Issuing body
API
Latest edition
8th Edition (2017)
Region
USA, Global
Equipment items
1
Scope
Wafer/lug/flanged/butt-weld check valves Class 125 through 2500.
Key requirements (7)
- Check valves — wafer, lug, double-flanged.
- Sizes: NPS 2 to 48; classes 125, 150, 250, 300, 600.
- Disk types: dual-plate (most common), tilting disc, swing.
- Hydrotest per API 598 — shell & seat.
- Disk closure spring: prevents slamming on flow reversal.
- Wafer style: bolted between flanges, lighter than flanged check.
- Selection: cracking pressure, allowable backpressure, fluid service.