UKOPA Recommendations for the Inspection and …

1 UKOPA Recommendations for the Inspection and Maintenance of Buried Pipelines Issue 2 December 2012 Reference: UKOPA /13/028 Disclaimer This document is protected by copyright and may not be reproduced in whole or in part by any means without the prior approval in writing of UKOPA . The information contained in this document is provided as guidance only and while every reasonable care has been taken to ensure the accuracy of its contents, UKOPA cannot accept any responsibility for any action taken, or not taken, on the basis of this information. UKOPA shall not be liable to any person for any loss or damage which may arise from the use of any of the information contained in any of its publications. The document must be read in its entirety and is subject to any assumptions and qualifications expressed therein. UKOPA documents may contain detailed technical data which is intended for analysis only by persons possessing requisite expertise in its subject matter.

2 Cover picture reproduced with kind permission of National Grid 2010 UKOPA pipeline Inspection and Maintenance Recommendations Issue 2 December 2012 ii Document developed by the UKOPA Risk Assessment Work Group (RAWG). Document History Date Document first published Issue 1 September 2006 Issue 2 December 2012 Internet Address: Email Address: UKOPA is formed as a Company Limited by Guarantee, funded as a non-profit making organisation by membership fees paid by the pipeline operator members. Registered in England and Wales Company No. 4052297 Registered Office: pipeline Maintenance Centre Ripley Road Ambergate Derbyshire DE56 2FZ The names of the directors may be obtained from the above address. UKOPA pipeline Inspection and Maintenance Recommendations Issue 2 December 2012 iii Contents INTRODUCTION .. 1 1. Scope .. 1 2.

3 Main Drivers for Inspection and Maintenance .. 1 Legislative Compliance .. 2 Operational Duty .. 2 Business and Economic Factors .. 2 Safety and Environmental Factors .. 2 Potential Damage Mechanisms .. 2 Third Party Activities .. 3 3. Legislative Requirements .. 3 4. Damage Mechanisms .. 4 Impact Damage .. 4 Ground Movement .. 4 Fatigue .. 5 Corrosion .. 5 Operator Error .. 6 5. Consequences of Failure .. 6 6. Maintenance and Inspection Activities .. 6 Safe Operating Limits (SOL) and Maximum Operating Pressure (MOP) .. 6 Provision of Information .. 6 Route 7 Condition Monitoring .. 9 Cathodic Protection .. 10 pipeline Facilities, Equipment and Components .. 11 Reporting of Damage and Defects .. 11 Emergency Maintenance and Repair .. 12 Defect Assessment .. 12 Modification and Repair .. 12 Records .. 12 pipeline Integrity Management .. 12 7 Defect 13 8 Emergency and Repair.

4 13 9 Keeping of Records .. 14 10 Modification and Repair Procedure .. 14 11 Review of Strategy .. 14 TABLE 1 - STATUTORY REQUIREMENTS .. 16 TABLE 2 - pipeline Inspection and maintenance MATRIX .. 17 TABLE 3 - RECOMMENDED pipeline Inspection and MAINTENANCE FREQUENCIES .. 18 UKOPA pipeline Inspection and Maintenance Recommendations Issue 2 December 2012 1 INTRODUCTION To ensure a high level of safety and reliability in operation, it is essential to have a system of Inspection and maintenance for steel pipelines and pipeline systems, and their ancillary equipment operating above 7 barg. The primary purpose of this strategy is to detect and prevent in-service damage, degradation, or defects which can lead to failures. This paper provides the basis for a common strategy towards meeting the above objective, allowing efficient and cost effective maintenance and Inspection whilst demonstrating compliance with appropriate legislation in the UK.

5 The maintenance strategies outlined in this document are considered best practice. Alternative strategies may be adopted if they can be demonstrated by the pipeline operator to result in equivalent levels of risk to those outlined in this document. In all cases, the maintenance strategies applied by the operator should be fully documented in terms of their scope, frequency and responsibility for their execution. 1. SCOPE This paper covers the maintenance and Inspection of buried steel pipelines operating at pressures greater than 7 barg. The requirements for maintenance on associated above ground installations are outside the scope of this document. Maintenance intervals should be set in accordance with the Recommendations given in PD 8010 2004 or IGE/TD/1 Edition 5. Alternatively, maintenance intervals can be set based on a risk based approach provided suitable reliability data is available to justify these risk based frequencies.

