Best Practices for Maintaining Double Switching Safety Valves

It is vital for any industrial plant to keep an effective overpressure protection system. Double-switching safety valves, which are also known as changeover valves, or switching safety valves, provide round-the-clock protection switching between two spring-loaded safety valves. Here is a simple guide in Indian English to make sure that the changeover valve operates efficiently.

1. Know Your Valve Components

A double-switching type safety valve assembly (typical one) has two spring-type valves which are connected to a common inlet in parallel and a three-way switch mechanism. There is an active and standby safety valve. Relief outlets at the bottom of each valve permit safe discharge previous to opening the system for service.

2. Set a Regular Inspection Routine

• How Often?   Every three months, or more frequently in harsh or dusty environments.

What to Check?

·         Look for rust, dents and oil leaks near the body of the valve.

·         Make sure that all the flange bolts are tight and leak resistant.

·         Make sure the valve is installed vertically and at the right height of the gas-phase interface.

A planned inspection schedule detects the early signs of wear and avoids sudden plant shutdowns.

3. Clean Moving Parts and Lubricate

Dust, and scale, and debris can hinder the switch mechanism. Follow these steps:

·         In a safe manner, isolate and depressurise the line.

·         Open the switch housing cover.

·         Clean moving parts with a clean and lint-free cloth and approved solvent.

·         Spray a light coat of high-temperature grease onto the areas of sliding contact.

Through frequent cleaning and lubrication, your double-switching safety valves have fast and dependable switching.

4. Test the Switching Mechanism under Load

A changeover valve working has to shift smoothly when fully pressurized. To test:

·         Bring about a manual switch-over with the system pressurised.

·         Feel the force needed; It should be light, particularly on the high-pressure types (as an example, Class 600 or more).

·         Listen for grinding or rattling sounds, which indicates misalignment or worn parts.

Regular functional tests assure that both safety valves can do the job and they do not stick.

5. Replace Seals and Gaskets on Schedule

With time, gaskets and O-rings become nonelastic and may leak. Watch for:

·         Non rapid weeping adjacent to bonnet or flange joint.

·         Pressure drift or poor pressure holding abilities

Use only seal materials specified by manufacturer for steam or for liquid or gas. Make records of seals replaced so as to plan future maintenance.

6. Calibrate Pressure Settings Accurately

Spring tension might fall with repeated use, thus test your set pressure every once in a while:

·         Lift the cap already existing on the adjustment of the relief valve.

·         Use a calibrated pressure gauge for determining “pop” pressure.

·         Adjust spring nut until you get to the setting required (e.g. PN16-PN100 or 150-600 lb classes).

·         Tighten lock nut and cover the cap with the seal.

Proper calibration will ensure that correct discharge capacity is maintained and also guard against false trips or overpressure.

7. Follow Safety Protocols During Servicing

·         Always vent through the relief port first, depressurise, then dismantle.

·         Use PPE appropriate to the temperatures of the media (-196 up to 570°C).

·         Lock out/tag out (LOTO) of the system if an accidental start-up needs to be prevented.

Loyal adherence to safety procedures ensures the protection of both personnel, and equipment.Knowing your double-switching safety valves, inspection, cleaning and lubricating parts, testing under load, replacing seals, and restoring set pressures means you provide uninterrupted reliable overpressure protection. Adopt these easy best practices now and put your changeover valve at its best condition and save yourself from expensive downtimes.