US-based corrosion specialist, Cortec Corporation has offered a guide to achieve successful preservation during the three main phases of a valve’s non-operational life-cycle in the oil and gas industry.

 

Before a pipeline or plant starts operating, thousands of components must be fabricated, assembled, and shipped to the construction site. Valves must be hydrostatically tested by the valve manufacturer to ensure no leaks, a Cortec release said. Hydrotesting of valves and components may also be done at coastal fabrication yards where components are assembled into modules and often shipped overseas halfway around the world.

 

Adding VpCI-649 to the hydrotest water does dual duty by protecting against flash rust from the hydrotest water and leaving behind a thin film of corrosion inhibitors that provide both contact and vapour-phase protection. This offers comprehensive coverage that is typically difficult to achieve due to valve intricacies. A higher dose can be used for an extended period of preservation. Another approach is to fog valve internals with CorroLogic VpCI-339 Fogging Fluid, a 100% vapour-phase inhibitor for void space protection.

 

VpCI Film

After internal protection, the entire valve can be enclosed in VpCI Film (available in multiple grades for different atmospheric exposure conditions) to keep the Vapour phase Corrosion Inhibitors from escaping and to protect the external surface without cumbersome coating or liquid rust preventative application. The valve is then ready to be shipped through all sorts of environments and arrive in like-new condition at the installation site.

 

Another critical phase of valve preservation ought to occur during warehousing of critical or operational spares. Protection methods are similar to those previously mentioned, with slightly different underlying reasons. For operational plants, preserving spare valves can mean the difference between millions of dollars saved, or millions of dollars lost for lack of a reliable spare to install when a replacement is needed. If all spares are rusty (as too often happens in non-climate-controlled warehouses or outdoor storage yards), maintenance personnel must choose between installing a rusty, potentially faulty valve that could lead to further failure and disaster, or waiting and experiencing downtime for days, weeks, or months before a replacement arrives.

 

A much easier path is to “clean, protect, and preserve” valves in advance with these three steps:

*Remove any existing rust (e.g., use a dip bath of VpCI-422, followed by rinsing and neutralisation with a VpCI-41x Series cleaner);

*Fog valve internals with VpCI-337 or CorroLogic VpCI-339 Fogging Fluid; and

*Cover openings or wrap the entire valve in VpCI-126 Film (indoor storage), VpCI-126 HP UV Shrink Film (outdoor storage), or MilCorr VpCI Shrink Film (outdoor storage) depending on the severity of the environment. 

 

Operating condition

This procedure leaves valves in operating condition, ready to use at a moment’s notice as soon as they are unwrapped.

 

A third important phase of valve preservation comes when the fluctuating oil and gas market makes mothballing and layup the most cost-effective option, shutting down drilling or refining operations until there is a brighter industry outlook. 

 

In the meantime, millions of dollars of equipment must be preserved so that their value is not lost during the idle period. Once again, valves fall into this category. They can be preserved in much the same way as described for other phases—ensure valves are clean and rust-free, add an internal source of vapour phase Corrosion Inhibitors, and protect externals with VpCI Film that has the appropriate degree of weather resistance. 

 

Special preservation

When the market brightens, crews can easily go in, remove the VpCI Film, and get the facility up and running without having to remove a lot of coatings or rust as might otherwise be needed.

 

Whatever the stage, valves are such a critical part of the oil and gas industry that they deserve special preservation attention for economic and safety reasons. 

 

Compared to the serious repercussions of inadequate preservation, corrosion prevention is extremely simple and cost-effective.-- TradeArabia News Service