From Ministry of Water DCOM Manual

1 Painting and protective coating

1.1 General

This Specification covers the general requirements and standards of workmanship and the painting and protective coatings required to be carried out by the Contractor of the works, except where particularly redefined in individual specification clauses or as necessary due to a particularly corrosive local environment, the possible reaction of escaping chlorine on the works or on the structures or the reaction of chlorine residuals on phenolic paints (e.g. inside pipelines), harmful or toxic paint in contact with process liquids, or other special requirements, in which case the Contractor submit his own special specification along with his tender. No alternative or substitute painting standard or specification will be accepted unless it is specifically required for the above stated reason. No painting or protective coating will be accepted by the Engineer unless it is at least to the standard and of the quality specified herein.

1.2 Contractor's Responsibility

The Contractor shall be responsible for the complete cleaning, preparation, priming, painting and protec¬tion of the works carried out by him.

1.3 Submissions

The Contractor shall, within 3 months of the date of acceptance of tender, deliver to the Engineer for approval triplicate copies of a comprehensive submission (in English) with samples, certification and data regarding the final materials, sources, manufacturer's instructions, methods of application, etc., which are specified or which he proposes finally to adopt to protect the works.
The samples shall include for all paints:

  • Applied coatings and colours on sample chips;
  • Reference samples of the paint.

The certification shall include:

  • The results of taste and odour tests for all coatings proposed or specified for any pipeline, or item of plant or surface which is designed to be or could normally be in contact with or feed into the water being processed1 stored or pumped;
  • The results of meaningful tests on the effects of water and/or any other chemical fluid or gas which the coating is specifically required to protect against, and to which, by nature of the works arrangements, the protected installations may be exposed.

The data should include:

  • A complete schedule of the protective coating and paint systems;
  • Colour charts for finishing coats (including the system colour notation);
  • Manufacturer's product data on the protective treatment, coatings and paint systems;
  • Manufacturer's preparation and application instructions;
  • Method of application.

The schedule required with the submission shall contain the following information, in detail:

  • Environment of item;
  • Type of surface;
  • Surface preparation;
  • Protective or paint system to be applied;
  • Name of coating manufacturer;
  • Brand name and reference number for each coat to be used;
  • Manufacturer's data sheet for each coat, including the technical description and formulation of paint, and the colour of each paint;
  • Colour of finishing coat stating the system colour notation;
  • Proposals concerning place of application and detailed method of application of each coat, including information on equipment to be used;
  • Wet film minimum and target thickness for each coat;
  • Dry film minimum and target thickness for each coat;
  • Density of paint for each coat and coverage of paint per unit volume including volume solids.

The work detailed on the painting schedule shall meet the requirements of the Specifications. Prior to the commencement of erection of the works, the Contractor shall submit quadruplicate and English copies of the final approved painting schedule to the Engineer and during the erection, testing and commissioning periods, maintain a copy of the document on site for his own use and shall provide a separate copy for exclusive use by the Engineer.

1.4 Appropriate Standards

Where no explicit instruction is given standards in the Specification or by the manufacturer concerning any particular aspect of the workmanship, materials or procedures in connection with anti-corrosion protective systems in the works for iron and steel structures, the relevant recommendations of the following standard or code of practice shall apply: DIN 50900 Corrosion of metal
DIN 50928 Protective coating of iron and steel structures against corrosion
DIN 18364 Surface protection of steel structures
DIN 50976 Hot-dip galvanized coatings on iron and steel articles
DIN 8565 and DIN 8567 Sprayed metal coatings

1.5 Local Conditions

All coatings shall be suitable for the long term protection of the plant under operational conditions at the site of installation. The Contractor's attention is specifically drawn to the extremes of temperature and humidity recorded in the region and he shall take into account possible abrasions, restricted ventilation, and the various potentially corrosive environments within the works buildings and structures.

1.6 Decorative Finish and Final Appearance

The Contractor is advised that internal civil works finishes, furnishings and decorative colour schemes in the main operational areas (e.g. upper filter gallery) should be of a pleasing appearance, coordinated and designed to produce a comfortable working environment. Accordingly, the Contractor shall allow for consultation with the Engineer regarding the final colour scheme and decoration of the works.

