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PMC and Engineering Upgrading 400 km 36" East Java Gas P/L

INTRODUCTION
The East Java Gas Pipeline (EJGP) consists of an offshore subsea 28” diameter pipe, 360 km long from Pageruan Island to Porong and an onshore pipeline, 70 km long from Porong to Surabaya and Gresik. The pipeline is used to flow gas from operations at Pagerungan Island to costumers in Surabaya and its surroundings; current flow is 250 MMSCFD and pipe flow capacity is 600 MMSCFD.

This pipeline has been operating since February 1994. After completion of the offshore pipe construction in March 1993, an ROV (Remote Operated Vehicle) survey was conducted to identify the offshore subsea pipeline condition. The survey found 338 freespans located between KP 0.940 through KP 263.370 (KP 0.000 starting from Pig Launcher on Pagerungan Island) with span lengths ranging from 7m to 183m.

Several freespans exceeded the Maximum Allowable Span (MAS) length, as specified in the original pipeline Design Basis (ref. Design Basis document or Philosophy Offshore Pipeline Vol.2/7 B1). From recent survey findings, the total number of freespans exceeding MAS is 126 spans. There are 57 existing grout bag supports and concrete mattresses between KP 0.960 andKP 42.700 in water depth of 11m to 48m.

In March 1999, an ROV survey between KP 0.800 through to KP 45.000 inspected grout bag condition and placement, as well as monitoring the development of freespans. The survey identified that existing grout bags were in good condition and that several freespans exceeded MAS but futher calculation concluded that those freespans were still within acceptable limits and would not create any problems in near future.

In June 2002, another ROV survey was conducted along offshore pipeline from KP 0.900 through to KP 321.000. The survey found that 57 existing grout bags were still in good condition and there were 1041 freespans having span in excess of 28m, a significant number of freespans were calculated to have zero remaining fatigue life calculated against international code (such as DNV).

PERTAMINA GAS intends to offer the rectification of Pagerungan to Porong 28” diameter gas pipeline (EJGP) freespans on an EPC (Engineering Procurement Contract) basis at a later point. However, PERTAMINA GAS will first conduct geotechnical, geophysical and metocean data aquisition to provide quality data for the engineering analysis of the pipeline integrity prior to the actual rectification work.

In 2007, rectification of pipeline started with grout bag method and after that with Gravel Dumping Method. Freespans rectification shall be carried out in Zones I, II and III of the East Java Gas Pipeline (EJGP) between KP 0.9 to KP 285.0.

OBJECTIVE AND SCOPE OF WORK
To gather sufficient quality and quantity of geotechnical, geophysical and metocean data to support engineering analysis of the pipeline integrity.

To conduct freespans Rectification of subsea 28” diameter gas pipeline to ensure the integrity of said pipeline. It is expected that the rectification program will ensure that the pipeline will be safe from over span, freespan and other hazards for its design life.

Project scope of work:
Scope of work The Provision of the Technical Assistance Services for The Project Management Consultant (PMC) of the EJGP Offshore Line Span Rectification Project is as the following:

  • Assist PERTAMINA DOH JJB in preparing two packages of work for rectification, that is survey and remedial work
  • Do the engineering for remedial work
  • Assist PERTAMINA DOH JJB in tendering and selection of the contractor for the two packages
  • Do the project management that include:
  • QA/QC and inspection so that the project completed on time, meet specification and not over budget
  • Project control, project optimization, and document control
  • Engineering design evaluation, review, and give recommendations for effective and efficient project execution
  • • Monitor project progress and field activities
  • • Project close out report

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