nes 791 part 1 requirements for weldable structural steels

Ministry of Defence Defence Standard 02-791 (NES 791)

Issue 1 Publication Date 01 April 2000

Incorporating NES 791 Category 2

Issue 2 Publication Date August 1987

Requirements For WeldableStructural Steels

Part 1Mild Steel-Plate, Sections And Bars

DStan

DStan 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) 791 Part 1 Issue 2 dated August 1987.

Ministry of Defence

Naval Engineering Standard

NES 791 Part 1 Issue 2 (Reformatted) August 1987

REQUIREMENTS FOR WELDABLE STRUCTURAL STEELS

PART 1

MILD STEEL—PLATE, SECTIONS AND BARS

This NES Supersedes

NES 791 PART 1 ISSUE 1

Record of Amendments

AMDT INSERTED BY DATE

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i

NAVAL ENGINEERING STANDARD 791

REQUIREMENTS FOR WELDABLE STRUCTURAL STEELS

PART 1

ISSUE 2 (REFORMATTED)

MILD STEEL—PLATE, SECTIONS AND BARS

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 DefenceSea Systems, Foxhill, Bath BA1 5AB

NES 791Part 1

Issue 2 (Reformatted)

iii

SCOPE

1. The requirements for a weldable steel for general structural and engineering purposes.

NES 791Part 1Issue 2 (Reformatted)

iv

NES 791Part 1


v

FOREWORD

Sponsorship

1. ThisNaval Engineering Standard (NES) is sponsored by theProcurement Executive, Ministryof Defence, Deputy Controller Warships, Section NA 132.

2. It is to be applied as required to any Procurement Executive, Ministry of Defence contract fora weldable steel for general structural and engineering purposes and is applicable to SurfaceShips and Submarines.

3. This NES comprises:

Requirements for Weldable Structural Steels

Part 1 Mild Steel—Plate, Sections and Bars

Part 2 Notch Tough Mild Steel—Plate

Part 3 ‘B’ Quality Steel—Plates and Sections

Part 4 ‘BX’ Quality Steel—Plate

4. If it is found to be technically unsuitable for any particular requirement the Sponsor is to beinformed in writing of the circumstances with a copy to Deputy Controller WarshipEquipment (DCWE), Section ME 241.

5. 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 theNES;

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

6. No alteration is to be made to this NES except by the issue of a formal amendment.

7. Unless otherwise stated, reference in this NES to approval, approved, authorized and similarterms means by the Procurement Executive, Ministry of Defence.

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

9. This NES has been reissued to update the Conditions of Issue, Introduction and Clauses 0202and 0203, also to amend Clauses 1.b., 2.a. and 2.c. resulting from the 1986 edition of BS 4360.

Conditions of Release

General

10. 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.

11. 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.

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


vi

MOD Tender or Contract Process

13. 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.

14. 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.

15. 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

16. 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.

17. 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.

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

Health and Safety

Warning

19. 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.

NES 791Part 1


vii

CONTENTSPage No

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

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

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

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

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

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

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

SECTION 1. MATERIALS AND MANUFACTURE 1.1. . . . . . . . . .1.1 Weight Rolling Margins 1.1. . . . . . . . . . . . . . . . . . . . . . .

SECTION 2. QUALITY OF FINISHED STEEL 2.1. . . . . . . . . . . . . .2.1 Surface Treatment 2.1. . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 3. QUALITY ASSURANCE DOCUMENTATION 3.1. . .

SECTION 4. IDENTIFICATION 4.1. . . . . . . . . . . . . . . . . . . . . . . . . . .4.1 Plates 4.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.2 Sections 4.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.3 Painted Markings 4.1. . . . . . . . . . . . . . . . . . . . . . . . . . . .4.4 Colour Coding 4.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

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

ANNEX C. SURFACE CONDITION OF HOT ROLLEDHEAVY PLATE, MEDIUM PLATE, AND WIDEFLATS OR UNIVERSALS STANDARD FORREFERENCE IN CASES OF DISPUTE C.1. . . . . . . . .

C.1 Scope C.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C.2 Definition C.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C.3 Surface Assessment C.1. . . . . . . . . . . . . . . . . . . . . . . . . . .C.3.1 Method C.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C.3.2 Surface Defect Area C.1. . . . . . . . . . . . . . . . . . . . . . . . . .C.3.3 Defect Depths C.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C.3.4 Significance of Defects C.2. . . . . . . . . . . . . . . . . . . . . . . .

FIGURE C.1 PLATES <12mm C.3. . . . . . . . . . . . . . . .FIGURE C.2 PLATES >12mm <20mm C.3. . . . . . . .FIGURE C.3 PLATES 20mm TO 50mm C.3. . . . . . . .

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

ALPHABETICAL INDEX


viii

NES 791Part 1


1.1

1. MATERIALS AND MANUFACTURE

a. The steel is to comply with the requirements of BS 4360 except where statedherein.

b. The grades of steel are to comply with the requirements of BS 4360; Grade 43Afor plates, sections and bars.