1.7 Coatings in Contact with Potable Water

Water in contact with the dried coatings shall not acquire an unpleasant taste or odour, shall not show the presence of dissolved phenols and shall not acquire more than 5 Hazen units of colour.

1.8 Trial Areas and Sample Pieces

Prior to the commencement of the site, painting work designated area(s) or section(s) of the works shall be completely painted as a sample of the work and workmanship to be carried out. The area(s) or section(s) shall include complete samples of all the major painting required in the works. The area(s) shall be offered for review by the Engineer and shall, upon approval, be then preserved as a reference standard for the work. No extra payment will be made for carrying out such protection or decoration in advance of the general work, or for the removal and repetition or improvement of the work if required by the Engineer in order to achieve the specified standard.

1.9 Precautions, etc.

All surface fittings, ironmongery, etc., except hinges shall be removed before painting and refixed on completion. They shall be entirely free of any droppings, paint smears and blemishes. Labels, pump and other machinery name plates, data plates, markings, etc., shall not be overpainted but carefully preserved by removal and replacement or by masking. The Contractor shall pay particular attention to the toxicity, inflammability and the explosive dangers related to the storage and application of the systems and shall take all precautions necessary to the satisfaction of the Engineer to protect his operatives, the public and other site personnel.

1.10 Work Succession

No one site coat may proceed in any section of the works until the entire section is complete and the Engineer has had notice of completion in order that he may inspect the work and authorize the application of subsequent coats. Each successive coat shall preferably be of different colour or shade to facilitate inspection. The Engineer may apply his own identification markings on undercoats to ensure full compliance with the Specification.

1.11 Application of Protective Coating and Paint System

Unless specifically specified elsewhere, the protective systems shall be applied in accordance with the manufacturer’s instructions to the full thickness range specified, particular note being taken of the requirements for the time interval between successive coats of the system. The coating thickness for painting on concrete or plaster surfaces shall be in accordance with the manufacturer's instructions or proposals.

1.12 Equipment and Condition

Brushes, tools and equipment shall be kept in a neat and clean condition. Painting shall not be carried out in the vicinity of other operations, which might cause dust. The final coat shall be uniform in colour and free from brush marks, runs or other defects.

1.13 Paint Thickness and Continuity

The Contractor shall provide and maintain, during manufacture and on site, gauges and measuring equip¬ment of an approved type to ensure that the specified film thicknesses are achieved, paint holidays are avoided, and adhesion is to the satisfaction of the Engineer. Wet film thickness gauges shall be provided to and used by each painter to check the rate of paint application. The thickness of the built-up dry film after each paint coat applied to steel or other magnetic surfaces shall be measured systematically with a dry film thickness gauge. The Contractor shall adopt holiday detection on concrete, steel and iron surfaces and shall use a suitable method of detecting pinholes in the coating system after trials on test plates, which shall be notified in advance to the Engineer. The sweep voltage on high voltage DC equipment shall not exceed half the voltage required to spark through the complete paint system specified. Gauges, instruments and meters shall be maintained in an accurate working condition and shall be made available to the Engineer for checking when requested. The following instruments, with the manufacturer's operating instructions, shall be provided, maintained and used by the Contractor's inspector. In addition, under the Contract a separate set shall be provided and maintained for the Engineer's sole use for the duration of the Contract:
• 1 adhesion tester, cover 0 to 280 kg/cm2;
• 1 DC high voltage holiday detector, 20 kV, with rechargeable batteries;v • 1 paint inspection gauge, 0 to 500 microns;
• 4 "wet-check" moisture meters with suitable concrete and timber scales;
• 1 dry film thickness gauge, 0 to 500 microns;
• 4 wet film gauges, up to 500 microns;
• 1 steel temperature gauge, up to 500C;
• 1 air humidity gauge;
• 1 air thermometer (maximum and minimum);
• surface profile gauge, up to 150 microns.
Daily checks shall be carried out and recorded on site in accordance with the provisions of DIN 55928.

1.14 Dry Film Thickness

References in the Specification to dry film thickness (DFT) shall mean the minimum dry film thickness measured with a suitable instrument, either of individual coats, or the total system, as specified in microns (um). The maximum permissible coat tolerance shall be + 15 %, - 0 % over the DFT.

