3 minute read
Pleix-Quip Africa
may result in usable damaged facing, Allowing flexibility in issue disposition. The ideal way to stack valves is to not put pressure on the facings and adequately protecting them from blunt trauma using flange protector and good bracing.
Corrosion Protection
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Valve manufactures need to develop a robust system of protection to ensure the valve are protected from corrosion for the full trip to the final destination. Common issues are as follows.
• Plastic Wrapped valves – Plastic wrap are commonly used to secure valves on pallets for domestic shipping. These kind of packaging may trap moisture within and cause severe corrosion to any non-protected surfaces. • Moisture Inside OEM Bags– Many manufacture would seal an entire crate of valves within large bags. If the air within these bags are moist, then during transportation, the colder climate will cause water to condense out of the air and cause unexpected corrosion of an otherwise “good” sealed bag. • Emulsified Grease – Sometime, heavy oil are used during production as in-process corrosion prevention. These oil end up being emulsified during hydrostatic testing of the valve and can result in delayed corrosion of the cavity. This is because the oil turn into a water+oil emulsion which slowly rust over time. The very item responsible for corrosion protection causing the rust! • Breaking OEM Seals – Valve often ship from manufactures fully sealed in an air tight environment to prevent rust during transport, these seals often are broken by workers to verify shipment during receiving process. these broken seals often are not repaired and would allow ingress of moisture into the storage container, fully saturating any desiccant that are placed within the container and render them useless. • Usage of Only Porous (“Wood”) Flange protector – If porous protector such as wood is used, it should not be in direct contact with the machined surfaces. If the porous material gets wet, it will hold the water next to material for an extended duration of time resulting in severe corrosion of facings. A common method to utilize wood protector is to use plastic or rubber covering between the wood protector and the flange facing. • Upright storage of geared valves outdoor – Gearbox are made so that there is a space between the stem-nut and the gearbox ID. This area is capable of holding large amount of moisture/water if not protected properly, leading to corrosion, and even inoperable valves. • Saturated desiccants – Most desiccants appears the same new and old. It’s important to utilize good storage practice, or desiccants with visual indicators to know if they are still effective. Manufacture often use a combination of inhibitors in the cutting fluid, testing fluid, and drying process to ensure rust free valves at the end of production. Final preservation should always involve the usage of a controlled atmosphere with sealed space, desiccant, and even Vapor Phased Inhibitor. Failure to have proper preservation or breach of this system can result in costly corrosion to the product.
Proper Support
The final storage issue that often arise is lack of proper valve support. These are fairly simple, but often committed, errors which have potential to causes damage to the valve. • Stem support on Large Bare Stem Valve (Gate) – Often times, gearbox would be removed from large gate valves during transit, or they would be ordered as bare-stem to be actuated elsewhere. These valves are always shipped in a horizontal position. As the stem packing were not built to support the weight of the stem, they can be crushed during shipment. In the best case scenario, the stem sealing characteristic of the valve is comprised, in the worst case scenario, the valve will suffer stem damage leading to visual leak. • Disc support on Check Valve – check valves, especially swing checks, needs to be shipped in a manner so that the disc will not slam repeatedly during transport, or damage can be done to the disc/seat, causing leakage. • Actuator Support – Heavy actuators are not designed to withstand rough environment of transportation hanging in mid air. Large and heavy actuated valve packages should be properly supported to avoid side loading damage to the actuator and valve. • Soft seat valve position – Some manufactures require their valve to be shipped fully open, or fully closed, depending on the design of the valve. Shipping soft seated ball valve in a half open position can jeopardize the performance of the valve.