1.1 Weight Rolling Margins

a. The specified weight for plates and sections is the maximum, and the rollingmargins are to be wholly under the specified thickness.


1.2

NES 791Part 1


2.1

2. QUALITY OF FINISHED STEEL

a. The quality of all finished steel is to be in accordance with BS 4360 Section 1except that in the assessment of plates the reference standard at AnnexC. of thisspecification is to apply. For all products the correction of minor defects is to belimited such that the thickness is not locally reduced by more than 4% belowtheminimum thickness otherwise allowed. Corrections of defects byweld repairis not permitted; options B11 and B12 of BS 4360 refer.

b. In the assessment of ‘fitness for purpose’ any defect of a type which could affectthis purpose in respect of possible stress raisers or sites of local corrosion, egsharp bottomed scars or pits (see Note), pitting with overhanging edges etc, thepurchaser is to report the product to the manufacturer for early agreement onrepair or replacement.

c. Additionally for plates, when the foregoing requirements have been met andthere are surface blemishes such that it is considered unsatisfactory, becausethe blemishes mar the appearance of the plate or would adversely affect theadhesion of a protective paint system, then Annex C. is to be used as the basisfor arbitration between the purchaser and the manufacturer.

Note: For the purpose of this NES a sharp bottomed scar or pit is defined as anyscar or pit which is greater than 0.2mm deep and the depth is greater thanthewidth. To assist in the assessment of borderline cases a reference blockis to be used as the datum. This block may be in the form of 50mm¢ 50mm ¢ 2mm with machined slots 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7mmwide. Other forms of approved assessment methods may be used as agreedbetween the QAR and the manufacturer.

2.1 Surface Treatment

a. All plates and sections are to be treated as follows:

(1) Less than 5mm thick to be pickled; 5mm thick and over to be abrasivelyblasted to a minimum of second quality finish in accordance withNES 755.

(2) Unless otherwise specified in the Contract Documents, immediately afterpickling or abrasive blasting an inspection in accordance with Clauses 2.a.to 2.c. Steel less than 5mm thick is to be oiled, 5mm thick and over is tobe coated with priming paint in accordance with NES 757.

(3) When plates and sections are to be galvanized the galvanizing is to be bythe hot dip process in accordance with BS 729. The spelter used is tocontain not less than 98.5% zinc and the weight of zinc deposited is to benot less than 1.2kg/m2.


2.2

NES 791Part 1


3.1

3. QUALITY ASSURANCE DOCUMENTATION

a. Certification is to be provided to the consignee in accordance with BS 4360 andis to include the chemical composition as determined by the ladle analysis. Thiscertification is required even when inspection has taken place. A copy of eachcertificate is to be supplied to the MOD Quality Assurance Representative.


3.2

NES 791Part 1


4.1

4. IDENTIFICATION

a. All finished products are to be correctly identified and are to be legibly markedwith the following information:

(1) Hard Stampedmarkings outlined by circling with paint of a contrastingcolour:

(a) Specification Number

(b) Cast Number

(c) Test Certification Number

(d) Manufacturer’s Works Code

4.1 Plates

a. These numbers are to be positioned at the top right and left hand corners, eitheron the edge of the plate or on the surface of the plate within 16mm of the plateedge.

4.2 Sections

a. These markings are to be on both ends.

4.3 Painted Markings

a. Markings are also to be located near one end of the plates and on both ends ofsections.

(1) Contract Number

(2) Destination

(3) Dimensions

(4) Customer Identification (last 7 digits of the NATO Stock Number (NSN)

For small sections and thin plate where the process route precludes individualmarkings the products are to be supplied suitably bundled and theidentification marks painted on metal tags.

4.4 Colour Coding

a. Colour coding on each plate is to be painted on diagonally opposite corners andon the ends of sections with a distinctive yellow colour. The ends of bars are tobe painted with a distinctive blue colour.


4.2

NES 791Part 1


A.1 ANNEX A.

ANNEX A.

RELATED DOCUMENTS

A.1 Reference is made to:

Referred to in Clause

BS 729 Hot Dip Galvanized Coatings on Ironand Steel Articles

2.1a.

BS 4232 Surface Finish of Blast-Cleaned Steelfor Painting

Annex C.

BS 4360 Weldable Structural Steels 1.a., 1.b., 2.a., 3.a.,Annex C.

NES 755 Abrasive Blasting of Steel 2.1a.

NES 757 Application and uses of Prefabrication(Shop) Primers

2.1a.


A.2ANNEX A.

NES 791Part 1


B.1 ANNEX B.

ANNEX B.

DEFINITIONS AND ABBREVIATIONS

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


B.2ANNEX B.

NES 791Part 1


C.1 ANNEX C.

ANNEX C.

