Lap Joint Flange & Stub End Assembly
Engineering definition, metallurgical mechanisms, standard testing specifications, and manufacturing guidelines for closed-die forgings up to 50 kg.
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A two-piece flanged connection consisting of a loose, backing ring flange that slips over a pipe and abuts against a forged butt-welded stub end.
Technical Explanation & Metallurgical Principles
Lap joint flanges (LJ) are widely utilized in costly stainless steel, nickel alloy, or titanium piping systems. The expensive alloy is used only for the wetted stub end, while the loose backing flange is forged from economical carbon steel. Furthermore, the free-rotating backing flange allows effortless bolt-hole alignment during installation.
Key Engineering Specifications & Parameters
| Technical Parameter / Metric | Engineering Benchmark / Value |
|---|---|
| Assembly | Loose forged backing flange + ASME B16.9 Type A stub end |
| Advantage | Effortless bolt-hole alignment & major material cost savings |
| Bore Radius | Generous radius machined into inner bore to seat over stub end fillet |
Application at Jayesh Forge (Rajkot Plant)
Supplied with ASTM A105 backing rings and SS 316L/Duplex 2205 forged stub ends strictly up to 50 kg for chemical process lines.
Related Materials, Standards & Products
Related Metallurgical & Testing Terms
Slip-On Flange (SO Flange)
A forged pipe flange designed to slide over the outer diameter of process pipe and be secured using two fillet welds (one internal and one external).
Weld Neck Flange (WN Flange)
The premier high-integrity forged flange configuration featuring a long, tapered circular hub that butt-welds seamlessly to process pipe.
ASME B16.5 Pipe Flanges Standard
The definitive American standard covering pressure-temperature ratings, materials, dimensions, tolerances, marking, and testing for pipe flanges NPS 1/2 through NPS 24.
Questions Regarding Lap Joint Flange & Stub End Assembly
Because the backing flange does not contact process fluid, it can be manufactured in inexpensive carbon steel rather than premium stainless alloy.
Request a Forging Quote with Lap Joint Flange & Stub End Assembly Compliance
Our Rajkot metallurgy desk is ready to review your technical drawings, testing protocols, and delivery schedules for custom closed-die forgings strictly up to 50 kg.