MEM05 Metal and Engineering Training Package SAMPLE. MEM05036C Repair/replace/modify fabrications. Learner guide Version 1

Transcription

1 MEM05 Metal and Engineering Training Package MEM05036C Repair/replace/modify fabrications Learner guide Version 1 Training and Education Support Industry Skills Unit Meadowbank Product code: 5531

2 Acknowledgments The TAFE NSW Training and Education Support Industry Skills Unit, Meadowbank would like to acknowledge the support and assistance of the following people in the production of this learner resource guide: Standards Australia AS 4100 Steel structures AS/NZS 1163 Cold-formed structural steel hollow sections AS/NZS 1170 Structural design actions - General principles AS/NZS 1554 Structural steel welding AS/NZS 3678 Structural steel - Hot rolled plates, floorplates and slabs AS/NZS 3679 Structural steel AS/NZS Structural steel - Hot rolled bars and sections AS/NZS 4680 Hot-dip galvanized (zinc) coatings on fabricated ferrous articles Writer: Ed Harkness TAFE NSW Reviewers: Jim Miles Project Manager: Stephen Davies Education Programs Manager TAFE NSW Enquiries Enquiries about this and other publications can be made to: Training and Education Support Industry Skills Unit, Meadowbank Meadowbank TAFE Level 3, Building J See Street MEADOWBANK NSW 2114 Tel: Fax: TAFE NSW (Training and Education Support,Industry Skills Unit Meadowbank) 2011 Copyright of this material is reserved to TAFE NSW Training and Education Support, Industry Skills Unit Meadowbank. Reproduction or transmittal in whole or in part, other than subject to the provisions of the Copyright Act, is prohibited without the written authority of TAFE NSW Training and Education Support, Industry Skills Unit Meadowbank. ISBN: TAFE NSW (Training & Education Support, Industry Skills Unit Meadowbank) 2011

3 Table of Contents General introduction Using this learner guide... 5 Fabrication replacement planning Fabricating a replacement structure Prior knowledge and experience Unit of competency overview Assessment Unit mapping... 9 Topic 1: Introduction to repairing, modifying and replacing fabrications Repair, replace, modify fabrications Safety Modifying a fabrication Personal protective equipment (PPE) Repair, replacement and modification to fabricated structures Repairing a fabricated structure Access to repair a fabricated structure Scheduling of repair work Ship repair Weld repairs Review questions Topic 1: Practical exercises Job 1.1: Beams and column welded assembly Job 1.2: Remove and replace wear plates Job 1.3: Additional decking plate and reinforcing an angle frame Topic 2: Replacing fabricated structures Review questions Topic 2: Practical exercises Job 2.1: Replacing a structural member Job 2.2: Modifying a support structure Job 2.3: Fabricating and fitting a permanent shading frame Topic 3: Modifying fabricated structures Process of modification to a fabrication Replacement of a fabricated structure Structural sections Modification safety Modification construction Steelwork installation Environmental factors Re-commissioning modified structures Review questions Topic 3: Practical exercises Job 3.1: Modifying beams to column welded assembly Job 3.2: Modifying composite structure Job 3.3: Modify decking plate and reinforced angle frame Replacing a fabrication Resource Evaluation Form Replacement improvements Road signage support frames TAFE NSW (Training & Education Support, Industry Skills Unit Meadowbank) 2011

