Submarine pipelines have high transportation efficiency and large transportation capacity, which are hardly affected by environmental conditions, and are widely used in oil and gas fields. Generally, there are two structural types of submarine oil transmission and insulation pipelines: pipe-in-pipe double-layer steel pipe structure and concrete weight coating single-layer steel pipe structure (concrete weight coating pipe or CWC pipe).

• Pipe-in-pipe double-layer steel pipe structure
  The steel inner pipe with pipe-in-pipe double-layer steel pipe structure is used to transport oil, gas and other media, while the steel outer pipe provides reliable protection and weighting for the thermal insulation layer. There is an anticorrosive layer and polyurethane foam thermal insulation material layer between the steel inner and outer pipes.
• Concrete weight coating single-layer steel pipe structure (concrete weight coating pipe or CWC pipe)
  concrete weight coating single-layer steel pipe structure (concrete weight coating pipe or CWC pipe) is composed of steel pipe, anti-corrosion layer, polyurethane foam insulation layer, polyethylene protective layer and concrete weighted layer from inside to outside. Using this single-layer steel pipe structure and replacing the outer steel pipe of double-layer pipe structure with concrete weighted layer can not only save 2/3 of steel, reduce the workload of pipe laying and welding, but also eliminate the corrosion and anti-corrosion of outer pipe, thus improving pipe laying efficiency and reducing pipeline cost. Therefore, in shallow waters, the concrete weight coating single-layer steel pipe structure (concrete weight coating pipe or CWC pipe) has a good development and application.

TechSolutions have a pipe production base in Wuxi, Jiangsu Province, China, which are fabricating concrete weight coating (CWC) pipe for several years. We can supply various types of concrete weight coating (CWC) pipes.

Concrete weight coating pipe can be designed into steel pipe with concrete coating layer of different types, different outer diameters, different weights, different thicknesses and different densities according to different submarine environments, and can also be processed with anti-corrosion coatings and insulating coatings.

TechSolutions provides different types of concrete weight coating (CWC) pipes as follows:

• Pipe diameter: 152.4 mm – 1524 mm (6” – 60”)
• Pipe thickness: SCH 20, SCH 40, SCH 80, etc.
• Applicable standard (steel pipe): API 5L Grade B to Grade 80, ISO 3183 Grade L245 to L555, GB, etc.
• Pipe length: Up to 12 meters
• Concrete density: 1.8 ton/ m3 – 3.5 ton/ m3 (Concrete formulation can be tailor-made to any specified density as per client requirement)
• Concrete thickness: 25 mm – 200 mm
• Concrete compressive strength: Up to 50 Mpa

Key Features of Concrete Weight Coating (CWC) Pipes

Concrete weight coating pipe consist of cement, water, aggregates and reinforcement materials, the advantage of CWC pipe is to fix the pipeline stably performances and provides effective mechanical protection. Compared with other insulation type like pipe-in-pipe double-layer steel pipe structure, CWC pipe is more efficient in saving cost, easy the pipeline installation and convenient the operations.

Concrete Weight Coating (CWC) Pipe Manufacturing Process

1. Before coating the concrete, the steel pipe normally shall be coated with an FBE coating.
2. Calculate the proportioned quantity of cement, iron ore, sand, and granite aggregate, they mixed them together to create a specified density required; During concrete buildup processes, control the steel wire mesh position will get a certain wire depth with the coating; Weighing each joint to verify if they meet the requirements of the project; Clean the concrete coated pipe ends and trimmed the excess wire. After curing in 30 days, the material could be ready for delivery.
3. The concrete coating can be done via machine or form-applied coating and can be prepared for any thickness at the job site. The external concrete coating is designed to protect the isolation coating of pipe from mechanical damage during repair, upgrading, construction, and operation. The concrete coating method is advanced and the best method of protecting pipelines which comply with regulatory procedures

Benefits for Cients of TechSolutions Concrete Weight Coating (CWC) Pipes

• Mechanical protection and negative buoyancy
• Anti-corrosion protection
• Excellent Compatibility
• Long-term adhesion to steel
• Well suited to reel laying methods
• High resistance to cathodic disbondment

Applicable Standards for Concrete Weight Coating Pipes or CWC PipeS of Submarine Pipelines Projects

• SY/T 10037- 2002 Code for submarine pipeline system (replacing SY/T 4804- 1992)
• GB/T 31316 General principles of cathodic protection in sea water
• ISO12473 General principles of cathodic protection in sea water
• ISO 11130:2017 Corrosion of metals and alloys — Alternate immersion test in salt solution
• ISO 9227:2017 Corrosion tests in artificial atmospheres — Salt spray tests
• ISO 21062:2020 Corrosion of metals and alloys — Determination of the corrosion rates of embedded steel reinforcement in concrete exposed to simulated marine environments
• DNV-OS-F101: Submarine Pipeline Systems – SAWL 245, SAWL290, SAWL 320, SAWL 360, SAWL 415, SAWL 450, SAWL 485, SAWL 555
• ISO 21809-5:2010: Petroleum and natural gas industries – External coatings for buried or submerged pipelines used in pipeline transportation systems – Part 5: External concrete coatings
• ASTM C42 Standard Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete
• ASTM C87 Test Methods for Effect of Impurities in Fine Aggregate on Strength of Mortar BS 1881 Methods of Testing Concrete
• ASTM C642 Standard Test Method for Specific Gravity, Absorption, and Voids in Hardened Concrete
• BS 3148 Test Methods for Water for Making Concrete
• BS 4449 Material Specification for Carbon Steel Bars for Concrete Reinforcement
• BS 4482 Hard Drawn Mild Steel Wire for the Reinforcement of Concrete
• BS 4483 Specification for Steel Fabric for the Reinforcement of Concrete
• ISO 4012 Test Specimen of Determination of Compressive Strength

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152.4 mm – 1,524 mm (6” – 60”)

SCH 20, SCH 40, SCH 80, etc.

API 5L Grade B to Grade 80, ISO 3183 Grade L245 to L555, GB, etc.

Up to 12 meters

1.8 ton/ m3 – 3.5 ton/ m3
(Concrete formulation can be tailor-made to any specified density as per client requirement)

25 mm – 200 mm

Up to 50 Mpa

Note: Above data can be adapted and may vary according to client’s requirement.