SSPC-SP12 / NACE 5 :- Surface Preparation and Cleaning of Steel and Other Hard Materials by High- and Ultra High- Pressure Water Jetting Prior to Recoating.

This standard requires water jetting at high- or ultra high-pressure to prepare a surface for recoating using pressure above 10,000 psi. Water jetting will not produce a profile; rather, it exposes the original abrasive-blasted surface profile. The specifier shall use one of the visual surface preparation definitions (WJ-1 to WJ-4) and one of the non-visual surface preparation definitions (SC-1 to SC-3) to specify the degree of visible and non-visible surface matter to be removed.

Pressure Categorization

• Low-Pressure Water Cleaning (LP WC) :- Cleaning performed at pressures less than 34 Mpa (5,000 psi)
• High-Pressure Water Jetting (HP WJ) :- Cleaning performed at pressures from 70 to 170 Mpa (10,000 to 25,000 psi)
• High-Pressure Water Cleaning (HP WC) :- Cleaning performed at pressures from 34 to 70 Mpa (5,000 to 10,000 psi)
• Ultrahigh-Pressure Water Jetting (UHP WJ) :- Cleaning performed at pressures above 170 Mpa (25,000 psi)

Visual Conditions of Surface Cleanliness

• WJ-1 :- Surface shall be free of all previously existing visible rust, coatings, mill scale, and foreign matter and have a matte metal finish
• WJ-2 :- Surface shall be cleaned to a matte finish with at least 95% of the surface area free of all previously existing visible residues and the remaining 5% containing only randomly dispersed stains of rust, coatings, and foreign matter
• WJ-3 :- Surface shall be cleaned to a matte finish with at least two-thirds of the surface area free of all previously existing visible residues (except mill scale), and the remaining one-third containing only randomly dispersed stains of previously existing rust, coatings, and foreign matter
• WJ-4 :- Surface shall have all loose rust, loose mill scale, and loose coatings uniformly removed

Non-Visual Conditions of Surface Cleanliness

• SC-1 :- Surface shall be free of all detectable levels of contaminants as determined using available field test equipment with sensitivity approximating laboratory test equipment. For purposes of this standard, contaminants are water-soluble chlorides, iron-soluble salts, and sulfates
• SC-2 :- Surface shall have less than 7 μg/cm2 chloride contaminants, less than 10 μg/cm2 of soluble ferrous ion levels, and less than 17 μg /cm2 of sulfate contaminants as verified by field or laboratory analysis using reliable, reproducible test equipment
• SC-3 :- Surface shall have less than 50 μg/cm2 chloride and sulfate contaminants as verified by field or laboratory analysis using reliable, reproducible test equipment