SPECIFICATION FOR

CUSTOMER

NAOC

PLANT LOCATION

NAOC PH BASE - NIGERIACode:3217.46.BASG.36908

PROJECT/UNIT

NEW PORT-HARCOURT BASE POWER GENERATION PROJECT Page 1 of 20Rev

0

GENERAL SPECIFICATION FOR

STRUCTURAL STEELWORK

MATERIALS AND FABRICATION

AT

NAOC PORT-HARCOURT BASE, NIGERIA

21/06/120Issued for ReviewH. DORDORD. AKANOR. OMIETIMI

DateRevDescription of RevisionPreparedCheckedApproved

CONTENTS

1.Scope

2.Codes and Standards

2.1 BRITISH CODES AND STANDARDS

2.2 PROJECT SPECIFICATIONS

2.3 sTANDARD STEELWORK DETAILS

2.4 AMERICAN STANDARDS

3.Types of construction

4.Steel Structures

4.1 MATERIALS

4.2 STRESSES

4.3 CONNECTIONS

4.4 TEMPORARY RESTRAINTS

5.Fabrication

5.1 ERECTION ARRANGEMENT DRAWINGS (MARKING PLANS)

5.2 FABRICATION DRAWINGS

5.3 INSPECTION

5.4 PROPRIETARY ITEMS

5.5 TRACEABILITY OF MATERIALS

5.6 MARKING STEELWORK

5.7 MACHINING

5.8 DRESSING

5.9 ALIGNMENT OF HOLES

5.10 ASSEMBLY

5.11 SAFETY-HOLES FOR MANLOCK BOLTS

6.Welding

6.1 WELDING PROCEDURES

6.2 WELDER QUALIFICATION

6.3 NON-DESTRUCTIVE TESTING OF WELDS

6.4 SCOPE AND FREQUENCY OF INPECTION

7.Flooring

8.Stairways

9.Ladders

10.Handrails and toe plates

11.Painting

12Erection Marking

13.Colour coding

14.Fireproofing

15.Shipping

1.ScopeThis Specification defines the basic requirements for detailing, supply and fabrication including NDT, coating, packaging and shipping of steelwork for structures, buildings and platforms for NEW PORT-HARCOURT BASE POWER GENERATION PROJECT, NIGERIA.2.Codes and StandardsAll work shall conform to the latest requirements of European Codes or British Standards and any local related statutory regulations, as listed in this Specification. In case of conflict between the various Codes and Standards, and/or this Specification, reference shall be made back to Employer or approved agent for resolution.

Unless specified otherwise, the international system of metric units (S.I.) is to be used.

Structural steelwork shall be designed in accordance with BS5950 Part1, and information supplied on drawings.

2.1British Codes and StandardsBS EN 287Approval Testing of Welders for Fusion Welding

Pt. 1: 1992Steels

BS EN 288Specification and Approval of Welding Procedures for Metallic Materials

Pt. 1: 1992 General Rules for Fusion Welding

Pt. 3: 1992 Welding Procedure Tests for Arc Welding of Steel

BS EN 571 Pt. 1: 1997 Non-Destructive Testing - Penetrant Testing -

. General Principles

BS EN 970 1997 Non-Destructive Examination of Fusion

Welds Visual Examination

BS EN 1714 1998

Non-Destructive Examination of Welded

Joints - Ultrasonic Examination of Welded

Joints

BS EN 10025 1993 Hot Rolled Products of Non-Alloy Structural

Steels. Technical Delivery Conditions

BS EN 10113

Hot Rolled Products in Weldable Fine Grained Structural Steels

Pt. 2: 1993 Delivery Conditions for Normalised/ Normalised Rolled Steels.

