Key facts
- Size range: 1/2″ – 24″
- Pressure class: CL150 – CL900
- Face type: RF / FF
- Standard: ASME B16.5
- Connection: Used with a stub end, butt welded
- Material: A105 ring, stub end to suit the line
Lap Joint Flange — Overview
A lap joint flange is a loose ring used with a stub end. The ring can be rotated on the pipe, which makes bolt holes line up easily and lets the flange be re-used when the line is taken apart.
Only the stub end, not the flange, is welded to the pipe. That means the ring can stay in a lower grade while the wetted stub end is made in the grade the service needs.
It is often chosen on stainless and alloy lines, where the expensive material sits in the stub end and the ring stays carbon steel.
Lap Joint Flange Specification
Standard range below. Anything outside it can be quoted on request — send the size, class and quantity you need.
| Standard | ASME B16.5 |
|---|---|
| Size range | 1/2″ to 24″ |
| Pressure class | CL150, 300, 600, 900 |
| Face type | Raised face (RF), flat face (FF) |
| Connection | Loose ring with stub end (butt welded) |
| Material grades | A105 ring; stub end in A182 F304/L, F316/L or alloy |
| Surface | Anti-rust oil or black paint |
| Marking | Size, class, standard and heat number on the rim |
| Packing | Fumigated wooden cases, seaworthy marking |
| Certificate | EN 10204 3.1 mill test certificate |
Material Grades We Stock
Carbon, low-temperature, alloy and stainless grades, all supplied with an EN 10204 3.1 mill test certificate.
Where It Is Used
The three project types that order this item most often.
Oil & Gas
Upstream and midstream lines, wellhead hook-ups and pipeline tie-ins where pressure classes run high.
Water & Desalination
Desalination plants, pumping stations and water transmission lines, in carbon or stainless steel.
Power & Process
Power plants, refineries and chemical process piping where heat resistance and traceability matter.
Send Us Your Specification
Size, standard, class and quantity is all we need. You will have prices, lead time and packing details within one working day.