Steel & Metal Product Catalog | Xin Wugang Steel

Project Overview

An offshore oil and gas production platform in the Gulf of Mexico underwent a retrofit project to upgrade its seawater ballast, process cooling, and supporting structural systems.The platform operated in a demanding marine environment where seawater pipelines were continuously exposed to high chloride concentrations. These conditions placed strict requirements on corrosion resistance, material reliability, and long-term operating performance.
To meet the project owner’s DNV offshore engineering requirements, the material supply package included 2205 duplex stainless steel seamless pipes, 2507 super duplex stainless steel pipes, Alloy 825 nickel alloy pipes, and DH36 marine structural steel plates and angle sections.
The 2205 duplex stainless steel pipes were specified for the main seawater ballast and process piping applications, while 2507 super duplex stainless steel and Alloy 825 nickel alloy materials were selected for locations with more demanding corrosion conditions.
DH36 marine structural steel was also supplied for the platform’s structural modification, reinforcement, and supporting components.
The project required coordinated material procurement, quality inspection, and complete documentation to support the offshore platform retrofit.

Project Requirements

The offshore platform retrofit required steel and alloy materials capable of meeting demanding marine operating conditions.
Seawater ballast and process cooling pipelines were exposed to chloride-rich seawater, creating potential risks of localized corrosion and long-term material degradation.

The customer established the following requirements:

•  DNV offshore compliance: Marine structural steel supplied to the project’s DNV classification and inspection requirements.
•  Chloride corrosion resistance: 2205 duplex stainless steel pipes for seawater ballast and process piping.
•  Enhanced corrosion protection: 2507 super duplex stainless steel pipes for high-chloride sampling lines.
•  Nickel alloy materials: Alloy 825 pipes for highly corrosive process branch lines.
•  Structural modification: DH36 marine steel plates and angle sections for platform reinforcement and supporting structures.
•  Quality verification: Solution heat treatment and non-destructive testing of duplex stainless steel and nickel alloy materials.
• Complete documentation: Material certificates and inspection records supporting project acceptance.

The material supplier needed to integrate corrosion-resistant piping materials and marine structural steel into a coordinated supply package.

Steel & Alloy Material Supply Details

A total of 211 metric tons of marine structural steel, duplex stainless steel, and nickel alloy piping materials were supplied for the project.

Material	Specification	Grade / Standard	Quantity
Marine Structural Steel Plate	16 × 2000 × 12000 mm	DH36 / DNV	86 Tons
Duplex Stainless Steel Seamless Pipe	OD 114.3 × 6.02 mm / OD 168.3 × 7.11 mm	2205 / ASTM A790	54 Tons
Super Duplex Stainless Steel Pipe	OD 76.1 × 4.8 mm	2507 / ASTM A790	18 Tons
Nickel Alloy Seamless Pipe	OD 60.3 × 4.2 mm	Alloy 825 / ASTM B423	11 Tons
Marine Angle Steel	∠120 × 12 mm, 12 m fixed length	DH36 / DNV	42 Tons

The supply package covered both corrosion-resistant process piping and steel materials for offshore structural modification.

Project Supply Solution

1. 2205 Duplex Stainless Steel Pipes for Seawater Ballast Systems
Seawater ballast and process cooling pipelines were key areas of the offshore platform retrofit.
These systems operated in direct contact with chloride-rich seawater, creating demanding requirements for piping material corrosion resistance.
For the main seawater pipelines, 54 tons of 2205 duplex stainless steel seamless pipes were supplied according to ASTM A790.
The specified dimensions included:

• OD 114.3 × 6.02 mm
• OD 168.3 × 7.11 mm

2205 duplex stainless steel combines austenitic and ferritic microstructures, providing high mechanical strength and improved resistance to chloride-induced stress corrosion cracking compared with conventional austenitic stainless steel grades.
The material was selected to support the operating requirements of the platform’s seawater-related piping systems.

2. 2507 Super Duplex Stainless Steel for High-Chloride Sampling Lines
Certain sampling lines on the platform faced more demanding chloride exposure conditions.
For these locations, the project specified 2507 super duplex stainless steel pipes with dimensions of OD 76.1 × 4.8 mm.
A total of 18 tons was supplied to ASTM A790 specifications.
2507 super duplex stainless steel offers enhanced resistance to pitting corrosion, crevice corrosion, and chloride stress corrosion cracking.
Its high chromium, molybdenum, and nitrogen alloy content makes it suitable for selected aggressive marine and offshore process applications.
The material selection provided an enhanced corrosion-resistant solution for the platform’s high-chloride sampling pipeline requirements.

