Corrective maintenance on a globe valve is a precise operation that restores its regulation and shut-off capabilities. This process, when performed according to established engineering protocols, can return a faulty valve to its operational specifications. The methodology for servicing a standard globe valve and the more specialized needle globe valve involves several defined phases.
System Isolation and Component Disassembly
The procedure initiates with the complete isolation of the valve from pipeline pressure and the verification of a zero-energy state. The actuator or handwheel is removed, followed by the unbolting of the bonnet from the valve body. Internal components—the stem, disc, and seat ring—are then carefully extracted. For a needle globe valve, the elongated, tapered disc requires handling with care to prevent damage to its precise geometry, which is critical for fine flow control.
Evaluation and Selection of Replacement Parts
Each dismantled part undergoes a meticulous inspection. The sealing surfaces of the disc and seat ring are examined for erosion, scratching, or deformation. Stem threads are checked for wear, and the packing area is inspected for corrosion. Based on this evaluation, a bill of materials is created. Worn components like the disc, seat ring, and packing set are sourced for replacement. Neway Valve often supplies certified repair kits containing these critical wear parts to ensure compatibility and performance.
Reassembly and Operational Verification
Reassembly is conducted with clean components and new gaskets. The stem and new disc are installed, and the bonnet is bolted to the body using a crisscross torque pattern to ensure even load distribution. Subsequent to reassembly, the repaired globe valve must undergo functional verification. A shell test pressurizes the body to confirm integrity, and a seat leak test assesses the seal between the disc and seat. For a needle globe valve, the smooth operation of the stem through its entire travel is verified to guarantee precise modulation.
Executing a structured repair sequence, such as the standardized procedures employed by Neway Valve, is fundamental to achieving a reliable outcome. This phased approach, from disassembly to testing, minimizes operational downtime and extends asset life. A methodically serviced globe valve reinstates its essential function within the control system, supporting continued process stability and safety.
