BGAS painting inspector LEVEL 2 Corrosion can be generally defined as “Degradation of a metal by chemical or Electrochemical means”. From this definition it is obvious that two mechanisms are involved, firstly an electrical circuit and secondly a chemical reaction. SURFACE PREPARATION METHODS STANDARDS If the products of the corrosion reactions, and other contaminants, were left on a substrate and paint applied over them, the adhesion of the coating and thus the coatings life would be far from satisfactory. Surface preparation involves removing these contaminants, and in some instances increasing the area available for adhesion by roughening up the substrate. A good surface preparation grade (degree of cleanliness) along with a suitable surface profile can give 10 years life from a typical four coat paint system. The same system applied over a substrate with little or no profile and contaminant remaining might give four to six years, or even less.
WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY PAINTING INSPECTION GRADE 3/2 (ATC88) TWI Ltd, Training and Examination Services CORROSION Electrical Circuit The Chemical Reaction SURFACE PREPARATION METHODS & STANDARDS Dry abrasive blast cleaning Abrasives Sizing of abrasives Adhesion and Profile Profile Shot blasted profile Profile measurement Assessing a profile to BS 7079 Pt C ISO 8503.1 Use of the comparators Using the comparators Preparation of steel substrate before application of paints and related products Abrasive Blasting Grades Equipment Considerations Air Blasting Water Blasting High pressure water blasting up to 30 000 psi (water jetting) High pressure water plus abrasive injection Low pressure water plus abrasive injection Steam Cleaning Air blasting with water injection Hand and power tool cleaning 7079 Pt A, ISO 8501, SS 05 59 00 Flame cleaning Method Pickling Vapour degreasing SURFACE CONTAMINANTS AND TESTS FOR DETECTION Test for soluble iron salts Test to detect soluble chlorides Other tests for salts Test to detect the presence of millscale Test to detect the presence of dust on a substrate Test to detect the presence of moisture on a substrate Test to detect the presence of oil or grease PAINT CONSTITUENTS AND BASIC TECHNOLOGY Binder Binder – solvent groups and compatibility Polymers Oils Pigments Rust inhibitive pigments Anticorrosive Metallic Pigments Opaque pigments Extender pigments Laminar pigments PVC 1 1 4 5 11 11 11 12 13 13 14 14 17 17 17 17 18 18 18 19 19 20 21 1 2 3 10 10 11 11 12 12 12 12 Solvents Other Additives Anti settling agents Plasticisers Driers Anti skinning SOLUTIONS AND DISPERSIONS Solutions Dispersions A suspension An emulsion DRYING AND CURING OF PAINT FILMS PAINT SYSTEMS Primer Mid-coats Finishing coats Moisture tolerant systems Powder coating materials Thermosetting Thermoplastic Sacrificial coatings WATER BORNE COATINGS PAINT MANUFACTURE Direct charge dispersing mills TESTING OF PAINTS FOR PROPERTIES AND PERFORMANCE Tests done on paint Determination of volatile, non volatile Flash point determination Paint density Relative density or specific gravity Hegman grind gauge Viscosity Kinematic viscosity Flow viscometers (Flow cups) FILM THICKNESSES Wet film thickness measurement Tests done on dry paint films Dry film thickness Test panels Calculations Destructive test gauges Non destructive test gauges Tests for mechanical properties on paint films Abrasion resistance Hardness Flexibility BS 3900 E1 Impact resistance Accelerated testing Drying and curing tests Ballotini test 13 14 14 14 15 15 1 1 1 1 2 3 3 1 1 1 7 1 3 8 9 9 10 11 BK drying recorders Other tests Mechanical thumb test Pencil scratch test (Wolff-Wilborn) Mechanical scratch test Gold leaf test Thumbnail test Opacity Hiding power charts and micrometer adjustable film applicator Degree of Gloss Adhesion ‘V’ cut test Cross cut (cross hatch test) Dolly test Hydraulic adhesion test equipment SPECIFIED COATING CONDITIONS Relative Humidity Dew Point The Whirling Hygrometer, Aspirated Hygrometer or Psychrometer Steel temperature measurement CATHODIC PROTECTION Sacrificial anode systems Impressed current system Interference Monitoring CP Cathodic disbondment HOLIDAY/PINHOLE DETECTION Voltage setting PAINT APPLICATION Brush application Roller application Spray application Conventional spray Airless spray Safety considerations Electro-static spray Other paint application methods METAL COATINGS Galvanising Sheradising Calorising Anodising Electro-plating Hot metal spraying Powder system Electric arc