Subsea Mooring Connector

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Subsea Mooring Connector

First Subsea's Ballgrab® Subsea Mooring Connector (SMC) is the industry’s leading mooring connector for deepwater mooring. SMCs are typically used in the mooring of Mobile Offshore Drilling Units (MODU), floating production storage and offloading vessels (FPSO), Floating Production Units, SPARs and Submerged Turret Production (STP) buoys.

The SMC uses our patented ball and taper technology to provide a two-part, male/female connection with a multi-point grip in direct proportion to the load applied. The SMC is self-aligning and self-energising, enabling fast installation of mooring lines in both deep and shallow water. 

With over 400 units supplied to date in over 40 subsea mooring installations worldwide, the SMC is designed and tested in accordance with certifying authority standards, and available in a range of sizes up to and over 2,600T MBL.

There are three types of SMC:

  • Series I - Rated up to 663T
  • Series II - Rated up to 1397T
  • Series III - Rated up to 2,600T

Ballgrab® Subsea Mooring Connectors offer:

  • Increased operational safety during mooring
  • Fast connection subsea - a typical connection time of less than 10 minutes
  • ‘Lean Installation’ reduces the size and number of required installation vessels, the time taken to complete the mooring installation and improves the efficiency of the mooring process
  • Simple mechanical connection – self-aligning and self-activating
  • The grip is proportional to load applied
  • There is no release under load
  • The ability to reconnect and connect if change out is required
  • Zero failures
  • Bespoke design to suit client requirements

The simplicity and speed of mooring line connection made possible using the Ballgrab® SMC allows significant vessel time savings. A typical connection time is less than 10 minutes from deployment, with on average 4 SMC connections completed per day.

For STP turret buoys, mooring line connections can be made on the buoy itself. It is no longer necessary to attach the mooring lines to the buoy ahead of tow out, making buoy lift out and towing offshore significantly easier as fewer vessels are needed.

Subsea Pin Type Connectors:

  • Cost sensitive
  • ROV push pin connection
  • Alternative to H-Link
  • Chain to chain connection
  • For further details

World Class Research

First Subsea's SMC exhibits high levels of strength and toughness, as well as outstanding fatigue behaviour over many years. Manufacture of the SMC is based on world class research into large scale metal forgings done by First Subsea and the University of Sheffield’s Institute for Microstructural and Mechanical Process Engineering (IMMPETUS). 

For each project, First Subsea is able to determine the steel chemical composition, forging and heat treatment process conditions needed to give consistent, optimum mechanical properties throughout the length of the mooring connectors.

Qualification and Technical 

Classification Approvals

All of First Subsea's SMCs meets classification society requirements laid down by:

  • DNV, ABS and BV
  • DIN EN ISO 9001-2008
  • ABS 2009 Certification of offshore mooring chain

Design, Assembly and Test

At First Subsea, every SMC is bespoke engineered using the latest Autodesk Design suite, Mathcad and Finite Element Analysis software to provide efficient designs.

Each SMC is assembled and tested at First Subsea's head office in Lancaster. The test facilities include a dedicated SMC test rig for proof load and Minimum Breaking Load (MBL) testing. We have recently upgraded our test facilities to 2,600T to ensure we stay the class leading supplier for deepwater projects. For each mooring project, a sacrificial SMC is tested to the full Minimum Break Load (MBL) and inspected to ensure a quality product is delivered.

The Ballgrab® SMC has been extensively fatigue tested to over 3 million fatigue cycles by DNV in their facilities in Oslo, using test criteria that significantly exceeds established norms for mooring equipment.

Installation, Service and Support

First Subsea provides a comprehensive mooring connector installation support service. Our engineers have considerable subsea and offshore experience and are present during the deployment of the two stage mooring system: pre-subsea installation of the receptacles on anchor piles, and subsequent installation of the male Ballgrab® connectors.

In the event a mooring line has to be disconnected, First Subsea provides 24/7 year-round after-sales support, to assist in the disconnection and reconnection of the SMC.

First Subsea Ltd