Haihao Group Delivers Custom ASTM A350 LF2 RTJ Flanges for an Indonesia Offshore Project
Haihao Group recently completed the production and shipment of a large batch of custom-engineered flange products for an industrial customer in Indonesia. The project involved multiple types of high-pressure ring-type joint (RTJ) flanges manufactured according to customer drawings and stringent inspection requirements.
The order included RTJ welding neck flanges, RTJ long welding neck flanges, blind flanges, hub flanges, and several special FVC-series flange designs. All products were manufactured from ASTM A350 LF2 flange forgings and supplied with comprehensive testing and certification documentation.
Project Overview
This shipment covered a wide range of customized flange configurations, including:
RTJ Long Welding Neck Flanges (RTJLWN)
- 12″ Class 900 RTJ FVC-V1
- 3″ Class 900 RTJ FVC-V3
- Multiple 2″ Class 1500 RTJ FVC-F designs
- Custom K-series and N-series flanges according to drawings
RTJ Welding Neck Flanges (RTJWN)
- 4″ Class 900 RTJ Welding Neck Flanges
- 30″ Class 900 Special RTJ Flange
Other Components
- 4″ Hub Flange
- 2″ Class 1500 RTJ Blind Flange
Every ASTM A350 LF2 flange was produced strictly according to customer-approved engineering drawings, ensuring dimensional accuracy and compatibility with the final equipment assembly.
Custom ASTM A350 LF2 flanges manufactured by Haihao Group
Designed for Low-Temperature Service
The selected material, ASTM A350 LF2 Class 1, is widely used for pressure-containing components operating in low-temperature environments.
Compared with standard carbon steel flanges, ASTM A350 LF2 flange products provide:
- Excellent toughness at low temperatures
- Good weldability
- Reliable pressure-retaining performance
- Enhanced resistance to brittle fracture
- Compliance with offshore and marine engineering requirements
For this project, all materials successfully met the required impact testing conditions at -46°C.
Low-Temperature Impact Testing Requirements
To ensure performance under severe operating conditions, the customer specified low-temperature Charpy V-notch testing.
The acceptance criteria included:
- Minimum average absorbed energy: 27 Joules
- Minimum single value: 20 Joules
- Test temperature: -46°C
Test specimens were prepared from dedicated qualification blocks to verify material toughness and compliance with project specifications.
Post Weld Heat Treatment Verification
One of the most critical requirements for this project involved post weld heat treatment (PWHT) qualification testing.
Test coupons were prepared according to customer specifications and subjected to PWHT under controlled conditions.
The heat treatment procedure included:
- Heating rate ≤ 64°C per hour
- Holding temperature between 595°C and 625°C
- Holding time of 2 hours and 30 minutes
- Cooling rate ≤ 80°C per hour
Following PWHT, additional inspections and mechanical testing were performed to verify that the ASTM A350 LF2 flange material maintained the required mechanical properties.
ABS 3.2 Certification and Inspection
All products were supplied with ABS 3.2 certification, a requirement commonly specified for offshore, marine, and critical industrial projects.
To achieve compliance, Haihao Group prepared dedicated test blocks and coordinated the required third-party witness inspections.
Inspection scope included:
Ultrasonic Testing (UT)
Ultrasonic examination was conducted to detect internal discontinuities within the forged components.
Magnetic Particle Testing (MT) or Penetrant Testing (PT)
Surface examinations were performed to identify possible surface defects and ensure flange integrity.
Dimensional Inspection
Critical dimensions such as neck length, hub thickness, saddle thickness, and RTJ groove geometry were carefully verified.
Material Traceability
Each flange was fully traceable from raw material procurement through final inspection and shipment.
Why RTJ Flanges Are Preferred for High-Pressure Applications
RTJ flanges are specifically designed for demanding services where leak prevention is essential.
Key advantages include:
- Superior sealing performance
- Reliable operation under high pressure
- Excellent resistance to vibration
- Suitable for offshore and energy facilities
- Reduced leakage risk compared with conventional raised-face flanges
The combination of RTJ design and ASTM A350 LF2 flange material makes these products particularly suitable for LNG facilities, offshore platforms, refineries, and petrochemical plants.
Haihao Group’s Capability in Custom Forged Flanges
This Indonesia project demonstrates Haihao Group’s ability to manufacture highly customized flange products requiring:
- Complex engineering drawings
- ABS certification
- Low-temperature impact testing
- PWHT qualification testing
- UT, MT, and PT inspections
- Special RTJ configurations
- Large-diameter forged flanges
With extensive experience in critical-service piping components, Haihao Group continues to support customers worldwide with reliable manufacturing solutions for offshore, marine, oil & gas, and industrial applications.
Need Custom ASTM A350 LF2 Flanges?
If your project requires engineered RTJ flanges, ABS-certified forgings, low-temperature pressure components, or drawing-based manufacturing, Haihao Group can provide complete production and inspection support.
Contact our technical team today for quotations, engineering assistance, and customized flange solutions tailored to your project requirements.