FAQs
I currently use wax in my shorted casings, why should I consider VCI as an option?
There may be several advantages to using VCI over other casing annulus protection methods. Casings may be either metallically or electrolytically shorted. Metal shorts can concentrate corrosion around the contact point of the two pipes. Electrolytically shorted pipes are usually shorted by water or other contaminants in the casing. VCI applied in a slurry/gel form, protects both in the liquid contact areas using soluble corrosion inhibitors, but also in the vapor space areas using VCIs. This chemistry also neutralizes the exist- ing contaminants whereas a wax fill will simply encapsulate them against the steel surface. VCIs can be removed and/or replenished without excavation or the use of steam that wax would require.
What other applications of VCI are used besides tank bottoms and pipe casings?
VCIs come in many forms, from powders and liquids to plastic, paper or foam sheets, greases and oils, rust removers, powder packets and capsules, and many more. They can be applied to virtually any enclosed environment, or be used to create the enclosed environment. Please ask a Zerust representative if you have any corrosion issues that you would like to solve.
Can I use VCIs in product pipelines?
Currently, VCIs are not used in active product pipelines. They are being used in pipelines that are under construction or have been hydro tested but waiting for commissioning, or in pipes that are being mothballed for a period of time. VCIs can be a cost effective alternative to Nitrogen blanketing in many cases.
Can I use VCIs for CUI (Corrosion Under Insulation)?
VCI is not currently being used to protect against CUI. It may be possible to develop a VCI system for new pipelines where insulation is required, or maintenance turnarounds where the cladding and insulation are being replaced. Talk to your Zerust representative to see if VCI can be applied to your insulated pipes.
What are the Risks of using Vapor Corrosion Inhibitors?
The majority of chemistries used in the Oil & Gas sector will cause "No Harm" to the current list of environments that they are used in. Such as tank bottoms, with or without liners, pipe casings, inside pipelines, cone or floating roofs. Some gasketing or yellow metal materials may be affected. If you have any questions or concerns, please ask a Zerust representative during the design stage.
How do you get VCI coverage everywhere under a tank floor?
Each tank foundation is unique in its design or materials used. VCI’s can be delivered under a tank in either a powder or liquid form and consist of both a Vapor (VCI) and a Soluble (SCI) component. In most cases the tank can be in-service during the installation. The SCI will neutralize any contaminants that it comes in contact with, while the VCI can travel through the substrate and protect the metal surfaces. Volumes and distances are calculated during the design phase to ensure that the surfaces which require corrosion protection are protected.
Can any tank foundation be protected by VCI?
Almost! There are several answers to this question, depending on the foundation design of the tank in question. Tanks which are resting directly on the ground, without a Release Prevention Barrier (RPB or Liner), are typically not good candidates for VCI, but please ask a Zerust representative. Virtually all tanks built on a gravel or concrete ring wall are excellent candidates.
What if I don't have a liner or RPB under my tank?
VCI - dry systems can be added to the chime of the tank floor and the VCI molecules can penetrate under the floor up to 12 to 15 feet. This provides protection to the vulnerable chime ring and annular plates, where most of the corrosion occurs on most tank floors.
My tank is on a concrete or asphalt pad and I don't have any Cathodic Protection, what are my options?
VCI can be applied to virtually any concrete or asphalt pad tank, most of the time, while the tank is in service. VCI can work symbiotically with Cathodic Protection, but since it is virtually impossible for CP to work with concrete or asphalt pads (as stated in API 651), VCI may be your only corrosion protection option.
Is VCI recognized by PHMSA as an approved corrosion protection option for breakout tanks?
No, but this does not mean that an owner cannot use VCI protection. PHMSA states that breakout tanks must be protected by Cathodic Protection. According to API 651, there are some tank foundation designs where CP will not work. Talk to a Zerust representative to better understand your options when CP systems fail or are not viable. In the State of Florida, regulators do accept the use of VCI in lieu of, or in conjunction with CP.
What type of pipe casing geometry is necessary?
