Haihao Group Delivers API 6A A350 LF2 CL1 Flanges for Russian Low-Temperature Wellhead Piping
Haihao Group recently completed fabrication and shipment of forged low-temperature flanges for a Russian oilfield client, combining API 6A Type 6B ring-joint units and standard ASME B16.5 blind flanges. All flanges are produced from A350 Gr. LF2 CL1 low-temperature carbon steel, with dedicated heat treatment locked in to satisfy strict Charpy impact requirements at -46°C.
API 6A Type 6B A350 LF2 CL1 ring joint weld neck and blind flanges for Russian low temperature wellhead project
Product Specification Table
| Item | Type | Size & Rating | Face Type | Material | Standard | Special Requirement |
| Weld Neck Flange | WN Flange | 7 1/16″ SCH160 CL5000 | RJ Type 6B | A350 Gr. LF2 CL1 | API 6A 60K | Heat treated, -46°C impact ≥27J avg / ≥22J min |
| Blind Flange | Blind Flange | 7 1/16″ CL5000 | RJ Type 6B | A350 Gr. LF2 CL1 | API 6A 60K | Heat treated, -46°C impact ≥27J avg / ≥22J min |
| Blind Flange | Blind Flange | 3″ CL1500 | RF | A350 Gr. LF2 CL1 | ASME B16.5 | Heat treated, -46°C impact ≥27J avg / ≥22J min |
API 6A A350 LF2 CL1 flanges are specified for this wellhead package because the site faces sustained cold ambient conditions, where ordinary carbon steel would risk brittle cracking under pressure fluctuations. The 7 1/16″ CL5000 RJ Type 6B weld neck and matching blind flange follow API 6A 60K design rules. Type 6B ring joint construction relies on metal ring gaskets rather than face-to-face contact, a proven sealing layout for high-pressure wellhead and Christmas tree assemblies.
We also supplied a 3″ CL1500 RF blind flange to ASME B16.5, made from the same A350 Gr. LF2 CL1 forging stock. Even though it follows a separate dimensional standard, it shares the identical impact acceptance criteria: average 27J, with no individual test piece falling below 22J at -46°C. Keeping consistent material and toughness rules across mixed API and ASME flange sets simplifies site QA and eliminates mismatched performance risks for the EPC team.
Machining tolerances for the RJ groove on the API 6A A350 LF2 CL1 flanges received extra inspection focus. A poorly machined RTJ groove can create leak paths once the system goes under working pressure, so our quality team verifies groove width, depth and surface finish before heat treatment and final marking. Every heat batch is fully traceable, with test records tied directly to each flange’s heat number.
For contractors sourcing mixed-standard wellhead flanges for cold-climate oil and gas projects, matching pressure class, flange face style and low-temperature toughness is far more critical than just matching nominal size. Many suppliers can provide A350 LF2 flanges, but fewer hold stable capability for API 6A Type 6B 5000# RTJ variants with certified sub-zero impact values. Haihao Group supports custom witness testing, third-party inspection and full material documentation packages for these high-risk wellhead components.
If your upcoming wellhead tender requires API 6A A350 LF2 CL1 flanges or ASME B16.5 LTCS blind flanges with documented -46°C Charpy results, our engineering team can review drawings, clarify gasket compatibility and lock in lead times for your project.