Preventing Cracking Pressure Surprises in Swing Check Valves

Practical calculations covering disc lift, hinge-pin strength, and joint integrity to avoid operational surprises during commissioning.

Swing check valve diagram

Understanding cracking pressure

The cracking pressure is the differential pressure needed to overcome seat friction, disc weight and hinge/guide resistance and allow the disc to open. Accurately predicting it ensures reliable start-up and reduces waterhammer risks.

Hinge-pin & disc loading

Design hinge pins for combined shear and bending. Include a bearing contact check and fatigue allowance if the valve cycles often.

Joint & bolting integrity

At high cracking pressures, body/cover joint integrity becomes critical — verify bolt preload and gasket seating to avoid leaks or joint failure during testing.

Field checklist

  1. Confirm disc weight and hinge offset
  2. Verify seat friction (on site if possible)
  3. Estimate cracking pressure with safety margin
  4. Document expected vs measured cracking pressure at FAT

Learn more

Use V-Calc's swing check module for automated cracking pressure estimations and hinge-pin checks. Open V-Calc