BS EN 225531995Welded, Brazed and Soldered Joints - Symbolic

Representation on Drawings

BS 4 Pt. 1: 1993Structural Steel Sections. Specification for Hot

Rolled Sections

BS 11

1985Specification for Railway Rails

BS 729 1971Specification for Hot-Dip Galvanised Coatings

on Iron and Steel Articles

BS 3692 1967Specification for ISO Metric Precision HexagonBolts, Screws and Nuts

BS 4190 1967Specification for ISO Metric Black Hexagon

Bolts, Screws and Nuts

BS 4320 1968Specification for Metal Washers for General

Engineering Purposes

BS 4592 Pt.1: 1995Industrial Type Metal Flooring, Walkways and

Stair Treads, Specification for Open Bar Gratings

BS 4848 Pt 4: 1972Hot-Rolled Structural Steel Sections Equal and . Unequal Angles

BS 4872Specification for Approval Testing of Welders when Welding .Procedure Approval is not required

BS 49211988Specification for Sheradised Coating on Iron or

Steel

BS 51351984Specification for the Process of Arc Welding of

Carbon and Carbon Manganese Steels

BS 5395Pt. 3: 1985Stairs, ladders, and walkways. Code of Practice

for the design of industrial type stairs,

permanent Ladders and walkways.

BS 5950 Structural Use of Steel in Building

Pt. 1: 1990 Code of Practice for Design in Simple and

Continuous Construction - Hot Rolled Sections

Pt. 2: 1992 Specification for Materials, Fabrication . , and Erection - Hot Rolled Sections

Pt. 5: 1998Code of Practice for Design of Cold , Formed Sections

BS 60721981Method for Magnetic Particle Flaw Detection

BS 63231982Seamless and Welded Steel Tubes for

Automobile, Mechanical and General

Engineering Purposes

BS 71911989Weld able Structural Steels for Fixed Offshore

structures

2.2Project Specifications10-CA-E-27012Specification for Structural Steelwork Erection

2.3 Standard Steelwork Details

Welding Symbols

Typical Connections

Flooring Penetrations

Handrails

Stairs

Ladders

Stiles and Low Walkways

Fireproofing

2.4American StandardsASME SEC IX PT QW ART IIIWelding Performance Qualifications

(Boiler and Pressure Vessel Codes)

3. Types of construction

This Specification applies to the use in structures of hot rolled steel sections, plates and tubular shapes. Cold formed sections may be used for purlins and cladding rails in non-aggressive and heated environments.

The selected design shall take account of safety and ease of erection, accessibility for painting and general maintenance. Lattice type structures, other than roof trusses, should therefore be minimised.

Where indicated, steel structures shall be fireproofed in accordance with AGIP/NAOC Plant standard practice.

Workshop fabrication of structural steelwork by welding is preferred. Field connections shall be bolted, except as noted on the design drawings. Connection details shall make provision for safe erection, e.g. by use of seating cleats, etc.

4.Steel Structures4.1 Materials

All material shall be from new stock.

Structural steel materials shall be in accordance with Appendix A of this specification.

All bolts shall be grade 8.8, in accordance with Appendix A of this specification.

Rolled sections shall conform to BS4.

Steel tubes shall conform to BS6323.

All nuts and bolts shall be supplied sherardised, but may be supplied galvanised providing the coating allows full free running of the nuts and washers without the threads having to be reworked or cut.

When the design drawings do not specify the grade of steel intended for connections and fittings, the appropriate grades are as specified in Appendix A.

4.2Stresses Design stresses shall be in accordance with BS 5950 : Part 1.

For structural elements continuously exposed to heat above 260C design stresses shall be reduced in proportion to the reduction in yield strength at the design temperature.

4.3Connections High tensile bolts shall be used for all site connections. Minimum size of bolts for main connections shall be 20mm diameter. Main connections shall include main beam to beam, main beam to column, column splices, main bracing, crane brackets and all beams carrying equipment loads, except as noted on design drawings.

M12 or M16 bolts may be used for site connections of secondary beams (up to 250mm deep), purlins, light bracing, platforms, framing, and similar members, except as noted on the design drawings.

Welding or bolting shall be used for shop connections. Except where butt welds are called for, all welds shall be continuous fillets, unless otherwise noted on the drawings.

