Check Valves · API 594 Model L
Dual Plate Lug Type Check Valve
Lug-bodied twin-disc check valve with the same spring-assisted, non-slam closure as the wafer (H) design, but with threaded lugs that retain the valve on one flange for dead-end maintenance—downstream piping can be removed without dropping the check valve from the line.
- Hermetic body: shaft and stop pin on support—no through-body drillings
- Stop pin prevents disc over-travel
- Scallop lug pattern minimizes weight
- Straight-through bore per API 594
- Bolts engage along full body length for secure lug grip
Wafer vs Lug — When to Specify Lug (Model L)
| Criterion | Wafer (H) | Lug (L) |
|---|---|---|
| Installation | Sandwiched between two flanges; one bolt set | Lugs bolt to one flange; downstream removable |
| Dead-end service | Not suitable | Yes — API 594 lug configuration |
| Maintenance | Must break both flanges | Remove downstream flange only |
| Weight / cost | Lowest | Slightly higher (lug ears, scallop machining) |