GTI offers re-glass services on all forms of glass lined steel especially to repair glass lined reactor accessories. We are accustomed to receiving a call from a customer explaining his plant is down and nobody has this in stock. Normally we do not have time to fabricate a new piece nor re-glass this unit. Do you have an option for us?
Often glasslined process equipment is removed from service or replaced at the discovery of a small area on an otherwise excellent piece. Many times the item is critical for production or a replacement cannot be reglassed or fabricated in a timely manner to meet production schedules. Tantalum, Teflon and organic compounds may considered although the life of the repair may be short and can result in increased damage.
Over the years GTI has invested significant time in furthering the application of local repairs utilizing several furnace configurations. The local repair provides a viable cost effective permanent repair returning the item to “like new” condition. It has become a rarity when we can’t repair an item using a local glass repair procedure.
Local glass repairs save significant time and effort. A complete re-glass process requires significant cycles of application and firing which require labor and time. A local glass repair reduces expense by limiting re-glassing to the affected area. Consequently fewer spray and fire cycles are required to achieve the required thickness.
An item that has been exposed to chemistry that will erode the surface of the glass can have additional coats of glass fused to the existing cover coat. Vitreous enamel coating on steel can be applied over a ground coat. This ground coat is fired at a much higher temperature than the cover coat. The original cover coat is applied in several coats to achieve the required thickness which is governed partially by coefficient of expansion characteristics.
Each coat consists of powdered glass applied in a slip form through a spray gun to a tightly controlled thickness standard. The coat is allowed to dry before the firing process. The firing process requires a detailed procedure to elevate the steel substrate, existing glass coat, and the freshly applied slip evenly through 7 steps controlling time and temperature to fuse all glass layers as 1 coating. Among the steps is a preliminary heat to 900F slowly to prevent thermal shock. The second step is a rapid 200F temperature rise called the bubble squeeze, in this phase we want to reduce bubbles in the glass. The next step is a slow heat from 1100F to 1250F to minimize any additional bubbles and allow a consistent temperature soak throughout the piece before progressing to the next step. The final heat step is to bring the glass to its 1475F melt point for all the glass creating a full fuse of the glass into 1 homogenous layer. The balance of the procedure provides steps for cooling the glass to achieve additional characteristics.
GTI regularly performs local repairs on Cryo-Lock™ shafts, hubs and other glass lined accessories. This process returns the accessory to new condition while saving time and a great deal of money. Key elements are; the right glass formulation, the right equipment, trained personnel plus the motivation to provide a customer with an economical and durable repair option.
Production of aggressive chemicals can erode glass. Normal glass thickness of 30 mils deteriorates leaving you with the choice to repair or replace your equipment. New glass can be applied with certainty. An incremental application process of spraying glass followed by carefully controlled firing will cause new glass to merge with the existing surface. This results in uniform coverage often with a different color of glass. The expert technicians at GTI can return an accessory with 48 to 55 mils of serviceable glass lined protection.
The following examples show how we use this capability to modify a shaft without resurfacing the entire piece:
- to replace a failed or unusable drive end
- to convert an agitator or shaft to a new style drive
- to add level lines
- to repair damaged flange faces on column sections
- to repair damage on a shaft or impeller blade
- to repair a damaged thermowell
A Cryo-Lock shaft re-glassed at the drive end:
In this case the drive end was replaced and local glass repair technique was used to create level indicators:
A baffle is repaired at GTI using the local glass repair technique:
Local glass repair to a column:
Using the local glass repair technique we replaced the drive end on this agitator while avoiding the labor and expense of re-surfacing the otherwise excellent piece: