Glass-Lined Reactor Inspection Guide

Why Glass Lining Condition Is the Single Most Important Factor

A used glass lined reactor can give years of additional service — but only if the borosilicate glass lining is intact. Unlike stainless steel or Hastelloy vessels, a glass-lined vessel with a compromised lining will expose the carbon steel substrate to the process fluid, causing rapid corrosion and contamination. Every inspection must start here.

Visual Inspection of the Glass Lining

Enter through the manway (or request a thorough video walkthrough if an in-person visit is not possible). Look for:

• Chips and spalls — mechanical impact damage, often near the agitator sweep zone or at nozzle edges. Small chips away from critical areas may be acceptable; deep chips that expose the substrate are not.
• Crazing and stress cracks — fine surface cracking in a network pattern. This may indicate thermal shock history or poor original firing. Crazing accelerates lining failure under cyclic temperature swings.
• Discolouration — dark or brown staining on the lining surface may indicate sub-surface corrosion of the base metal, which means the lining has already been breached in those areas.
• Nozzle edges and ports — the highest-stress points. Check all nozzle flanges, the agitator entry port, the bottom outlet, and any thermowell connections.

Spark Testing (Holiday Testing)

Visual inspection alone is insufficient. A used glass reactor should be spark-tested with a high-voltage holiday detector. The probe is passed slowly over the lining surface; any pinhole or thin spot will arc and identify the exact location of the defect. Demand a spark test report — ideally witnessed — before finalising any purchase of a used glass lined reactor.

Holiday testing voltage is typically set to the glass thickness specification (commonly 2,000 V for 1 mm lining, though this varies by OEM). If the seller cannot confirm the lining specification, request the original manufacturing records or contact the OEM with the serial number.

Agitator and Mechanical Seal Inspection

The agitator on a used chemical reactor of the glass-lined type uses a glass-coated impeller and a glass-coated shaft. Inspect for:

• Lining condition on the impeller blades and shaft — same criteria as the vessel
• Shaft runout — excessive runout causes the impeller to contact the vessel wall, which is the primary cause of lining chips in the lower section
• Mechanical seal or packing condition — worn seals allow process contamination and should be budgeted for replacement
• Drive gearbox condition — check oil level, listen for unusual noise, confirm the gear ratio is appropriate for your process viscosity

Jacket and Nozzle Inspection

The jacket on a used high pressure reactor vessel (glass-lined type) is typically designed for steam or cooling water. Check:

• Jacket design pressure and temperature rating on the nameplate — confirm it suits your heat transfer requirements
• Scale or fouling inside the jacket (a borescope or flushing test can reveal this)
• Nozzle flange faces — corrosion or pitting on the carbon steel flanges is common after outdoor storage and may require machining before use

Documents to Request

For a used glass-lined reactor for sale, request the following from the dealer before committing:

• OEM nameplate data sheet (vessel design pressure/temperature, jacket rating, working volume)
• Most recent spark test / holiday test report
• Repair history and any lining repair certificates
• Previous inspection or pressure test certificates
• Photographs of internals, agitator, nozzles, and bottom outlet

If the seller cannot provide at least a spark test report and nameplate data, factor inspection cost into your offer or walk away from that unit.

Sizing Check Before You Buy

Confirm working volume, nozzle schedule (number, size, position), and the agitator entry configuration matches your process requirements. Glass-lined vessels are costly to modify — adding or relocating nozzles requires specialist relining. Buy the closest match to your P&ID from the start.

SIGMA Process Equipment carries used glass lined reactors and a broader range of used reactors for sale including SS 316L and Hastelloy units. All units are inspected and documented before export. Send an RFQ with your capacity and nozzle requirements.