Transmission Line Support Structures Asset Management Plan D08/99418 Issue 4.0, October 2012
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Transmission Line Support Structures Asset Management Plan Issue 4.0, October 2012
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This document is the responsibility of the Network Performance and Strategy Team, Transend Networks Pty Ltd, ABN 57 082586 892. Please contact the Network Performance and Strategy Manager with any queries or suggestions.
Next Review
This document has a normal scheduled review frequency of 2.5 years from date of last approval.
Responsibilities
Implementation
All Transend staff and contractors.
Compliance
All group managers.
Minimum Requirements
The requirements set out in Transend’s documents are minimum requirements that must be complied with by Transend staff, contractors, and other consultants. The end user is expected to implement any practices which may not be stated but which can be reasonably be regarded as good practices relevant to the objective of this document.
This document is protected by copyright vested in Transend Networks Pty Ltd. No part of the document may be reproduced or transmitted in any form by any means including, without limitation, electronic, photocopying, recording or otherwise, without the prior written permission of Transend. No information embodied in the documents that is not already in the public domain shall be communicated in any manner whatsoever to any third party without the prior written consent of Transend. Any breach of the above obligations may be restrained by legal proceedings seeking remedies including injunctions, damages and costs.
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Transmission Line Support Structures Asset Management Plan Issue 4.0, October 2012
Record of revisions Section number
Detail Revised extensively – please review accordingly
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Transmission Line Support Structures Asset Management Plan Issue 4.0, October 2012
Table of contents Executive Summary ........................................................................................................................... 8 1
2
3
General ...................................................................................................................................... 9 1.1
Introduction .................................................................................................................. 9
1.2
Purpose ......................................................................................................................... 9
1.3
Scope ............................................................................................................................ 9
1.4
Objectives ..................................................................................................................... 9
1.5
Strategic context ......................................................................................................... 10
1.6
Asset management information system ...................................................................... 11
Asset category description ..................................................................................................... 12 2.1
Related Standards and Documents ............................................................................. 12
2.2
Transmission line support structure types .................................................................. 13
2.2.1
Support structure asset specification .......................................................................... 13
2.2.2
Supporting structure fittings and hardware ................................................................ 18
2.3
Age profile .................................................................................................................. 21
2.3.1
Steel lattice towers (galvanised) ................................................................................. 22
2.3.2
Steel lattice towers (weather resistant steel)............................................................... 22
2.3.3
Wood poles ................................................................................................................. 23
2.3.4
Steel poles................................................................................................................... 24
2.3.5
K-poles ....................................................................................................................... 24
2.3.6
Economic life ............................................................................................................. 25
Condition monitoring practices ............................................................................................. 25 3.1
Defect management practices ..................................................................................... 25
3.2
Asset specific condition monitoring activities ........................................................... 25
3.2.1
Steel lattice towers (galvanised) ................................................................................. 25
3.2.2
Steel lattice towers (weather resistant steel)............................................................... 25
3.2.3
Wood poles ................................................................................................................. 26
3.2.4
Steel poles................................................................................................................... 26
3.2.5
K-poles ....................................................................................................................... 26
3.3
Asset condition summary ........................................................................................... 26
3.3.1
Steel lattice towers (galvanised) ................................................................................. 26
3.3.2
Steel lattice towers (weather resistant steel)............................................................... 28
3.3.3
Wood poles ................................................................................................................. 30
3.3.4
Steel poles................................................................................................................... 30 Page 4 of 48
Transmission Line Support Structures Asset Management Plan Issue 4.0, October 2012
4
5
6
7
3.3.5
K-poles ....................................................................................................................... 31
3.3.6
Warning signs ............................................................................................................. 32
3.4
Special operational and design issues ........................................................................ 33
3.4.1
Operational issues....................................................................................................... 33
Asset Performance .................................................................................................................. 34 4.1
Service obligations for network assets ....................................................................... 34
4.1.1
Hydro Tasmania ......................................................................................................... 34
4.1.2
Major Industrial direct customer connections ............................................................ 34
4.2
Key performance indicators ....................................................................................... 35
4.2.1
Performance summary ................................................................................................ 35
