CCI multi-component program solves vent valve leakage
A Saudi gas plant was having a problem with vent valve leakage. CCI engineers inspected one of the twelve valves on the site, to find the root cause of the leakage. They discovered that construction and pipeline debris (most likely weld slag and gasket remnants) was being pushed through the system damaging the valve seat. Secondly, it was discovered that finer, pieces of debris were scratching the plug and sealing surfaces, both of which cause balance seal leakage. There also was direct corrosion of the bonnet.
The plant needed to have its valve internals (plug and balance seal) protected from pipeline debris and corrosion.
The solution was a five-component upgrade in vent valve design. The major component of the upgrade was CCI's proprietary Redundant High Pressure (RHP) seating technology. RHP utilizes a double seat, the first being a special high-pressure soft seat, while the second is a high-pressure hard seat.
Another component of the upgrade was the installation of a sophisticated inlet debris blocker which excludes the heavier debris and permits the finer debris to pass through, while not affecting vent capacity.
The blocker removes much of the debris so most of the scratching and gouging caused by the large debris is eliminated. The filter's outer strainer spacer and inner mesh plate allow a continuous stream of finer, smaller debris to flow through the filter without damaging the valve or seals.
The upgrade also included:
- Installation of a stainless Steel bonnet to prevent corrosion;
- A new balance seal arrangement with wiper rings;
- Special case-hardening of the plug.
After a four-month monitoring period, no leakage was observed. 
A final inspection revealed that the debris blocker successfully excluded larger debris and let smaller debris flow through. It was also discovered that:
- There was no corrosion in the new bonnet cavity;
- No scratches of any kind were found on the hardened plug;
- The RHP seal and back-up hard seat were found in perfect condition;
- The valve is easily rebuilt, tested and returned to service.
As a result, valves with the debris blocker upgrade, now have repeatable, proven zero-leakage. In this service environment, repeatable zero-leakage has never previously been achieved.
The entire upgrade of the plant's 12 vales took approximately two years.
As a side benefit, this solution pays off for the customer by eliminating undesired venting and minimizing the emission of methane, a greenhouse gas. Elsewhere in the region, some neighboring countries of Saudi Arabia are eager to comply with the 1997 Kyoto Protocols which call for a reduction in harmful greenhouse gases like methane. RHP seats have already helped one emirate in the region comply with the Kyoto Protocols.
Published in Solutions Oil & Gas 2005
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