nes 764 flame metal spraying and hot dip galvanizing of ships structure and fittings category 2

Ministry of Defence Defence Standard 02-764 (NES 764)

Issue 1 Publication Date 01 April 2000

Incorporating NES 764 Category 2

Issue 3 Publication Date January 1988

Flame Metal Spraying AndHot Dip Galvanizing Of

Ships Structure And Fittings

DStanDStan is now the publishing authority for all Maritime Standards (formerly NESs). Any reference to any other publishing authority throughout this standard should be ignored.Any queries regarding this or any other Defence Standard should be referred to the DStan Helpdesk as detailed at the back of this document.

AMENDMENT RECORD

Amd No Date Text Affected Signature and Date

REVISION NOTE

This standard is raised to Issue 1 to update its content.

HISTORICAL RECORD

This standard supersedes the following:

Naval Engineering Standard (NES) 764 Issue 3 dated January 1988.

Ministry of Defence

Naval Engineering Standard

NES 764 Issue 3 (Reformatted) January 1988

FLAME METAL SPRAYING ANDHOT DIP GALVANIZING

OFSHIPS STRUCTURE AND FITTINGS

This NES Supersedes

NES 764 ISSUE 02

Record of Amendments

AMDT INSERTED BY DATE

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2

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5

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iNAVAL ENGINEERING STANDARD 764

ISSUE 3 (REFORMATTED)

FLAME METAL SPRAYING AND HOT-DIP GALVANIZING

OF SHIPS STRUCTURE AND FITTING

The issue and use of this Standard

is authorized for use in MOD contracts

by MOD(PE) Sea Systems and

the Naval Support Command

ECROWN COPYRIGHT

Published by:

Director of Naval ArchitectureProcurement Executive, Ministry of DefenceFoxhill, Bath BA1 5AB

NES 764Issue 3 (Reformatted)

iii

SCOPE

1. This NES describes the application of metal by molten spray to protect steel structure andfittings from corrosion where applicable on Surface Ships and Submarines.

2. Guidance for the hot-dip galvanizing of structural steel is also included.

3. The application of metal bymolten spray for engineering purposes (eg the repair ofmachineryparts) is not included.


iv


v

FOREWORD

Sponsorship

1. ThisNaval Engineering Standard (NES) is sponsored by theProcurement Executive, Ministryof Defence, Deputy Controller Warships (DCW), Section NA 131.

2. It is to be applied as required by any Procurement Executive, Ministry of Defence contract forthe flame metal spraying and hot-dip galvanizing of Surface Ships and Submarines structureand fittings.

3. If it is found to be technically unsuitable for any particular requirement the MOD(PE) is tobe informed in writing of the circumstances with a copy to Deputy Controller WarshipEquipment (DCWE), ME 241 for Ship Systems and Equipment.

4. Any user of this NES either within MOD or in outside industry may propose an amendmentto it. Proposals for amendments which are:

a. not directly applicable to a particular contract are to be made to the Sponsor of the NES

b. directly applicable to a particular contract are to be dealt with using existing proceduresor as specified in the contract.

5. No alteration is to be made to this NES except by the issue of an authorized amendment.

6. Unless otherwise stated, reference in this NES to approval, approved, authorized or similarterms, means by the Ministry of Defence in writing.

7. Any significant amendments that may be made to this NES at a later date will be indicatedby a vertical side line. Deletions will be indicated by 000 appearing at the end of the lineinterval.

8. This NES has been reissued because of update to NES format.

Conditions of Release

General

9. This Naval Engineering Standard (NES) has been prepared for the use of the Crown and ofits contractors in the execution of contracts for the Crown. The Crown hereby excludes allliability (other than liability for death or personal injury) whatsoever and howsoever arising(including but without limitation, negligence on the part of the Crown, its servants or agents)for any loss or damage however caused where the NES is used for any other purpose.

10. This document is Crown Copyright and the information herein may be subject to Crown orthird party rights. It is not to be released, reproduced or published without written permissionof the MOD.

11. The Crown reserves the right to amend or modify the contents of this NES without consultingor informing any holder.

MOD Tender or Contract Process

12. ThisNES is the property of the Crown and unless otherwise authorized in writing by theMODmust be returned on completion of the contract, or submission of the tender, in connectionwith which it is issued.


vi

13. When this NES is used in connection with aMOD tender or contract, the user is to ensure thathe is in possession of the appropriate version of each document, including related documents,relevant to each particular tender or contract. Enquiries in this connection may be made ofthe local MOD(PE) Quality Assurance Representative or the Authority named in the tenderor contract.

14. When NES are incorporated into MOD contracts, users are responsible for their correctapplication and for complying with contracts and any other statutory requirements.Compliance with an NES does not of itself confer immunity from legal obligations.