1.15 Colour Coding

Pipework, tanks and ducting shall be colour coded by totally painting with the appropriate code colour as specified. The principal code colours shall be as follows: Contents Description Colour Potable water Blue Hot water Crimson Raw water Light green Irrigation water Medium green Waste water Dark green Fire fighting water (including sprinkler systems and hydrants) Signal red Oil and fuel oil Brown Gas for fuel Yellow ochre Chlorine liquid and gas Yellow Compressed air Light blue Air (ventilation and air conditioning ducts) Silver

The definition RAL - notation of the colours mentioned above shall be subject to Engineer's approval after the commencement of the works. The colour coding for other minor pipelines, etc., will be notified to the Contractor prior to the commencement of erection. All pipes and tanks shall also bear painted labels to indicate the contents. Lettering shall be in both and English. Labels on pipework shall incorporate arrows showing the direction of flow within the pipework. Black lettering shall be used on organe, yellow and green and white lettering shall be used on red and blue. Sufficient labels shall be used to ensure adequate identification throughout the length of the pipe runs. These shall be located at least adjacent to each flange or disconnecting joint, where pipework passes through walls, floors, crosses doorways and other access ways and at intervals in long runs of pipework.

1.16 Knotting and Stopping

Knotting shall comply with DIN 4062. Stopping for concrete or sand/cement plastering shall be of similar material to the background and shall have a similar surface finish. Stopping for woodwork, hardboard and plywood shall be a proprietary spirit-based wood filler, tinted to match the woodwork. Parts to be subjected to manufacturer's shop testing shall not be stopped or surface treated prior to satisfactory completion of the testing. Thereafter the specified treatment shall be applied.

1.17 Paint Source and Supervision

All paint shall be "new" and "fresh" and obtained from approved manufacturer(s). If so directed by the Engineer, the Contractor shall ask the paint manufacturer(s) to spot-check the preparation and painting and submit to the Engineer and the Contractor a written report on his observations.

1.18 System to be Compatible and Complete

All coatings, stopping, primers, compatible and undercoats and finishing paints of any one complete protective system shall be compatible with each other and the completed system shall provide continuous, pore-free coatings resistant to physical and chemical disintegration in the environment in which they are to be used. As far as is practicable, materials, forming any one protective and/or decorative system used in the permanent works, shall be obtained from one manufac¬turer.

1.19 Bitumen Coating

Bitumen coatings shall be to DIN 18195, 18336 and DIN 18337. Suitable grades shall be selected where the coating will be in contact with potable water.

1.20 Identification

All paint shall be supplied in sealed containers bearing the following information in addition to any statutory requirements:
• Manufacturer's name, initials or trade mark;
• Whether priming, undercoat or finishing coat;
• Whether for interior or external use;
• The colour reference number;
• The method of application (e.g. brush);
• The batch number and date of manufacture of re-test
• The shelf life of the contents.
Containers for materials other than paints shall bear as much of the above information as appropriate.

1.21 Storage and Use of Paint, Thinners etc.

Paint, thinners, etc., shall be stored in sealed containers in a lock-up store at a temperature of not less than 40C and not more than 270C. Any special storage conditions for the paint recommended by the manufacturer shall be observed.

1.22 Paint Preparation

Paint shall be supplied from the Contractor's paint store to the painters ready for application. Any addition of thinners shall be made in the store under supervision and up to the limit detailed on the appropriate manufacturer's paint data sheet for the particular method and conditions of applications concerned.

1.23 Waste

The Contractor shall provide on site suitable moveable receptacles into which are to be placed all the liquid, slops, washings, etc. All solid refuse or inflammable residues shall be removed from site or carefully burned. No refuse shall be deposited on any soil or disposed down any permanent sanitary fittings, sinks or drains. The Contractor shall immediately clean up any unauthorized deposition and remove from the site any employee found to be responsible.

1.24 Spray Application

The equipment to be used for spray application shall be in strict accordance with the paint manufacturer's instructions for each coating material. Any runs shall be immediately brushed out.

1.25 Brush Application

The shape and quality of the brushes shall be suitable for the work to be carried out. Extension handles to brushes shall not be permitted.