Most geometries are acceptable for VCI gel. However, 2 vent pipes are recommended with one vent accessing the top of the casing and the other accessing the bottom of the casing.
What type of testing should be performed on the casing before introducing VCI Gel?
Typically, a low pressure test is performed on the casing. That involves capping one vent pipe and introducing compressed air at ~5 psig. The casing should not drop much pressure when the disconnected from the compressed air.
There may be several advantages to using VCI over other casing annulus protection methods. Casings may be either metallically or electrolytically shorted. Metal shorts can concentrate corrosion around the contact point of the two pipes. Electrolytically shorted pipes are usually shorted by water or other contaminants in the casing. VCI applied in a slurry/gel form, protects both in the liquid contact areas using soluble corrosion inhibitors, but also in the vapor space areas using VCIs. This chemistry also neutralizes the exist- ing contaminants whereas a wax fill will simply encapsulate them against the steel surface. VCIs can be removed and/or replenished without excavation or the use of steam that wax would require. |
| VCIs come in many forms, from powders and liquids to plastic, paper or foam sheets, greases and oils, rust removers, powder packets and capsules, and many more. They can be applied to virtually any enclosed environment, or be used to create the enclosed environment. Please ask a Zerust representative if you have any corrosion issues that you would like to solve. |
| Currently, VCIs are not used in active product pipelines. They are being used in pipelines that are under construction or have been hydro tested but waiting for commissioning, or in pipes that are being mothballed for a period of time. VCIs can be a cost effective alternative to Nitrogen blanketing in many cases. |
| VCI is not currently being used to protect against CUI. It may be possible to develop a VCI system for new pipelines where insulation is required, or maintenance turnarounds where the cladding and insulation are being replaced. Talk to your Zerust representative to see if VCI can be applied to your insulated pipes. |
| The majority of chemistries used in the Oil & Gas sector will cause "No Harm" to the current list of environments that they are used in. Such as tank bottoms, with or without liners, pipe casings, inside pipelines, cone or floating roofs. Some gasketing or yellow metal materials may be affected. If you have any questions or concerns, please ask a Zerust representative during the design stage. |
Each tank foundation is unique in its design or materials used. VCI’s can be delivered under a tank in either a powder or liquid form and consist of both a Vapor (VCI) and a Soluble (SCI) component. In most cases the tank can be in-service during the installation. The SCI will neutralize any contaminants that it comes in contact with, while the VCI can travel through the substrate and protect the metal surfaces. Volumes and distances are calculated during the design phase to ensure that the surfaces which require corrosion protection are protected. |
| Almost! There are several answers to this question, depending on the foundation design of the tank in question. Tanks which are resting directly on the ground, without a Release Prevention Barrier (RPB or Liner), are typically not good candidates for VCI, but please ask a Zerust representative. Virtually all tanks built on a gravel or concrete ring wall are excellent candidates. |
| VCI - dry systems can be added to the chime of the tank floor and the VCI molecules can penetrate under the floor up to 12 to 15 feet. This provides protection to the vulnerable chime ring and annular plates, where most of the corrosion occurs on most tank floors. |
| VCI can be applied to virtually any concrete or asphalt pad tank, most of the time, while the tank is in service. VCI can work symbiotically with Cathodic Protection, but since it is virtually impossible for CP to work with concrete or asphalt pads (as stated in API 651), VCI may be your only corrosion protection option. |
| No, but this does not mean that an owner cannot use VCI protection. PHMSA states that breakout tanks must be protected by Cathodic Protection. According to API 651, there are some tank foundation designs where CP will not work. Talk to a Zerust representative to better understand your options when CP systems fail or are not viable. In the State of Florida, regulators do accept the use of VCI in lieu of, or in conjunction with CP. |
| Most geometries are acceptable for VCI gel. However, 2 vent pipes are recommended with one vent accessing the top of the casing and the other accessing the bottom of the casing. |
| Typically, a low pressure test is performed on the casing. That involves capping one vent pipe and introducing compressed air at ~5 psig. The casing should not drop much pressure when the disconnected from the compressed air. |