Related Documents

15. In the tender and procurement processes the related documents listed in each section andAnnex A can be obtained as follows:

a. British Standards British Standards Institution,389 Chiswick High Road,London W4 4AL

b. Defence Standards Directorate of Standardization and Safety Policy,Stan 1, Kentigern House, 65 Brown Street,Glasgow G2 8EX

c. Naval Engineering Standards CSE3a, CSE Llangennech, Llanelli,Dyfed SA14 8YP

d. Other documents Tender or Contract Sponsor to advise.

Note: Tender or Contract Sponsor can advise in cases of difficulty.

16. All applications to Ministry Establishments for related documents are to quote the relevantMOD Invitation to Tender or Contract Number and date, together with the sponsoringDirectorate and the Tender or Contract Sponsor.

17. Prime Contractors are responsible for supplying their subcontractors with relevantdocumentation, including specifications, standards and drawings.

Health and Safety

Warning

18. ThisNESmay call for the use of processes, substances and/or procedures thatmay be injuriousto health if adequate precautions are not taken. It refers only to technical suitability and inno way absolves either the supplier or the user from statutory obligations relating to healthand safety at any stage of manufacture or use. Where attention is drawn to hazards, thosequoted may not necessarily be exhaustive.


vii

CONTENTSPage No

TITLE PAGE i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SCOPE iii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FOREWORD v. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Sponsorship v. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Conditions of Release v. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

General v. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MOD Tender or Contract Process v. . . . . . . . . . . . . . . . . . . . . . . . . .

Related Documents vi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Health and Safety vi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Warning vi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CONTENTS vii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 1. MATERIALS 1.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .TABLE 1.1 MATERIALS AND EQUIPMENT 1.1. . .

SECTION 2. SAFETY PRECAUTIONS 2.1. . . . . . . . . . . . . . . . . . . .2.1 Flame Pistols 2.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.2 Gas and Oxygen Cylinders 2.1. . . . . . . . . . . . . . . . . . . .2.3 Gas and Air Hoses 2.2. . . . . . . . . . . . . . . . . . . . . . . . . . .2.4 Ventilation Supply and Exhaust 2.2. . . . . . . . . . . . . . . .2.5 Cleanliness 2.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.6 Lighting 2.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.7 Protective Clothing 2.3. . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 3. EXTENT OF METAL SPRAYING 3.1. . . . . . . . . . . . .3.1 Internal Areas 3.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.2 External Areas 3.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 4. SURFACE PREPARATION 4.1. . . . . . . . . . . . . . . . . . .

SECTION 5. METAL SPRAYING 5.1. . . . . . . . . . . . . . . . . . . . . . . . .5.1 Sprayed Metal Systems 5.1. . . . . . . . . . . . . . . . . . . . . . .5.2 Application of the Coatings 5.1. . . . . . . . . . . . . . . . . . . .5.3 Repair of Metal Sprayed Coatings 5.2. . . . . . . . . . . . . .

SECTION 6. EQUIPMENT 6.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 7. QUALITY ASSURANCE 7.1. . . . . . . . . . . . . . . . . . . . .

SECTION 8. TREATMENT OF METAL SPRAYED SURFACES 8.18.1 Internal 8.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8.2 External 8.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 9. HOT-DIP GALVANIZING 9.1. . . . . . . . . . . . . . . . . . . .TABLE 9.1 COATING WEIGHT 9.1. . . . . . . . . . . . . .


viii

ANNEX A. RELATED DOCUMENTS A.1. . . . . . . . . . . . . . . . . . . .

ANNEX B. DEFINITIONS AND ABBREVIATIONS B.1. . . . . . . .

ANNEX C. METHOD OF CHECKING THE ADHESION OFTHE ZINC SPRAY TO THE STEEL SURFACES C.1.

ANNEX D. PROCUREMENT CHECK LIST D.1. . . . . . . . . . . . . . .

ALPHABETICAL INDEX


1.1

1. MATERIALS

a. References to zinc in this NES mean zinc in accordance with Zn2 (99.95% zinc)or Zn3 (99.5% zinc) as given in BS 3436.

b. References to aluminium for metal spraying in this NES mean aluminium inaccordance with G1B (99.5% Al) or G1C (99% A1) as given in BS 1475.

c. The particulars of the materials and equipments to which this NES refers areas follows:

