hgj229-91工业设备、管道防腐蚀工程英文版

hgj229-91工业设备、管道防腐蚀工程英文版内容摘要：

tal during welding. (1) Butt weld seam (2) Fillet welding (3) Outer corner weld seam (4) Internal corner weld seam Fig. Requirements for weld seams — 7 — 3. Metal Surface Pretreatment General Provisions The quality grade for metal surface pretreatment shall conform with the following provisions: For rust removal by manual means or powered tools, the metal surface pretreatment quality will be in two grades: St2 and St3。 For rust removal by jetting or sand blasting, the metal surface pretreatment quality will be in four grades: Sa1, Sa2, Sa2189。 and Sa3。 For flame rust removal, the metal surface pretreatment quality grade shall be F1。 For chemical rust removal, the metal surface pretreatment quality grade shall be Pi. For the metal surface pretreatment quality grades in rust removal by manual means or powered tools, jetting or sand blasting and flame, provisions in ―Rust grades and preparation grades of steel surfaces before application of paints and related products‖ (GB892388) shall be implemented. Standard for chemical rust removal quality grade Pi: The metal surface after pickling, neutralization, passivation and drying shall be pletely free of grease, oxidant scale, rust or other foreign matter. Electrolyte on the metal surface shall be cleaned with water, so that the metal surface shows a homogeneous color, without yellow rust stain. The metal surface after sand blasting treatment shall be in an even rough surface, and there shall be no obviously visible pit or burr except pits caused by original rusting on the steel plate or mechanical damage. When there is no quality requirement on the surface pretreatment for metal with anticorrosion liner or coating, the quality of metal surface pretreatment shall meet the provisions in Table . Table Quality requirements of anticorrosion liner or coating on metal surface pretreatment No. Category of anticorrosion liner or coating Pretreatment quality grade 1 Metallizing, thermosetting phenolic resin paint Sa3 2 Rubber liner, lead lining, glass fiber reinforced plastic liner, resin cement brick plate liner, silicon cement brick plate liner, anticorrosion coating on internal wall of chemical equipment, soft PVC plate bonded liner Sa2189。 3 Silicon cement brick plate liner。 oil based, bitumen based or tar based coating Sa2 or St3 or F1 4 Lead liner plate, soft PVC plate liner hollow laid or fixed with screws on holding down steel strips Sa1 or St2 or Pi — 8 — Note: Pi shall only be applied to lead lining, silicon cement brick plate liner or cases for which spraying and jetting cannot be proceeded. Before pretreatment of metal surface, surface cleaning shall be done with one or several of the following methods according to the type of contaminants, severity of contamination and shape and size of equipment. Metal surfaces contaminated by grease can be cleaned with anic solvent, hot alkali or emulsifying agent, and their formulation and process conditions can be in accordance with the provisions in Tables ~ in Appendix B hereto. Metal surfaces contaminated by anic materials or oxidants or attached with old liner or coating can be cleaned by steaming, cooking, baking, burning, knocking or shoveling. In treating thin walls, care must be taken to avoid deformation of housing. Baking or burning method must not be used to clean surfaces of annealed steel or quenchable hard steel. Treatment with Manual Means or Powered Tools As powered tools, pneumatic (motordriven) brushes and grinding wheels or various dust removing machines can be used. For manual treatment, hand hammer, scraper, shovel, wire brush and abrasive cloth (paper), etc. can be used. In treatment with manual means or powered tools, means or tools that may damage or deform the metal surface must not be used. Dry blasting treatment When dry blasting treatment is adopted, proper provisions shall be made to prevent dust from spreading. The pressed air shall be dry and clean, containing no water or oily dirt, and can be used only after qualification with the following inspection method: placing a target plate with white cloth or paint in the pressed air flow for 1 min., and there shall be no oil or water stain on it when checked visually. The packing in the air filter shall be replaced periodically, and blocked liquid in air buffer tank shall be drained in time. The abrasives shall have a fair hardness and impact toughness, must be clean, and shall be sieved before use to ensure that there is no oily dirt in it. Natural sand shall be hard and edged diamond sand, quartz sand, silicon riverbed sand or sea sand, with moisture content no greater than 1%. The operation process parameters of pressurized dry blasting treatment shall conform to the provisions in Table . — 9 — Table Process parameters of pressurized dry blasting treatment No. Type Granular size position Standard sieve (mm) Min. air pressure at nozzle inlet (MPa) Min. nozzle dia. (mm) Blasting angle (degree) Distance (mm) 1 Quartz sand All passing No. 7 sieve, not passing No. 45 sieve, residual on No. 20 sieve not less than 40% 8 30~75 80~200 2 Silica river sand or sea sand All passing No. 7 sieve, not passing No. 45 sieve, residual on No. 20 sieve not less than 40% 8 30~75 80~200 3 Diamond sand All passing No. 10 sieve, not passing No. 45 sieve, residual on No. 30 sieve not less than 40% 6 30~75 80~200 4 Chill iron sand or pellets All passing No. 18 sieve, not passing No. 45 sieve, residual on No. 30 sieve not less than 85% 5 30~75 80~200 5 Steel wire chips Chips with a dia. of and a length equal to dia., with deviation no more than 177。 40% of diameter. 5 30~75 80~200 **6 Iron or steel。