【正文】 ing on steel materials surface. Except other design stipulated standard, coating should not be done under the following conditions: ⑴ Surface of austenite stainless steel ⑵ Galvanized surface ⑶ Polished surface ⑷ Plasticcoated surface or chameleon paintcoated surface ⑸ Name plate, marking plate or docket Standstill equipment, piping and their accessory steel structures made by manufactures are required to be coated with priming coat, according to design specification. The followings should be coated in fabricating yard: ⑴ Equipment, piping and their accessory steel structures setup in fabricating yard. ⑵ Equipment, piping and their accessory steel structures, which have been coated with priming coat in manufacturing factories and need being shaved as well as coated with top coat in fabricating yard. ⑶ Equipment, piping and their accessory steel structures, which have been coated with top coat and need supplemental coating of damaged location in fabricating yard. Buried equipment piping should be given anticorrosion coating. Corrosion on steel surface caused by corrosive substance from atmosphere may be classified into three kinds of deepetching, moderate corrosion and weak corrosion according to their corrosion degree, see Table . Quality, usage, and matching scheme of normal coating anticorrosion of equipment and piping, see Appendix B. Estimated use level of coating, see Appendix C. — 7 — Table Corrosion degree on steel surface caused by corrosive substance from atmosphere Corrosive substance and acting condition Corrosion degree Grade Action Relative moisture of air (%) Deep etching Moderate corrosion Weak corrosion Corrosive gases① Ⅰ — 60 — — √ ③ Ⅱ — — — √ Ⅲ — — √ — Ⅳ — √ — — Ⅰ — 60~75 — — √ Ⅱ — — √ — Ⅲ — — √ — Ⅳ — √ — — Ⅰ — 75 — √ — Ⅱ — — √ — Ⅲ — √ — — Ⅳ — √ — — Acid fog Inanic acid Large amount 75 √ — — Small amount 75 √ — — ≤ 75 — √ — Organic acid Large amount 75 √ — — Small amount 75 √ — — ≤ 75 — √ — Particles② slightly soluble Large amount 60 — — √ soluble, slightly hygroscopic — — √ soluble hygroscopic — √ — slightly soluble Large amount 60~75 — — √ Soluble, slightly hygroscopic — √ — soluble hygroscopic — √ — slightly soluble Large amount 75 — — √ Soluble, slightly hygroscopic √ — — Soluble hygroscopic √ — — — 8 — Corrosive substance and acting condition Corrosion degree Grade Action Relative moisture of air (%) Deep etching Moderate corrosion Weak corrosion Spatter Industrical water pH 3 — — √ — pH ≤ 3 — √ — — salt solution — — √ — — inanic acid — — √ — — anic acid — — √ — — alkali solution — — √ — — general anic liquid — — — — √ Note: ① classification of corrosive gases, see Table 。 “○ ” indicate ordinary quality, able to be used。 “△ ” indicate unsuiable coating for using because of price and construction, etc. — 10 — Except the following conditions, heatinsulated equipment and piping should be coated by 12 courses of anticorrosion paint of phenolic or alkyd resin: ⑴ Important insulating equipment and piping used in coastal and humidity area should be coated with hightemperature priming coat according to using conditions. ⑵ Adhesive bitumen primer , petroleum asphalt or asphalt priming coat can be used to coat cold preservation equipment and piping, with suitable 12courses coating. Total thickness of anticorrosion coating for onground equipment and piping should be adapted to the specifications in Table . Table Total thickness of coat dry film of onground equipment and piping (?m) Corrosion degree Total thickness of coat dry film Important or hard to repairing location inside outside Deep etching ≥ 200 ≥ 250 Increasing 12 coating courses Moderate corrosion ≥ 150 ≥ 200 Weak corrosion ≥ 100 ≥ 120 Note : Total thickness of paint film of hightemperature coating is 4060μ m. Anticorrosion coating using life of onground equipment and piping should be adapted to the turn round of plant, less than two yeas are unsuitable. Requirement of rustremoving grade of priming coat for steel material surface should agree to specification in Table of steel material of rust grade D should be rustremoved by using injection or slinging. Table Requirements of suface rustremoving grade of priming coat for steel material Primer sort Rustremoving grade Deep etching Moderate corrosion Weak corrosion Phenolic resin Sa St 3 St 3 Asphalt Sa or St 3 St 3 St 3 Alkyd resin Sa St 3 St 3 Vinyl perchleride Sa Sa ? Vinyl etch Sa Sa ? Bitumineus epoxy Sa St 3 St 3 Epoxy resin Sa Sa ? Polyurethane anticorrosive Sa Sa ? Organic silicon heatresistance ? Sa Sa Chlorosulfonated polythene Sa Sa ? Alloprene Sa Sa ? Inanic zincrich Sa Sa ? — 11 — Anticorrosion of buried equipment and piping Rustremoving grade of surface of buried equipment and piping ought to be Grade St 3. Rustremoving grade should be determined according to Table based on soil corrosion grade. Table Grades of soil corrosion and anticorrosion Soil Soil corrosion quality Anticorrosion corrosion grade Electrical resistivity (?m ) Salt content (mass ratio %) Moisture content (mass ratio %) Ampere density (mA/cm2 %) pH value grade deep 50 12 Extra reinforcement Moderate 50100 512 reinforcement Weak 100 5 ordinary Note: If any value of the items is higher than the corresponding target shown in the table, the anticorrosion grade should be increased in one class. Anticorrosion grade should be extra reinforcement grade fo