Material Quantity Specification NATO Stock No

3.2mm, 12kg coil 3439995264188

Wire, spray gun, 3.2mm, 25kg coilBS 1475

3439995264189, p y g ,aluminium 2.0mm, 12kg coil

BS 14753439995264190

2.0mm, 25kg coil 3439995264191

3.2mm, 12kg coil 3439995264194

Wire, spray gun, 3.2mm, 25kg coilBS 3436

3439995264195, p y g ,zinc 2.0mm, 12kg coil

BS 34363439995264196

2.0mm, 25kg coil 3439995264197

20 cu ft

Cylinder oxygen 110 cu ft 6830999422250y yg220 cu ft 6830999422251

10 lb 6830992245324

24 lb 6830992245326

28 lb 6830992245327

Cylinder propane 42 lb 6830992245329y p p50 lb

75 lb 6830992245328

100 lb 6830992245325

10 cu ft cylinder 6830992203828

Acetylene technical 100 cu ft cylinder 6830999422218y200 cu ft cylinder 6830992240439

Metal sprayingp y gequipment (pistols,q p (p ,nozzles, regulators, Proprietary, g ,flow meters,

p y,

stands, etc

ConcentratedGeneral Purpose DG Ships 305 7930992346817pcleaner

p

Metallic zinc-richBS 4652

8010995432432

priming paintBS 4652

Bituminous Solution 5 gallon TS 10195A 8010999429290

TABLE 1.1 MATERIALS AND EQUIPMENT


1.2


2.1

2. SAFETY PRECAUTIONS

a. The danger of explosion or fire is ever present during the setting up of theequipment and carrying out the metal spraying work, and until the equipmenthas been removed from the work area. It is therefore essential that precautionsare taken throughout these periods. Guidance on precautions which experiencehas shown to be necessary to guard against the risk of fire and explosion is givenin the following Clauses in this section.

2.1 Flame Pistols

a. Flame pistols and associated equipment must be used and maintained inaccordance with the manufacturers instructions. Cleanliness and leak freeconnections are essential. Ignition is only to be within gas free areas.

b. The spraying pistol is always to be lit up, adjusted, and shut off strictly inaccordance with the manufacturers instructions. When in use the pistol is notto be pointed at other persons, combustible materials or gas cylinders.

c. If the pistol back fires in use, close the pistol valve to prevent major damage tothe unit, then shut off the fuel gas cylinder valve. Immediately reopen the pistolvalve, allowing air to flush nozzle ports for about half aminute. If, on relightingcorrectly, the back fire is repeated, shut off as above and ascertain the cause.

d. When the spraying unit is to be laid aside after use, both the fuel gas and oxygencylinder valves are to be closed and the hoses and pistol purged of all residue gasby a reverse flow of compressed air (using suitable adaptors) from the gun endof the hoses to open air.

2.2 Gas and Oxygen Cylinders

a. The following precautions are to be taken when using or storing gas and oxygencylinders.

b. On no account are oxygen and fuel gas cylinders to be stored in the same areaand near compartments in which metal spraying is being undertaken, and careis to be taken to see that full and empty cylinders are clearly distinguishable andkept well apart.

c. When cylinders have to be stored or sited out of doors, they are to be protectedfrom rain, and the direct rays of the sun. Gas cylinders in particular, are to betreated with care, and not subject to knocks, blows or excessive heating, and areto be kept in an upright position at all times.

d. If by arrangement with the Shipbuilders or Ship repairer, they are permitted tobe placed on the ship, they are never to be sited between decks.

e. It is important that no oil, grease, or fatty substances are allowed to come intocontact with oxygen cylinders, regulators, or filters. Oil and grease in thepresence of oxygen are EXTREMELYEXPLOSIVE. It is also important that nogrit or other foreign matter is allowed to enter, or remain on fittings carryingcombustible gases or oxygen.

f. Keys of gas cylinders must always be a perfect fit on the spigot, andmaintainedin good condition. When not in use the reducing valve fittings and the outletvalve control are to be removed taking care to ensure that the cylinder valve isfully closed before removal.

g. All cylinders are to be fitted with Non Return Valves.


2.2

2.3 Gas and Air Hoses

a. Only British Standard approved reinforced rubber hoses and connectors ofcorrect distinguishing colours and adequate internal diameter are to be used forgas and air supplies to the metal spraying pistol. The British Standarddistinguishing colours for the hoses are:

Orange for propane gasRed for acetyleneBlue for oxygenGreen or Black for compressed air.

b. Care is to be taken to ensure that hoses are securely attached to connectors bymeans of suitable approved hose clips. When two lengths of hose require to becoupled together, special couples only are to be used.

c. All hoses supplying fuel gas to the spraying pistol are to be supported andsecured in such a manner that they are free from kinks, and not exposed topossible damage from heat, sharp edges, footwear or heavy objects.

d. The hoses are to be frequently inspected to ensure that they have not becomecut or cracked. Hoses that show any defects are to be replaced immediately.