4 Topic 1: Introduction to repairing, modifying and replacing fabrications State reasons why repair to a fabrication may be necessary: corrosion erosion timeline Objectives At the end of this topic you will be able to: List the general safety requirements of conducting repairs, replacements and modifications to fabrications in workshops and construction sites: OHS procedures work method statements (WMS) safe operation procedures (SOP) safe work statements (SWP) personal protective equipment (PPE) marking tools holding devices special purpose measuring tools Outline the necessity to either repair, replace or modify a fabrication: replacement cost accessibility expected life span of fabrication Describe three categories of repair, replacement or modification work: failure of the structure in service change in the function of the structure initial material selection State the assessment procedures relating to repair, replacement and modification to a fabrication: repair, replacement or modification assessment inspection non-compliances non-destructive testing (NDT) Outline the process of repair, replacement and modification work: contracts scope of work timeline engineering drawings work analysis codes, standards and specifications work completion dates timelines List and explain the process of conducting repairs to ships' hulls: damage assessment work safety requirements repairs conducted inspection and compliance Explain the necessity of reinforcing a repaired fabrication: recurring damage additional strengthening extending life span of repair corrosion resistance. Hull Repair Page 11 of 58

5 Repair, replace, modify fabrications The terms repair, replace or modify can all be used generally to mean the same thing; to correct a fabricated structure. A steel stairway for instance could have the handrails repaired, replaced or modified resulting in a correction to the structure. However the terms repair, replace or modify can also mean: immediate repairs to a structure where damage has occurred completely replacing a structure that no longer serves its purpose planned modifications to a structure to improve its functionality. This learning resource will describe both of these explanations, providing students with detailed information on why a fabricated structure would be repaired, replaced or modified. Safety In general, any repair, replacement, or modification to a fabricated structure would take place either: at the fabrication workshop, or on-site. DANGER CONSTRUCTION SITE UNAUTHORISED PERSONNEL KEEP OUT Fabricated replacement or modification work would be constructed at the fabricator s workshop followed by transportation and on-site installation, whilst repair work to an existing fabricated structure might be done entirely on-site. Because of the differing work locations fabricators should be familiar with both site and workshop safety codes of practice in relation to: occupational health and safety rights and responsibilities in metal fabrication industries work method statements (WMS) safe operation procedures (SOP) safe work statements (SWP). Before being allowed to commence work on-site, fabricators may be required to complete a site safety induction programme in order to be familiar with policies and practices for work related hazards as: manual handling and safe lifting practices working on elevated platforms entering confined spaces site duty of care policy site housekeeping accident and incident reporting machinery operation on-site use of welding and thermal cutting equipment. The examples given here are a guide only to typical on-site safety and will vary according to the type of construction site and work environment. Personal protective equipment (PPE) Personnel working in metal fabrication industries are required to wear safety equipment to protect themselves from the dangers associated with: welding thermal and mechanical cutting materials handling high noise levels. Fabricators working on-site need to protect themselves from hazards associated with site work such as: head protection sun protection wet weather and other climatic situations high visibility clothing working within confined spaces working at heights fire prevention. As with all personal protective equipment, it should: be worn according to the directions of the site safety policy be worn correctly to manufacturers' instructions fit correctly and be in good condition. Page 12 of 58

6 Repair, replacement and modification to fabricated structures A fabricated structure is designed and constructed to meet specific applications as requested by the client. For example: the steel beam and column supports for a warehouse must be capable of safely spanning the area required and support the warehouse roof an aluminium walkway bridge must be correctly fabricated and welded to allow the public safe access to marine vessels at a waterfront location stainless steel balustrades and fittings need to withstand corrosive environments when used as lustre finish fittings on apartment balconies. Structural columns supporting universal beams At the time of manufacture the structure must meet the needs of the client and be constructed in accordance with the design engineers requirements. The design and function of a fabricated structure must also meet applicable industry codes and standards, such as any state or territory regulatory codes of practice. For example, the fabricated steelwork for a retail shopping complex and multi-storey car park must conform to the following structural standards as well as many other building codes: AS/NZS 1170 AS/NZS 3679 AS 4100 AS/NZS 1554 Structural design actions - General principles Structural steel Steel structures Structural steel welding Aluminium walkway bridge Initial design and construction needs to be thorough as any repair, replacement or modification to a fabricated structure after construction and installation will be very expensive to complete. Stainless steel balustrade Necessity to repair, replace or modify a fabrication However, in time, repair, replacement or modification work may become necessary for such reasons as: failure of the structure in service - cracks appearing in highly stressed areas due to inadequate welding or under-design would require repairs to be performed change in the function of the structure: - an increase in service load may require a structure to be modified to strengthen it accordingly. Page 13 of 58