3. Alloy 825 Nickel Alloy Pipes for Highly Corrosive Process Lines
In addition to duplex stainless steel piping, the offshore platform required nickel alloy materials for localized highly corrosive process applications.
The supply package included 11 tons of Alloy 825 nickel alloy seamless pipes, manufactured to ASTM B423 specifications.
The specified pipe dimension was OD 60.3 × 4.2 mm.
Alloy 825 is a nickel-iron-chromium alloy containing molybdenum and copper, developed for resistance to a range of corrosive environments.
For this project, Alloy 825 was specified for highly corrosive process branch lines where enhanced corrosion resistance was required.
The use of nickel alloy piping complemented the duplex stainless steel systems, enabling material selection according to different service conditions.

4. DH36 Marine Steel Plates for Platform Structural Retrofit
The platform modification also required marine structural steel materials for supporting structures and reinforcement work.
A total of 86 tons of DH36 steel plates was supplied with dimensions of 16 × 2000 × 12000 mm.
The materials were specified according to the project’s DNV requirements.
DH36 is a high-strength marine structural steel grade used in shipbuilding and offshore structural applications.
Its mechanical properties and impact toughness characteristics make it suitable for structural components subject to demanding marine service requirements when properly specified and qualified.
The supplied plates supported the platform’s structural modification work.

5. DH36 Marine Angle Steel for Railings and Reinforcement Supports
In addition to steel plates, the project required 42 tons of DH36 marine angle steel for platform railings and reinforcement brackets.
The supplied angle sections featured:

•  Size: ∠120 × 12 mm
•  Fixed length: 12 meters
•  Grade: DH36
• Classification requirements: DNV

The angle steel provided materials for auxiliary platform structures and reinforcement components.
By supplying marine steel plates and angle sections together, the procurement package supported coordinated structural material delivery for the retrofit project.

Quality Control and Inspection

Quality verification was a critical part of the project, particularly for duplex stainless steel and nickel alloy piping used in aggressive offshore environments.
The supplied duplex stainless steel and nickel alloy materials underwent solution heat treatment and non-destructive testing according to the project requirements.

Solution Heat Treatment
Duplex stainless steel and nickel alloy materials underwent the specified solution heat treatment processes to support their required material properties.

Non-Destructive Testing
Required non-destructive inspections were completed to verify material quality and compliance with project acceptance requirements.

DNV Offshore Requirements
The supplied materials met the specified project requirements for offshore corrosion service and marine structural applications.

Complete Material Documentation
The required material and inspection records were provided to support project verification and final acceptance.

The inspection and documentation process supported reliable material acceptance for the offshore platform retrofit.

Project Results

The offshore platform retrofit project was successfully completed with the required steel and corrosion-resistant alloy materials supplied and accepted.
The 2205 duplex stainless steel, 2507 super duplex stainless steel, and Alloy 825 nickel alloy materials completed the specified solution heat treatment and non-destructive testing requirements.
The material inspection results met the project’s DNV offshore corrosion service requirements, while the complete documentation package supported the project acceptance process.
The structural steel and corrosion-resistant piping materials were successfully integrated into the platform modification work.
Following the retrofit, the platform’s seawater piping systems demonstrated stable operation and resistance to chloride-related corrosion under the reported service conditions.
The project demonstrated an integrated material supply solution for offshore facilities operating in demanding seawater environments.

Project Value Delivered

The project highlighted the importance of application-specific material selection and quality assurance for offshore platform modifications.

•  Corrosion-resistant piping: 2205 duplex stainless steel provided the specified material solution for seawater ballast and process cooling systems.
• High-chloride applications: 2507 super duplex stainless steel supported sampling lines exposed to more aggressive chloride conditions.
• Nickel alloy capability: Alloy 825 pipes addressed localized highly corrosive process piping requirements.
• Marine structural materials: DH36 plates and angle sections supported platform reinforcement and modifications.
• Quality assurance: Solution heat treatment, non-destructive testing, and complete documentation supported material acceptance.
• Successful retrofit completion: Coordinated delivery supported the platform modification and stable operation of the upgraded seawater piping systems.

Corrosion-Resistant Steel & Alloy Solutions for Offshore Engineering

Offshore oil and gas platforms require carefully selected materials to withstand seawater exposure, chloride-rich environments, and demanding operational conditions.
From marine structural components to seawater cooling systems and process piping, material selection plays an important role in long-term equipment reliability.
Our project-based supply solutions support offshore EPC contractors, marine engineering companies, platform operators, and industrial equipment manufacturers.
Our material supply capabilities include:

•  DH36 and other marine structural steel plates
•  Marine steel angles and structural profiles
•  2205 duplex stainless steel pipes
• 2507 super duplex stainless steel pipes
•  Alloy 825 nickel alloy pipes
•  Corrosion-resistant steel and alloy piping materials
•  Customized project procurement and inspection documentation support

Looking for corrosion-resistant materials for an offshore platform project?

Contact our team with your required material grades, pipe dimensions, applicable standards, corrosion service conditions, and inspection specifications to discuss a suitable project supply solution.