AB 2 gap).
• Never testing for oil when fisheyes appear after “perfect” blast.
• Using one steel-grit system for all alloys.
• Applying carbon-steel white-metal expectations to galvanizing.
• Skipping sieve/mix checks when profile mysteriously changes mid-week.

Closing Domain 5 Equipment & Standards Arc

Together, AB media standards + field verification protect the cleanliness grades you enforce with SP and WJ documents. Special-substrate standards keep Level 2 from treating every surface like structural carbon steel. Master both, and you complete the intermediate surface-preparation standards skill set the July 2026 CIP Level 2 blueprint expects in Domain 5.