J collar is a forged component used to grip the pipe in order to install subsea pipeline in deep water using J-LAY mode system. It is a safe and reliable way to install very heavy pipelines.
Currently, there are two mainstream methods for deepwater pipeline installation: S-Lay and J-Lay. S-Lay is suitable for shallow to medium water depths, where the pipeline enters the water from the stinger at the stern, forming an "S" curve as it is laid onto the seabed.
When the water depth reaches hundreds or even thousands of meters, J-Lay becomes the preferred choice. The pipeline leaves the lay vessel in a near-vertical configuration, extending downward along the sag bend to the seabed, forming a "J" shape. This near-vertical configuration allows for a larger bending radius and minimizes bending stress, making it particularly suitable for ultra-deepwater, large-diameter, and heavy-wall pipeline installation.
In a J-Lay system, there is an inconspicuous yet crucial component: the J-Collar (also known as the hanging collar).
The J-Collar is a forging used to clamp the pipeline. During installation, it is connected to the pipeline via butt welding, and then the lifting system safely lowers the J-Collar and the pipeline into the water. In J-Lay operations, the weight of the pipeline, which can reach hundreds or thousands of tons, must be supported and transferred by the J-Collar. It serves as both a load-bearing interface and a positioning alignment interface, ensuring precise centering during lifting and lowering operations, thereby reducing the risk of pipeline damage.
In other words, reliable J-Lay pipelaying is impossible without a dependable J-Collar. Its structural performance directly impacts installation safety and seabed reliability.
Despite its small size, the J-Collar must withstand extreme challenges: deep-sea low temperatures and high pressures, continuous currents, and long-term corrosion from harsh media. Therefore, designing and manufacturing it is no easy task.
Before delivery, every J-Collar model must undergo rigorous Finite Element Analysis (FEA) to verify design safety and correctness under various stress loads, temperatures, and pressure conditions. Quality control spans the entire process, from raw material verification (chemical composition, tensile, impact, hardness, HIC, and SSC testing) to non-destructive testing (ultrasonic, penetrant, and magnetic particle), and finally to hydrostatic testing and coating performance testing (adhesion > 2,500 psi, cathodic disbondment < 7 mm/28 days/82°C).
Type 1---J-collar without Weld Overlay
Type 2---J-collar with Weld Overlay
J-collar is connected to pipeline by butted welding when installation. And then the J-collar and pipeline are put into water safely by lifting system.
Application Range
Nominal pipe size (NPS):
6” to 24”
Service:
Standard (i.e. crude oil, natural gas, etc.) or Sour (i.e. hydrogen sulfide, carbon dioxide, etc.)
Design dimension:
As per DNVGL-ST-F101 or customer’s specification
Design temperature range:
-29°C to 121°
Design:
ASME BPVC, Section VIII, Division 1 and 2
DNVGL-ST-F101 Submarine pipeline systems
NACE MR0175 Sulfide Stress Cracking Resistant Metallic Materials for Oilfield Equipment
ASTM A694 Standard Specification for Carbon and Alloy Steel Forgings for Pipe Flanges, Fitting, Valves, and Parts for High-Pressure Transmission Service
Material
J-Collar： ASTM A694 F60/F65 with quenching and tempering
Weld Overlay (if required)：Inconel 625
External Coating：HBE-OS recommended by Roc-Master
