Step-by-Step Guide: How to Repair and Protect High-Temperature Process Vessels
Process vessels play a vital role in a variety of industries, particularly within the oil & gas and petrochemical sectors. These vessels often contain high-temperature media within highly corrosive environments. Such challenging conditions lead to issues such as erosion, corrosion and chemical attack, which are exacerbated further by elevated temperatures and entrained solids.
Such issues can lead to several costly implications including:
• Lost production
• Unplanned shutdowns
• Shorter service life
• Frequent maintenance expenses
• Poor performance
• Un-safe operation of the vessel
However, traditional repair methods can be both time-consuming and costly, often necessitating dangerous hot work. Belzona’s high-temperature epoxy applications for industrial equipment repair simplify maintenance procedures and extend the life of valuable assets.
In this video, we will show you how to repair and protect process vessels using innovative Belzona solutions. We will demonstrate the application process for pit filling with Belzona 1511 and lining with Belzona 1593, however other materials can be specified depending on the operating conditions.
Before a high-temperature process vessel can be lined, it is crucial to carry out a pitting repair with an epoxy paste. Belzona 1511 (Super HT-Metal) is an ideal choice as it is a heat-resistant epoxy paste, specifically designed to repair and rebuild areas damaged by corrosion or erosion at elevated temperatures. It can withstand immersed service environments up to 150°C (302°F) and is dry heat resistant up to 210°C (410°F). Its excellent chemical resistance and durability make it well-suited to lining high-temperature process vessels.
STEP ONE:
Surface Preparation Prior to Application of Belzona 1511 (Super HT-Metal)
To ensure a successful pitting repair application, proper substrate preparation is essential. First, the surface must be grit blasted to Swedish Standard Sa2½ (near white metal finish) with a minimum profile of 3 mils (75 microns). It is also vital to ensure the soluble salt contamination levels are below 20mg/m2 (2ug/cm2).
Throughout the preparation and application process, environmental conditions should also adhere to those laid out in the Instructions for Use (IFU). This preparation ensures the Belzona 1511 (Super HT-Metal) will adhere strongly to the vessel’s surface.
Prepare the surface to Swedish Standard Sa2½
Mix the base and solidifier of high-temperature epoxy paste to achieve a uniform colour
STEP TWO:
Mixing the Heat-Resistant Epoxy Paste
Next, measure out the heat-resistant epoxy paste, Belzona 1511 (Super HT-Metal), at a metric ratio of five parts base to one part solidifier. Mix the two parts thoroughly, using a figure of eight motion, to achieve a uniform streak-free grey colour.
STEP THREE:
Apply the First Coat
Once mixed, carefully use a brush to wet out the substrate with an initial layer, pressing hard into crevices as this helps to prevent air entrapment. Then move on to rebuilding with more product, using a Belzona applicator to restore the surface to its original profile. Ensure the epoxy paste is spread evenly and covers the entire damaged area.
Apply the Belzona 1511 (Super HT-Metal) using a brush in firm, circular motions
STEP FOUR:
Leave the High-Temperature Epoxy Paste to Cure
For the final step in the process vessel application, allow the Belzona 1511 (Super HT-Metal) enough time to cure, forming a strong durable repair. Please note the length of time taken to cure varies depending on application temperature so be sure to consult the IFU for specific timings.
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Once pitting damage has been repaired, Belzona recommends protecting the vessel using a high-temperature epoxy coating, such as Belzona 1593. This product was designed to provide long-term protection for process vessels operating in harsh conditions, including elevated temperatures up to 320°F (160°C) under continuous immersion in aqueous/hydrocarbon conditions.
HIGH-TEMPERATURE COATING APPLICATIONSTEP ONE:
Surface Preparation Prior to Application of Belzona 1593
The Belzona 1511 (Super HT-Metal) repair has a 24-hour overcoat window, during this time the Belzona 1593 can be applied with no additional surface preparation. If applying the coating outside of this window, the surface will need frost blasting to achieve a surface profile of 1.6 mils (40 microns) prior to the epoxy coating being applied.
Apply the Belzona 1511 (Super HT-Metal) using a brush in firm, circular motions
STEP TWO:
Mixing the High-Temperature Coating
Next, transfer the entire contents of the Belzona 1593 Solidifier container into the Base container (or measure out a ratio of 11:1). The two components should then be mixed thoroughly to achieve a uniform colour, free of any streaks.
STEP THREE:
First Coat of Belzona 1593
Using a brush or Belzona applicator, apply the anti-corrosion coating directly onto the prepared surface, ensuring a consistent coating. More detailed areas, such as brackets and welds, may need to be stripe-coated before the main application area. Once a uniform thickness is achieved, take regular wet film thickness readings and adjust accordingly. Make sure to evenly coat the entire prepared surface, as well as any nearby surfaces that need protection.
Apply the first coat of heat-resistant epoxy coating, Belzona 1593
Apply a Second Coat of Belzona 1593
STEP FOUR:
Applying the Second Coat
As soon as the initial coat is sufficiently firm, a second coat should be applied for greater corrosion and chemical protection. Whilst this is usually six to eight hours after the application of the first coat, the timeframes vary depending on application temperature, so please refer to the IFU for more specific overcoat information.
STEP FIVE:
Leave Anti-Corrosion Coating to Cure
Once the second coat has cured, a DFT test should be performed to ensure the final target thickness has been achieved. Any areas that do not meet this target can be marked up and a local repair coat can be applied.
The fast-curing time of Belzona 1593 will allow a quick return to service, and once cured, this product forms a robust, chemical-resistant lining. Additionally, the system withstands the steam-out process up to 482°F (250°C) and rapid depressurisation.
Once cured, perform a DFT test to ensure target thickness has been achieved
