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www.sea-technology.com September 2014 / st 21 signifcance of full compliance with IMCA guidelines, and what the safety and legal consequences of noncompliance may be, so as to allow themselves to make an informed choice when deciding which ALB product to purchase. Testing, Proving, Certifying A signifcant number of man- ufacturers of such bags simply produce their ALBs based on their in-house designs. These are then sent out with in-house certifcates (sometimes car- rying the IMCA logo, despite not being IMCA industrial members, nor indicating in what way and to what ex- I MCA D-016 (Rev 3) guidelines are generally recognized by the international marine and off- shore contracting community as the nearest thing to a defning global standard when it comes to the construction, testing, certifcation and use of open-ended air lift bags (ALBs). These bags are typically carried aboard a vessel by diving com- panies and the diving divisions of offshore instal- lation contractors for general subsea support in spreads typically up to 5-tonne capacity. Larger bags, typically in the 10-to-35-tonne range, are generally preferred for salvage opera- tions. Draft reduction for a rig coming into or out of drydock is another ma- jor application for ALBs, in the range of 20 to 50 tonnes. ALBs are also suitable for large-scale offshore support projects, such as the Lundin (Stock- holm, Sweden) FPSO mooring retrieval proj- ect using 50-tonne bags, which will be discussed later. It is, therefore, hardly surprising that most man- ufacturers of ALBs, in a competitive market, claim that their bags are in com- pliance with IMCA guide- lines. However, when you scratch below the surface of some of these claims it becomes apparent that these manufacturers are at best in partial compliance with these IMCA guide- lines. It is vitally important that purchasers and users of ALBs understand the Importance of Air Lift Bags' Compliance With IMCA Guidelines Following D-016 is Essential for ALBs By Chris Sparrow (Top) Unique Seafex's largest, 50-tonne model undergoing drop testing per IMCA guidelines. (Middle) Subsea view of a Seaf- lex 50-tonne ALB in use during Lundin FPSO mooring retrieval offshore Tunisia in September 2012. (Bottom) Surface view of a Seafex 50-tone ALB offshore Tunisia in September 2012.