What Is SPM?

Single Point Mooring (SPM)—the "rotating socket" of deep-sea floating hulls, and also the "golden single point" with the highest concentration of anchor chain orders. 

Mooring a 300,000-ton VLCC at sea, where the shore is invisible, allows it to unload 2 million barrels of crude oil as if it were docked at a port, all thanks to Single Point Mooring (SPM). A buoy, several ultra-high-strength anchor chains, and a multi-channel rotating head form the common "first station" for global deep-sea oil and gas, floating wind power, and LNG transportation. 

I. Why Choose "Single Point"? 

1. Investment = 1/10 of a Terminal: A 300,000 barrels/day export SPM at the Búzios oil field in Brazil cost $180 million, while a land-based terminal with the same throughput costs over $1.8 billion. 

2. Construction Period = 3 Months: The Pazflor project in Angola took 92 days from anchor chain loading to buoy commissioning, while traditional terminals average 42 months. 3. Unlimited Water Depth: The SPM (Surface Mount Mill) system in the Mero oil field in West Africa operates at a record-breaking water depth of 2,130 m; the SPM system outside Zhanjiang Port in China also allows VLCCs to unload in water depths of 50 m, avoiding port entry. 

II. The "Skeleton" of the SPM – Anchor Chains are Key:

 - Floating Bollards/Turrets: Diameter 12–18 m, internal rotating head with a load capacity of 2,000 t, secured to the seabed by 4–8 anchor chains. 

- Anchor Chains: R4S (yield strength 580 MPa) and R5 (690 MPa) are now the mainstream; single chain length 275–335 m, breaking load 745–950 t, DNV-GL requires an impact energy ≥50 J at -40 ℃. 

- Rotary Joint: 6–10 inch multi-channel, capable of simultaneously transporting crude oil, natural gas, electricity, and fiber optic signals while rotating 360°, with a leakage rate of <0.1 L/h. 

- Quick Disengagement Device (QCDC): Automatically disengages within 3 minutes under typhoon-force winds (level 10), ensuring the safety of the vessel and chain; during Typhoon Kompasu in 2021, the SPM at the Hainan Lingshui 17-2 project successfully disengaged and was reconnected 42 hours later with zero oil spill. 

- Subsea Flow: 18 km of flexible riser + steel pipe directly connects to onshore storage tanks, forming an integrated unloading channel from pontoon to pipeline to storage area. 

III. Overview of Global Star Projects 

- Brazil Búzios FPSO: 7 SPM units, sharing a 2,100 t R5 Φ102 mm chain; in May 2022, a single shipment of 1.8 million barrels set a new single-point export record. 

- Pazflor FPSO, Angola: The 6-point mooring system was replaced with a 4-point SPM (Self-Mooring Platform), saving 600 tons of anchor chain and reducing project CAPEX by $120 million. 

- Lingshui 17-2 Deepwater Gas Field, China: The world's first to adopt a hybrid "deepwater semi-submersible platform + SPM" model, operating at a water depth of 1500 m, using 1680 tons of R4S Φ84 mm chains, and commencing production in June 2021, with a daily gas transmission capacity of 10 million cubic meters. 

- Rotterdam Gate LNG, Netherlands: The FSRU achieves an unloading rate of 8000 m³/h through SPM, completing 170,000 cubic meters of cargo in 72 hours during peak winter periods, replacing 12 km of onshore pipeline. 

- Hywind Scotland, UK: The world's first commercial floating wind farm, with 5 six-MW turbines sharing 3 SPM mooring systems, 1,350 tons of R3S Φ74 mm chains, and a 97% availability rate since commissioning in 2017. 

IV. Floating Wind Power Brings a New Wave of Chain Demand 

GWEC statistics show that global floating wind power will add 6.3 GW from 2025 to 2030, corresponding to 200,000 tons of mooring chains, with a compound annual growth rate of 37%. South Korea's Gray Whale 3 and Norway's Goliath Phase II have confirmed the adoption of the SPM system. Each 15 MW turbine requires 4×150 m R4S chains, weighing 240 tons—one wind farm alone consumes the equivalent of 400,000 tons of VLCC mooring chains. 

V. Advantages and Disadvantages of SPM 

Advantages

① Flexible Site Selection: No need for port dredging; suitable for water depths of 20–2,000 m. 

② Lower Investment: Cost is only 8–15% of a terminal with the same throughput. 

③ Quick Detachment: Detachment in 3 minutes during typhoons; average recovery time is 18 hours. 

④ Environmental Benefits: Leakage from the enclosed rotating head is <0.1 L/h, meeting IMO zero-emission requirements.  

SMEOCEAN is a professional anchor chain manufacturer. If you have any mooring chains in need, please contact us; we will provide you with the most professional service and products.

More Links:

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