All main connections shall be provided with a minimum of two M20 bolts.

Lock nuts shall be provided for all connections securing runway beams to main framing, members supporting vibrating equipment, and/or where stress reversal occurs.

4.4Temporary RestraintsThe design drawings shall show the positions on the structure where temporary bracing or restraints are necessary until walls, floors or other non-steel structures are built.

5.Fabrication Fabrication shall comply with the requirements of BS 5950: Part 2.

The radius of re-entrant flame cuts shall be as large as possible, but not less than 20mm, except in small members where this is impracticable.

Ends of columns shall be sawn square. Column end plates shall be measured for flatness with a straight edge not exceeding 1m long. The end plate shall be machined if the gap between the plate and straight edge exceeds 0.75mm. Joint assembly of column and end plate shall be jigged.

All fabricated frames shall be suitably braced to prevent distortion during transit.

Frames, platforms, stairs and handrails shall be shop assembled in the largest units suitable for handling and transportation.

Attachments to pressure vessels are not covered by this Specification.

5.1Erection Arrangement Drawings (Marking Plans) Marking plans shall be prepared by the Steelwork Fabricator showing plans and elevations at a scale large enough for erection marks for all members to be shown.

The erection arrangement drawings shall show grid locations as indicated on the design drawings, main dimensions, member levels and centre lines. Enlarged scale details shall be shown where required to show the assembly of members.

5.2Fabrication DrawingsFabrication drawings (based on standard drawings where applicable) shall show all necessary details and dimensions to enable fabrication of components to proceed.

5.3InspectionThe Steelwork Fabricator shall record all testing of materials, weld equipment, consumables, dimensional checks, surface checks, weld inspections, protective treatment, etc.

5.4Proprietary ItemsAll proprietary items shall be used in accordance with the Manufacturer's recommendations and instructions.

5.5Trace ability of MaterialAll steel and bolts supplied ex-mills or from merchant's stock shall be covered by test certificates (including impact tests) and each fabricated component shall be traceable to a certificate.

5.6 Marking Steelwork

Individual pieces shall be capable of positive identification at all stages of fabrication.

Completed components shall be marked with a durable and distinguishing erection mark in such a way as not to damage the material. Hard stamping may be used, except where otherwise specified on the design drawings. Hard stamping shall not be within 100mm of any weld.

Where areas of steelwork are indicated on the drawings as being unmarked, they shall be left free of all markings and hard stamping.

5.7MachiningThe thickness shown on the drawings of elements that require machining shall mean the minimum thickness after the machining operations.

5.8Dressing Cut edges shall be dressed to remove burrs and irregularities. Holes shall be dressed as required to remove burrs and protruding edges.

Sharp edges shall be dressed, but a 90( rolled, cut, or sheared edge is acceptable without further treatment.

5.9 Alignment of HolesAll matching holes for fasteners or pins shall align with each other so that fasteners can be inserted without undue force through the assembled members in a direction at right angles to the faces in contact. Drifts may be used but holes shall not be distorted, nor cause distortion to the final assembly.

5.10Assembly All components shall be assembled within the tolerances specified in BS5950, and in a manner such that they are not bent, twisted or otherwise damaged.

Drifting of holes to align the components shall be permitted, but must not cause damage or distortion to the final assembly.

Components shall be checked for dimensional accuracy and conformity to drawings.

Fabricated components which are stored prior to being transported shall be stacked clear of the ground and arranged so that water cannot accumulate. They shall be kept clean and supported in such a manner as to avoid permanent distortion.

Individual components shall be stacked and marked in such a way as to ensure that they can easily be identified.

5.11 Safety-Holes for Manlock BoltsIn order to enable steel erectors to clip their safety harnesses to steelwork with Manlock bolts, 22mm diameter holes shall be provided adjacent to all connections. As a general guide line and to give the Erectors maximum working scope, holes should be positioned as follows:

Beam to Column ConnectionThree separate holes required:

a)500mm above top flange of beam, on centre line of column web.

b)500mm below bottom flange of beam (or haunch) on centre line of column web.

c) 500mm from end of beam, on centre line of beam web.

