Introducing the GROTH 12-TH Thief Hatch

Storage Tank- Gauge Hatches


The GROTH Model 12-TH Thief Hatch was designed to out perform the competition, with industry leading high flow rates and precision tolerances to provide a superior sealing performance.

Storage Tank- Gauge Hatches


The leakage is less than 1 SCFH of air @ 90% of the set pressure.

Why Thief Hatches are required?

Because we always make sure that:

Protect your tanks

Protects tank from overpressure/vacuum when sized properly.

Meet industry compliance

Minimizes evaporation emissions.

Features & Benefits

Superior Sealing Performance

  • Precision machining and manufacturing to accomplish superior sealing.
  • Ultra-tight sealing reduces product leakage and fugitive emissions.
  • Active envelope pressure gasket that expands around the base to increase seal
Storage Tank- Gauge Hatches
Storage Tank- Gauge Hatches

Industry Leading Flow Rates

  • Higher flow capacity to protect from excessive pressure build up.
  • Precision machining and manufacturing to accomplish high flow rates

Direct Replacement & Easy Maintenance

  • Direct replacement for any standard round API 12 thief hatch.
  • Designed for easy maintenance, thus reducing downtime and lowering operational cost.
  • Incorporates a mechanical lock system to be used with a pad lock or lock out bar
Storage Tank- Gauge Hatches

Technical Details

  • Size: 8” (200 mm)
  • Bolting: API 12
  • Available Pressure Settings: 4, 6, 8, 12, 16, 24 & 32 osig
  • Available Vacuum Settings: 0.4, 0.9 & 3.5 osig
  • Leak Rate: 1 SCFH air @ 90% of set pressure
  • Materials of Construction: Casting: Aluminum (Non-Sparking), Envelope Gasket: HNBR, FKM, or Fluorosilicone, Vacuum Diaphragm: HNBR, FKM, Fluorosilicone, or Fluoropolymer
  • Optional: Polyester/PTFE Coating
  • Accessories: Flange (base) Gasket, Mounting Kit


Flow Curves