How do you inspect a gate valve?

Blind Plate Test:

1. Open the gate plate.
2. Allow the system pressure in the valve to rise to the specified value.
3. Close the gate plate.
4. Open the blind plate on one side to check the sealing surface for leakage.
5. Repeat the test until it is qualified.

What are the procedure of overhauling gate valve?

The procedure of overhauling the gate valve is as follows:

1. Open the wheel nut and remove the hand wheel.
2. Open the gland bolts and slacken the gland flange and the gland bush.
3. Open the bonnet bolts and remove the bonnet along with the bonnet and the valve wedge.
4. Unscrew the valve stem from beneath the bonnet.

What is the purpose of the backseat test for a gate valve?

The test pressure is first applied with the valve off the backseat, the stem is monitored for visible leakage, and then the valve is put on backseat and monitored for visible leakage. If the backseat doesn’t leak during the test, then is it acceptable to re-pack a valve on the back seat?

What is difference between globe valve and gate valve?

The main difference between globe and gate valve is in the form of the inner elements and the form of the flow inside the both valves. Globe valve has very good throttling ability while gate valve is not used for throttling.

How do you clean a gate valve?

Use a small screwdriver to scrape any loose debris out of the grooved channel that acts as the valve’s gate guide. Clean this thoroughly; even a small amount of buildup will prevent the valve from closing completely. Slide the gate back into its guide and tighten the top of the housing with a wrench.

Can gate valves be repaired?

A malfunctioning gate valve is not difficult to repair, but it is even easier to prevent. These problems are typically caused by mineral buildup, so you should fully close and open your gate valves every few months to clear potential problems.

How does a gate valve fail?

The most common causes of gate valve failure are wear and corrosion. Gate valves tend to wear out over time. And corrosion can cause the disc to stick in either the open or closed position. When the handle is forced, the stem leading from the handle to the disc will often break, rendering the valve useless.