Offshore Cable

These cables are designed for power transmission and instrumentation application on offshore units. It is also known as oil and gas cables.

As the marine environment is very harsh; therefore, the offshore cable should be powerful and durable so that the cables can survive in tough conditions.

Offshore cables have resistance against mud, fire, humidity, oil, acids, and saltwater corrosion. Offshore cables are used at offshore platforms to preserve human safety and the environment.

Every offshore platform needs an extensive integrated power, control, instrumentations, and communication system to perform well in harsh working situations.

Figure 1: What is Offshore Cable?

Offshore Cables come in a wide variety. They have a lot of types, and each type has its own advantage.

There are various types of offshore cables that include RFOU, BFOU, TFOU, RFCU, RU cable, BU cable, RFOU(c), RFOU (I), and BFOU(c)

Figure 2: Types of Offshore Power Cables

Types of Offshore power cables are RFOU, BFOU, TFOU, RFCU, RU, BU.

Types of VFD cables are TFOU-VFD, RFOU-VFD, BFOU-VFD.

Types of Instrumentation cables are RFOU (i), RFOU(c), RFOU (i &c), BFOU(i), BFOU(c), BFOU (i &c).

Earth cable: P15 UX.

The specifications of offshore cables include:

• Conductor
• Insulation
• Sheath
• Identification
• Temperature rating
• Voltage rating

These specifications vary in different types of cables. Mostly tinned copper annealed conductors are used.

High oil-resistant, low-smoke halogen-free sheaths are used with protective insulation.

Different cables have different conductor operating temperature range. Similarly, the voltage rating is different in different cables.

Figure 3: BFOU Cable

BFOU is a fire-resistant, halogen-free, and mud resistant offshore power cable. It is used for fixed installation on offshore units. BFOU is produced according to the NEK 606 and IEC 60092-353 standards.

It is a fire-resistant cable made of materials that are non-flammable. So, the cable doesn’t melt or drip even when exposed to fire. BFOU is tested against the temperature of at least 830 C so that it meets the IEC 60331 standards.

Figure 4: RFOU Cable

RFOU is a flame retardant, low smoke, halogen-free, and mud resistant offshore power cable. This cable is designed specially to resist fire, and it is self-extinguishing.

RFOU cables pass several tests to meet the standards set by IEC, e.g., it meets the IEC 60032-3-22 standard, which is the test against high temperatures.

This is a NEK 606 standard offshore cable. It is used for fixed installation on offshore units.

Both RFOU and BFOU cables are offshore power cables that are used in the harsh marine environment. They are used in several ways, like for oil rigs, drilling rigs, and offshore platforms.

RFOU and BFOU both ate halogen-free cables. This feature makes them safe and toxic-free. These offshore power cables meet strict safety and fire standards.

Both RFOU and BFOU are mud resistance. Hence, they are the perfect choice for oil rig facilities.

The only difference between them is that the RFOU is a flame-retardant cable, while the BFOU is a fire-resistant cable.

Figure 5: BU Cable

BU cable is a fire-resistant non-armoured offshore power cable. It is used for fixed installation on offshore units and oil gas platforms.

It consists of tinned stranded copper wire conductors. A fire-proof mica tape as a fire barrier is used over the conductor. It is a halogen-free mud-resistant cable.

Figure 6: RU Cable

RU cable is NEK 606 standard non-armored offshore power cable. These cables are used for fixed installation on offshore units. 

RU cable is a flame-retardant cable sheathed by low smoke and halogen-free thermosetting compound. It can be mud-resistant if requested.

Figure 7: BFCU Cable

BFCU cables are fire resistant offshore power cables. They are armored cables used for fixed installation for power, control, or lighting in both safe areas and critical systems where there is a requirement for fire-resistant cables.

Figure 8: RFCU Cable

RFCU cables are armored cables. They are used for fixed installation for power, control, or lighting in safe areas where cable protection is required.

These cables have an amazing mud resistant version. RFCU cables can be used in areas exposed to mud and drilling.

Figure 9: VFD Cable

VFD stands for Variable Frequency Drive. These cables are often referred to as variable-speed drive cables or adjustable-speed drive cables.

They are used for providing proper shielding to reduce noise and provide a low-impedance signal return path.

Figure 10: Offshore Wind Cables

Offshore wind has made it very big in the past few years. They are basically the wind turbines that use the natural wind to create electricity.

