Super Duplex F55 & Alloy 625 Blind Flanges Shipped to Singapore for High-Pressure Sour Service

Haihao Group has completed inspection and shipment of a batch of high-performance blind flanges for a Singapore-based energy project. This order mixes compact blind flanges and API 6A Type 6BX RTJ blind flanges, specially engineered for harsh sour service conditions where standard carbon steel or common duplex parts cannot maintain stable sealing and corrosion resistance.

The super duplex F55 compact blind flange with IX seal ring is built to BS EN ISO 27509, rated 2500# at 16 inch size. This F55 blind flange meets strict NACE MR-01-75 sour requirements, with controlled ferrite content kept between 35% and 60%. Every F55 blind flange passes ASTM G48 corrosion testing and Charpy impact test at -46°C, delivering average 45J and minimum 35J toughness to avoid brittle failure under low-temperature offshore conditions.

Super duplex F55 and Alloy 625 NACE blind flanges, API 6A 6BX RTJ and ISO 27509 compact blind flange shipped to Singapore by Haihao Group

Also included in this consignment is the 11 inch, 10000 PSI API 6A Type 6BX RTJ blind flange made from ASTM A182 F55. The 6BX RTJ design is widely trusted for wellhead and high-pressure piping isolation, and this F55 blind flange retains full NACE compliance for H₂S-containing environments. Unlike conventional flanges, the RTJ groove provides reliable metal-to-metal sealing even under pressure fluctuation common in upstream systems.

For the smaller bore isolation point, we supplied a 2-1/16 inch, 10000 PSI API 6A Type 6BX RTJ blind flange in ASTM B564 UNS N06625, also known as Alloy 625. This Alloy 625 blind flange has passed ASTM G28 corrosion assessment as required by the project specification. All blind flanges in this shipment go through full PT inspection before packing, to catch surface defects that could compromise sour service integrity.

Projects in Singapore offshore and subsea sectors often combine different pressure classes and alloy grades in one piping package. Many suppliers struggle to source and test both super duplex F55 and Alloy 625 blind flanges under one order. Haihao Group supports mixed material, mixed standard flange packages, with full material traceability, third-party corrosion reports and mechanical test documentation ready for client review.

If you are sourcing NACE-compliant blind flanges for sour gas, high-pressure wellhead or seawater cooling lines, get in touch with our engineering team for technical quotation and test schedule alignment.