Hastelloy Valve 

What is a Hastelloy valve? 

A Hastelloy valve is a valve that is made of nickel-based alloy known as hastelloy. The two primary elements used to make the hastelloy material are nickel-chromium and nickel-molybdenum. The Hastelloy material has excellent properties relative to other traditional alloys making it one of the preferred alloys used in valve industries. One of the superb properties of this material is its excellent corrosion resistance and high resistance to oxidizing agents and acids. The melting temperature of this material is 1260^oC making this valve suitable for use in both low and high temperatures. The material is very strong, which makes the valve ideal for use in high-pressure applications without. However, the Hastelloy valve is very heavy compared to other valves because of the high density of Hastelloy material (8890 kg/m³). Hastelloy valve manufacturers design this valve to operate manually or automatically. The manual valve has a handwheel for applying torque to operate. Turning the handwheel in the anticlockwise direction opens the valve for fluid flow. Turning the handwheel in clockwise direction closes the valve. The valve is suitable for various applications, such as cryogenics, acids, boilers, mining, water supply, and the oil industry among others.

Types of Hastelloy valves 

Hastelloy ball valve 

This is the type of Hastelloy valve that uses a ball-shaped component to open and close fluid flow. The ball component has a through-hole at its center. The ball bore is set between the valve seats to allow fluid flow through the valve. An actuator or a handwheel sets the ball component to allow or close the fluid flow. This type of valve is versatile for vapors, gases, and liquids.

Figure: hastelloy ball valve.

How does the hastelloy ball valve work? 

This valve operates by turning the handwheel for 90^o degrees to either start or stop flow. Rotating the handwheel in the anticlockwise direction causes the ball bore to turn for a quarter turn and become aligned to the pipe connected to the valve. As such, the fluid finds the valve open and flows through. When the handwheel is rotated in the clockwise direction, it causes the ball to make a quarter turn and become perpendicular to the pipe connected to valve. The ball and valve seat make a tight seal which then prevents any fluid flow through the valve.

Advantages of Hastelloy ball valves 

• Quick and easy to operate.
• Simple and compact design.
• Versatile in size.
• Low-pressure drop.
• Easy to install and repair due to its simple design.

Disadvantages of Hastelloy ball valves 

• Quick opening and closing cause water hammer and overpressure.
• Not ideal for throttling applications.

Hastelloy plug valve 

A Hastelloy plug valve is a valve that uses a cylindrical or conically tapered plug to open and close fluid flow. Hastelloy valve manufacturers design the plug with a through-hole at its center. The fluid flows through the central hole when the valve is started. The valve is operated using a handwheel, electric or pneumatic actuator. A component known as a stem connects the plug to the handwheel. This valve is capable of various flow rates and pressure levels since it is versatile in size.

Figure: Hastelloy plug valve.

How does a Hastelloy plug valve work? 

This valve operates by turning the plug for a quarter-turn angle similar to the hastelloy ball valve. Turning the handwheel 90^o degrees causes the plug bore to rotate and align itself concentric to the pipe connected to the valve. As such, the fluid finds the valve passage free and thus flows through the valve. The valve closes when the handwheel is rotated in the opposite direction for another quarter. This rotation forces the plug hole to rotate and align perpendicular to the pipe connected to the valve. The plug and valve seat make a tight seal that prevents fluid flow through the valve. Hastelloy plug valve manufacturers design some valves with more than one middle hole for multi-port fluid flow. The port’s positions determine when the valve is open or closed.

Figure: Working of hastelloy plug valve.

The advantages of Hastelloy plug valves are:

• Simple and compact design.
• Easy to operate.
• Few rotating parts; cheap repair and maintenance.
• Low resistance to fluid flow and thus low-pressure drop.
• Easy to repair, install, and clean.

Disadvantages of Hastelloy plug valves: 

• Not recommended for throttling applications.
• Needs high torque to operate.

Hastelloy Check Calve 

This is the type of Hastelloy valve used to prevent fluid flowing in the reverse direction. Due to its work, it is also known as a non-return valve, or one-way valve, since it only allows fluid flow in one direction only. Whenever fluid attempts to reverse flow direction, the valve shuts up immediately. Hastelloy check valve manufacturers design this valve without a valve stem, handwheel, or actuator. This is because it is engineered to open and close automatically depending on the level of fluid flow pressure.

Figure: Hastelloy check valve.

How does a Hastelloy check valve work? 

A check valve operates on the principle of pressure difference. The valve disc lifts when the pump starts, or the upstream pressure exceeds the downstream pressure. As such, the valve opens, and fluid flows through. When the pump is stopped, or the upstream pressure reduces than the downstream pressure, the valve disc moves downwards immediately and closes to prevent any fluid flowing to the upstream side. This type of valve is suitable in applications that demand high levels of hygiene or where the downstream fluid is likely to contaminate the upstream fluid.

Figure: Working of a hastelloy check valve.

The advantages of the Hastelloy check valve are:

• Automatic operation.
• Cheaper relative to other valves.
• Low-pressure drop.
• Fast in operation.
• No reverse flow.

Disadvantages of Hastelloy check valves: 

• They are prone to water hammers since they close or open very fast.
• Not recommended for pulsating flow.

Hastelloy gate valves 

A Hastelloy gate valve is a valve that operates by lifting the closing component known as the gate or disc. When the gate/disc moves downwards to the seating position, it closes fluid flow. This type of valve occupies a small space along the pipe axis and does not restrict fluid flow when fully opened. Hastelloy valve manufacturers design this valve to operate using a manual handwheel, electric or pneumatic actuator. As such, this valve can be manual or automatic per the user’s preferences.