The offshore wind farm cables are installed from land at a power source to sea at the turbines. The process of installing the portion of cable from land to sea can also be known as nearshore cable installation.

Offshore wind farms are created on large bodies of water. These bodies can be lakes or oceans as they harvest the wind energy to generate electricity.

Offshore wind energy has more than 2000 gigawatts (GW) of potential energy. With the help of offshore wind cables, these offshore wind farms produce a lot of clean and reliable electricity.

These cables are specially designed for drilling rigs. They are also used for onshore and offshore platform applications.

They are built to last in harsh conditions. These cables are resistant to mechanical stress, drilling mud, oil, moisture, and severe temperatures.

Figure 11: Type P Cable

Type P Cables are specifically designed for installation and use in harsh offshore and onshore drilling rigs environments. These cables have to survive against extreme conditions.

These conditions include severe cold, high heat, constant vibration, drilling mud, mechanical stress, and salt corrosion.

The different types of cables used in the oil and gas industries are:

• Polyurethane Jacketed Cable
  These are flexible cables suitable for indoor and outdoor general-purpose applications.
• Polyethylene Jacketed Cable
  These are moisture-resistant cables typically used in wet environments. Generally, the polyethylene insulation is stiff, but the stiffness can vary based upon high and low-density forms.
• Armoured Cable
  Armoured cables are usually steel wired cables, which means a hard-wearing power cable designed for the supply of main electricity.

This extra protection is provided against harsh environments. These cables are used for underground systems, cable networks, power networks, outdoor and indoor applications, and cable ducting.

NEK 606 standards cover the basic requirements of optical fiber cables, Hydro Carbon Fire Resistant (HCF) cables, and Jet Fire (JF) resistant cables that include the specifications for halogen-free and mud resistant low and high voltage power, control, lighting, instrumentation, and telecommunication.

These are the standards or technical specifications set for marine applications. Offshore oil and gas industries, ship manufacturing, and other industries that use earth, power, or instrumental cables must use the offshore cables that are up to NEK606 standards.

Figure 12: Where to Buy Offshore Cables?

Jiangsu Yuanyang Cable Co., Ltd. is the No. 1 offshore cable manufacturer company in China. It was founded in 1992. Since then, the company is dedicated to the research, development, and manufacture of marine, offshore and naval cables.

All of the company cables are certified and approved by ABS, BV, CCS, LR, DNV-GL, RINA, RS, NK, KR.

The flexible payment terms make it convenient for the buyers to deal with the company. Moreover, any type of queries and complaints are attended to quickly and responded to within three days.

A large stock of cables is available in the company that ensures quick response and fast shipment.

Figure 13: TFOU Cables

These are the electric power cables, which are flame retardant, halogen-free, and low-smoke.

The conductor consists of annealed, plain, or tinned copper strands that provide high conductivity.

Figure 14: Current Carrying Capacity of Offshore Cables

The current carrying capacity of a cable depends on its size and core. For example, the current-carrying capacity of a 1.5 mm2 single core cable is 23 Amperes, whereas it is 16 Amperes in a three or four cores cable.

Similarly, in a 50 mm2 cable, it carries 196 Amperes in a single core and 167 Amperes in a double core cable. So, the current carrying capacity varies with the size of the cable.

According to the cable quality, various certificates are given to the companies. These certificates are given by many classification societies. The better standards offered by a cable are judged by the number of certificates the cable has.

Given below is a list of a few important classifications:

ABS

Certification offered by the American Bureau of Shipping.

DNV-GL

It is one of Europe’s leading certification, DNV-GL. It is a merger of a German and a Norwegian company.

The offshore cable is designed for electrical power and instrumentation application on an offshore unit. As the cable works in isolated environments and cannot be reached immediately in case of any emergency, that’s why it has to fulfill all safety standards very strictly.

NEK 606 and IEEE 1850 are the two standards for offshore cables. They make sure that the cables are mud resistant and halogen-free that makes them toxic-free and safe. The cables are designed specifically to stay protected against drilling oils and hydrocarbons.

They are resistant to high temperatures, humidity, vibration, oil, acid, and saltwater corrosion.

Along with being resistant, these standards make sure that the installation of the cable is done with proper engineering practice and a strict set of regulations.

Offshore cables are cost-efficient. They are almost the same as the price of other marine cable wires. The cost of offshore cable totally depends on which cable type you are buying and in which size.  

Every cable varies in size and types, thus also varying in price. However, we offer competitive prices to our customers and free delivery services.