system Wire and pistol system COATING FAULTS COLOUR The Munsell colour system 11 11 11 12 12 12 12 12 14 14 15 15 16 16 16 1 2 1 3 1 1 2 6 1 1 1 2 2 1 The BS 4800 colour system The BS 5252, framework for colour co-ordination for building purposes HEALTH AND SAFETY Hazard warning symbols Responsibilities Dräger tube and Dräger bellows Using the tubes and bellows DUTIES OF AN INSPECTOR LIST OF SPECIFICATION AND BS NUMBERS QUALITY Quality assurance Quality control Quality related standards Quality related definitions (from the above) REVISION QUESTIONS Corrosion OP – Monday Surface preparation - Monday Surface preparation – Tuesday Paint technology (1) - Wednesday Paint technology (2) - Wednesday Paint testing – Thursday Revision questions general – Friday Revision questions PA 10 specific B Gas 3.2 Maths Exercises Density and SG exercise RH and DP exercise Appendix A Appendix B INSULATION General Acoustic cladding General Materials Application of materials Thermal insulation General Materials Insulating materials Protective coverings Fixing materials Application of materials Appendix C DATA SHEET EXAMPLES 1 1 1 1 1 10 12 14 15 16 3 3 4 5 5 6 CORROSION Corrosion can be generally defined as “Degradation of a metal by chemical or Electro-chemical means” From this definition it is obvious that two mechanisms are involved, firstly an electrical circuit and secondly a chemical reaction Electrical Circuit In a corrosion circuit the current is always D.C (Direct Current) It is conventionally thought that a current passes from positive + to negative -, i.e from anode to cathode In fact electrons are flowing in exactly the opposite direction, from cathode to anode For corrosion circuit to exist three things are needed: a) Anode An anode is a positively charged area It becomes positively charged because the atoms release two electrons each, thus causing an imbalance between protons and electrons, positive and negatively charged units In it’s passive state, the iron atom has 26 of each, protons and electrons, when the two electrons are released the atom still has it’s 26 protons, but now only 24 electrons In this state the atom is now an ion, overall positively charged by two units and written as Fe++ (An ion is a charged particle, and can be positive or negative, a single atom or a group of atoms, known as a molecule.) This losing of electrons can be shown as: - Fe Ỉ Fe++ + 2e The Fe++ is called a positive iron ion An ion can be positive or negative and is a charged particle, an atom or a group of atoms A passive iron atom Fe 26 protons and 26 electrons An iron ion Fe++, 26 protons and only 24 electrons Nucleus Figure 1.1 iron atoms Painting Inspection Grade 3/2 Rev April 2004 Corrosion 1.1 Copyright © 2003, TWI Ltd WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY b) Cathode A cathode is a negatively charged area where there are more electrons than needed in its passive state These are electrons released from the anode At the cathode the electrons enter into the electrolyte to pass back to the anode c) Electrolyte An electrolyte is a substance, which will conduct a current and be broken down by it, (dissociate into ions) Water is the most abundant electrolyte and also very efficient Acids, alkalis and salts in solution are also very efficient electrolytes As the electrons pass into the electrolyte it is dissociated into positive and negative ions, as shown by the formula: -2H22H+ + 2OĦ Simultaneously the electrons couple back with the Hydrogen ions to form two full Hydrogen atoms, which join together diatomically to form Hydrogen gas This is termed as being evolved, or given off from the cathode The hydroxyl ions return to the anode through the electrolyte carrying the electrons The corrosion triangle, as shown below, can illustrate the electrical circuit The electron circuit can be seen to be from anode A, to cathode C, through the electrolyte E, back to A E A C Figure 1.2 The corrosion triangle The Chemical Reaction From the above we can see that no chemical reaction, (combination of elements) has occurred at the cathode, or in the electrolyte The chemical reaction, the formation of corrosion products, only occurs at the anode The positive iron ions, Fe++, receive the returning hydroxyl ions and ionically bond together to form iron hydroxide, which is hydrous iron oxide, rust, and is shown by the formula: Fe++ + 2OĦỈ Fe (OH)2 It is now apparent that corrosion only occurs at the anode, never at the cathode Hence the term cathodic protection If a