4.3
Benchmarking ............................................................................................................ 35
4.3.1
External benchmarking............................................................................................... 36
Risk .......................................................................................................................................... 37 5.1
Business risks ............................................................................................................. 37
5.2
Asset risk .................................................................................................................... 38
5.2.1
Health Index ............................................................................................................... 38
5.2.2
Probability of Failure.................................................................................................. 39
5.2.3
Circuit criticality factor .............................................................................................. 39
5.2.4
Consequence of Failure .............................................................................................. 39
5.2.5
Risk ............................................................................................................................. 39
5.2.6
Risk analysis and mitigating strategies ...................................................................... 40
5.2.7
Monitoring and review ............................................................................................... 42
Demand Analysis .................................................................................................................... 42 6.1
Planned augmentation ................................................................................................ 42
6.2
Asset specific implications ......................................................................................... 42
Lifecycle Management Plan ................................................................................................... 42 7.1
Issues summary .......................................................................................................... 42
7.2
Maintenance plan ....................................................................................................... 43
7.2.1
Preventive maintenance .............................................................................................. 44
7.2.2
Corrective Maintenance ............................................................................................. 45
7.2.3
Spares management .................................................................................................... 45
7.2.4
Technical support ....................................................................................................... 45
7.2.5
Transmission line support structure replacement strategies ....................................... 46
7.2.6
Transmission line support structure replacement program ........................................ 46
7.3
Disposal plan .............................................................................................................. 46
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7.4 8
Technology and innovation ........................................................................................ 46
Financial Summary ................................................................................................................ 47 8.1
Operational expenditure ............................................................................................. 47
8.2
Capital expenditure..................................................................................................... 47
8.3
Investment evaluation................................................................................................. 47
List of figures Figure 1
Asset Management Document Framework ................................................................ 11
Figure 2
Steel lattice tower (galvanised) .................................................................................. 14
Figure 3
Steel lattice tower (weather resistant steel) ................................................................ 15
Figure 4
Wood pole structure ................................................................................................... 16
Figure 5
Steel pole structure ..................................................................................................... 17
Figure 6
K-pole structure .......................................................................................................... 18
Figure 7
Climbing barrier ......................................................................................................... 19
Figure 8
Fall arrest system ........................................................................................................ 20
Figure 9
Warning signage ......................................................................................................... 21
Figure 10
Identification labels .................................................................................................... 21
Figure 11
Steel lattice towers (galvanised) age profile ............................................................... 22
Figure 12
Steel lattice towers (weather resistant steel) age profile ............................................ 23
Figure 13
Wood pole structures age profile................................................................................ 23
Figure 14
Steel pole structures age profile ................................................................................. 24
Figure 15
K-pole structures age profile ...................................................................................... 24
Figure 16
Steel lattice tower (galvanised) defect summary ........................................................ 27
Figure 17
Steel lattice tower (galvanised) defect breakdown ..................................................... 27
Figure 18
Steel member corrosion .............................................................................................. 28
Figure 19
Steel lattice tower (WRS) defect summary ................................................................ 28
Figure 20
Steel lattice tower (WRS) defect breakdown ............................................................. 29
Figure 21
Steel lattice tower (WRS) corrosion ........................................................................... 29
Figure 22
Steel pole defect summary ......................................................................................... 31
Figure 23
Internal corrosion of K-pole support structure ........................................................... 32
Figure 24
Warning sign defect summary .................................................................................... 32
Figure 25
Faded warning sign .................................................................................................... 33
Figure 26
ITOMS benchmarking metrics ................................................................................... 36
Figure 27
Asset risk framework.................................................................................................. 40
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Transmission Line Support Structures Asset Management Plan Issue 4.0, October 2012
List of tables Table 1
Transmission line support structure assembly types (as at July 2012) ....................... 13
Table 2
Transmission line support structure fittings (as at June 2012) ................................... 18
