Pipe Stub Ends
NUMET ALLOYS precision-manufactures premium pipe stub ends designed exclusively for use with Lap Joint Flanges. Engineered to reduce overall material costs and dramatically simplify pipeline installation, our stub ends allow the backing flange to rotate freely, ensuring rapid and flawless bolt-hole alignment in systems requiring frequent dismantling and inspection.
Detailed Technical Specifications
Long Pattern: Conforms to ASME B16.9 (Allows for greater clearance during welding).
Type B: Designed for use with Slip-On Flanges (acts as a backing flange).
Type C: Fabricated from standard pipe with a flared end.
Alloy & Exotic: Duplex UNS S31803, Super Duplex, Inconel, Monel
Carbon Steel: ASTM A234 WPB
Schedules: Sch 5s, Sch 10s, Sch 40s (STD), Sch 80s (XS), Sch 160.
Dimensions (ASME B16.9 & MSS SP-43)
Long pattern stub ends follow ASME B16.9; short pattern stub ends follow MSS SP-43. The lap outside diameter G is the same in both standards — only the overall length F differs, and that is the practical difference between the two patterns. The two are not interchangeable in a fixed spool.
Lap Joint Stub Ends — Length (F) & Lap Diameter (G)
ASME B16.9 / MSS SP-43| SizeNPS | Outside Dia.mm | Lap Dia. Gmm | Lap Dia. Ginch | F Longmm | F Longinch | F Shortmm | F Shortinch |
|---|---|---|---|---|---|---|---|
| 1/2 | 21.3 | 34.9 | 1.375 | 76.2 | 3.00 | 50.8 | 2.00 |
| 3/4 | 26.7 | 42.9 | 1.688 | 76.2 | 3.00 | 50.8 | 2.00 |
| 1 | 33.4 | 50.8 | 2.000 | 101.6 | 4.00 | 50.8 | 2.00 |
| 1-1/4 | 42.2 | 63.5 | 2.500 | 101.6 | 4.00 | 50.8 | 2.00 |
| 1-1/2 | 48.3 | 73.0 | 2.875 | 101.6 | 4.00 | 50.8 | 2.00 |
| 2 | 60.3 | 92.1 | 3.625 | 152.4 | 6.00 | 63.5 | 2.50 |
| 2-1/2 | 73.0 | 104.8 | 4.125 | 152.4 | 6.00 | 63.5 | 2.50 |
| 3 | 88.9 | 127.0 | 5.000 | 152.4 | 6.00 | 63.5 | 2.50 |
| 3-1/2 | 101.6 | 139.7 | 5.500 | 152.4 | 6.00 | 76.2 | 3.00 |
| 4 | 114.3 | 157.2 | 6.188 | 152.4 | 6.00 | 76.2 | 3.00 |
| 5 | 141.3 | 185.7 | 7.313 | 203.2 | 8.00 | 76.2 | 3.00 |
| 6 | 168.3 | 215.9 | 8.500 | 203.2 | 8.00 | 88.9 | 3.50 |
| 8 | 219.1 | 269.9 | 10.625 | 203.2 | 8.00 | 101.6 | 4.00 |
| 10 | 273.1 | 323.9 | 12.750 | 254.0 | 10.00 | 127.0 | 5.00 |
| 12 | 323.9 | 381.0 | 15.000 | 254.0 | 10.00 | 152.4 | 6.00 |
| 14 | 355.6 | 412.8 | 16.250 | 304.8 | 12.00 | 152.4 | 6.00 |
| 16 | 406.4 | 469.9 | 18.500 | 304.8 | 12.00 | 152.4 | 6.00 |
| 18 | 457.2 | 533.4 | 21.000 | 304.8 | 12.00 | 152.4 | 6.00 |
| 20 | 508.0 | 584.2 | 23.000 | 304.8 | 12.00 | 152.4 | 6.00 |
| 22 | 558.8 | 641.0 | 25.250 | 304.8 | 12.00 | Not covered | — |
| 24 | 609.6 | 692.2 | 27.250 | 304.8 | 12.00 | 152.4 | 6.00 |
Long pattern (ASME B16.9) gives a tapered hub and enough barrel length for the backing flange to be drawn back and rotated a full 360° for bolt hole alignment, and is preferred for higher pressure and temperature duty. Short pattern (MSS SP-43) is used where space is tight and with lighter schedules, commonly with a slip-on flange used as the backing flange. MSS SP-43 does not tabulate NPS 22 short pattern.
Lap thickness is not a fixed figure in either standard — it is at least the nominal wall of the matching pipe, so it follows the schedule you specify. Fillet radii are 1/8" to 1/2" depending on size for stub ends used with lap joint flanges, and near square for stub ends backed by slip-on flanges. Dimensions are nominal values from the referenced standard and are shown for reference only; tolerances apply as specified in the standard. Sizes above 24" NB and non-standard combinations are manufactured to order. For certified drawings against your line list, contact our technical team.
Core Advantages
Significant Cost Efficiency
Because only the stub end comes into contact with the fluid, you can utilize a high-grade exotic alloy for the wetted stub end while using a highly economical carbon steel backing flange.
Rapid Bolt Alignment
The accompanying lap joint flange rotates freely over the pipe, eliminating the need to perfectly align bolt holes during the welding process, drastically cutting installation time.
Maintenance Accessibility
Highly recommended for piping systems requiring frequent dismantling for inspection and cleaning, allowing for rapid unbolting without disturbing the welded joint.