Three Common Questions & Answers in China Valve Industry

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Common Inquiries Regarding Chinese Valves

Inquiry 1: How Do Rising Stem and Non-Rising Stem Gate Valves Differ?

Definition & Configuration of Rising Stem and Non-Rising Stem Valves in China

Both Rising-stem and Non-rising-stem configurations are prevalent in gate valve manufacturing.

In a Rising-stem gate valve, the stem is attached to the closure element (gate disc) and remains stationary, moving perpendicularly away from the flow when the handwheel is turned. As the handwheel rotates, the thread of the stem above the packing box retracts the gate from the flow stream, resulting in the stem rising above the handwheel. The connection between the handwheel and the stem converts the rotary motion of the handwheel into the linear motion required for the stem.

Conversely, a Non-rising-stem gate valve features a stem threaded to the gate disc with a nut. The gate's movement is linear along the stem while the handwheel turns, allowing the stem to rotate without rising.

The distinctive characteristics of rising and non-rising stem gate valves are:

Rising stem valves are primarily designed with an outside screw and yoke (OS&Y) mechanism, which keeps the stem threads insulated from contact with the medium, whereas the threads of a non-rising stem are exposed. As a result, the rising stem can be lubricated easily, while non-rising stems are more prone to corrosion. The position of a rising stem valve can be easily monitored on-site, unlike a non-rising stem valve which needs a position indicator to show the valve's status. Non-rising stem gate valves are usually preferred in spaces with restrictions and are generally more affordable compared to their rising counterparts of the same size and rating.

Inquiry 2: What is the Distinction Between Reduced Bore and Full Bore Valves?

The fundamental disparity between full bore and reduced bore valves lies in their sizing.

A full bore valve features a bore diameter equivalent to the internal diameter of the associated piping, while a reduced bore valve possesses a narrower bore diameter. For instance, in a 4-inch full bore ball valve, the internal bore is also 4 inches; in contrast, the internal diameter in a reduced-standard ball valve is only 3 inches.

Full bore ball valves are advantageous in situations where low flow resistance is critical, such as on pump suction pipes, where pressure fluctuations can compromise performance. They are also ideal for handling flows with mixed liquids and solids, which may experience blockages if flow is restricted. Standard (reduced)-port ball valves are typically used in applications where pressure loss and material behavior are not significant concerns, offering advantages of reduced size and cost.

If stringent flow rate requirements aren’t in place, selecting a standard (reduced) port valve could be economical while reducing overall weight.

Inquiry 3: What Does CS ENP Stand For?

Inquiry 3: What Does CS ENP Stand For?

For additional information from an industrial valve manufacturer, please reach out to us. We will deliver expert responses.

In some ball valves, the trim is characterized as 'CS ENP 75 micron.' What do COB and ENP signify?

CS refers to Carbon Steel, while ENP signifies Electroless Nickel Plated for Chinese valve balls. The industrial valve bodies (including ball valves, globe valves, and wafer check valves) may undergo ENP plating for several reasons.

ENP's Role for Valve Balls in Ball Valves:

Corrosion Resistance: The primary use of electroless nickel technology is to provide exceptional defense against corrosion in diverse aggressive environments. ENP serves as a protective barrier that creates a sealed coating, effectively shielding against corrosive substances. This contrasts with sacrificial coatings, like zinc, which protect the substrate by self-sacrifice.

Deposit Hardness: Hardness of the deposit is a significant feature of ENP coating. Influencing factors include film composition, heat treatment temperature, and duration. Typical micro-hardness for as-plated ENP deposits ranges between 500 to 720 VHN, compared to electronically deposited nickel typically around 150-400 VHN.

Wear Resistance: Electroless Nickel Phosphorus coatings are chosen for various applications due to their wear resistance. This is mainly due to their inherent hardness, self-lubrication, excellent corrosion protection, and uniform deposits. The wear characteristics of ENP layers can be augmented by introducing inert particles such as PTFE or Silicon Carbide to formulate a composite coating.

If tasked with selecting industrial valves for a project or maintenance and provided specifications, congratulations!

However, have you thoroughly considered whether the given specifications are accurate, and if the chosen valves will adequately serve their purpose?

Several assumptions often accompany valve selection, including:

• &; this is what we used before; but in a completely different application

• &; contractor X advised this; based on what evidence?

• &; the site standard is X; but will that valve type function effectively in this circumstance?

• &; we have always opted for this; yet have been facing frequent malfunctions and downtime

Choosing the right valve selection from the outset is of utmost importance, and in this article, I will guide you through a straightforward 10-step process to ensure that your valve selection is founded on facts rather than assumptions.

If you seek further details, please visit industrial valve supplier.