structure can be made to be the cathode in a circuit, it will not corrode The corrosion triangle shows the three elements needed for corrosion to occur, anode, cathode and electrolyte If any one of these three is removed from the triangle, corrosion cannot occur The one most commonly eliminated is the electrolyte Placing a barrier between the electrolyte and the anodic and cathodic areas, in the form of a coating or paint system does this If electrolyte is not in direct contact with anode and cathode, there can be no circuit, and so no corrosion Painting Inspection Grade 3/2 Rev April 2004 Corrosion 1.2 Copyright © 2003, TWI Ltd WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY The basic corrosion reaction, as explained above, occurs fairly slowly at ambient temperatures In common with all chemical reactions certain factors can increase the reaction rate, listed below are some of these Temperature Steel, in common with most metals, is thermodynamically unstable The hotter the steel is the faster the corrosion will occur Hygroscopic Salts A hygroscopic salt is one, which will attract water and dissolve in it When salts are present on a substrate and a coating is applied over them, water will be drawn through the film and the resulting solution builds up a pressure under the film Eventually the film is forced up to form blisters These blisters are called osmotic or hygroscopic blisters, and are defined as ‘pinhead sized water filled blisters’ Sulphates and Chlorides are the two most common salts, chlorides predominant in marine environments, and sulphates in industrial areas and sometimes agricultural Aerobic conditions, (presence of oxygen) By introducing oxygen into the cathodic reaction the number of Hydroxyl ions doubles This means that double the number of iron ions will be passivated and therefore double the corrosion rate Shown by :2H2O + O2 + 4e Ỉ 4OHPresence of some types of bacteria on the metal surface, for example Sulphur Reducing Bacteria, better known as SRBs, or MEMs, Metal Eating Microbes Acids and alkalis Bi-metallic contact Otherwise known as Bi-Metallic Corrosion Metals can be listed in order of nobility A noble metal is one, which will not corrode In descending order, the further down the list the metal is, the more reactive it is, and so, the more anodic it is, the metal loses its electrons to become reactive ions The degree of activity can be expressed as potential, in volts The list can be called a Galvanic List, but when the free potentials of the metals are known it can also be called the Electro Motive forces series or the Electro-Chemical series Below is a list of some metals in order of nobility with potentials as measured using a copper/copper sulphate half cell reference electrode, in seawater at 25oc MATERIAL Graphite Titanium Silver Nickel 200 Lead Admiralty Brass Copper Tin Mill Scale Low Alloy Steel Mild Steel Aluminium Alloys Zinc Magnesium KNOWN POTENTIAL AV VALUES + 0.25 v 0.0 v - 0.1 v - 0.15 v - 0.2 v - 0.3 v - 0.35 v - 0.35 v - 0.4 v - 0.7 v - 0.7 v - 0.9 v - 1.0 v - 1.6 v Painting Inspection Grade 3/2 Rev April 2004 Corrosion 1.3 Copyright © 2003, TWI Ltd WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY From the list above it can be seen that millscale is immediately above steel on the galvanic list This means that millscale is cathodic to steel, and if left on the surface of steel will accelerate the corrosion of the steel substrate Millscale is formed during the rolling operation of steel sections e.g RSC, RSA, RSJ The oxides of iron form very quickly at temperatures in excess of 580c The first oxide formed is FeO, iron oxide, the next is Fe3O4 and last of all Fe2O3 Common names in order are Wustite, Magnetite and Haematite These oxides are compressed during the rolling operation to produce blue millscale The thickness of millscale varies from 25 to 100 um Because millscale is only produced during rolling, when it has been removed by any surface preparation method, it can never re-cur Painting Inspection Grade 3/2 Rev April 2004 Corrosion 1.4 Copyright © 2003, TWI Ltd WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY SURFACE PREPARATION METHODS & STANDARDS If the products of the corrosion reactions, and other contaminants, were left on a substrate and paint applied over them, the adhesion of the coating and thus the coatings life would be far from satisfactory Surface preparation involves removing these contaminants, and in some instances increasing the area available for adhesion by