2.4 Ventilation Supply and Exhaust

a. It is important that an efficient system of flameproof ventilation providing atleast 15 volume air changes per hour is installed and maintained inCompartments where metal spraying work is being carried out.

b. The ventilation trunkings are to be constructed of suitable soundnon-flammable material adequately secured and protected from damage.

c. The exhaust ventilation trunking within the compartment is to be positionedat the highest and lowest points in the compartment to dispose of any possibleaccumulation of gases.

2.5 Cleanliness

a. Accumulations of zinc and aluminium spray dust with abrasive blasting dustarisings are potentially explosive and fire hazardous. Therefore regular cleaningoperations to avoid such accumulations are to be carried out. Particularattention being paid to the inside of exhaust ventilation where heavily oxidizedabrasive blasting dust is likely to settle and mix with the sprayed metal dustarisings.

b. Arisings from cleaning operations are to be removed from the ship and safelydisposed of.

c. On no account is the dust exhausted during abrasive blasting and metalspraying to be collected in the same container.

d. Likewise zinc and aluminium dust will react with water and give off hydrogen,which produces an explosive mixture in the presence of air. In view of this onno account is the metal powder arisings to be discharged into water traps, forcollection purposes.

2.6 Lighting

a. Adequate flameproof and dust proof lighting giving a high standard ofillumination is to be provided during the whole course of abrasive blasting andmetal spraying work.


2.3

2.7 Protective Clothing

a. All operators are to be issued with, and wear overalls, gloves, tinted goggles, andrespirators either fed with a clean filtered air supply, or fitted with dust andfume cartridges.


2.4


3.1

3. EXTENT OF METAL SPRAYING

a. The areas selected for metal spraying will be listed in Contract Documents. Theextent of metal spraying is to be kept to the minimum consistent with adequateprotection of structure and fittings against corrosion. DCW will provideguidance when proposed omissions are under discussion.

3.1 Internal Areas

a. Internal areas to be metal sprayed include inner bottom; wet bilges; uppersurfaces of all longitudinals inmachinery spaces; bathroom, laundry and galleystructures except where neoprene polymeric epoxy, latex or ceramic deckcoverings will be laid; inaccessible structure; any other areas considered torequire this standard of preservative treatment.

3.2 External Areas

a. External areas to be metal sprayed include all steel decks and the bottom 75mmof all adjacent superstructures, edgestrips and coamings excluding those ofaluminium. Helicopter landing decks and aircraft Flight Decks ARENOT to bemetal sprayed.


3.2


4.1

4. SURFACE PREPARATION

a. The following requirements are to be met before the structure concerned isprepared for the application of the metal sprayed coatings.

(1) All welding required to be carried out on surfaces and the reverse side ofsurfaces including the securing of minor fittings and attachments is to becompleted.

(2) All welds are to be continuous, and ground flat and smooth, andsurrounding weld spatter removed.

(3) All portable items which might otherwise obstruct free access for thepreparation, coating, and subsequent inspection of areas of structure, areto be removed whilst the work is in progress.

(4) Sharp edges on attachments, seatings etc are to be slightly rounded off toapprox 2mm radius.

(5) Where thework is of necessity and is required to be carried out in the openair in wet or cold weather conditions, suitable weatherproof covers are tobe erected over the areas being treated as protection from the weatherelements.

b. When all the above requirements have been satisfactorily complied with, thestructure and fittings are to be prepared in the following manner.

c. All the surfaces are to be initially washed and cleaned of all oil, grease, dirt andother foreign matter by washing and scrubbing with general purpose detergentto DG Ships 305 and then abrasive blasted to the BS 4232 1st Quality (SA 3)standard of finish using Grade G 24 chilled iron grit, to produce a blast cleanedsurface profile 100 microns. On no account is copper slag, or other forms ofabrasive to be used for the purpose.

d. The initial washing and abrasive blasting of the surfaces is to be carried outfollowing all the instructions with respect to procedures, precautions,environmental conditions, and Quality Assurance requirements contained inSections 5 and 6 of NES 755.

e. Where the abrasive blasting is carried out by open circuit blasting methods,suitable screens are to be erected to confine the spread of abrasive to within theworking area, so as to avoid contamination of equipment, and injury to personsworking in the vicinity.

f. After an area has been abrasive blasted in preparation for the application of thecoating, it is to be thoroughly cleaned of all spent abrasive grit, and residue dustparticles using a suitable vacuum cleaner fitted with a brush attachment for thefinal clean.

g. Thereafter the prepared surface is not to be allowed to become contaminated inany way before the metal coating is applied. Personnel employed on finalcleaning of the abrasive blasted areas and the application of the metal sprayedcoatings, are to wear clean overshoes and gloves, where it is necessary to walkon, or handle the areas being treated.


