Overview — Why a Checklist Matters
API 6D defines minimum requirements for pipeline valves. A robust design package requires dozens of calculations — from primary membrane stresses to operational torque envelopes. This checklist condenses the essential items into a repeatable workflow that yields a fully traceable submission.
1. Shell & Component Thickness (Clause 5.1.2)
Start by determining the body internal diameter and design pressure. The wall thickness equation (per ASME/API references) uses allowable material stress at design temperature and includes corrosion allowance. In practice:
- Record inside diameter (ID) and design pressure (P).
- Obtain material allowable stress (S) at design temperature.
- Compute required thickness: t = f(P, ID, S, corrosion).
- Check top cover, pup-piece and bonnet with the same inputs.
Tip: Keep the material database centrally managed so allowable stresses update automatically when temperature changes.
2. Seat & Sealing Loads
Seat area determines the pressure load acting on the closure member. Translate pressure into seat force and then calculate required seating preloads (gaskets, springs) and seating torque. Break out:
- Seat outside diameter and contact geometry
- Seat friction coefficient & hydrodynamic effects
- Torque to open/close (break and running torque)
3. Stem Design and MAST
MAST — Maximum Allowable Stem Torque — is a composite safety check combining:
- Stem shear and bending limits
- Bearing friction and bearing contact stress
- Key or slot stress checks (if applicable)
Calculate torsional shear using T/J relations and compare to material shear capacity. Always document assumptions (surface finish, lubrication, bearing clearance).
4. Actuation & Torque Envelope
Split torque into:
- Preload & seating torque
- Hydrodynamic running torque
- Breakout torque (static friction)
- Safety margin and actuator sizing
The deliverable should include a torque vs angle chart and a final recommended actuator torque & gearbox ratio.
5. Joint & Bolting Checks
Check the bolted joints (body/bonnet/top cover) for gasket seating pressure, bolt preload, and shear/bolt stress per the applicable flange/joint standard (often ASME B16.34 references). Provide bolt selection with proof load & factor of safety.
6. Document & Trace
Your package should include an inputs list, calculation steps (with formulas), assumptions, materials table, bolt table, and an outputs summary with PASS/FAIL entries. V-Calc automates this export to Word/Excel and keeps calculation history for audits.
Summary
Use this checklist to validate internal designs and vendor submissions. The difference between a green review and an RFI often comes down to traceability — every calculation must cite inputs, references, and assumptions.
See V-Calc Ball Valve Module Professional Calculation Services