In the ten years since its first installation, the SALM (single anchor leg mooring) has been applied at many locations throughout the world, both for conventional oil import and export terminals and for deepwater production storage and loading facilities. Eleven SALMs have been installed, and six more are now on order. This paper describes the design of and experience with these SALMs. Special attention is given to the Okinawa SALM. which was overhauled in 1979 after 7-1/2 years of service. and which is similar to the SALMs now being installed at LOOP. Operation and maintenance problems with SALMs have been few. The SALM has proven to be a safe, reliable, and efficient means of mooring and loading or unloading both large and small tankers. Experience and continued research have lead to design improvements which are now being incorporated in new SALMs.
In November, 1969. the first SALM (single anchor leg mooring) began loading oil at Brega. Libya. In the ten years since then, the SALM has been widely accepted as a safe. efficient means of mooring and loading or off10ading oil tankers. Three firms, SOFEC. SBM Inc., and IMODCO, now market the SALM under license from Exxon Research and Engineering Co. (ER&E).
This paper traces the development of the SALM from its conception in the mid 1960s to the present. It describes the design of and experience with the installed SALMs and the plans for those now on order. Tables 1 and 2 list the SALMs now in service throughout the world and the SALMs on order as this paper is written. Figure 1 shows the range of water depths in which SALMs are installed.
Development of the SALM did not cease with the first SALM at Brega. The Okinawa SALM, installed in 1971. was the prototype for the shallow water terminal-type SALMs. having the fluid swivel assembly mounted directly on the mooring base. That SALM was overhauled for the first time last year. after 7-1/2 years of trouble-free service. Subsequent examples of this design have incorporated multi product swivels. at Ju'aymah and Azzawiya. The LOOP SALMs will incorporate other new features. such as elastomer bearings in the hose arm and load monitoring.
The Brega SALM has evolved into deeper and more sophisticated deep-water production systems. The Thistle SALM, besides being the deepest SPM in the world. has the swivel placed within the buoy to prevent pollution and facilitate maintenance. The Santa Barbara and Fu1mar SALMs will permanently moor storage vessels with rigid yokes.
The SALM has had a remarkably successful early career. and has proven itself as a safe and efficient mooring and cargo transfer system for tankers. The SALM is frequently selected over other SPMs for offshore tanker terminals because of the inherent safety of the system. For example. tankers can overrun the mooring buoy without damaging the fluid swivel assembly or other critical cargo transfer components. As with any new concept. some problems have been experienced; however, resolution of these has led to even more reliable designs.
In the mid 1960s. an ER&E study concluded that new concepts would be needed to moor and load the very large tankers then contemplated for the 1970s. A major research and development program was initiated in 1966 to develop a new tanker mooring system (Refs. 2 and 4). Several promising concepts were evaluated through model testing and preliminary development studies. From these investigations. it was concluded the SALM, originally suggested by Esso Standard Libya personnel, was the most promising and feasible alternative. The principal reason for selecting the SALM was safety