4.2

h. The abrasive blasting is to be so arranged for an area abrasive blasted duringa working shift, to be coated with the full specified sprayed metal thicknessbefore the cessation of the working shift. In any event the abrasive blastedsurface is not to be allowed to remain bare for more than 6 hours before beingovercoated.

i. If despite these requirements areas abrasive blasted show signs of deteriorationbefore being overcoated the areas affected are to be reabrasive blasted to therequired standard before the sprayed metal coating is applied.


5.1

5. METAL SPRAYING

5.1 Sprayed Metal Systems

a. The sprayed metal systems to be applied to structure are as follows:

(1) Exterior Weatherdecks. A duplex sprayed metal system consisting of50 microns of zinc, overcoated with 100125 microns of aluminium, toproduce a total thickness of not less than 150 microns.

(2) Weatherdecks to be fitted with wood decking. 150 microns of zinc.

(3) Internal Structure (except Feed Water Tanks). Zinc to a totalthickness of not less than 150 microns.

(4) Feed Water Tanks.Where Feed Water Tanks are specified to be metalsprayed the coating is to consist of 200 microns of aluminium.

5.2 Application of the Coatings

a. The application of the sprayed metal coatings is generally to be in accordancewithBS 2569Part 1 except where augmented ormodified in the aforementionedor following Clauses.

b. The metal to be sprayed is to be in wire form of no more than 3.2mm diameter,and applied using a suitable flame metal spraying pistol asmentioned in Clause6.a. On no account is metal in powder form to be used.

c. The metal coating thickness is to be built up in one continuous operation, bysuccessive passes over the surface in one direction, and considerablyoverlapping each pass in order to produce an even overall thickness and avoidcorrugations in the coating finish.

d. On no account is an initial thin flash coat of metal to be applied to abrasiveblasted surfaces to serve as a holding coat whilst the remaining surfaces arebeing abrasive blasted prior to applying the full thickness of the metal.

e. When applying the duplex zinc aluminium metal coating system no more than2 hours are to be allowed to lapse between the completion of the application ofthe zinc and overcoating with the aluminium.

f. During application of themetal coatings it is important that every effort ismadeto constantly keep the spray nozzle at the distance from the surfacerecommended by the manufacturer of the equipment and to direct the sprayedmetal vertically on to the surface being coated. The speed to which the pistol ispassed over the surface during application is also to be taken in relationship tothe rate to which the wire is melted and atomized.

g. Care is also to be taken to ensure that the metal spraying wire is kept free ofkinks, and passes freely through the spraying pistol.

h. The metal sprayed coatings are to be of fine texture free from lumps, coarseareas and loosely adherent particles, and of even thickness.

i. On no account are surfaces to be allowed to become contaminated whilst testsare being applied. Personnel employed on the application work are to weargloves and clean overshoes whilst walking on or cleaning the surfaces. Thesurfaces being metal sprayed are also to be continuously cleaned of metal dustarisings using a vacuum cleaner during application.


5.2

j. When an area abrasive blasted and metal sprayed adjoins areas still to betreated, the finished area is to be protected against damage from abrasiveblasting and abrasive given inbedment by covering with suitable sheeting, butallowing a sufficient uncovered margin for overlapping with the metal forjoining up purposes when the adjoining area is subsequently coated.

k. The metal sprayed coating is to be sealed by overcoating with the first coat ofthe specified paint system immediately the application has been completed.

5.3 Repair of Metal Sprayed Coatings

a. Areas of damaged metal sprayed coatings are to be repaired by reabrasiveblasting and remetal spraying the affected areas, following the procedures andto the standards already mentioned for the preparation and metal spraying ofsurfaces. Where circumstances prevent the use of abrasive blasting equipment,the areas in question are to be carefully scraped back to sound surroundingedges, and then power abrasive disced to theSVENSK STANDARDSIS 0559 00(Swedish C St 3 pronounced metallic sheen appearance), followed by makinggood by over coating with multiple coats of zinc rich epoxy paint Type 3 toBS 4652 to produce a total dry film thickness of at least 100 microns beforetouching up with the specified paint system.


6.1

6. EQUIPMENT

a. The approved process formetal spraying is by the use of wire fed proprietary fuelgas/oxygen spray guns. Electric arc spray processes are not approved.

b. The makers instructions for the use, handling and maintenance of equipmentmust be complied with. These instructions will detail the type of fuel gas andpressures of gas, oxygen and compressed air required, type of flame, angle ofoperation and distance of gun nozzle from the prepared surface.

c. If the makers instructions are not provided a test area is to be sprayed startingwith fuel gas at 1.7 bar, oxygen at 1.38 bar and compressed air at 4.14 bar withthe gun nozzle square to and approx 300mm from the surface. Pressures, angleof spray and distance from surface are then to be adjusted until the trial areais satisfactorily sprayed.

