Materials of Construction (MOC)
| Component | Material Specification |
|---|---|
| Body & Bonnet | Stainless Steel (ASTM A351 Gr. CF8/CF8M) |
| Stem / Spindle | SS 304 / SS 316 |
| Seat / Trim | PTFE / RPTFE / Integral |
Technical Specifications
| Parameter | Specification / Standard |
|---|---|
| Manufacturing / Design Standard | ASME B16.34 / API 603 / API 6D |
| Testing Standard | API 598 / EN 12266-1 |
| Pressure Rating | Class 150 to Class 600 / PN16 / PN40 |
Features & Benefits
Extended Bonnet Above Frost Line
Extended neck positions the packing gland and stem seal above the frost line (typically 150--250 mm above the pipeline insulation), preventing ice crystal formation on the packing and ensuring reliable stem seal operation during cryogenic cycling.
Austenitic SS316L Body
Low-carbon austenitic SS316L (CF3M) retains full ductility and impact toughness at -196 deg C, unlike ferritic or martensitic steels that become brittle and fracture in cryogenic service.
Cryogenic Packing Materials
Specially compounded PTFE/RPTFE/UHMWPE V-ring packing sets retain sealing flexibility and compression recovery at -196 deg C, preventing the seal leakage common in standard packing at cryogenic temperatures.
Anti-Blowout Stem
Stem is mechanically retained by the extended bonnet geometry and cannot be ejected under pressure, meeting API 600 / API 602 safety requirements even with the actuator removed.
Fire-Safe Graphite Backup
Graphite braided packing backup ring provides fire-safe stem sealing capability if the primary cryogenic PTFE packing is damaged by fire exposure, meeting API 607 fire-safe requirements.
Directional Flow Marking
Body is clearly cast-marked with flow direction arrow to ensure correct installation (flow under the disc for best shutoff, over the disc for throttling) -- critical for achieving rated leakage class in cryogenic service.