7 Initial material selection - the physical properties of the original metal used in construction are no longer suitable due to a change in the production process, thus requiring certain parts of the structure to be replaced Maintenance to fabricated structures may simply be an ongoing necessity and would be factored into the initial design of the structure. For example a road or rail bridge may require exposed metal surfaces to be protected by regular painting to limit the corrosive effects of its location. Even though a much less corrosive metal could have been used at the time of construction, regular painting is a more cost-efficient alternative to initial high costs of a corrosion resistant metal. Corrosion due to environmental and location factors Other factors which could warrant a repair, replacement or modification to a fabricated structure could include: poor initial design requirements to meet new federal or state environmental codes client request for modifications weather and other climactic environments wearing of parts in erosive and corrosive service conditions. Repairing a fabrication would also extend the service life of the structure, greatly reducing the expense involved in replacement or modification. Steel bridges around the world are continually painted to control corrosion Assessing repair, replacement and modification work As described earlier, in time, the repair, replacement or modification to a fabricated structure may become necessary for a range of reasons. The decision as to whether a fabricated structure is repaired, replaced or modified is based on the extent of engineer s inspections and written reports. A report on a fabricated structure deemed as requiring repair, replacement or modification work could include the following: a detailed description of why work on the structure is required scope of inspection carried out identification of defects, faults or non-compliances found non-destructive examination (NDE) conducted. Failure of a bolted steel connection in service Page 14 of 58

8 The inspecting engineer s report would also include recommendations as to the extent of the work required to again allow the fabricated structure to become compliant with the appropriate codes and standards. At this point an informed judgement would be made as to the most economical action to be taken on whether to repair, replace or modify the fabricated structure. Mayne and Cooper Structural Engineering Inspection Services Engineers report compiled for West Coast Bridge Repairs Pty Client: Necessary action determined Wollowong Municipal Council Project: Repair and modification to two lane traffic bridge Cover page from an Engineer s report Implications of the action taken to repair, replace or modify the fabricated structure must also be addressed. For example, modification work to reinforce the jacket legs of an oil platform cannot interfere with the quantity of oil the platform sends ashore each day. Therefore, any repair, replacement or modification work must also consider; continuation of the structure s operation necessary shut-down of the structure partial closure of the structure forecasted work completion date and re-commissioning of the structure. On-site repair work to a fabricated structure Process of repair, replacement and modification work The planned course of action, whether repair, replacement or modification work to the existing fabricated structure will set in place a series of actions by the engineer and fabricator. Documentation would include: tendering and securing of contracts scope of work timeline of repair, replacement and modification work scope of engineering drawings analysis of task requirements codes, standards and specifications of work to be completed work completion dates identified. Page 15 of 58