Note: The fuel gas pressure quoted is for propane; considerable alteration maybe necessary for other fuel gases or gun nozzle sizes employed.

d. If the equipment is fitted with flow meters the test spray is first to be tried withminimum flows, gradually increasing the flows until optimum sprayperformance is achieved.

e. Fluctuations of pressures of fuel gas, oxygen and compressed air will result innon-uniform spray application.

f. Moisture and/or oil in the compressed air will have a deleterious affect on themetal sprayed coatings. Only dry compressed air is therefore to be used.

g. Large gauge wires produce coarse finishes.

h. Too rapid a feed of wire produces lumpy finishes and too slow a feed anexceptionally fine oxidized coating.


6.2


7.1

7. QUALITY ASSURANCE

a. The Quality Assurance Representative (QAR) is to be satisfied that all therequirements listed in Clause 4.a. have been met before the commencement ofthe surface preparation and application of the metal sprayed coatings, and thatthe equipment intended for use is efficient, safe for use, and maintained in aserviceable condition.

b. The QAR is to satisfy himself that the abrasive grit, andmetal wire intended foruse are of the grade and quality called for.

c. The Contractor undertaking the work is to provide evidence that the operatorsto be employed have been properly trained in the operation and use of all themain associated ancillary equipment and are fully conversant with all therequirements.

d. The surface preparation, and application of the metal coatings is not to becarried out when the relative humidity is above 70% nor where the steelsubstrate temperature falls less than 3 C above the dew point.

e. If necessary these conditions are to be brought about by using suitableflameproof dehumidifiers set to work at least 24 hours before thecommencement of the abrasive blasting and metal spraying work operationduring the whole course of the blasting and metal spraying work, and until thesprayed metal surface has been sealed with the first coat of the specified paintsystem.

f. Relative humidity, ambient temperature and substrate temperature readingsare to be taken before, midway, and at the end of each shift and the relevantdetails recorded and documented.

g. Each stage of the surface preparation and application of the coatings is to beinspected both during and after completion and any descrepancies rectifiedbefore the next stage is commenced.

h. On no account are abrasive blasted or sprayed metal coated surfaces to beallowed to become contaminated in any way before being overcoated. Theovercoating time constraints mentioned in Clauses 4.h., 5.2e., and 5.2k. are tobe strictly observed.

i. When flat surfaces such as decks are being treated personnel employed on theremoval of spent abrasive grit, and dust after abrasive blasting and thesubsequent application of the sprayed metal and sealing of the coating oncompletion, are towear gloves and clean overshoes whilst carrying out thework.Supervisors and Quality Assurance Representatives are also to be likewisedressed. Foot traffic by persons other than mentioned above, over areas beingtreated is to be prohibited whilst the work is in progress and until finallycompleted.

j. The thickness of the metal coating being applied is to be frequently measuredboth during and on completion to ensure that the specific thickness is deposited.Areas found lacking in this respect are to be further metal sprayed until therequired thickness is achieved.

k. The thickness is to be measured using suitable commercially availableelectro-magnetic type instruments calibrated and operated strictly inaccordance with the manufacturers instructions for the purpose required. Onno account are magnetically operated type instruments such as the Microtest,Tinsley, pull off, or elcometer 101 thickness gauges to be used for the purpose.


7.2

l. The finished metal sprayed surface is to be inspected for uniformity of texture,and fine matt appearance, free from coarse areas, and loosely adherentparticles. In addition the adhesion of the sprayed metal coating to theunderlying steel substrate, and the intercoat adhesion between the zinc andaluminium is to be tested to the procedures and instructions contained inAnnexC.

m. Areas where the adhesion or surface finish is found to be unsatisfactory are tobe blast cleaned free of the defective coating, and re-metal sprayed to therequired standards.

n. The QAR is to record and document all the relevant details concerning thework.Such details are to include relative humidity, ambient and surface temperaturereadings, standards of abrasive blasting and metal spraying achieved, methodof abrasive blasting, and type ofmetal spraying equipment and size of wire used,together with the total thickness measurement readings of the sprayed metaldeposited.

o. For the zinc and aluminium system the thickness of the zinc and aluminiumcoatings are to be measured and recorded separately.


8.1

8. TREATMENT OF METAL SPRAYED SURFACES

8.1 Internal

a. Where abrasive blasted steel surfaces have been sprayed with metal to the fullthickness specified, the first coat of the appropriate paint system in accordancewith and or NESs, 753, 763, 765, 774, or as otherwise specified in the ContractDocuments, is to be applied before deterioration or contamination occurs.Dehumidification and temperature control is to be provided as stated inNES 755 (Section 5 Clause 0511).

