Stub ends (lap joint stub ends) – the companion fitting to lap joint flanges. Butt weld ends per ASME B16.9, NPS 1/2″ – 24″, SCH5S – SCH80, carbon steel and stainless.
What Is a Stub End?
A stub end is a short pipe piece with one beveled butt-weld end and one flared (lap) end. Welded to the pipe, its flared face backs a loose lap joint flange that rotates freely on the pipe. This pair replaces an expensive flange wherever bolt alignment, rotation or material economy matters – the rotating flange can be cheap carbon steel even when the pipe is expensive stainless, and lining up bolt holes takes seconds.
Specifications
| Item | Range |
|---|---|
| Size | NPS 1/2″ – 24″ (DN15 – DN600) |
| Wall | SCH5S, 10S, 40S, 80S (stainless); SCH10-SCH80 (carbon) |
| Standard | ASME B16.9 (long pattern), MSS SP-43 (short pattern stainless) |
| Types | Type A (lap thickness = pipe wall), Type B (reinforced lap) |
| Materials | A234 WPB, A403 WP304/304L/316/316L |
| Lap face | FF or RF, gasket surface finish machined |
Type A vs Type B
Type A – the whole stub (including the lap) is one thickness; standard for general service. Type B – the lap is thicker than the pipe wall, used when the lap face takes gasket stress on thinner-wall pipe or where frequent re-torquing is expected. The matching lap joint flange is sized by the lap diameter – tell us the stub type so the flange bore matches.
Where Stub Ends Are Used
Stainless and alloy lines where flanges would be the costliest component (the lap joint ring can be carbon steel galvanized); lines requiring frequent dismantling – filter skids, temporary equipment; alignment-critical connections to equipment nozzles; and glass-lined or lined pipe systems where the flange must not rotate against the lining.
FAQs
Do stub ends come with the flange? They are ordered separately, but we quote them as a matched pair – stub end plus correctly-bored lap joint flange – so the lap diameters agree.
Long or short pattern? Long pattern (B16.9) is the carbon steel default; short pattern (SP-43) is common in stainless to save material. Confirm with your line spec. Ask us.
More: Flange Types Guide · What Is a Flange? · Schedule Chart · NPS vs DN · All Articles
Specify the stub end and backing flange together
Include the backing flange and gasket requirements when requesting a stub end. The pipe connection and the lap geometry must both be defined for the assembled joint.
| Order detail | What to provide |
|---|---|
| Pipe end | Specify nominal size, outside diameter, weld-end wall thickness and end preparation. |
| Pattern and length | Identify the required pattern, overall length and dimensional standard, or provide a controlled drawing. |
| Lap geometry | Show lap diameter, thickness, radius and sealing-face requirements where these are controlled by the project. |
| Materials and scope | List stub-end and backing-flange materials separately and state whether the inquiry includes the flange, gasket and bolting. |
Before you order
Review the backing flange fit and the sealing arrangement before ordering replacement parts. Confirm that the proposed material combination is acceptable for the service and project specification.
Does a stub end quotation automatically include the backing flange?
Specify the required scope explicitly. List the stub ends, backing flanges, gaskets and bolting as separate items or identify the required complete assembly.
Related products and references
Request a quotation — send your specification, quantity and drawing to info@pipingfitting.com.