Important Guidelines for Globe valve installation and maintenance

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’s 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.

How Does a Globe Valve Work?

Before diving into troubleshooting and seeking a globe valve repair kit, it’s helpful to briefly explain how they are constructed and control flow. This will make troubleshooting steps and replacing components much easier to understand.

Globe valves consist of three main sections:

Valve Body:

The central housing contains all internal components and the flow passage. It’s typically a two-piece body bolted together.

Bonnet:

The upper section is attached to the body, which holds the disc/plug assembly and the packing box.

Disc/Plug:

The moving regulating element is attached to the stem. It raises or lowers to adjust the flow.

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.

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’s seat ring.

Proper Installation of a Globe Valve

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.

Flow Direction:

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.

Proper Orientation:

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.

Pipe Stresses:

Use pipe supports and braces to remove weight or side loads on the valve, which could cause body warping.

Thermal Relief:

Allow space for extended bonnets to expand/contract without contacting other equipment. Consider bellows-sealed valves for this purpose.

Proper Insulation:

Never insulate the bonnet or handwheel, as this can cause overheating and damage the packing and stems.

Troubleshooting Common Globe Valve Issues

Despite best installation practices, globe valves may eventually experience issues from wear, contamination, or erosion. Here are the most common problems:

External Leaks:

Leaks from bonnet gaskets or packing glands during operation indicate seal wear. Lightly tighten packing gland nuts—but 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.

Internal Leaks:

Fluid leaking from the valve outlet when fully closed indicates internal damage. The disc likely isn’t sealing properly against the seat, allowing fluid to pass through the sealing surfaces. This is a major issue requiring disassembly to access internal components.

Other Issues:

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.

Any of these operational changes signal the need for inspection and rebuild. Early detection reduces overall wear.

Disassembly Process for Globe Valves

Once an issue is diagnosed, it’s time to disassemble the globe valve for internal access. This requires careful organization of removed components. Follow these step-by-step guidelines:

1. Isolate the valve and relieve pressure. Drain any trapped fluid. Remove insulation if present.
2. Document the original orientation and settings like the handwheel position. Take pictures for reference later.
3. Loosen and remove the bonnet from the body. Inspect gaskets for damage.
4. Extract the plug/disc assembly and stem. Note the packing.
5. Remove seats, guides, and other internal components from the body if present.
6. Clean all parts and degrease if necessary without damaging surfaces.
7. Inspect the internal parts and plan repairs. Thoroughly check each removed part for:
   • Cracks, especially in threaded areas of the body/bonnet. Welding repairs may be required.
   • Erosion in the valve cavity or chemical damage. Replace affected parts.
   • Buildup or deposits that hinder valve function and may need cleaning.
   • Corrosion or pitting that may affect safety or sealing.
   • Scratches, wear, flattened seats, and loose stem fittings.
   • Leak points—note any specific areas that allow leakage.
   • Other defects—scratches, missing parts, misalignment, etc.

Reassembling Globe Valves After Maintenance

Once all worn components are replaced, carefully reassemble the globe valve in reverse order:

1. Clean body passageways and seating surfaces from old gasket residue.
2. Install a new seat ring, guides, plug tip (if used), and other internal parts.
3. Insert the plug/disc into the valve stem and attach it to the body.
4. Insert new packing and spacers onto the stem and place them in the packing box.
5. Fit a new gasket and carefully install the bonnet with the body. Tighten flange bolts.
6. Adjust the valve and packing nuts to slightly compress the packing box to ensure no stem leaks.
7. Check handwheel movement through the full stroke. Lightly lubricate the stem and pack if needed.
8. Return the valve to its original position. Adjust pressure and check for any leaks during operation.
9. Consider keeping spare gaskets, packing materials, and other parts on hand for future maintenance.

At CareWater we provide all types of valves and a full range of products and services, which you can explore on our website.