roughening up the substrate A good surface preparation grade (degree of cleanliness) along with a suitable surface profile can give 10 years life from a typical four coat paint system The same system applied over a substrate with little or no profile and contaminant remaining might give four to six years, or even less Therefore two factors need to be considered when inspecting a surface preparation Degree of cleanliness Surface Profile (degree of roughness) If a specification gives criteria for both of these factors, then quality is not achieved until both criteria are satisfied Surfaces can be prepared for paint application in several different ways, each one varies in cost, efficiency, ease and suitability a) b) c) d) e) f) g) Dry Abrasive Blast Cleaning Water Blasting Hand and Power Tool Cleaning Flame Cleaning Pickling Vapour Degreasing Weathering Dry abrasive blast cleaning Dry abrasive blast cleaning involves compressing air and forcing it along a hose and out of a small aperture called a nozzle A pressure of 100 psi results in the air exiting the nozzle at approximately 450 mph If abrasive particles are mixed in with the air and travel at the same speed, they will carry a lot of work energy This energy is used in chipping away millscale and other detritus from the substrate With some abrasives part of the energy is used in shattering into small pieces and with others all the energy is used in impinging into the steel surface, roughening the surface and increasing the surface area to increase adhesion properties Because all standards refer to the amount of contamination remaining on the surface, the longer the time spent on this operation, the higher the degree of cleanliness Painting Inspection Grade 3/2 Rev April 2004 Surface Preparation 2.1 Copyright © 2003, TWI Ltd WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY PA10 Institution of Gas Engineers (IGE) Recommendations* *These Recommendations are available from 21 Portland Place, London WIN 3AF IGE/SR/3 - Electrical equipment in gas production, transmission, storage and distribution IGE/SR/4 - Low pressure gasholders storing lighter-than-air gases IGE/SR/5 - Opening of gas works plant and working in confined spaces IGE/SR/12 - Handling of methanol IGE/SR/21 - Blast cleaning operations IGE/TD/6 - Handling, transport and storage of steel pipes, bends, tees, valves and fittings G11 - Notes for guidance on the issue of Permits to Work CW5 - Code of Practice for the selection and application of field applied external pipework coatings PA9 - Technical specification for paint properties and performances requirements DIS 3.1 - Engineering Procedures - Safety - Health and Safety at Works DIS 3.5 - Engineering Procedures - Health, Safety and Environmental Protection Transco specifications Other Transco publications - Handbook on Safe Handling of Substances in Use within the Gas Industry - Computerised Information System for Substances in Use in Transco (CISSUB) J020 ( Rev 08/98 ) Painting Inspection Grade 3/2 - 37 - 47 Appendix A - 38 - Painting Inspection Grade 3/2 J020 ( Rev 08/98 ) 48 Appendix A PA10 APPENDIX B SAFETY B.1 GENERAL Personnel shall comply with all relevant regulations when cleaning, painting and disposal procedures are being carried out (see Statutes and Regulations, Appendix A) Attention is drawn to the safety section of paint manufacturer's data sheets, to IGE/SR/21, BS EN 345, 355, 358/361 to 365, to DIS 3.1 and DIS 3.5 B.2 SAFETY PRECAUTIONS ON SITE B.2.l All site work is normally subject to a Permit to Work system, (see G11) The Contractor shall comply with the requirements of this system at all times No work shall be allowed to take place until a Permit to Work or form of authority has been issued A representative shall be nominated by the Contractor to act on his behalf; his duties shall include obtaining Permits to Work or forms of authority This representative shall agree with the Engineer at the beginning of each day, or by alternative arrangement, the extent of the work to be undertaken and the precautions needed Once agreed, this programme shall not be modified unless further permission is obtained The Contractor's nominated representative shall be responsible for ensuring that the Permit to Work or form of authority in force is always appropriate to the work being undertaken B.2.2 Delay in the provision of Permits to Work or forms of authority will be avoided if prior warning is given to the Engineer This shall ideally be two days' advance notice in order that