9 Repairing a fabricated structure Performing repair work to a fabrication may be necessary due to a number of reasons, some examples include: Access to repair a fabricated structure On-site repair work requires access to the fabricated structure which may entail a shut-down of normal activity. This can create other problems such as: Corrosion - rusting due to the effects of weather, or deterioration of the surface protection - corrosive effects of a substance being handled. Erosion - erosive effects of frictional and metal to metal contact - erosive effects of an abrasive material in contact with the fabricated structure. Mechanical failure - damage to a part of the structure as the result of unintentional impact - over-loading of the structure. Damage to a road bridge On-site repair to a fabricated structure might consist of existing parts being repaired by: thermal cutting mechanical pressing welding bolting This type of repair would be the most cost efficient as existing parts are being repaired, and replacement parts are kept to a minimum. A time-line for repair to a fabricated structure would also be established prior to work commencing. public road closures causing traffic difficulties food and beverage processing equipment closure disrupting production temporary disruption to essential utilities such as gas, electricity or water reduction in productivity of primary resources in the mining industries. Scheduling of repair work Repaired bridge Good planning can effectively minimise such disruptions by scheduling repair work to be completed at set times such as holiday periods. This type of work, commonly known as a shut-down, would be programmed for completion together with other essential repairs, replacements or modifications during the annual holiday period for operating staff. A coal handling plant for example may require essential repairs to a fabricated steel structure. Whilst the equipment is off-line, other work could be completed such as: the repair or replacement of conveyor belts the removal of waste build-up in chutes and hoppers replacement of worn bucket links checking and up-grading of electrical and mechanical equipment A strict time-line for completion of the contract work and re-commissioning would allow the plant to recommence productivity as scheduled. Page 16 of 58

10 Ship repair A major area of fabrication repair work is the repair of merchant and naval ships. Ships hulls are often damaged as the result of collisions during docking, at sea, or whilst navigating estuary channels. Steel hulled bulk carriers loaded with iron ore, coal or primary produce such as grain or wheat could sustain major hull damage, requiring them to be dry docked for repair. Damage to aluminium hulled naval ships may have occurred during service, requiring immediate repairs to allow the vessel to again be sea-worthy. As well as hull repairs, ships are dry docked for anti-fouling, painting and the replacement of rudders and propellers. Shipping insurance companies require most vessels to be dry docked twice every five years to ensure seaworthiness. A typical repair to a ship s hull would consist of: Bulk carrier dry docked for hull repair access to the vessel to inspect the damage that has occurred hull damage assessed for level of repair required area prepared for work to safely commence fabricators, welders and auxiliary staff conduct necessary repairs repaired hull inspected and vessel issued with compliance report. Vessels may be hauled or retrieved for repair by using floating dry docks, which are types of submersible pontoons used for docking vessels and can be towed to the location of the ship to conduct repairs. Vessel hull prepared for a plate insert and weld repair Completed repair Page 17 of 58

11 Weld repairs Welds deposited on to repaired structures such as road bridges or ships hulls will require inspection and some method of non-destructive testing (NDT) to be carried out. D Welds inspected and non-destructively tested Weld inspection is required to verify the completed weld conforms to relevant standards; the same standard may require welds to be tested using a non-destructive testing method such as liquid penetrant or magnetic particle testing. Reinforcement of a repair Cracks detected by NDT at the toe of the weld Repairing a fabricated structure will correct the damage that has occurred due to any of the reasons previously mentioned in this resource. However, the fabricator should consider reinforcing the repaired structure in order to help minimise similar damage occurring in the future. D section D - D Beam flanges reinforced in area subjected to greater stresses Additional plating to a metal surface will help strengthen the repaired part, extending the life of the structure and delaying the time between future necessary repairs. A repaired part subjected unavoidable corrosive attack could be plated with stainless steel in order to reduce the inevitable corrosion that will occur. Page 18 of 58

12 Review questions These questions will help you to revise what you ve learned in Topic 1: Introduction to repairing, replacing and modifying fabrications. 1. List two (2) safety hazards associated with site work. 6. Briefly explain the term shut-down in relation to the repair to a fabricated structure. 2. Before fabricators are given permission to work on site, they must first complete a: liability disclaimer form site safety induction first aid course fork lift licence test 3. A fabricated structure is designed to meet the needs of the: federal regulatory code of practice state regulatory code of practice engineer client 4. In the space provided, briefly explain why it is important that the initial design and construction of a fabricated structure is thorough. 5. List the three (3) categories where it may be necessary to repair, replace or modify a fabricated structure. 7. Naval and merchant ships often repaired in: wet docks port docks sea docks dry docks 8. State the major reason why deposited welds used to repair a steel bridge may require inspection and testing. Page 19 of 58