Beam to Beam ConnectionTwo separate holes required:

a)500mm from centre line of connection beam, through the web of the fixed beam.

b) 500mm from end of beam to be fixed, through centre line of beam web.

This list may not cover every circumstance. It is the responsibility of the Fabricator to position the holes, e.g. the 500mm dimension may be varied to suit a particular requirement. Holes must be provided (and allowed for in any calculation) at every connection. Where it is impractical to drill a hole through a member, welded on lugs, cleats, or shaped plates with the requisite hole shall be provided.

6.Welding Welding shall be in accordance with BS 5135.

Welding symbols shall be in accordance with BS EN 22553.

All welding shall be performed in an area protected from rain, wind and air-borne dust and sand.

Part to be welded shall be carefully prepared. Alignment, jigging and welding sequences shall be such as to minimise distortion and residual stress.

Butt welds shall be made in at least two passes such that filler metal is deposited over the whole thickness of the joint.

Prepared weld profiles shall be checked by gauges before welding.

6.1Welding Procedures Written welding procedures shall be prepared and tested in accordance with BS EN 288: Part 3.

All weld procedures shall be qualified to suit the design temperature specified in Appendix A, and due consideration shall be given to the requirements of Appendix D of BS 5135 as appropriate. All samples shall be impact tested with a minimum acceptance criteria of 27J min average (average of three specimens), 20J min (individual value).

The procedure shall identify material, weld geometry, tolerances, welding process, pre-heat temperature and welding position to be used.

Welding procedures shall be qualified by procedure qualification and shall be approved by an independent Inspection Authority.

Welding Procedure sheets shall be made available to the welder prior to the commencement of the work and shall be available to the Design Engineer or Inspection Authority on request.

6.2Welder Qualification

Welders shall be tested to meet the requirements of BS EN 287: Part1, and/or ASME Section IX.

In the case of welders engaged on fillet welding only, BS 4872: Part1.

Welder testing shall be witnessed and certificates endorsed by an independent Inspection Authority.

Certificates may be updated at six-monthly intervals, subject to the welder having been engaged on appropriate work in the intervening period.

6.3Non-destructive Testing of Welds Visual inspection shall be made in accordance with guidance given in BS EN 970, after completion of all welding over the full length of the weld.

All NDTs shall be performed by personnel qualified to a recognised national or international standard (e.g. PCN, etc.).

Magnetic particle inspection (MPI) shall be in accordance with the recommendations given in BS 6072.

Dye Penetrant Inspection (DPI) shall be used in accordance with the recommendations given in BS EN 571-1.

The test results shall be recorded and be available for inspection by the Design Engineer.

Where ultrasonic examination is required, it shall be made in accordance with BS EN 1714, level C.

6.4Scope and Frequency of InspectionAll welds shall be visually inspected along 100% of their length. In addition NDTs shall be performed on the following:

a) Fillet welds with throat thickness greater than 15mm shall be MPI tested.

b) Fillet welds where the connecting material is thicker than 20mm shall be MPI tested.

c) Butt-welds where the connecting material is 15mm or thinner shall be MPI tested.

d) Butt-welds where the connecting material is thicker than 15mm shall be ultrasonically tested.

Non-destructive testing shall be carried out for the first ten identified joints of each type, having the same basic dimensions, material grade and weld geometry, welded to the same procedures. Thereafter one in five joints of each butt-welded type, and one in ten joints of each fillet-welded type, shall be tested.

The acceptance criteria for any welding shall be in accordance with BS 5135 Category B.

Where field welding is used, 100% of all types of weld shall be subjected to NDT. All field welds shall be MPI/DPI tested as a minimum.

7.Flooring Standard Details shall be in accordance with AGIP/NAOC Plant Standard Practice.

