Pro Installation Tips for Zerust’s Chime Ring Dry Corrosion Inhibitor Delivery System
Many of the contractors we work with will likely agree that Zerust’s Chime Ring Dry IDS installation process isn’t overly complicated, but it does require an attention to detail. In this post I will review what the Chime Ring Dry IDS is, an overview of the installation steps, and tips from tank owners and installers for ensuring a quality installation for effective corrosion protection.
What does the Zerust Chime Ring Dry IDS do?
The Zerust patented ReCAST-SSB Chime Ring Dry IDS solution is a method by which Vapor Corrosion Inhibitors (VCIs) are introduced below the tank bottom for corrosion protection. The Chime Ring Dry IDS is recommended for storage tanks with concrete or bitumen foundations and can be used for storage tanks that are in or out-of-service.
Overview of Zerust’s Chime Ring Dry Installation Steps
- Vapor Corrosion Inhibitors (VCIs) are introduced through Zerust’s dry sleeve system.
- Perforated PVC pipe is installed around the entire annular chime area.
- The VCI dry sleeves are installed into the PVC chime ring and the system is sealed to create an enclosure to maintain the VCIs.
- The VCIs migrate and absorb onto the metal surface.
- The diffusion of VCIs provides corrosion protection in the critical 3 to 4 meters from the annular chime ring.
PVC Ring System – Avoid Over-Stressing Components
The intention of a PVC ring system is to create a micro-environment under the periphery of an aboveground storage tank, that restricts the movement of anticorrosive chemicals when introduced.
Due to climate and the expansion/contraction during normal tank use, the chime area is quite dynamic. As a consequence, components should never be strongly bent or stretched.
Consider the PVC pipe used to contain the dry Zerust chemical. Despite size considerations and connections, unforeseen obstructions such as anchor bolts, product pipes and other attachments could inhibit the contiguous path of the PVC carrier pipes around the tank base. As modifications are made, it’s important to remember that the pipe should never be adversely flexed. Stresses held in the pipe while under flex, may lead to fracture as temperatures drop.
In addition, adhesives employed may fail and rebounding of the pipe could rupture the overcoat materials that form the chime seal. Likewise, application of viscoelastic membranes (Viscotaq, Stopaq, etc.) must be given the same consideration. Stretching to make a curve or extend the reach of a roll can result in shrinkage that will lead to a system failure.
PVC Ring System Installation Takeaway Tips
- Inventory all pvc parts and compare to shipping papers to ensure all materials are present.
- “Dry-fit” parts to confirm parts easily form the planned configuration.
- Do not introduce adverse stress into the system when modifying from the planned configuration.
Surface Preparation Matters
Consider the value of a clean substrate. A large amount of research and manufacturing go into the films, caulks and sealants used in a chime ring protection system. This is all reflected in the cost of such items, which alone, should warrant exercising care in their use. Caulk, tape and topcoat are all expected to adhere to the three common substrates of concrete, epoxy coating and steel. Although the PVC pipe is part of the system, it can theoretically move independent of the tape and topcoat without causing a problem, as long as all edges are sealed against water egress and entry.
Preparation of the concrete should be accomplished through abrasive blasting or *pressure washing, resulting in a surface that is free of efflorescence, loose material and oil/grease. Refer to **SSPC-SP12 (NACE 5) and SSPC-SP13 (NACE 6) respectively. Should the concrete have been painted with the same two-part epoxy as used on the tank, tightly adhering paint remaining is acceptable.
Bare steel may be found on the edge of the chime and is most efficiently treated following the SSPC-SP3 specification. Rapid processing is necessary as flash rust will appear quickly following such preparation. During the cleaning process, bedding material such as cellulose fiber board (Homasote) may be discovered under the chime. Loose pieces should be removed but only so much as to allow for the chemical treatment of the chime area.
The shells of petroleum tanks are most often coated with a two-part epoxy paint that will chalk when exposed to UV light. This chalking essentially makes the tank “self-cleaning”. Chalk, however, requires removal before caulking/coating/taping. Evaluation by way of ASTM D-4214 (tape or cloth rub method) is helpful in confirming cleanliness. In addition, a solvent wipe with a completely fugitive solvent (one that leaves no residue) such as ethanol, methanol, isopropanol, xylene, toluene or acetone is appropriate to remove any oil or grease. A common error is to use “Mineral Spirits” for cleaning surfaces to be painted. Mineral Spirits are captured from the distillation of crude oil starting at 266F and continuing to 392F. With a 126-degree range, the composition can vary considerably. Consequently, higher boiling oils can often find their way into “mineral spirits” which can linger on a surface for months, preventing adhesion of subsequently applied coatings. Finally, Scuff-sanding to impart a slight roughness enhances mechanical adhesion and should always be considered as part of the preparation process.
Surface Preparation Points to Remember & Reference
- Poor surface preparation is the number one cause of system breach
- Entities such as The Society for Protective Coatings (SSPC) and NACE provide some of the best guidelines for surface preparation.
- The article “Clearing Up Surface Prep Standards” from CoatingsPro is also a good reference.
*Pressure washer of 5000+ psi performs best.
**This is intended to be a general reference for the Zerust Chime Seal System. All manufacturers directives should be followed for each specific coating, caulk and tape application. In the absence of such, the Steel Structures Painting Council (SSPC) and National Association of Corrosion Engineers (NACE) can provide excellent guidelines.
Overall, the Zerust Chime Ring Dry IDS solution can be easily installed with these few helpful tips in mind.
- Inventory pvc parts, dry-fit, and do not overstress the pvc system
- Follow Proper Surface Preparation Guidelines
- Contact Zerust if you have any installation questions.
Questions about the installation process for Zerust’s Chime Ring Dry IDS solution? Contact us.
Please contact Zerust Oil & Gas here and see how we can help you with your corrosion mitigation needs.