Table 3
Transmission line support structure economic lives .................................................. 25
Table 4
Wood pole defect rates ............................................................................................... 30
Table 5
Transmission line support structure risk analysis for ‘HIGH RISK’ ......................... 41
Table 6
Life cycle issues ......................................................................................................... 43
Table 7
Merits of aerial and ground based inspections ........................................................... 44
Table 8
Preventive maintenance strategies.............................................................................. 45
Table 9
Transmission line support structure performance improvement initiatives .................................................................................................................... 47
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Transmission Line Support Structures Asset Management Plan Issue 4.0, October 2012
Executive Summary This document defines the strategies for the management of Transend’s extra high voltage (EHV) transmission line support structures for a ten year planning period. The objective of this plan is to manage business risk to within acceptable levels by achieving reliable asset performance at minimal life-cycle cost. The strategies included in this asset management plan have been developed taking into account past asset performance, good electricity industry practice and the need for prudent investment to optimise the asset life-cycle. The condition assessment and maintenance practices for transmission line support structures are revised where appropriate to sustain and improve transmission line support structure reliability and optimise transmission system performance. This implies that transmission line support structures will be subjected to incremental renewal as components decay or fail. In this manner, transmission line support structures are kept in an acceptable operational condition as reliable and economic assets. It is widely recognised by utilities that transmission line support structures have an economic life expectancy of 60 years for steel construction, and 45 years for wood construction1. As such, incremental component renewal may no longer be economically viable when a transmission line support structure approaches its economic age. Transmission line support structures will therefore be assessed periodically to optimise the economic, operational and safety considerations1. The principal means of degradation of the main body of steel lattice transmission line support structures is corrosion. The remedial focus is towards early detection, treatment or if the corrosion is advanced, replacement of the members. For the small number of wood pole transmission line support structures in the network the main causes of degradation are as a result of impact damage, wood decay or insect attack, fire and other environmental factors such as lightning. Transend’s small population of steel K-poles is over 80 years of age and is exhibiting signs of deterioration. It is considered prudent to commence the programmatic replacement of these high risk assets, particularly considering that these structures are located on a radial 110 kV transmission line where a single asset failure will result in an immediate and sustained interruption to supply. Signage, climbing barriers, and various other component fittings are integral for the safe operation of the transmission system and an average 10 year economic life is considered appropriate to ensure operational integrity and statutory compliance1. Transend, consistent with electrical utilities globally, has demonstrated that aerial condition assessments by helicopter are the most cost effective way to manage the inspections program in Tasmania. Nonetheless, ground based condition assessments are also vital to the whole condition assessment program; even though they are more expensive on a unit comparison basis. Continuous reviews ensure that there is a balance between ground and aerial inspections to best meet Transend’s objectives. The successful implementation of the strategies detailed in this asset management plan is aimed at managing Transend’s business risk to within acceptable limits by addressing transmission line support structure performance. The ongoing preventive maintenance practices will enhance transmission circuit availability, resulting in sustained levels of good service to customers.
1
Sinclair Knight Merz – Assessment of Economic Lives for Transend Regulatory Asset Classes (November 2007)
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1
General
1.1 Introduction Transend’s vision is to be a leader in developing and maintaining sustainable networks. In keeping with this vision the Board has identified the strategic performance objectives of improvement of business processes, and strategies to improve productivity and realise efficiency gains, as key goals upon which overall business performance enhancement must be based. Transend actions its philosophies for asset management process through asset management plans. These documents disaggregate the network infrastructure into subsets of like assets. An asset management plan is available for each subset. This asset management plan is one of a set of plans that discuss the basis behind Transend’s operational and capital expenditures. Transend aggregates its network-wide asset management philosophies and action plans into a biennially published Transmission System Management Plan (TSMP) that is made available to key stakeholders, including technical and economic regulators. The strategies identified in this asset management plan have been developed taking into account past asset performance, good electricity industry practice and the need for prudent investment to optimise the asset life-cycle.
1.2 Purpose This asset management plan defines the asset management objectives and strategies specific to transmission line support structure assets. This plan reports on Transend’s assessment of work needed to achieve the service level and performance goals for the asset class at least life-cycle cost.
1.3 Scope This asset management plan covers all transmission line support structures including, but not limited to;
support structures types (eg lattice steel structures, steel poles, wooden poles);
support structure fittings and hardware; and
emergency restoration structures.
1.4 Objectives The objectives of this asset management plan are to;
present an overview of the transmission line support structure population;
minimise the business risk presented by transmission line support structures;
achieve reliable asset performance consistent with prescribed service standards;
quantify the risks specific to transmission line support structures and identify corresponding risk mitigation strategies;
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Transmission Line Support Structures Asset Management Plan Issue 4.0, October 2012
ensure the effective and consistent management and coordination of asset management activities relating to transmission line support structures throughout their life-cycle;
demonstrate that transmission line support structures are being managed prudently throughout their life-cycle;
ensure asset management issues and strategies as they relate to transmission line support structures are taken into account in decision making and planning; and
define the future operational and capital expenditure requirements of transmission line support structures.
