Blast Pot Pop-Up Valve Maintenance Chart

Q: What is the correct torque for pot lid bolts?

Pot lid bolts: tighten in a star pattern (not sequential) to 25-30 Nm for 100-200L pots, 35-45 Nm for 300-500L pots. Uneven or over-tightening compresses the gasket unevenly, causing blow-by and pressure loss. Under-tightening allows abrasive to escape. Use a calibrated torque wrench — hand-tightening is insufficient and over-tightening damages the gasket seating.

Maintenance Strategy Asset

Official BLAST APEX Internal Seal Reference Guide for shipyard and shop supervisors.

Download PDF Checklist

Pressure Failure Diagnosis

Symptom	Technical Root Cause	Required Action
Slow Pressure Build	Worn Gasket / Debris on Seat	Clean Ring / Replace Gasket
Abrasive Pulsing	Unstable Internal Seal	Check Pop-Up Stem Alignment
Constant Air Leak	Gasket Inversion / Hardening	Mandatory Seal Replacement
No Depressurization	Clogged Exhaust Path	Purge Exhaust Muffler

Seal Stability Logic

The pop-up valve is the heart of pot pressurization. Even a 5% seal leak causes a technical pressure drop at the nozzle, leading to irregular surface profiles and increased abrasive consumption. Moisture in the air line accelerates seal rot; always verify your **Moisture Separator** performance before shift start.

Inspection Intervals

Daily: Visual check for seal leaks
Weekly: Clean gasket & seat ring
Monthly: Measure gasket hardness

Frequently Asked Questions

What causes a blast pot to lose pressure when not blasting?

Pressure loss when pot is pressurized but no blast is occurring: (1) Pop-up valve seat worn or damaged. (2) Gasket failure — replace pot body gasket. (3) Blowdown valve not sealing. (4) Moisture in airline — water corrodes valve seats. Even a 5% pressure leak causes visible blast quality degradation.

How often should pop-up valve gaskets be replaced?

Pop-up valve gaskets (silicone or Buna-N): replace every 400-600 operating hours, or when visible compression set is observed. In coastal environments with moisture in the air, inspect every 200 hours. Keep spare gaskets on hand — a failed gasket stops the job.

What is the correct torque for pot lid bolts?

Pot lid bolts: tighten in a star pattern to 25-30 Nm for 100-200L pots, 35-45 Nm for 300-500L pots. Uneven or over-tightening compresses the gasket unevenly, causing blow-by and pressure loss. Under-tightening allows abrasive to escape. Use a calibrated torque wrench.