Specification and Scope of the API STD 598 Standard
The API STD 598 standard regulates inspection protocols, supplementary checks, and hydraulic testing for valves, including gate valves, ball valves, plug valves, and butterfly valves. Technical requirements cover all types of seat seals, including resilient (soft), metal, and composite designs.
According to EV Group China standards, the category of resilient elements includes:
- Soft seat seals, including elements with solid or semi-solid lubricants (e.g., lubricated plug valves).
- Hybrid seats combining metal and soft components (specifically, laminated ring seals).
- Any other seat materials whose leakage rates meet the limits specified in Table 5 of this standard.
API STD 598 is a supplementary industry standard to the base API specifications. Upon agreement between the customer and the EV Group China engineering department, these testing methods may be applied to other types of pipeline valves. Ordering parameters requiring clarification are listed in Appendix A.
Test protocols include mandatory Factory Acceptance Tests (FAT), as well as additional inspections conducted according to the buyer’s specifications at production sites. Procedures may be performed either at the manufacturer’s facility or at a location approved by both parties.
List of Mandatory Tests and Inspections
In accordance with API STD 598 regulations, valves undergo the following control stages:
- Shell test.
- Backseat test.
- Low-pressure closure tightness test.
- High-pressure closure tightness test.
- High-pressure Double Block and Bleed (DBB) closure tightness test.
- Visual and dimensional inspection (VDI) of cast body parts.
- High-pressure pneumatic shell test.