MÁSTER EN ESTUDIOS INGLESES Y COMUNICACIÓN MULTILENGÜE

8.1 DESIGN CONDITION CHANGES

The operating authority shall ensure that where any changes to the originally approved design conditions occur or are proposed, these changes are fully assessed to ensure the integrity of the pipeline is not impaired and that safety of the public, operating personnel or protection of the environment is not diminished.

The changes may require the modification and re-approval of operating, maintenance and emergency procedures and to the MAOP and design life.

The following list is given as a guide to items of change that should initiate an assessment:

(a) Process fluid.

(b) Pressure and temperature.

(c) Land use location class.

(d) Pipeline damage or deterioration.

(e) Pipeline modification.

(f) Pipeline raising/lowering.

(g) Pipeline route relocation.

(h) Pressure control and protection systems including logic changes.

(i) Design life extension.

The assessment shall include, as appropriate, a review of the following:

(i) The location class.

(ii) The boundaries of the location class and the location of physical barriers or other features that could restrict the movement of these boundaries.

(iii) Management of risk to the public, property, environment or to the pipeline in accordance with AS 2885.1.

(iv) The protection measures required against third-party damage in accordance with AS 2885.1.

(v) The physical characteristics of the pipeline, including the diameter, wall thickness, SMYS, fracture toughness properties, strength test pressure and leak test pressure.

NOTE: These may be determined from records or, in the absence of records, by testing.

(vi) The physical condition of the pipeline as determined from records of the operation and maintenance and from reports of examinations, inspections and monitoring, including those pertinent to corrosion mitigation.

(vii) The design pressure.

(viii) The action that is required for the approval of a revised MAOP.

The results of the investigation shall be used as the basis for the confirmation of, or the need to, review the MAOP, and shall be documented and approved.

8.2 PRESSURE TESTING OF DESIGN CONDITION CHANGES

Where a change in a design condition occurs, and where a pipeline, which has been strength-pressure tested previously to an appropriate pressure, is in good physical condition, the results of that strength test shall be used to determine the MAOP.

Where a pipeline has not been strength-pressure tested previously to the pressure appropriate to the location or is in a poor condition, the pipeline shall be tested in accordance with AS 2885.1 and the results of that pressure test used to determine the MAOP. The condition of the pipeline shall be determined through a formal engineering investigation.

8.3 PIPELINE MODIFICATIONS

Where a pipeline is modified and the modifications may result in a change to the MAOP, (e.g., the addition of a branch line or the inclusion of a pressure-containing component) the MAOP of the modified pipeline shall be determined in accordance with AS 2885.1, and approved.

8.4 REVIEW OF PRESSURE-CONTROL AND OVER-PRESSURE PROTECTION SYSTEMS

Pressure-control and over-pressure protection systems, including compressor supplier packages control software, shall be suitable for and effective at the operating pressure and at the MAOP. Any changes to pressure-control and over-pressure protection systems shall be approved.

Suitability of systems shall be reviewed at approved intervals and in conjunction with changes to supply capacity.

8.5 REVIEW OF DESIGN LIFE

Where it is intended to operate a pipeline beyond its design life then, prior to the expiry of the design life, an engineering investigation shall be made of the design, operating conditions and history of the pipeline, to determine its condition and any limits for continued safe operation.

The engineering investigation shall include verification of the following issues:

(a) Proof of structural integrity in accordance with this Standard, to confirm the pipeline can continue to contain the hydrocarbons at the design conditions.

(b) Where the pipeline has been subjected to corrosion, as defined in accordance with AS 2885.1, the configuration of the defects, the rate of corrosion and the minimum remaining wall thickness shall be determined and used in the engineering investigation.

(c) The completion of a fracture control plan in accordance with AS 2885.1, and the identification of the proposed fracture control methods.

(d) The completion of a risk assessment conducted in accordance with AS 2885.1 and the identification of the proposed mitigation methods.

(e) The identification of any additional requirements that enable the pipeline to comply with the latest versions of AS 2885.1 and AS 2885.2 current at the time of the review.

(f) The identification of any tenure issue (ie. permit to occupy expiry) or statutory requirements (ie. pipeline licence renewal).

(g) Review of the adequacy of the safety and operating plan, operating and maintenance, emergency response, and safety and environmental procedures.

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Upon completion of the review, and prior to the expiry of the design life, all issues identified in the engineering investigation shall be addressed, and the pipeline records amended in accordance with the requirements of this Section.

The pipeline shall be operated only under the conditions and the limits so established and approved.

8.6 REVIEW OF MAXIMUM ALLOWABLE OPERATING PRESSURE (MAOP) The MAOP of each pipeline shall be reviewed at approved intervals not exceeding 5 years and, if necessary, amended whenever there are changes (including corrosion or damage) that could adversely affect the safety of the public, the operating personnel or the integrity of the pipeline. Investigations, tests and calculations shall be made during the review to establish the current condition of the pipeline and to determine an MAOP in accordance with AS 2885.1, this Section and Appendix D.

