Garden Banks 388 Pipeline Jumper Testing and Installation
Authors: Hale J.R. , Davis S.W. , Prescott C.N. 
Published: October 2008

This paper describes practical aspects of the diverless jumper connection system used to connect Enserch's two 12-inch pipelines to the subseatempiatein2110 feet water depth. The paper is a follow-on paper to OTC 7543 which describes engineering aspects of the same jumper system. Project costs, schedule, and details of the jumper testing and installation are discussed. Testing was performed to verify ]umper design and installation operations. Offshore installation used two measurement methods for verification of jumper geometry.

INTRODUCTION

Two rigid pipe jumpers were connected in August of 1994, one each for oil and gas export, in 2110 feet water depth. The jumpers were made of 12.75"0 × 0.888" wall thickness API-5L Grade X8Opipe, with lengths of 71' and 105' for the oil and gas lines respectively. All subsea activities were performed using Remotely Operated Vehicles (ROVS); including jumper measurements and installation. Prefabricated jumper pieces were sent offshore where final cuts and welds were made. Prior to offshore activities, testing of all jumper components and fully assembled jumpers were performed. Testing included full scale failure tests of the load limiting flange, tank tests using ROVS to verify diverless operations, and simulated jumper measurement and fabrication on shore. The previous paper (OTC 7543), presented at last years OTC, addresses in some detail the design considerations. It discusses election of the connection method, describes each of the main jumper components, presents jumper flexibility and stress analyses, and describes in general the installation procedure.

PROJECT SCHEDULE

The overall project schedule from study phase through Installation took 1 year and 4 months beginning in May of 1993. Evaluation of connection methods and installation options took two months. Jumper design began in July of 1993, and was complete in October of 1993 (a total durationof four months). Supply of mechanical connectors and jumper fabrication was bid in November, and awarded in the first week of December 1993. Enserch received delivery of the first components in April, and final components at the beginning of June, 1994. Pipeline installation began in May, 1994 and was complete by mid August of 1994. Jumper installation occurred during the last two weeks of August 1994.

PROJECT COSTS

Because of the fast project schedule, jumper connectors and pre-fabricated jumper piping assemblies were bid together. Included in the jumper package were two spare cullet connectors, functional testing of the connectors, and ROV wet testing of the connectors. This portion of the package cost approximately $700,000. Additional jumper testing and components cost less than $200,000;h?ckfting load-limiting flange testing, measurement tool testing, site integration testing, and fabrication testing. Ail offshore jumper operations were performed using the DB-50. Slightly less than 4 days total, for both jumpers, were attributable to jumper operations (including sled installation). This equates to approximately $600,000. Therefore, the total costs attributable to the jumpers, Incorporating engineering, was approximately$1,600,000.

JUMPER SYSTEM DESCRIPTION

The components of the rigid jumper system developed for the GB 388 project include:Jumper or spod piece, including:Mechanical connection system at each end