A globe valve is a common and essential component in a wide range of industrial piping applications. Its time-tested design makes it well-suited for flow control and frequent on\/off operations. However, all valves will eventually require maintenance or repair. Let\u2019s go over the complete process of best practices for globe valve installation and maintenance, including disassembly, troubleshooting common issues, and rebuilding globe valves to a like-new condition.<\/p>\n
Before diving into troubleshooting and seeking a globe valve repair kit, it\u2019s helpful to briefly explain how they are constructed and control flow. This will make troubleshooting steps and replacing components much easier to understand.<\/p>\n
Globe valves consist of three main sections:<\/p>\n
The central housing contains all internal components and the flow passage. It\u2019s typically a two-piece body bolted together.<\/p>\n
The upper section is attached to the body, which holds the disc\/plug assembly and the packing box.<\/p>\n
The moving regulating element is attached to the stem. It raises or lowers to adjust the flow.<\/p>\n
After that, many interchangeable finishing components line the flow direction of the globe valve, including seats, guides, and discs\/plugs specifically designed for certain applications.<\/p>\n
To open and close the disc, the handwheel rotates the stem to raise and lower the disc\/plug off the seat. This allows or restricts flow through the valve body. Globe valves are not fully shut off until the hard disc rests on the body\u2019s seat ring.<\/p>\n
Once the optimal globe valve and trim are chosen for an application, key considerations come into play for proper installation. The key is configuring the valve to allow proper disc movement and prevent fluid damage.<\/p>\n
Globe valves operate in only one direction. The arrow on the body indicates the correct flow. Always install it so the flow enters beneath the seat.<\/p>\n
Valves perform best when installed horizontally with the handwheel in the upright position. This allows the disc to fully close on the seat. Vertical installation may hinder full closure.<\/p>\n
Use pipe supports and braces to remove weight or side loads on the valve, which could cause body warping.<\/p>\n
Allow space for extended bonnets to expand\/contract without contacting other equipment. Consider bellows-sealed valves for this purpose.<\/p>\n
Never insulate the bonnet or handwheel, as this can cause overheating and damage the packing and stems.<\/p>\n
Despite best installation practices, globe valves may eventually experience issues from wear, contamination, or erosion. Here are the most common problems:<\/p>\n
Leaks from bonnet gaskets or packing glands during operation indicate seal wear. Lightly tighten packing gland nuts\u2014but frequent loosening\/tightening will speed up packing wear. Significant packing replacement may be needed. Also, inspect bonnet gaskets if leaks appear between the body halves. Loose flange bolts can also cause leaks over time.<\/p>\n
Fluid leaking from the valve outlet when fully closed indicates internal damage. The disc likely isn\u2019t sealing properly against the seat, allowing fluid to pass through the sealing surfaces. This is a major issue requiring disassembly to access internal components.<\/p>\n
Additional problems include difficulty turning the handwheel due to debris buildup, noisy flow, and bonnet emissions. Stiff handwheels and hard closing at the end result from the loss of lubricants that reduce friction in the packing.<\/p>\n
Any of these operational changes signal the need for inspection and rebuild. Early detection reduces overall wear.<\/p>\n
Once an issue is diagnosed, it\u2019s time to disassemble the globe valve for internal access. This requires careful organization of removed components. Follow these step-by-step guidelines:<\/p>\n