This specification covers hot dip galvanizing applied to general steel articles after fabrication. This specification does not apply to pre-galvanized goods. Such as galvanized wires, tubes or sheet and galvanizing through electro plating. All hot dip galvanizing work must be performed in accordance to BS 729: 1971. 2. APPLICABILITY
This procedure is applicable to the construction of the concrete chimney of the power station of Manjung 4, 1 x 1000 MW Power Plant Project, Malaysia. 3. REFERENCES
The documents connected to this method statement are:
Contract Nr. MCB/PC /E52 /GPBP-FERBECK/02/12/2742 Drawing Nr. MNG/04/P/UHN--B023D/GA/800 " Chimneys - General Layout " Document MNG/04/P/UHN--B026C/MS/871 "Method Statement & Risk Assessment Concrete Windshield”
Drawing Nr. MNG/04/P/UHN--B025B/SA/807 "LADDERS AND REST LANDINGS - GENERAL LAYOUT" Drawing Nr. MNG/04/P/UHN--B026A/SA/810 "ROOF PLATFORM AT EL.+193.50 - GENERAL LAYOUT" Drawing Nr. MNG/04/P/UHN--B026C/SA/813 "SUPPORT PLATFORM AT EL.+188.20 - GENERAL LAYOUT" Drawing Nr. MNG/04/P/UHN--B026C/SA/817 "GUIDE PLATFORM AT EL.+119.00 - GENERAL LAYOUT" Drawing Nr. MNG/04/P/UHN--B026C/SA/821 "GUIDE PLATFORM AT EL.+49.00 - GENERAL LAYOUT" Drawing Nr. MNG/04/P/UHN--B026C/SA/825 " CIRCULAR WALKWAY AT EL. +99.00 - GENERAL LAYOUT" Drawing Nr. MNG/04/P/UHN--B026C/SA/829 " WALKWAY AT EL. +31.50 - GENERAL LAYOUT" Drawing Nr MNG/04/P/UHN--B025C/SA/842 " STEEL LINER GENERAL LAYOUT" Drawing Nr MNG/04/P/UHN--B025C/SA/849 " INLET DUCT GENERAL LAYOUT" Document MNG/04/P/UHN--B02--/ED/881 "HSE Plan"
4. RESPONSIBILITIES
The Project Engineer has the responsibility to obtain approval of the present procedure prior to commence the concrete work. The Site Manager, in charge for the windshield construction, has the responsibility for the application of this procedure.
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The Quality Control Manager has the responsibility for the planned inspections and for the preparation of relevant documentation. 5. DEFINITIONS
In the document, the following words are used: stack: term used for the chimney subject of this procedure; windshield: outer shell of the stack, made of reinforced concrete (concrete and rebar); slipform: technical device made of a sliding formwork, jack-bars and jacks designed for a continuous erection of the concrete windshield; liner: inner part of the stack, which will be implemented after the construction of the windshields and their accessories; FIC: acronym of FERBECK INDUSTRIAL CHIMNEYS; Owner: final client.
6. STANDARD
The following standards will be applied to this work : BS 729: 1971
7. PREPARATION
All fabricated steel members for hot dip, galvanizing must be designed and fabricated in a manner to prevent distortion. Combination of thick and thin metal should be avoided. Columns & beams must be welded with strengthening gussets and webs Welded areas must be free of welding slag and spatters to avoid uncoated spot. All steel members must preferably be fabricated to allow single dip within the dimension of 12:-5meiers{length}x 1.8 meters (width)x 2;.:6 meters (depth): Steel items must be freed of paint, lacquer and heavy oil prior to delivery to the galvanizer For hollow sections and vessels, ventilation and drainage holes must be provided to prevent air pockets and blockage of zinc flow . Items must be properly packed and tagged for identification and easy handling.
8. HOT DEEP GALVANIZING
All articles shall be handled in such a manner as to avoid any mechanical damage, loss and to minimize distortion. Design or fabrication features that may lead to difficulties during galvanizing must be pointed prior to dipping. Galvanizing parameters such .as galvanizing temperature, time of immersion and withdrawal speed shall be employed to suit the requirements of the articles.
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The composition of zinc in the galvanizing bath shall not be Jess than 98.5 % zinc. Laboratory test reports on the zinc composition must be available for inspection purpose.
9. COATING REQUIREMENT
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The thickness of the galvanized coating shall confront to Table 1 in BS 729'1971. Upon request, the thickness of the galvanized coating shall be checked by the galvanizer's using a SIRIM approved magnetic measuring device before the galvanized goods are released. In the event of any dispute, stripping test shall be carried out in accordance with BS 729: 1971 Appendix A. For centrifuged items, galvanized nuts must be re-tapped oversize after galvanizing to fit.
FINISHING
The galvanized coating shall be continuous, adherent, as smooth and evenly distributed as possible and free from any defect that is detrimental to the performance of the coated article. On silicon-killed steels, the coating may be dull grey, provided the coating is sound and continuous. The integrity of the coating shall be determined by visual inspection and coating thickness measurements Where slip factors are required to enable high strength friction grip bolting these shall be obtained after galvanizing by suitable mechanical treatment of the faying surface.
