Lap Joint flanges are a RING that slips over the back of a Stub End. The Stub End provides the sealing face -- LJ flange rings make bolt hole alignment fast and disassembly easy.
Lap Joint (LJ) flanges are a flat ring with bolt holes and a slightly larger bore than a standard flange. They are designed to slip over the back of a Stub End -- a separate short pipe nipple with a rounded shoulder. The LJ flange ring sits behind the Stub End shoulder, allowing rotation for bolt hole alignment and easy disassembly without disturbing the pipe weld.
IMPORTANT: The Lap Joint flange ring is not the same product as the Stub End itself. They are two separate components that work together as a system. Supply is reviewed per inquiry against standard, pressure class, NPS, grade and facing (Stub End face).
Reviewed against your required standard, pressure class and nominal pipe size.
LJ flange rings commonly produced to ASME B16.5 for flange dimensions. Stub End (butt-weld end) dimensions reference ASME B16.9 for butt-weld fittings. ASTM B363 covers titanium pipe flanges including LJ type.
Class 150 through Class 2500 per ASME B16.5. Pressure rating is determined by the LJ flange ring. The Stub End facing must match the LJ flange ring pressure class.
Industry Standard: NPS ½ through NPS 24 per ASME B16.5 for LJ rings. Stub End sizes follow ASME B16.9 butt-weld fitting range. Custom Manufacturing: larger and non-standard sizes evaluated per request. Actual Supply Availability confirmed per inquiry.
Piping systems that require frequent disassembly for cleaning, inspection or reconfiguration.
Corrosion-resistant connections where future equipment removal is anticipated.
Flexible experimental piping that benefits from adjustable bolt hole alignment.
They are two separate products. The Lap Joint flange ring is a flat bored disc with bolt holes that slips over the pipe. The Stub End is a short pipe nipple with one end flared into a rounded shoulder and the other end butt-welded to the pipe. The LJ flange ring sits behind the Stub End shoulder. Together they form a lap joint connection. One cannot function without the other.
Yes, LJ flange rings can be supplied separately if you already have Stub Ends in stock. We will need the Stub End specification (NPS, schedule, facing, standard) to confirm compatibility.
Please specify whether you need LJ flange rings only or a matched set with Stub Ends. Include standard (e.g., ASME B16.5), pressure class, nominal pipe size (NPS), grade, facing and quantity. We will confirm availability and supply conditions. For drawing-based or custom requirements, you may share your drawings with our sales team by email or WhatsApp after initial contact. Include material grade, dimensions, tolerances, quantity and drawing reference.
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