SURFACE CONDITION OF HOT ROLLED HEAVY PLATE, MEDIUM PLATE, AND WIDEFLATS OR UNIVERSALS STANDARD FOR REFERENCE IN CASES OF DISPUTE

C.1 SCOPE

a. The surface conditions which supplement the quality requirements of BS 4360for hot rolled heavy and medium plate, also hot rolled wide flats or universalsin thicknesses up to 50mm; for thickness over 50mm special agreements maybe made. The requirements for the surface condition of these steel products areto be used as a basis for arbitration between the supplier and the customerwhere the customer or his representative considers plate surface condition tobe unsatisfactory.

C.2 DEFINITION

a. This NES relates solely to defects within the rolling margin, and is concernedwith those minor defects which arise in processing despite regular maintenanceof equipment and inspection controls, such as scale, pitting, scores, smallblisters and light surface laminations (slivers or shell). These are not readilyseen in the scaled condition and are revealed after descaling.

b. Within the terms of this NES a surface defect is a surface blemish or group ofminor blemishes which do not affect fitness for purpose but mar the surfaceappearance of the plate.

C.3 SURFACE ASSESSMENT

C.3.1 Method

a. Both surfaces are to be inspected and assessed independently, bearing in mindthat the resulting thickness must not be less than the minimum permissible.The inspection of plates is to be carried out in good lighting conditions(preferably 400 lux) or with the use of a local light source, in a practical mannerby slowly walking the length of the plate.

b. The depths of surface defects are measured with a surface depth gauge.However, with a little experience it is possible to estimate surface defect depthvisually with a sufficient accuracy having taken the precaution of gauging somesurface defects in the light conditions prevailing.

C.3.2 Surface Defect Area

a. The surface defect area is to be regarded as the area which is circumscribed bya line drawn round the limit of the surface defect at a distance of 80mm. If thesurface defects are significant, ie outwith the standard indicated inFIGURE C.1, FIGURE C.2 and FIGURE C.3, then it is this area that is likelyto be affected by grinding and fairing into the surrounding material.

b. The defect area is expressed as a percentage of the total area of that surfacecontaining the defect.

C.3.3 Defect Depths

a. In the case of clusters of surface defects, the average depth is to be used fordetermining if rectification is warranted.


C.2ANNEX C.

C.3.4 Significance of Defects (FIGURE C.1, FIGURE C.2 and FIGURE C.3)

a. The maximum permissible depth and area of defect have been related to platethickness, considering three broad thickness ranges for the sake ofpracticability viz: up to and including 12mm; over 12mm to less than 20mm;20mm to 50mm and are given in FIGURE C.1, FIGURE C.2 and FIGURE C.3.The smallest defect depth considered is 0.15mm, slightly above the maximumsurface roughness amplitude of 0.1mm for blast cleaned surfaces as defined inBS 4232.

b. Defects within the allowable range (Area A) are considered so insignificant thatrectification is not required. Defects outside this area are normally rectified towithin the permissible range. However, rectification need not be carried out ifthe usefulness of the plate is not impaired by the defects present.

NES 791Part 1


C.3 ANNEX C.

FIGURE C.1 PLATES <12mm

FIGURE C.2 PLATES >12mm <20mm

FIGURE C.3 PLATES 20mm TO 50mm


C.4ANNEX C.

NES 791Part 1


D.1 ANNEX D.

ANNEX D.

PROCUREMENT CHECK LIST

TITLE ........................REFERENCE .................................

Notes:1. This Check List is to ensure that certain aspects of this Naval Engineering

Standard 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 specific data is2. Clauses where a preference for an option is to be used or where specific data isto be added are included in the Check List.

3. Each item is to be marked either

! = included

NA = not applicable

CHECKNo CHECK CLAUSE No ! or NA

1 Assessment of Quality of steel 2.a.−2.c.

2 Surface treatment of plates 2.1a.


D.2ANNEX D.

NES 791Part 1


INDEXINDEX.1

ALPHABETICAL INDEX

AAssessment, defects, 2.1

BBlemishes, 2.1

CCertification, 3.1

Chemical composition, 3.1

Colour coding, 4.1

DDefects, 2.1

Definitions, 2.1

GGrades, 1.1

MMarkings

Hard stamped, 4.1Painted, 4.1

PPlates, 4.1

QQuality finished steel, 2.1

RReference block, 2.1

SSections, 4.1

Surface assessment, C.1

Surface treatment, 2.1


INDEX INDEX.2

WWeight rolling margins, 1.1

Inside Rear Cover

© Crown Copyright 2000

Copying Only as Agreed with DStan

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File Reference

The DStan file reference relating to work on this standard is D/DStan/69/02/791.

Contract Requirements

When Defence Standards are incorporated into contracts users are responsible for their correctapplication and for complying with contractual and statutory requirements. Compliance witha Defence Standard does not in itself confer immunity from legal obligations.

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.

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