All of our offshore cables are inspected before shipment (third party inspection on request). We ensure full re-fund to customers if the order doesn’t satisfy requirements.

We can use offshore cables on numerous platforms; these include:

• Shipboard Wiring
  Offshore cables are mainly used in shipment wiring. They are installed in shipments to provide protection in the harshest environment.
• Offshore Platforms and Applications
  Which type of wire to use clearly depends on how distant is the shore. Offshore cables are used in offshore platforms like offshore wind farms.
• Installations at The Sea for Setting Up Oil Rigs
  Offshore cables are installed at the sea as they are used for the installation and setting up of oil rigs.

Figure 15: Offshore Wire

The wires designed for offshore units to transmit power are called offshore wires. They transmit high voltage, medium voltage, and low voltage as well. These wires are of many types.

They are made up of different materials, and every material must be halogen-free, low smoke, flame retardant, and possess every quality a wire should have to survive in tough conditions.

These wires are tested carefully and are certified by various classifications so that they are fully secured and protected even in harsh environments.

Offshore wires are resistant to many conditions such as mud, oxidation, fire, flame, acid, and many others that can damage a wire.

Figure 16: Offshore Instrumentation Cable

Offshore instrumentation cables are multiple conductor cables. They convey low energy electrical signals. They are used for monitoring and controlling electrical power systems and their associated processes.

In this cable, copper conductors are used to maintaining high system accuracy and sensitivity.

The conductors used in this cable possess thermoelectric properties, which are the same as that of the thermocouple used for sensing the temperature.  

Figure 17: Different Features of Offshore Cables

Many features constitute a high-quality offshore cable that fulfills international standards. Here are some important features that make a cable durable and reliable.

Flame Retardant

IEC 60332-1 & IEC 60332-3-22 is an EIC standard to check the cable for its flame-retardant characteristic that is used for power cables and several other cables. These tests are taken under very high-temperature.

It is very important for the cable to pass this test to ensure safety on ship vessels and protect them from being at risk. In case of fire exposure, the cable burns at a very slow speed that makes it flame retardant. They are made up of materials that make them retardant to flames, and they are also self-extinguishing.

Zero Halogen

By zero halogen, we mean that the cable is free of halogen, and it does not have chlorine, fluorine, bromine, iodine, and astatine. These chemicals are highly reactive, so halogen-free cables are more protective and durable.

Low Smoke

Another important feature that offshore cables need to have to ensure the safety of life on ships is low smoke emission. The purpose is that in case of fire, the cables should not create smoke. After the test for smoke density, the cable fulfills the IEC 61034-1, 2 standards.

Fire Resistant

Another IEC standard is IEC 60331. It’s a test that will check the resistance offered by an offshore cable in case of a fire situation. This test checks that the cables remain intact under very high temperatures. These are difficult to burn and do not melt easily. Moreover, they prevent the spread of fire.

Mud resistant

To overcome any negative effects that can occur due to corrosion, the offshore cables must be mud-resistant. Saltwater, oil, and acid make the mud destructive for offshore cables. Therefore, a special coating of chemicals is added to protect the cables from corrosion.

Figure 18: Are Offshore Cables Mud Resistant?

Yes, this is a necessary feature an offshore cable must possess. A cable is made mud-resistant by applying a special coating on it. The consequences faced, when exposed to mud, are overcome by this special chemical coating.

To make the cable suitable for installation and functioning in rough and tough conditions, the sheathing compounds play a vital role. They protect the cable from corrosion. Oil, acid, and saltwater are also harmless because of this coating.

Figure 19: Are Offshore Cables Fire Resistant?

Offshore cables must be fire-resistant. They need to keep supplying power even in the event of a fire so that the emergency circuits and signals can work in such situations. These cables are tested on a high-temperature flame for a long period of time.

To pass the test, the cable must withstand the intensity of the temperature without any failure. This is one of the basic features an offshore cable must possess.

Figure 20: Offshore Earth Cables

Earth cable P15 is designed according to NEK 606 and IEC 60092-353 standards. Its voltage rates 0.6/1kV and its maximum operating temperature are 90℃. On offshore units and for fixed installations, earth cable P15 is used.

It’s a tinned copper wire conductor with polyolefin SHF2 insulation. The earth cable is flame retardant, low smoke, mud-resistant, and halogen-free.

What are the Different Verification Processes of an Offshore Cable?