8.2 External

a. Steel weatherdeck surfaces which have been abrasive blasted and sprayed withthe full thickness of zinc, ie 150microns and are subsequently to be covered withwood decking, in accordance with NES 156, are to be sealed, beforedeterioration or contamination can occur, with a coat of bituminous solution toTS 10195A.

b. Where weatherdeck surfaces and the bottom 75mmof steel superstructure havebeen abrasive blasted and sprayed with zinc followed by aluminium to a finishedtotal thickness of 150 microns, the appropriate paint system specified inNES 753 and Class or Ship drawings is to be applied before deterioration orcontamination occurs. Dehumidification and temperature control is to beprovided as stated in NES 755 (Section 5 Clause 0511).


8.2


9.1

9. HOT-DIP GALVANIZING

a. Hot-Dip Galvanizing is to be carried out in accordance with BS 729 or BS 2989,whichever is appropriate for the article or structural material being galvanized.

b. The coating weight determined by dividing the total weight of the depositedgalvanizing by the total surface area treated is to produce the ratios as shownin TABLE 9.1:

Category Thicknesses Coating Weight

Steel structurals andarticles which are notcentrifuged

5mm and over

under 5mm

not less than 610g/m2


Grey and malleable ironcastings


Threaded work and otherarticles which arecentrifuged


Steel sheet and coil under 5mm not less than 460g/m2

TABLE 9.1 COATING WEIGHT

c. Tubes on which screw threads are required are to be galvanized before thethreads are cut.

d. NES 155 is to be referred to for certain areas where galvanizing is prohibitedor mandatory.

e. NES 507 is to be referred to for information on galvanizing requirementsspecifically applicable to electrotechnical equipment.


9.2


A.1 ANNEX A.

ANNEX A.

RELATED DOCUMENTS

A.1 Reference is made to:

Referred to inClause

BS 729 Hot-dip galvanized coatings on iron andsteel articles

9.a.

BS 1475 Wrought aluminium and aluminium alloysfor general engineering purposes: wire

1.b., TABLE 1.1

BS 2569 Pt 1 Sprayed metal coatings Pt 1. Protection ofiron and steel by aluminium and zincagainst atmospheric corrosion

5.2

BS 2989 Continuously hot-dip zinc coated and iron-zinc alloy coated steel: wide strip, sheet/plate and slit wide strip

9.

BS 3436 Ingot zinc 1., TABLE 1.1

BS 4232 Surface finish of blast-cleaned steel forpainting

4.c.

BS 4652 Metallic zinc-rich priming paint (organicmedia)

5.3, TABLE 1.1

TS 10195A Paint systems, bitumen, for defence equip-ment types I, II and III

TABLE 1.1, 8.2

SVENSKStandardSIS 05 59 00

Pictorial Surface Preparation Standards forPainting of Steel Surfaces

5.3

NES 155 Structural Practices in Steel Surface Ships 9.d.

NES 156 Wood Decking 8.2

NES 507 Materials and Finishes for Electro-technicalEquipment

9.e.

NES 753 WeatherdecksPreparation and Painting 8.1, 8.2b.

NES 755 Abrasive Blasting of Steel 4.d., 8.1, 8.2b.

NES 763 Preservation and Painting of Compartmentsin Surface Ships

8.1, Annex D.

NES 765 Requirements for Painting of MachineryCompartments in Steel Hulled SurfaceShips

8.1, Annex D.

NES 774 Requirements for Preparation and Paintingof Submarines

8.1

DG Ships 305 General Purpose Cleaning Liquid Detergent TABLE 1.1, 4.c.


A.2ANNEX A.


B.1 ANNEX B.

ANNEX B.

DEFINITIONS AND ABBREVIATIONS

B.1 There are no Definitions and Abbreviations for this NES.


B.2ANNEX B.


C.1 ANNEX C.

ANNEX C.

METHOD OF CHECKING THE ADHESION OF THE ZINC SPRAY TO THE STEELSURFACES

EQUIPMENT REQUIRED

C.1 Straight edge.

C.2 Hardened steel scriber ground to a sharp 30 point.

METHOD

C.3 Using a straight edge and a hardened steel scriber, score two parallel lines in thecoating at a distance apart equal to approximately ten times the average coatingthickness. The cuts are to penetrate through the full depth of the coating to the basemetal and, by the application of sufficient pressure, be achieved in the minimumnumber of strokes.

C.4 Should any part of the coating between the lines break away from the base metal itis to be deemed to have failed the test.

C.5 The items or areas selected for this test is to be agreed between the Contractor andthe responsible Quality Assurance Authority.

C.6 The test is destructive and the damaged area must be locally reblasted and re-metalsprayed in accordance with this NES.


C.2ANNEX C.


D.1 ANNEX D.

ANNEX D.

D.1 PROCUREMENT CHECK LIST

TITLE .....................

