Valve Installation 101: A Complete How-To Guide
5 min read
Overview
Installing valves is very important. It affects how well the system works and how easy it is to maintain. This guide explains how to install general valves. For special valves, follow specific instructions. Always ensure the installation is safe. It should be easy to operate, maintain, and take apart.
General Guidelines
- Training: Maintenance workers and pipefitters should be able to read pipeline installation diagrams and understand valve symbols. They should follow these diagrams for installation. They should also be capable of making necessary modifications to the installation position and direction of general valves when needed.
- Height: The valve handle should ideally be about 1.2 meters above the ground. If the handle is more than 1.8 meters high, use a platform for valves that are frequently operated. This makes it easier to reach and operate the valves.
- Access: For valves installed over 1.8 meters high and not frequently operated, use chain wheels, extension rods, movable platforms, or ladders. If a valve is below the operating floor, use extended rods or underground wells with cover plates for safety.
- Orientation: Valves on horizontal pipelines should have stems pointing upwards. Downward stems are inconvenient for operation and maintenance and can cause corrosion. Avoid installing ground valves at an angle as this can make operation difficult.
- Clearance: Valves installed in parallel should have enough space for operation, maintenance, and disassembly. Handwheel clearance should not be less than 100mm. For closely spaced valves, stagger the arrangement to ensure ease of access and operation.
- Support: Large valves with high torque or low strength should have supports to reduce the strain on the pipeline. This helps in maintaining the integrity of the system and ensures the longevity of the valves.
- Environment: Pressure-reducing valves should not be installed in locations prone to impact. Install steam safety valves indoors with discharge lines leading outside, and ensure oil and gas safety valves discharge above the roof. For toxic or explosive media, safety valves should discharge through closed pipelines to collection systems.
Installation Positions and Directions
- Flow Direction: Many valves have specified flow directions marked with arrows. Ensure the flow direction matches these arrows during installation. This is crucial for the proper functioning of the valves.
- Specific Valve Types:
- Gate Valve: Usually, there is no specified flow direction for gate valves, except for cryogenic types which have a pressure relief hole to prevent dangerous pressure build-up.
- Globe Valve: The flow direction is usually from below the valve seat. Incorrect installation can increase resistance, make operation difficult, and cause excessive wear on the valve components.
- Check Valve: The flow direction should match the arrow on the valve body. Incorrect installation can prevent the valve from functioning properly and can lead to system failures.
- Butterfly Valve: The installation should align with the direction of the arrow on the valve body to ensure proper operation.
- Throttle Valve: Should be installed according to the arrow on the valve body to ensure proper function and longevity.
- Safety Valve: Must be installed upright to maintain proper operation. Incorrect installation can lead to serious safety hazards.
- Pressure-Reducing Valve: The flow direction should match the arrow on the valve body to ensure the valve reduces pressure correctly.
- Steam Trap: The flow direction can vary based on the valve’s structure. Always refer to the product manual and arrow direction for proper installation.
- Ball Valve, Butterfly Valve, Diaphragm Valve: These can be installed in any position, but if they have transmission devices, they should be installed upright.
- Three-Way Ball Valve: Preferably installed upright to ensure ease of operation and maintenance.
Protective Measures
- Safety Valves: Generally, isolation valves are not installed before or after safety valves, except in specific cases. For example, when dealing with solid impurities, install a lead-sealed gate valve for maintenance purposes. The gate valve should be in the fully open position to avoid affecting the safety valve's operation.
- Check Valves: To prevent reverse flow and ensure product quality, install one or two cut-off valves before and after the check valve. This allows for easy maintenance and repair of the check valve without disrupting the entire system.
- Valve Supports and Platforms: For valves installed at high elevations or in difficult-to-reach places, use platforms, ladders, or supports to ensure safe and easy access for operation and maintenance. This is especially important for large and heavy valves that require frequent adjustments.
- Insulation: For valves exposed to extreme temperatures, use insulation to maintain optimal operating conditions. This prevents heat loss and protects the valve components from temperature-related damage.
- Filtration and Cleaning: Install filters and cleaning valves to prevent debris from entering the valve and causing damage. This is crucial for maintaining the integrity of the valve's sealing surfaces and ensuring smooth operation.
Installation Process
- Preparation: Before installation, ensure that the valve specifications match the system requirements. Clean the valve components thoroughly and check for any damage or defects. This includes checking the sealing surfaces and ensuring there are no obstructions.
- Pipe Cleaning: Clean the pipelines and equipment to remove oil, welding slag, and other debris. This prevents damage to the valve sealing surfaces and ensures smooth operation.
- Handling: For valves larger than DN100mm, use lifting tools to handle the valves. Secure the ropes to the flange or bracket, not the stem or handwheel, to prevent damage. Lift and place the valves gently to avoid any impact or stress on the valve components.
- Alignment and Welding: Align the valve flange with the pipeline flange carefully to avoid misalignment. Use appropriate gaskets and tighten bolts symmetrically to ensure a proper seal. For threaded valves, use suitable sealing materials like PTFE tape or sealant to prevent leaks.
- Post-Welding: Inspect the welds thoroughly and conduct X-ray inspections for critical valves if necessary. After welding, flush the pipeline and valve to remove any remaining debris. This step is crucial to ensure the system is clean and ready for operation.
- Final Checks: Perform a final check on the valve and pipeline system to ensure everything is installed correctly and functioning properly. This includes checking for leaks, verifying the flow direction, and ensuring all connections are secure.
Conclusion
Proper valve installation is essential for ensuring safe and efficient operation, minimizing maintenance issues, and extending the valve's service life. By following the correct procedures and considering the specific requirements for different valve types, you can achieve a reliable and functional system.
FAQs
- What height should valve be installed at?
- Valve handles should be about 1.2 meters above the ground for easy access. If they are higher, use platforms or extensions for frequent operations.
- How should valves on horizontal pipes be oriented?
- Valve stems should point upwards to avoid corrosion and ease of operation. Downward stems are inconvenient and can cause maintenance issues.
- What should be done if a valve is installed over 1.8 meters high?
- Use chain wheels, extension rods, platforms, or ladders for infrequent operation valves to ensure safe and easy access.
- How are flow directions determined if not marked on the valve?
- Determine the flow direction based on the valve's structural principles and ensure it matches the intended flow of the system. Always refer to the product manual if available.