Blind Faith’s clever connections
  from: Offshore Engineer
  Tuesday, April 29, 2008

Performing a deepwater Gulf of Mexico subsea tie-in between Williams’ Devils Tower and Chevron’s Blind Faith export pipelines required innovative subsea installation and connection methodologies. OE reports how the job was done.

Subsea jumper installation in 5100ft of water was the challenge facing Williams Field Services in connecting the new Blind Faith oil and gas export pipelines to the Canyon Chief gas and Mountaineer oil export lines serving Devils Tower.

For this tie-in work,Williams opted to use proven technologies, but packaged differently from conventional jumper installations, according to Huy Phan, the company’s project manager, now assigned to commercial development of Williams’ western GoM deepwater and onshore assets. +

Both of the Blind Faith export pipelines are terminated with conventional PLEMs, providing a horizontal connector for the tie-in and a vertical connector for a future tie-in connection point. Both connectors are of the ROV-operable/installable clamp type.

The joining method of the pipelines and the jumper type employed set a unique backdrop for the work, Phan told a Marine Technology Society luncheon in Houston last month. An ROV operable/installable mechanical pipe end connector, fitted with an integral clamp connector hub that rested on an ROVinstalled mud mat, joined the bare ends of the Canyon Chief and Mountaineer pipelines.

After the mechanical connectors were installed, metrology was performed to create a neutral-state horizontal jumper for joining the mechanical connector hub and the Blind Faith PLEM.

Of compliant ‘Z-bend’ design, the neutral- state horizontal jumper was elastically pre-deformed using a bowstring system during installation to provide installation clearances and facilitate the neutral stress state postinstallation. Once landed, the bowstring was relaxed, allowing the jumpers to expand to fit between the hubs.

After expansion and make-up, an ROV operated hydraulic torque tool tightened the clamp connectors. The integrity of the connections was verified via an annulus test to check the integrity of the seal. After installation, the jumper remains in a minimal residual stress state atypical of most horizontal jumpers. According to Phan, the horizontal jumper was preferred to a vertical jumper because it provides a more compact and lighter connection system, allowing for a wider choice of installation vessel. The clamp-type connectors are half the weight of traditional collet-type connectors and require no running tools. In addition, the horizontal Z-bend offers greater compliancy to assist with alignment issues and minimizes stress after installation.

In carrying out the Blind Faith export pipeline jumper installations,Williams used connection systems, tooling suites and installation methodologies that will become part of the company’s new pipeline emergency repair kit for 12-18in diameter lines in up to 10,000ft of water (OE last month).

The kit, to be housed in a new facility in Ragley, Louisiana, includes diverless clamp connectors for surface or subsea repairs and diverless mechanical pipe connectors. OE

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