Figure: Hastelloy gate valve.

How does a Hastelloy gate valve work? 

This valve operates by rotating the handwheel several times. Rotation of the handwheel in an anticlockwise direction causes the valve stem to move upwards. Moving the stem upwards causes the valve disc or gate to move up. This leaves the valve open, allowing fluid flow. When the valve handwheel is rotated in the clockwise direction, the valve stem moves downwards to the seating position. In this case, the valve is closed, and no fluid flows. Hastelloy gate valve manufacturers do not guarantee the use of this valve in throttling because the high pressure and flow rate erode the gate and may cause damage.

Figure: Working of a hastelloy gate valve and its components.

The advantages of Hastelloy gate valves are: 

• It is suitable for high-pressure and high-temperature applications.
• It has a low-pressure drop when fully opened.
• It is ideal for bi-directional flow.

Disadvantages of Hastelloy gate valves 

• Not suitable for throttling fluid flow.
• It is slow in operation; the valve operator must turn the handwheel several times to open/close the flow.

Hastelloy globe valve 

This is the type of valve designed with a spherically shaped body. The valve uses a disc to control fluid flow. Hastelloy globe valve manufacturers recommend this valve for use in throttling fluid flow. It is the best valve for regulating fluid flow compared to all other valves discussed. The valve is operated either manually or automatically using an electric or pneumatic actuator. This valve is similar to the Hastelloy gate valve but is faster to run since it requires a few turns to open or close. However, this valve design leads to high-pressure drops, unlike all the other valves discussed above. It also has a complex design since internal components are installed within the valve cavity.

Figure: Hastelloy globe valve.

How does a Hastelloy globe valve work? 

The valve operates by turning the handwheel either clockwise or anticlockwise. When the handwheel is rotated in the anticlockwise direction, the valve stem moves upwards together with the valve disc. This leaves the valve open, and thus fluid flows through. When the handwheel is rotated in the clockwise direction, the stem moves downwards together with the valve disc, and therefore the fluid flow is stopped. When throttling is required, the handwheel is rotated slightly in the anticlockwise direction leading to partial flow through the valve.

Figure: Working of a hastelloy globe valve.

Advantages of Hastelloy globe valve

• They perform well in throttling fluid flow.
• Faster in operation relative to gate valves.
• Has perfect shut-off free from leakage.

Disadvantages of a Hastelloy globe valve 

• Has a high-pressure drop.
• Heavy relative to other valves.

Applications of Hastelloy valves 

These valves are used in many industrial applications as shut-off and throttling valves. Some of the most common applications of this valve are:

• Steam power plants to control the flow of water and steam.
• Boiler feed systems to control the flow of water.
• Commercial and domestic water supply.
• Paper and pulp industries.
• Chemical processing.
• Crude oil industries.
• Mining applications.
• Transportation of gas and oil.
• Agriculture, food, and beverage industries.
• Pharmaceutical industries.
• Marine applications.

Advantages of Hastelloy valves 

• These valves have high strength suitable for high pressure and flow rate.
• Hastelloy material has a high melting point making the valve ideal for high-temperature applications.
• It is versatile since it can be used in different industrial applications.
• Hastelloy is resistant to corrosion; thus, the valve can withstand corrosive and oxidizing media.
• Hastelloy valves are easy to weld.
• Have long service life.

Disadvantages of Hastelloy valves 

• These valves are heavy due to the high density of Hastelloy material.
• Hastelloy is hard to machine, which makes the valve quite expensive.

Troubleshooting hastelloy valves 

No fluid flow through the valve 

• Blocked pipe. Check the line feeding the valve for blockage and remove any foreign material.

Handwheel is hard to operate. 

• Foreign material clogged inside the valve. Disassemble the valve as the hastelloy valve manufacturer recommends and clean off foreign materials.
• Damaged stem. Repair or replace the valve stem.

Fluid leakage between the valve and pipe joint 

• Damaged or worn-out gasket. Replace the gasket.
• High fluid pressure. Use the valve at the recommended pressure range. For high fluid pressure, use a high-rated valve.
• Loose connection. Tighten the bolts and nuts connecting the valve and the pipe.

Fluid leakage through the valve seat 

• Worn out seats. Replace the valve seats.
• Worn out disc/plug/ball. Replace the disc/ball/plug.
• Dirt on the seat. Clean off the dirt.

The valve does not close or open completely

• Dirt on the valve stem. Clean the dirt.
• Dirt on the valve seat. Clean the dirt.

Summary 

Hastelloy valves are made of Hastelloy material. These valves operate by using a manual handwheel, electric or pneumatic actuator. The valve operates by turning the handwheel or hand lever for manual valves. The actuator rotates the valve stem for automatic valves to move the valve disc/ball. Moving the ball/disc makes the valve either open or closed. This type of valve is robust and thus suitable for high-pressure and high-temperature applications. It resists corrosive and oxidizing media.

Hastelloy valve manufacturers produce various types of this valve, such as check valves, gate valves, plug valves, ball valves, and globe valves. Industries that use these valves include foods and beverages, mining, steam power plants, commercial water supply, oil and gas, agriculture, and chemical and petrochemical industries among others. The advantages of this valve are high strength, resistance to corrosion, versatility in size and application, and durability. However, these valves are heavy and expensive compared to other valves, such as stainless steel and brass.