8.7 REVIEW OF LOCATION CLASSES

At approved intervals not exceeding 5 years and at any time when patrolling indicates the possibility of a need to change the classification of a location, the classification of the locations along the route of the pipeline shall be reviewed and, if necessary, changed.

Appropriate corrective action shall be taken, including a risk assessment carried out in accordance with the requirements of AS 2885.1.

8.8 REVIEW OF RISK ASSESSMENT

As part of any design review for change of use or extension of design life and at a period not exceeding 5 years (or as approved) an identification shall be made of the threats that could result in hazardous events affecting the pipeline. Threat mitigation procedures, failure analysis and risk evaluation shall be reviewed at those times.

Notwithstanding the above, the risk assessment is a live document, and new or changed threats, and methods for their mitigation should be added to the risk assessment and operating procedures whenever they are identified.

8.9 OPERATION OF A SUSPENDED PIPELINE

The operation of a pipeline shall be considered as suspended where the pipeline is maintained in a non-flowing condition for an extended period beyond the established maintenance routine.

Where a pipeline is suspended for an indefinite period for a later alternative use, the following conditions apply:

(a) Where in accordance with AS 2885.1, the pipeline is considered as not being subject to internal corrosion, the hydrocarbon contents of the pipeline may be stored within the pipeline for the duration of the suspension.

(b) Where in accordance with AS 2885.1, the pipeline is considered as being subject to internal corrosion, the pipeline shall be purged or flushed to remove all hydrocarbons, dried and filled with an approved fluid to an above-atmospheric pressure.

(c) The normal pipeline operating functions of patrols, cathodic protection monitoring, corrosion and coating surveys and reporting shall continue in accordance with the operating procedures, and Sections 3 to 8 inclusive.

(d) The level of pressurization shall be monitored.

(e) Maintenance shall be completed to preserve the structural integrity of the pipeline in accordance with Section 5.

The suspension of above-ground pipelines shall be subject to a risk assessment.

The suspension of a pipeline shall be approved and subject to an annual review to determine if the pipeline should be abandoned.

The decommissioning and preservation of associated plant shall also be completed.

8.10 ABANDONING A PIPELINE 8.10.1 General

When a pipeline is to be abandoned, an abandonment plan, including an environmental rehabilitation plan, shall be compiled and approved. The sequence of decision making required to develop and implement the plan should be in accordance with Figure 8.10.1.

When a pipeline is abandoned, it shall be disconnected from all sources of hydrocarbons that may be present in other pipelines, processing plant, meter stations, control lines and other appurtenances, and shall be purged of all hydrocarbons and vapour with a non-flammable fluid. Disposal of the purging fluid shall meet all relevant environmental and safety requirements.

8.10.2 Abandonment in place

When abandonment in place is approved, the pipeline section shall be abandoned in such a way to ensure that ground subsidence and the risk of contamination of the soil or ground water is minimized.

Where cathodic protection is applied, to prevent the eventual collapse of the pipeline, the responsibility for maintenance of the system shall remain with the pipeline operator and appropriate records shall be kept.

NOTE: Consideration should be given to filling the abandoned pipeline with an inert substance.

8.10.3 Abandonment by removal

When abandonment by removal is approved, the removal of the pipeline section shall meet all relevant safety, and environmental requirements. The requirements for pipeline removal shall be considered as similar to pipeline construction, and shall comply with the relevant requirements of Clause 9.4.3 and AS 2885.1.

8.11 ABANDONMENT OF ABOVE-GROUND PIPELINES Above-ground pipelines shall be abandoned by removal of the pipeline.

8.12 ADDITIONAL REQUIREMENTS FOR ABANDONMENT

When a pipeline is abandoned, the following additional requirements shall be completed:

(a) The cutting of all buried pipelines at a minimum of 750 mm below natural surface or at the pipeline depth, whichever is the lesser.

(b) The removal of all buildings, fences and equipment.

(c) The removal of all signage associated with the pipeline on completion of the post abandonment maintenance period.

(d) Except where cathodic protection is required in accordance with Clause 8.10.2, the cathodic protection system including buried cables, impressed current units, power lines, solar arrays and batteries are to be removed. Anode and earthing beds are to be disconnected at 600 mm below the natural surface level.

(e) All interference mitigation bonds with third party structures to be removed, that is the pipeline has to be mechanically and electrically disconnected from all other structures.

(f) Obtaining landowner releases for the completed abandonment.

(g) The relinquishing of the easement where no future or continuing use of the easement is proposed.

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8.13 ABANDONMENT RECORDS

Where abandonment in place is approved, on completion of the abandonment of the pipeline section in situ, as executed drawings, complying with AS 1100.401, identifying and locating sections of the abandoned pipeline, shall be prepared as part of the relinquishment procedure.

These records shall be made publicly available to prevent possible mistakes in identifying an abandoned pipeline as an operational pipeline.

Records of approved changes of operating conditions, all engineering investigations and work carried out in connection with any change in the operating conditions shall be maintained until the pipeline is abandoned or removed.

FIGURE 8.10.1 PIPELINE ABANDONMENT FLOW CHART

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