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The Importance of Underwater Connectors
Wet-mate connectors are the linchpin of a successful underwater application. Unless you identify the right subsea connectors for your project, it could be dead in the water, or, at the very least, require frequent, expensive repairs.
To prevent unnecessary repairs, let’s review the typical options available for underwater cable connectors, the benefits and shortcomings of each, and what considerations should be key to your decision-making process.
Types of Underwater Cable Connectors
Underwater connectors, also known as wet-mate connectors, subsea (electrical) connectors, or marine connectors, are designed to be mated or unmated in wet environments and are capable of withstanding the most extreme environments, from corrosive seawater and pressure to vibration and shock.
A traditional underwater connector relies on a watertight seal. Several variations have been developed over time to achieve this, including the following.
Rubber-Molded Wet-Mate Connectors
A wet-mate connector is created between a female connector end and a glass-reinforced, epoxy bulkhead connector through a locking sleeve as well as neoprene or polyurethane overmolding.
Rigid Shell Wet-Mate Connectors
Rigid shell wet-mate connectors are molded into a rigid body to offer greater stability, strength, and lockability. Two connector halves are screwed together, sealing the junction with an O-ring.
Fluid-Filled Wet-Mate Connectors
For this component, a chamber is filled with oil or another dielectric fluid to isolate the contacts from water. As the ends are mated, the contact pins are wiped clean by the diaphragm in the face of the receptacle.
Inductive Couplings
These pinless, subsea connectors attach magnetically without exposing any conductive parts to the outside environment.
How do you determine which type of standard wet-mate connector is best for your needs? Let’s take a deeper dive into the specs for each.
Factors to Consider When Choosing Subsea Electrical Connectors
The industry’s long-standing underwater interconnect solutions vary in application, material, and design. A typical underwater cable connector often features O-rings, gasket seals or oil bladders, and copper contacts.
Before settling on the right waterproof assembly for your implementation, be sure to evaluate the following key criteria.
Material
The metal used for your subsea connector must be strong enough to withstand its intended marine environment. Depending on a project’s needs, such as extreme corrosion resistance, tensile strength, minimal electrical conductivity, or high melting point, 316 stainless steel, Inconel, and titanium are considered three materials of choice.
Typically, 316 stainless steel is preferable for subsea electrical connectors because it’s well-equipped to resist corrosion after undergoing design and manufacturing processes that involve welding. The resulting underwater cable connectors can also withstand high-corrosion environments and boast considerable resistance to heat.
A variation of stainless steel and Inconel is considered a superalloy due to its mechanical strength, surface stability, and corrosion resistance. Though that is the case, few pure metals have more strength than titanium. This is because it has an extremely high corrosion resistance and a tensile strength that’s at least double that of aluminum.
Cost of Subsea Connectors
From a cost perspective, stainless steel is a reasonable choice for wet-mate connectors and will stand up to the elements quite well. However, for applications that require truly exceptional corrosion and heat resistance, titanium is the preferred option.
Performance
Peak performance in the field is where it matters. Some subsea connectors boast guarantees of remaining operational underwater for up to 25 years with long-term water resistance. On the other hand, certain underwater cable connectors are considered difficult to implement in the field due to a tendency to leak or become compromised at a certain pressure rating.
Pressure
As your waterproof assembly is submerged deeper underwater, the equipment is subjected to increasing amounts of pressure reaching up to and often greater than 10,000 psi. Without the right subsea electrical connector for your application, this amount of force can negatively impact any number of components, increase system failures, or jeopardize operations.
Cable Assembly
Typical subsea connectors come in a wide range of cable assemblies, including electrical, fiber optic, or pressure-balanced, oil-filled.
Rating
Wet-mate connectors are rated for an application’s specific depth and pressure. For example, a subsea connector may have a mated pressure rating of up to 20,000 psi but is tested in an even more rigorous marine environment.
Lead Time of Subsea Electrical Connectors
A long lead time generally is required as traditional wet-mate connectors take 18 weeks, or more than 4 months, from the time an order is placed until delivery (and that’s without any disruptions in the supply chain).
Overall, researching each of these seven key criteria relative to the specifications needed for your project will help in identifying the best traditional wet-mate connectors for your application.
It’s important to note that regardless of the advancements made over the years, underwater connectors still mix electricity with water. Traditional underwater connectors attempt to exclude water from their contacts by using rubber seals, oil, or moving parts.
Despite the industry’s best efforts, these wet-mate connectors are expensive, run the risk of high failure rates due to corrosion and other environmental factors, and can pose a potential safety risk.