REFERENCE .....................

Notes:

1. This Check List is to ensure that certain aspects of this Naval EngineeringStandard are consulted when preparing a Statement of TechnicalRequirements for a particular application.

2. Clauses where a preference for an option is to be used or where specificdata is to be added are included in the Check List.

3. Each item is to be marked either:

p = includedNA = not applicable

CHECKNo CHECK

CLAUSENo

p orNA

1. The areas selected for metal spraying are to belisted

3.a.

2. Where abrasive blasted steel surfaces have beensprayed with metal to the full thickness speci-fied, the first coat of the appropriate paint sys-tem in accordance with NES 763, 765 or Con-tract Documents is to be applied

8.1

3. Only approved type of metal spraying equip-ment and abrasive grit to be specified

5.2b., 6.a.

4. Metal not to be used in powder form 5.2b.


D.2ANNEX D.


INDEXINDEX.1

ALPHABETICAL INDEX

AAir hoses, 2.2

Application, 5.1, 5.2

Areas, external, 3.1, 8.1

Areas, internal, 3.1, 8.1

Areas, selected, 3.1

CCleanliness, 2.2

Coating weight, 9.1

Cylinders, 2.1

DDehumidification, 7.1, 8.1

Discharge, ventilation, 2.2

EElectrotechnical equipment, 9.1

Environmental conditions, 4.1, 7.1

Equipment, 1.1, 2.1, 2.2, 6.1, 7.1

FFlame pistols, 2.1

Flameproofing, 2.2

Flow meters, 6.1

GGas cylindersprecautions, 2.1

Gas hoses, 2.2

HHoses, 2.2

Hot-dip galvanizing, 9.1

LLighting, 2.2


INDEX INDEX.2

MMaterials, 1.1

OOperators requirements, 7.1

PPaint system, 5.2, 7.1, 8.1

Preparation, cleaning, 4.1, 5.1

Preparation, protection, 4.1, 5.1, 7.1

Preparation, welds, 4.1

Pressures, fuel gas, oxygen, air, 6.1

Protective clothing, 2.2

QQuality control, 7.1, 7.2

RRegulators, 2.1

TTemperature control, 7.1, 8.1

Thickness of coatings, 5.1, 7.1

Trunking, 2.2

Tubes, 9.1

VVentilation supply and exhaustprecautions, 2.2

WWood decking, 8.1

Inside Rear Cover

Crown Copyright 2000

Copying Only as Agreed with DStan

Defence Standards are Published by and Obtainable from:

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GLASGOW G2 8EX

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File Reference

The DStan file reference relating to work on this standard is D/DStan/69/02/764.

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Revision of Defence Standards

Defence Standards are revised as necessary by up issue or amendment. It is important thatusers of Defence Standards should ascertain that they are in possession of the latest issue oramendment. Information on all Defence Standards is contained in Def Stan 00-00 Standardsfor Defence Part 3 , Index of Standards for Defence Procurement Section 4 Index of DefenceStandards and Defence Specifications published annually and supplemented regularly byStandards in Defence News (SID News). Any person who, when making use of a DefenceStandard encounters an inaccuracy or ambiguity is requested to notify the Directorate ofStandardization (DStan) without delay in order that the matter may be investigated andappropriate action taken.

CONTENTSTITLE PAGESCOPEFOREWORDSponsorshipConditions of ReleaseGeneralMOD Tender or Contract Process

Related DocumentsHealth and SafetyWarning

1. MATERIALSTABLE 1.1 MATERIALS AND EQUIPMENT

2. SAFETY PRECAUTIONS2.1 Flame Pistols2.2 Gas and Oxygen Cylinders2.3 Gas and Air Hoses2.4 Ventilation Supply and Exhaust2.5 Cleanliness2.6 Lighting2.7 Protective Clothing

3. EXTENT OF METAL SPRAYING3.1 Internal Areas3.2 External Areas

4. SURFACE PREPARATION5. METAL SPRAYING5.1 Sprayed Metal Systems5.2 Application of the Coatings5.3 Repair of Metal Sprayed Coatings

6. EQUIPMENT7. QUALITY ASSURANCE8. TREATMENT OF METAL SPRAYED SURFACES8.1 Internal8.2 External

9. HOT-DIP GALVANIZINGTABLE 9.1 COATING WEIGHT

ANNEX A. RELATED DOCUMENTSANNEX B. DEFINITIONS AND ABBREVIATIONSANNEX C. METHOD OF CHECKING THE ADHESION OF THE ZINC SPRAY TO THE STEEL SURFACESANNEX D PROCUREMENT CHECK LISTALPHABETICAL INDEX

nes 764 flame metal spraying and hot dip galvanizing of ships structure and fittings category 2

Documents

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