Open grid flooring shall be serrated rectangular open grid type with load bearing bars 30mm deep x 5mm thick at 30mm cross centres with cross bars at 100mm centres, hot dip galvanised after fabrication, and complying with BS 4592: Part 1 (see also Appendix A to this Specification).

Open grid flooring shall be attached to the supporting steelwork with clips or other effective means. Holes or cut-outs in panels shall be made by the flooring manufacturer and have perimeter stiffening strips or toe plates welded in. This work shall be carried out before galvanising.

Solid floor plate shall have a raised pattern affording a non-slip surface and shall be 6mm minimum thickness exclusive of pattern.

Solid floor plates shall be attached to the supporting steelwork with proprietary connectors, unless otherwise noted on the design drawings. Unsupported edges shall have a 60 x 10mm butt-strap. A 13mm diameter drainage hole shall be provided for every 1.5m of floor plate, with a minimum of one hole per panel, unless shown otherwise on design drawings.

Deflections for any floor panel shall not exceed span/200 or 10mm whichever is smaller.

Galvanising shall be in accordance with BS 729.

8.Stairways Standard Details shall be in accordance with AGIP/NAOC Standard Practice.

Stairs shall have a minimum clear width between stringers of 750mm.

Main access and escape stairs shall have a minimum clear width of 1000mm, unless otherwise required by local regulations.

Treads shall be serrated rectangular pattern open grid type (25mm x 5mm bearing bars at 30mm cross centres with bars at 100mm cross centres) with non-skid abrasive nosings, hot-dip galvanised after manufacture for 750mm width stairs. For 1000mm wide stairs, 30mm x 5mm bearing bars at 30mm cross centres shall be used.

9.LaddersStandard Details shall be in accordance with AGIP/NAOC Standard Practice.

10Handrails and toe platesStandard Details shall be in accordance with AGIP/NAOC Standard Practice

11.Painting Steelwork shall be prepared, primed and shop painted in accordance with AGIP/NOAC Standard Practice.

Steelwork to be galvanised shall be in accordance with BS729.

Steelwork to be fireproofed shall be prepared and primed in accordance with AGIP/NAOC Standard Practice.

In order to minimise coating damage all reasonable care shall be taken when handling steelwork between stages in painting, and especially when slinging and loading steelwork which has received its final coat.

No material shall be shipped until the final shop coat of paint is thoroughly dry and clearly colour coded.

Adequate packing, crating, blocking and/or bracing shall be provided to prevent damage to the fabricated material while loading, in transit and while unloading.

Paint shall be excluded from areas within 50mm of joints to be field welded.

Temporary steelwork shall be painted white or fluorescent.

12. Erection Marking

Every component which is individually assembled or erected at the site shall be allocated an erection mark.

Members which are identical in all respects may have the same erection mark.

Erection markings corresponding to erection drawings shall be painted in letters a minimum of 40mm high on all members.

All bundles shall be tagged with non-destructible labels.

13. Colour coding

All fabricated structural steel, including galvanised steel, shall be identified with an approved colour code.

14. Fireproofing

Fireproofing materials shall be applied in accordance with AGIP/NAOC Standard Practice.

of fireproofing shall be as specified on the design drawings.

15. Shipping

The sizes of fabricated pieces shall be as large as practical considering means of transportation between the fabricating shop and the site.

Small pieces shall be bundled with steel bands to prevent damage during shipment and to facilitate unloading.

Loads shall not contain materials for more than one Material Requisition.

Bolts and nuts shall be shipped assembled, in clearly marked containers, packed for each structure and colour coded to suit.

Steelwork members shall be shipped in erectable lots, i.e. columns shall be shipped together with the connecting beams, bracing, connection cleats, ladders, walkways, platforms, handrail, bolts, fastenings, etc. In the case of multi-storey structures, the lower levels shall be shipped before the upper ones. The lots shall be dispatched in erectable sequence.

TO BE IN ACCORDANCE WITH AGIP/NAOC PLANT STANDARD PRACTICE

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