1.26 Metal Coatings

Metal coatings required for protective purposes on any item of metalwork shall be applied after fabrication of the items is completed, including all punching, welding, drilling, grinding, screw tapping and cutting, and after the removal of surface defects. Tapped holes shall be blanked off before the metal coating is applied.

1.27 Prefabrication Primers

Unless otherwise specified, prefabrication primers for steelwork shall comply with the relevant DIN standards and contain corrosion-inhibiting pigments, adhere firmly to the substrate and form suitable bases for the succeeding coats in the protective paint system.

1.28 Surface Preparation by Blasting

All surfaces to be coated shall be free of scale, rust, grease, oil, dust and other deleterious materials. The surface finish of blast cleaned steel shall be in accordance with the relevant DIN standard and to a visual standard in accordance with SIS OS 59 00 at the time of painting. The blast profile shall be within the limits 50 - 75 microns. Abrasives shall be restricted to re-usable iron or steel (grit and shot) or copper slag. The type and grades of abrasive shall be selected in accordance with the appropriate DIN standard. Within four hours of completion of surface preparation, and before surface re-rusting occurs, a coating of primer shall be applied to avoid deterioration of the prepared base metal. No contamination shall be permitted to occur between blast cleaning and primer coating.

1.29 Dehumidification Required for Special Purposes

The Contractor shall supply and operate such dehumidification equipment as may be necessary to preserve blast cleaned surfaces in a pristine condition until they can be coated and/or to provide the curing conditions necessary for such coats.

1.30 Classification of Painting

Lettered classification of surfaces shall be used for the purpose of identifying the protective coating specified herein:
"A": Surfaces above process liquid level and not liable to splashing thereby, in non-aggressive atmosphere;
"B": Surfaces in contact with untreated or treated water for potable use;
"C": Surfaces below process liquid level or liable to splashing thereby in non-aggressive solutions and/or atmospheres.
For the Contractor's convenience the painting require¬ments are summarized in Table 1-5, Annex to the General Specifications, scheduling some of the work.

1.31 Embedded Steel

Steel which is to be totally embedded in concrete shall be cleaned to Swedish Standard 5t2 and shall not be primed.

1.32 Uncoated Surfaces

The only surfaces of iron or steelwork or non-corro¬sion resistant materials which are to be left unprotected by paint or metal coating are:
• The internal surfaces of boxes or hollow sections which are of dimensions too small to permit access for painting either at the fabrication stage or for maintenance during the operation life of the steelwork and which are to be hermetically sealed by welding;
• Those surfaces of built-in iron or steel members which are to have concrete cast against them;
• Machine bright parts and bearing surfaces which shall be thoroughly cleaned, polished and protected from corrosion by painting with one coat of a mixture of white lead and tallow or other similar approved material before despatch. The Contractor shall provide solvent for removing the treatment;
• Parts which are specified to include corrosion allowances instead of protective coatings.
Surfaces of iron or steel members which are to have concrete cast against them shall be clean and free of deleterious matter and loose rust at the time of concreting. The paint protection system, to be applied to the permanently exposed faces of these members before the members are built in1 shall be continued for 50 mm as marginal strip along the contact surface. No paint containing aluminium in metallic form shall be allowed to come into direct contact with the concrete.

1.33 Repair of Damaged Work - General

Unless specified elsewhere, areas of paint on steel-work which have been damaged shall be cleaned to sound material and the edges of the undamaged paint smoothed with sand-paper to a gentle bevel. The specified paint system shall then be applied in accordance with manufacturer's instructions to bring the damaged area up to the same state of protection as the surrounding paintwork, with each coat of new paint overlapping the corresponding existing coat of paint by at last 50 mm. Where epoxy coatings are damaged, suitable repair supplied by the manufacturer of the original coating shall be applied in accordance with the manufacturer's instructions.

1.34 Fastenings

Bolts, nuts and washers and other demountable fastenings of all galvanized parts and also aluminium alloy parts shall be in stainless steel to the appropriate DIN standard and shall remain unpainted. P.T.F.E. washers shall be fitted beneath bolt-head and washer when fastening galvanized and aluminium alloy parts. Fastenings, except high tensile, of all ferrous parts shall be steel prepared and galvanized to or sheradized to the relevant DIN standards, primed and painted in accordance with location. Unless specifically approved and required for superior protection, electro-galvanizing, nickel, cadmium or any other plating process, except chromium plating, will not be acceptable, and shall not be offered.