6 Additionally, Inspection regimes should be drawn up for items of equipment on above ground installations that are within the scope of the Pressure Systems Safety Regulations (PSSR), which require that the Inspection requirements and frequencies for pressure vessels, pipework and protective devices are identified on the relevant Written Schemes of Examination (WSOE). This document focuses on maintenance and Inspection strategies for buried pipelines and is not intended to cover other safety management requirements, training and competency requirements, emergency planning, operating and maintenance plans, that will be a part of the pipeline operator s broader safety management strategy. 2. MAIN DRIVERS FOR Inspection AND MAINTENANCE In general terms, the integrity of a pipeline is most secure whilst it remains buried. A strategy of maintenance requirements, in the form of route surveillance, condition monitoring and Inspection , will help ensure that unnecessary intrusive maintenance is greatly reduced, if not avoided.

7 UKOPA pipeline Inspection and Maintenance Recommendations Issue 2 December 2012 2 The following identifies the main issues that determine the need to carry out maintenance and Inspection activities and suggests a strategy which must be developed to ensure a robust and economic means of undertaking these activities. Legislative Compliance Maintenance and Inspection requirements must comply at all times with any statutory or legislative requirements. The main legislative driver in the UK is The Health and Safety at Work Act (1974) and the associated Regulations: The Pipelines Safety Regulations 1996 (PSR) and The Pressure Systems Safety Regulations 2000 (PSSR). In addition, the operators of natural gas pipelines must comply with the Gas Safety (Management) Regulations, which require that operations and maintenance procedures are described in the Safety Case for the conveyance of gas.

8 A summary of legislative drivers is given in Table 1. Operational Duty The life cycle of a pipeline can be considered to follow the bath tub failure probability curve with higher incidences of failure in early life followed by a fairly constant failure rate which gradually increases towards the end of the pipeline s life. With pipelines, early life failures generally result from damage associated with construction and commissioning. A constant failure rate is then generally observed during the operating life, which is mainly due to random mechanical damage. A gradual increase in failure rate then may be caused by age and duty related damage mechanisms. A maintenance and Inspection strategy should be applied which can accommodate the early failures, minimise and respond to random failures, and anticipate and avoid predictable failures due to age and duty deterioration mechanisms.

9 Business and Economic Factors The maintenance and Inspection strategy should ensure transportation and delivery of the product to the satisfaction of the operator and/or the customers. It should be robustly planned to optimise performance by increasing the overall life and ensuring that the probability of failure remains at an acceptable level whilst minimising overall operating costs. Safety and Environmental Factors Effective maintenance and Inspection is essential to minimise the risks to safety and the environment caused by pipeline failure. It is also essential to ensure maintenance and Inspection activities minimise impact on the safety of the public, staff and contractors or on the local environment. Potential Damage Mechanisms UKOPA pipeline Inspection and Maintenance Recommendations Issue 2 December 2012 3 For pipelines operating in the UK, the main causes of failure are identified as impact damage due to 3rd party interference, ground movement, corrosion, fatigue, and operator error.

10 These causes of failure should be considered when determining maintenance and Inspection activities. A robust emergency response should also be available to react to unforeseen situations. Third Party Activities It is essential that all reasonable precautions are taken to reduce the risk to pipelines being struck or damaged by third party activities. Monitoring of building developments should also be undertaken to control potential proximity and population density infringements along the pipeline route. Additional liaison with local authority planners will establish at an early stage any proposals for building work that may affect the integrity of the pipeline . Further details are provided in Section 6. Third parties planning to undertake work in the vicinity of the pipeline should be provided with pipeline location information. For high risk work, consideration should be given to physically marking out the pipeline route and supervising the third party work.