prior arrangements can be initiated and completed Proper planning of the work programme is required as no additional payments shall be permitted for delays in obtaining the necessary permits or authorities B.2.3 Inspector If the contract is scheduled to last for more than six weeks, the Contractor shall notify the Factory B.2.4 All pressurised equipment, associated nozzles, etc., and electrically or pneumatically operated power tool equipment shall be earthed 'No Smoking' regulations shall be observed, and Transco reserves the right to demand the removal from site of any person who disregards this instruction Fires or flames shall not be used for the cleaning out of paint kettles, etc., or for disposal of rubbish B.2.5 The Contractor shall not operate any Transco valves or plant on site B.2.6 The Contractor shall note that certain areas on the installation are termed 'hazardous' When working in such areas, the use of non-spark tools for cleaning purposes and flameproof equipment shall be compulsory B.2.7 Where sheeting is used (e.g for protection against accidental paint spillage), it is essential that the material be non-flammable Tarpaulin sheets shall not be permitted on the site B.2.8 During the work, the site shall be kept in an orderly manner and no materials or plant shall be placed in any buildings or positions where they could present a hazard to persons passing by on their normal duties B.2.9 Vehicles shall only be allowed on site at the discretion of the Engineer Vehicles so admitted shall keep to the roadways They shall proceed as directed by Transco staff and be accompanied by a Contractor's representative from and to the main gate of the site J020 ( Rev 08/98 ) Painting Inspection Grade 3/2 - 39 - Appendix B PA10 B.2.10 If doubt exists regarding the demarcation of hazardous areas, working areas, or the requirement of any form of authority or Permit to Work, the Engineer shall provide an interpretation B.2.11 The Contractor shall acquaint himself with all installation safety and security restrictions B.2.12 In the event of an accident on site, the Contractor shall notify the Engineer and details shall be entered in the installation's Accident Record Book This does not relieve the Contractor of his own responsibilities in this respect B.2.13 The method of work and the equipment used by the Contractor may be inspected by the Engineer at any time without prior notice No inspection shall in any way relieve the Contractor of any responsibility, under the Factories Acts 1961, or otherwise, in the method of work or use of equipment B.3 ENVIRONMENTAL REQUIREMENTS B.3.1 Environmental protection B.3.1.l All waste materials resulting from surface preparation and painting operations covered in this Specification shall be properly disposed of in accordance with the requirements of the Environmental Protection Act - EPA - (Duty of Care) B.3.1.2 When surface preparation and painting operations covered in this specification are carried out in the vicinity of rivers, lakes or other water courses, special precautions may be necessary to prevent the possibility of pollution Care shall be taken to ensure operations are carried out in accordance with the requirements of the Water Resources Act B.4 STATUTORY REGULATIONS B.4.1 All operations covered in this specification shall be subject to the Health and Safety at Work etc Act 1974 and other relevant legislations, such as European Union (EU), and regulations as listed in IGE/SR/12, Appendix B.4.2 Due regard shall be taken in respect of the legislation regarding the use and care of protective clothing and other safety aids B.4.3 It is an obligation that Transco will ensure that all personnel involved in the activities covered in this specification, be made fully aware of the relevant safety aspects, including the dangers of toxic materials B.4.4 Attention is drawn to the Transco publication entitled Handbook on the Safe Handling of Substances in Use within the Gas Industry, or, alternatively, the Computerised Information System for Substances in Use in Transco (CISSUB) database All activities concerning these substances shall have been subjected to an assessment under the Control of Substances Hazardous to Health (COSHH) Regulations B.4.5 Containers and any associated packaging shall, where appropriate, be marked in accordance with the Certification, Packaging and Labelling (CPL) Regulations for Carriage of Dangerous Goods by Road and Rail 1994 and Chemicals Hazard Information and Packing (CHIP) Regulations - 40 - Painting Inspection Grade 3/2 J020 ( Rev 08/98 ) Appendix B Appendix B INSULATION General The following text deals with acoustic cladding and thermal insulation The materials used for both applications may be split into three separate types: Insulating materials Protective coverings Fixing materials All insulating materials must be stored in dry conditions under cover During installation, weatherproof sheeting must be used during inclement weather and after each day’s application Installation must be performed generally to standards normally accepted as first class workmanship The finished cladding must be of good appearance and free from dents and sharp edges Nameplates, code inspection plates and stampings on equipment must be left permanently visible and the cladding must be properly sealed around them If the above requirement is impracticable, a second plate supplied by British Gas and permanently marked with the same information and with the work ‘DUPLICATE’ must be fixed on the outside of the cladding in the most convenient, adjacent position Acoustic cladding General The relevant British Gas standards are: BGC PC PWC1 Part Part - Acoustic cladding Cladding of gas pipe and equipment Notes for guidance Cladding is defined as ‘an assembly comprising porous insulation material with a metal outer jacket’ The purpose of the cladding in this application is to cut down noise, typically by 10 – 20 dB Painting Inspection Grade 3/2 Appendix B Materials The insulation is usually in the form if semi-rigid sections For small bore pipework, 25 mm diameter and below, flexible wool or fibrous materials may be used The insulation is typically 50 – 100 mm thick and must comprise of non-toxic materials including materials which release non-toxic fumes during a fire The metal jacket must be aluminium alloy, or galvanized mild steel sheet where greater rigidity is required The thickness of the jacket must be related to the durability and strength required, ease of fitting and costs but will normally be between 0.71mm and 1.6 mm thick Galvanized materials, or any materials which contain zinc, must not be used on stainless steel due to the danger of causing zinc embrittlement Insulation banding may be metallic or non-metallic If metallic, it must be of the same material as the jacket Mastic sealants and rubber or neoprene bedding strips used must be suitable for use at temperatures between –200C to 500C with occasional increases up to 800C Nuts, bolts, screws and washers must be either stainless steel or zinc metal coated mild steel Application of materials The basic sequence for the application of acoustic cladding: Preparation Insulation plus fixing Repeat insulation and fixing if required Metal cladding plus fixing All surfaces to be clad must be clean and dry For pipework up to approximately 300 mm, preformed section of insulation must be cut and profiled to fit, and secured at 450 mm intervals with banding strip For greater diameters, flexible flat forms of insulation, e.g mattresses, must be used The jacket should not be allowed to come into direct contact with the noise radiating structure or with its supports, but should cover the whole noise radiating area without gaps or voids The finished insulation must be even, solid, tightly joined and well secured Where two layers of insulation are specified, then both the longitudinal and circumferential seams must be staggered Painting Inspection Grade 3/2 Appendix B The insulation must be completely covered by a metal jacket All overlapped joints must be at least 25 mm, bonded with mastic sealant, and must be arranged to shed water The metal jacket must never touch the pipe or equipment Clearance between the metal jacket and branches should be approximately mm and filled with mastic Potential metallic contact at other similar locations is also important to consider The metal jackets of all acoustic cladding must be continuously bonded together by a strip of jacketing metal and connected to the pipe, however, cladding must not act as an electrical bridge over isolation joints Thermal insulation General The relevant British Gas standard is: BGC PS PWC2 - Thermal insulation of above ground pipework and equipment The insulation in this application is used for heat conservation, cold conservation, personnel protection, anti-condensation, frost protection and for the maintenance of operating temperatures Temperatures applicable are from –2000C to 10000C depending on the application Materials Insulating