1.35 Painting and Protection of Bolted Connections

Joints areas of bolted connections shall be masked to maintain the surfaces free from any paint applied prior to making the connections. Masking shall be removed before erection. After installation and after all bolts have been tightened, the area of the connection shall be cleaned to remove all dirt, dust, oil or other contaminant. Particular care shall be taken to ensure that all traces of oil and grease are removed from bolts, nuts and washers. Bolts, nuts and washers and any exposed at bolted connections shall also be primed as specified, particular care being taken to ensure that any crevices are fully sealed. The remaining coats of the paint system shall then be applied. Following painting and where the bolted connections are in an area to be backfilled (pipe trench flanges, etc.) the bolts, nuts and washers and the entire joint assembly shall be carefully packed with an approved purpose made water proof protective paste (non sol¬vent) and finally wrapped with an approved protective paste impregnated tape to completely encase the assembly. Pipe joint protection shall continue along the length of the barrel for a distance of 200 mm.

1.36 Copper and Brass

Copper pipes and brass fittings shall be painted where they are located in aggressive locations, or to colour code the function.

1.37 Plaster and Concrete Protection

Where specified or required for the protection of the work or the containment or storage of chemical solutions, concrete or rendered surfaces shall be protected with paint systems accordingly to Table 4 in the Annex to the General Specifications.

1.38 Preparation of Concrete and Rendered Surfaces

Concrete and rendered surfaces shall be thoroughly cured in accordance to the manufacturer's instructions before the application of any painting system is begun.

1.39 Minimum Thickness and Adhesion Tests for Painting Systems for Concrete and Plaster

The total dry film thickness of any used paint system shall have a minimum value of tests for 0.75 mm. In order to restore the coating integrity and plaster thickness whenever the paint inspection gauge is used or wherever the coating has been otherwise damaged, the surface shall be abraded for 50 mm around such damage and the area touched in with not less than two thick applications. Adhesion tests will be carried out on the cured coating using the test equipment supplied under the Contract in accordance with the best practice. The resulting test specimen shall show no indication of poor adhesion to the substratum, residual laitance or intercoat adhesion weakness.

1.40 Preparation of Plaster, Brickwork and Concrete Surfaces

Efflorescence present on the surface of internal plaster, brickwork and concrete shall be removed by scraping and brushing before any surface paint is applied. When fluorescence has been removed surfaces shall be left for at least three days before priming. Painting shall be deferred where further salt deposits form on the surface during this period. Plaster surfaces to be painted shall be cleaned down, smoothed as necessary, and all cracks shall be filled with stopping for plaster. All fittings shall be carried out before paint is applied to the surface. Brickwork, blockwork and concrete surfaces shall be cleaned of all contaminating matter before being primed. Subject to the approval of the Engineer large holes which would cause a break in the paint film shall be filled with mortar, the surface being rubbed down to match the surrounding areas.

1.41 Preparation of Wood Surfaces

Wood surfaces shall not be painted when the moisture content of the timber measured with an electric moisture meter exceeds 12 % for interior surfaces and 18 % for exterior surfaces. Hardwoods and soft woods for which a clear finish is specified shall be rubbed down with abrasive paper to give a smooth surface which shall be free from contaminating substances, scratches and other imperfections. Prior to coating all nail and screw holes, etc., shall first be stopped. Surfaces which are to be painted shall be rubbed down to remove all contaminating substances and imperfections which would be visible in the finished paint film. The surfaces of knots and resinous streaks shall then be painted with two coasts of knotting, the first being allowed to dry before the second is applied. The surfaces of timber treated with a water-borne preservative by an impregnation process shall be rubbed down and dry brushed to remove all traced of efflorescence before the primer is applied. Where surfaces are suspected of being infected with mould they shall be thoroughly treated with a fungicide.

1.42 Final Treatment of Wood, Plaster, etc

The final painting system required in the works is given in Table 5 in Annex to the General Specifications, and is presented to tenderers for guidance to include such work in their supply under this Contract.