Verifying quality throughout the project is very necessary to minimize the risk of failure. For this reason, the cable has to go through different verification processes. That include:

• QA/QC process definition
• Technical design verification
• Bid evaluations
• Inspection and test plan verification
• Factory auditing
• Manufacturing witnessing
• Installation witnessing
• Witnessing cable system commissioning and many more

DNV GL and ABS verify and certify the land and offshore cables.

The core of the cable consists of layers of fibers and wires. These wires are covered with a protective layer to keep the cable safe from water.

The cables are thicker nearshore, whereas their width minimizes in deepest oceans. The conductors are made of tinned copper or aluminum with a steel core to give the cable its required strength.

 Each conductor consists of several strands and wires twisted together. The offshore wire comprises insulation and material that doesn’t get damaged by the strong vibrations and tough conditions of the marine environment.

The thickness of offshore cable varies. The nominal cross-sectional area ranges from 1 mm2 to 300 mm2. The thickness of the cable depends on the current carrying capacity of the wires and the cores used in those cables.

The greater the current-carrying capacity is, the thicker the cable will be.

Different processes are used to lay offshore cables. Depending on the type of seabed or the onshore conditions, various machines and ways are used to dig the ditch for cables. The cables are laid down with the help of heavy machinery in deep oceans and offshore wind farms.

If the seabed is sandy or muddy, the machines pump the water and make room for cables. Whereas, when the seabed is harder and rocky plowing, and milling methods are used. These two methods cut the rocks and make room for the cables.

Another way of laying the cables is covering. In this method, the seabed or the surface is hard enough to break down. So, the cables are laid and are then covered with sand, rocks, or concrete.

As the offshore power cables are installed in environments with harsh conditions so, they need to be protected. On every wind farm, the cables are installed in numerous kilometres. Underwater cables also need to be protected and safe.

These types of environments tend to damage the cables more. The cables are protected with insulations and coatings (while manufacturing), and while installation, the cables are protected through trenching and burial.

For offshore cable installation, many different environments need to be considered. There are two main fields of application for the offshore cable:

1. Connections over oceans, lakes, or similar

The methods for installing cables on the seabed are:

• Water-jetting

It’s an effective method for laying cables in sandy and muddy seabed. Hydraulic water-jets are used to pump the water that dissolves the seabed. After laying the cables, the bottom material covers it and returns to its original position.

• Milling

It’s a time consuming and expensive way to dig the cables. This method is used in the areas where the seabed is very hard and rocky. It is usually the last option to use.

• Plowing

This is a method that involves the risk of damaging the cable. A plow of 10-30 tons is dragged behind the ship. Digging the ditch and installing the cable are both done in the same operation. This method is suitable for the harder seabed.

• Covering

Sometimes when digging the ditch is not possible, the cables are laid and covered with different materials like concrete, rocks, and sometimes with a mixture of sand and rocks.

2. All Connections Regarding Offshore Wind Farms

In the wind farm, there are many connections between the wind turbines and the different sub-stations in the park. All these need secure cable connections. The cables are installed within the foundation to the bottom of the turbine.

From the foundation, it is connected to the grid on the seabed through a J-tube. When the J-tube ends, the cable uncovers and buries in the seabed and then is drawn to the next wind turbine.

Access to offshore facilities is difficult. Therefore, it is vital for the cables to meet safety standards. The offshore cables are halogen-free to make them toxic-free and safe. They must be resistant to fire, flame, mud, oxidation, oil, acid, low and high temperatures, humidity, and saltwater.

Safety standards are provided by different companies. They give certificates and approvals after checking the cables. From manufacturing to installation, the safety standards need to be fulfilled.

The offshore VFD cables are used for controlling speed. These are the variable-speed drive cables and adjustable-speed drive cables. As per offshore cable standards, these cables must be halogen free, flame retardant, and mud-resistant.

Whereas the offshore instrumentation cables are used for monitoring and controlling electrical power systems. Data is transferred through these cables. These cables also meet all the safety standards an offshore cable must-have.

Figure 21: Importance of Offshore cables in Oil and Gas Industries

Reliable and durable cables are extremely important in the oil and gas industries. Many different types of cables are used in these industries, like polyurethane jacketed cables, polyethylene cables, and armored cables.

The cables used in these industries need to be strong enough to work in harsh environments. The high-temperature environment involves a high-risk factor. For this reason, the cables must be flame and fire-resistant.

The cables must be rugged and chemical resistant. The jacketing and insulation choices must be considered intelligently and carefully to minimize the risk factor.