materials The insulating materials proposed for any application must be selected from the following types: a) b) c) d) e) f) g) h) i) Glass fibre Foamed glass Rock wool Modified slay wool Expanded perlite Vermiculite (loose granular fill) Calcium silicate Phenolic foam (not within buildings – toxic during combustion) Polyisocyanurate (not within buildings – toxic during combustion) The insulating materials used must not contain substances which support pests or encourage the growth of fungi They must not cause a known hazard to health from particles or toxic fumes, during application, whilst in use or on removal The insulating materials used may be applied in layers depending on the total thickness required; in some cases up to approximately 400 mm total thickness may be specified Painting Inspection Grade 3/2 Appendix B Protective coverings Protective coverings include: Vapour seals – vapour sealing compound, preferably trowelling grade, which has an interposed scrim cloth made of woven glass cloth Vapour sealing tape may also be used Vapour seals are used for cryogenic applications Metal cladding – galvanized mild steel must be used, unless stainless steel is being insulated, in which case aluminium alloy sheet is used Hard-setting composition/self-setting cement and glass cloth may also be used as protective coverings as an alternative to metal cladding in certain circumstances Fixing materials To hold down insulating materials and protective coverings, the following may be used: a) b) c) d) e) f) g) h) i) Wire netting – used to hold down insulation but only used with hard-setting or self-setting cement as a protective covering Binding wire Binding tape Fixing bands Self-tapping screws Nuts, bolts and other fastenings Adhesives Anti-abrasion compound Joint sealant Application of materials The basic sequence for application for general heat conservation and protection: Preparation Insulation plus fixing Repeat insulation and fixing if required Metal cladding plus fixing, or self-setting or hard setting cement The basic sequence for application for general cold conservation and cryogenic service: Preparation Insulation plus fixing Repeat insulation and fixing if required Vapour seal Metal cladding Painting Inspection Grade 3/2 Appendix B As far as possible, insulation of pipework must be performed with preformed sections of insulating materials not exceeding m in length Each layer of insulation is secured with binding wire every 150 mm on pipework; the wire must not be allowed to cut into the insulation If insulating equipment, fixing bands are used every 300 mm Metal cladding must be applied so that all overlapped joints must be at least 75 mm (40 mm on 40 mm diameter pipe and below) The overlapped joints must be arranged to shed water The metal cladding must never touch the pipe or equipment Fixing bands must be used every 450 mm Painting Inspection Grade 3/2 Appendix B Painting Inspection Grade 3/2 Appendix B Appendix C DATA SHEET EXAMPLES Painting Inspection Grade 3/2 Appendix C Painting Inspection Grade 3/2 Appendix C Painting Inspection Grade 3/2 Appendix C Painting Inspection Grade 3/2 Appendix C Contact us for information on our wide range of courses at: Training and Examination Services TWI Ltd Granta Park Gt Abington Cambridge CB1 6AL, UK TWI Training & Certification (SE Asia) No Jalan TSB 10 SG Buloh Ind Park SG Buloh Selangor Darel Ehsan Malaysia Tel: +44 (0)1223 891162 Fax: +44 (0)1223 891630 Email: trainexam@twi.co.uk Tel : 603-61573528/6 Fax : 603-61572378 E-Mail : twisea@tm.net.my TWI Technology Centre (N East) Aurora Court Barton Rd Riverside Park Middlesbrough TS2 1RY, UK TWI Training and Examination Services PO Box 52721 Abu Dhabi Tel: +44 (0)1642 210512 Fax: +44 (0)1642 252218 Email: twinorth@twi.co.uk Tel: +971-2-6270750 Fax: +971-2-6270424 E-mail: twimeast@emirates.net.ae Painting Inspection Grade 3/2 Appendix C ... produces such as Sulphate salts Painting Inspection Grade 3/2 Rev April 2004 Surface Preparation 2.21 Copyright © 2003, TWI Ltd WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY Painting Inspection Grade... give a darker appearance Painting Inspection Grade 3/2 Rev April 2004 Surface Contaminants 3.3 Copyright © 2003, TWI Ltd WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY Painting Inspection Grade... E.g Methyl Ethyl Ketoxime Painting Inspection Grade 3/2 Rev April 2004 Paint Constituents 4.15 Copyright © 2003, TWI Ltd WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY Painting Inspection Grade