Subsea Constructions

Dual Subsea Isolation Valves

Every export pipeline and infield flowline includes a subsea safety isolation valve (SSIV) to protect the platform a possible fire in the area. There are 5x12” dual infield SSIV skids, 2x32” gas export single SSIV skids and 1x16” condensate export single SSIV skid. Each SSIV skid is supported by a Mudmat and 4 piles.

All SSIV and ROV maintenance valves are interchangeable and retrievable with a valve retrieval frame.


The key components in the SSIV skid are:

  • SSIV Valve
  • ROV Maintenance Valve
  • 2” Gate Valves
  • 1” MEG Valves (infield only)
  • Moffat Hot Stab
  • Tees
  • Flanges (c/w Anti Snag Protectors)
  • Anodes
  • FMC Controls Equipment and Pressure & Temperature Transmitters
  • Spring-Lok Connectors
  • Line Pipe, Small Bore Piping
  • Hydraulic Tubing & Electrical Cables
  • Flanges Anti Snag Protection Shrouds

Build Sequence SSIV

  • Typical SSIV Foundation
  • SSIV Skid Structure
  • Valve Module Retrieval Frame
  • SSIV Module (Hydraulically Actuated Valve Module)
  • Block Valve Module (ROV operated Valve Module)
  • SSIV Header Anchor and Header Guide

Factory Acceptance Testing

Factory Acceptance Testing (FAT) is a process that evaluates the equipment during and after the assembly process. FAT verifies that it is built and operating in accordance with design specifications.

FAT ensures that the components and controls are working properly according to the functionality of the equipment itself.

FAT is beneficial not just for the buyer and end users but for the manufacturer as well.  Both parties can be assured that the equipment meets all the contractual specifications and any issues can be addressed before arriving at the customer’s site.

At BOS Shelf, FAT is performed after mechanical completion (fit up, welding, NDT, coating etc.) of spools and structures. FAT is performed and controlled by an approved FAT procedure specific to the asset and is witnessed and approved at all stages by BOS Shelf QC and Client QC Representative. The FAT schedule is planned and notification of all tests and trials is sent to all parties prior to commencement of any activity.