1.5
Strategic context
The asset management plan is part of a suite of documentation that supports the achievement of Transend’s strategic performance objectives and, in turn its mission. The asset management plans define the issues and strategies relating to transmission system assets and detail the specific activities that need to be undertaken to address the identified issues. Figure 1 shows the Transend documents that support the asset management framework, referenced to the corresponding IIMM documentation and/or process, adapted to meet Transend’s specific needs. The diagram highlights the existence of, and interdependence between, strategic, tactical and operational planning documentation
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Transmission Line Support Structures Asset Management Plan Issue 4.0, October 2012
Figure 1 Asset Management Document Framework
I.I.M.M. Asset Management Philosophy & Framework (adapted)
Corresponding Transend documentation and systems
Organisational Strategic Plan Vision, Mission, Objectives, Level of Service, Business Policies, Risk
Corporate Plan Vision, Mission, Performance Objectives, Areas of Strategic Focus, Grid Vision Policies Safety, Environment, Risk Management
Asset Management Policy
Asset Management Policy
Optimised asset management strategy, objectives, level of service targets & plans
Asset management processes, procedures & standards for each asset type
Implement asset management solutions Asset solutions – operate, maintain, renew, develop, retire Non-asset solutions – demand management, insurance, failure management
Asset data and information systems
1.6
Strategic Planning
Transmission System Management Plan Asset Management Framework Asset Management Strategy Transmission System Performance Objectives Planning & Service Delivery Asset Management Support Systems Asset Class Profiles Asset Management Strategies Area Development Plans Drivers for Development Regulatory Processes Asset Creation Asset Augmentation Capital Expenditure Profiles Project Technical Justification
Tactical Planning
Asset Management Plans and Reports Asset Overview Performance Issues and Strategies Asset Life-Cycle Management Operating and Capital Expenditure Profiles Risk Management Condition Assessment Reports Technical Standards Maintenance Standards Project Definition and Specifications Technical Information Standards
Operational Planning
Integrated Works Program Consolidation and Optimisation of Works Plans Works Planning and Scheduling Outage Planning
Asset Management Information System (AMIS)
Asset management information system
Transend maintains an Asset Management Information System (AMIS) that contains detailed information relating to the transmission line support structure population. It is a tool that interlinks asset management processes through the entire asset lifecycle and provides a robust platform for extraction of relevant asset information. The following AMIS standard provides additional information relevant to transmission line support structures: Page 11 of 48
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D06/19077
WASP Asset Register – Data Integrity Standard – Support Structure
Transend’s Geographic Information System (GIS) also captures asset data associated with transmission lines. This data is stored in a standalone database with links into WASP
2
Asset category description
Transmission line support structures comprise the physical infrastructure from which insulators, electrical conductors or associated hardware are attached or suspended. Transmission line support structures include:
all the structural components above the foundation interface; and
various safety and functional fittings attached to the structure. These include warning signs and labels, fall arrest systems and climbing barriers
2.1
Related Standards and Documents
Technical requirements for transmission line support structures are detailed in the following standard specifications:
D03/6112
Overhead line design – Detailed procedures
AS/NZS 7000:2010
National Fall Protection Guidelines for the Electricity Industry
NENS 05-2003
Transmission Circuit Name Abbreviations Standard
TNM-GS-809-0032
D05/10726 Transmission Line Support Structure Climbing Barrier Standard
TNM-GS-809-0049
D05/12858 Transmission Line Design Standard
TNM-GS-809-0058
D05/5870
Hazard/Incident Notification Form
TNM-GS-809-0098
D05/9256
Site Names and Abbreviation Standard
TNM-GS-809-0193
D05/40065 System Spares Policy
TNM-PY-809-0461
D07/67177 Transmission Line Construction Standard
TNM-GS-809-0524
D07/15661 Geographic Information System (GIS)
TNM-SY-809-0657
D05/2191
TNM-GS-809-0203
Access Control Standard
D04/25163 Steel Lattice Support Structure Inspection Report Form
TNM-GS-809-0389-001
D04/25166 Wood Pole Support Structure Inspection Report Form
TNM-GS-809-0389-002
D04/25168 Pre-fabricated Tubular Steel Support Structure Inspection Report Form
TNM-GS-809-0389-003
D12/8563
Environmental and Safety Management System Manual
D08/3395
Sinclair Knight Merz, ‘Assessment of Economic Lives for Transend Regulatory Classes’, 2008
D08/51503 Transend document, ‘Annual Planning Report’, Transend Networks, 2008 D12/24505 Transend document, ‘Annual Planning Report’, Transend Networks, 2012
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D08/22311 Transend document, ‘Transmission System Management Plan’, Transend Networks, 2007 D11/113760 Transend document, ‘Transmission System Management Plan’, Transend Networks, 2011 D10/51845 Fall Arrest Systems Strategy Review In general, structures have been designed to a range of standards over the last 90 years. Structures built since the mid-1960s were designed in accordance with ASTM/ASCE and Australian Standards. Prior to 2010, structures were also designed in accordance with “ENA C(b)1-2006 Guidelines for the design of overhead distribution and transmission lines”. In 2010 this guideline was superseded by “AS/NZS 7000:2010 - Overhead line design – Detailed procedures”.
2.2
Transmission line support structure types
2.2.1
Support structure asset specification
Transend maintains 7964 support structures on the transmission system. Of these, 7798 support structures are owned by Transend, and 166 are owned by a third party. As shown in Table 1, most support structures are of the steel lattice (galvanised) type. Table 1
Transmission line support structure assembly types (as at July 2012)
Owner and service status Transend (in service)
Support structure material Steel
Support structure type Lattice tower (galvanised)
79
Lattice tower (weather resistant steel)
477
6
Single pole
482
6
K-poles
75
1
Lattice mast (weather resistant steel)
26
