Which is more commonly used, gate valve or globe valve?

The degree of common use of gate valves and globe valves depends on the specific usage scenarios and needs, and it is impossible to generalize which one is more commonly used.

Gate valves and globe valves both play an important role in industrial control. The gate valve drives the gate plate to move up and down in the channel through the valve stem to achieve opening and closing. The structure is clear and the operation is convenient. It is particularly suitable for environments that require rapid opening and closing or handling of large amounts of fluids, such as the switch control of water, oil, and other pipelines. The globe valve, with its unique 90-degree rotating valve disc design, compact structure, and excellent sealing performance, is often used in situations where precise control of fluid flow is required, such as the cutoff and regulation of steam and liquid.

Therefore, when choosing a gate valve and a globe valve, it is necessary to decide based on the specific usage scenarios and needs. If you need to open and close quickly or handle a large amount of fluid, a gate valve may be more suitable; if you need to precisely control the fluid flow or require higher sealing performance, a globe valve may be more commonly used.

What are the Defining Features of a Heavy Pattern Brass Gate Valve?

In the world of fluid control, not all valves are created equal, even within the same material family. Brass gate valves, commonly used for water, oil, and gas applications, are typically available in standard and heavy pattern designs. The "heavy pattern" designation refers to a valve that is constructed with increased wall thickness, larger dimensions, and more robust components compared to its standard counterpart. This enhanced construction is not for handling higher pressures alone, but for withstanding more demanding service conditions, including thermal stress, mechanical shock, and prolonged wear.

The primary characteristic of a heavy pattern brass gate valve is its increased durability. The thicker body and bonnet walls provide a greater margin of safety against cracking or distortion under pressure surges or line stress. The stem is often of a larger diameter, reducing the risk of bending or shearing during operation. Furthermore, the gate and seat areas are more substantial, which can extend the valve's service life in applications where frequent cycling or minor abrasive particles are present. While both standard and heavy pattern valves may be rated for similar cold working pressures, the heavy pattern valve's additional mass and strength make it a consideration for industrial settings, commercial buildings, or critical applications where long-term reliability is prioritized over initial cost.

What are the Corrosion Resistance Properties of Chemical Globe Valves?

In chemical processing industries, the selection of valve materials is primarily dictated by their ability to resist corrosion from a wide spectrum of aggressive media. Chemical globe valves, valued for their precise flow control and shut-off capabilities, are constructed from a variety of materials chosen for their specific corrosion resistance properties. The performance of these valves is not just a function of the base material, but also of the internal "trim" components—the stem, disc, and seat—which can be different materials optimized for the service conditions.

Stainless steel, particularly grades like 304 and 316, is a common choice. Grade 316 stainless steel, with its addition of molybdenum, offers improved resistance to pitting and crevice corrosion in chloride-containing environments compared to 304. For more demanding applications, alloys with higher chromium, nickel, and molybdenum content are used. Alloy 20 (Carpenter 20) provides good resistance to sulfuric acid and many other corrosive chemicals. Hastelloy C (a nickel-chromium-molybdenum alloy) is noted for its resistance to oxidizing and reducing acids, including nitric and hydrochloric acid. Duplex and Super Duplex stainless steels, with a mixed austenitic-ferritic microstructure, offer high strength and resistance to chloride stress corrosion cracking.

Beyond metallic valves, chemical globe valves are also manufactured from non-metallic materials. PVC, CPVC, and Polypropylene valves offer broad corrosion resistance to acids, bases, and salts at moderate temperatures. PTFE (Teflon) or PFA-lined valves provide nearly universal chemical inertness, making them suitable for handling the aggressive chemicals, such as hydrofluoric acid or hot concentrated acids. The corrosion resistance of a chemical globe valve is therefore a system property. It involves matching the wetted materials—both body and trim—to the specific chemical, concentration, temperature, and pressure of the process to ensure leak-free operation and a extended service life.

What Design Considerations are Important for Marine Industrial Valves?

Valves used in marine and offshore environments face a unique set of challenges that demand specific design considerations. The combination of a corrosive atmosphere, constant motion, limited space, and the critical need for operational reliability dictates a rigorous approach to valve selection and engineering. Marine industrial valves must be designed to perform consistently in conditions that would rapidly degrade standard industrial equipment.

A primary design consideration is corrosion resistance. The salt-laden marine atmosphere is highly corrosive to carbon steel. Consequently, marine valves are often constructed from corrosion-resistant materials such as bronze, brass, stainless steel (particularly 316/L), or duplex stainless steels. For larger cast steel valves, robust protective coatings and cathodic protection systems are typically specified. The design must also account for galvanic corrosion, which can occur when dissimilar metals are in contact in an electrolyte like seawater, influencing material pairing choices.

Onboard ships and offshore platforms, space is at a premium, and overall weight impacts stability and fuel efficiency. Marine valves are often designed with more compact face-to-face dimensions compared to their land-based equivalents, as defined by standards like MSS SP-134. Operational reliability under dynamic conditions is also essential. Valves must be designed to function effectively even when the vessel is experiencing pitch and roll. This can influence the design of actuation systems and the internal geometry of check valves to ensure proper closing. Furthermore, fire safety is a paramount concern. Critical valves in fuel and cargo systems must comply with fire-safe design standards, such as API 607 or API 6FA, which require the valve to maintain a seal for a specified period during a fire. Finally, ease of maintenance and repair in a confined, remote environment is a driving factor behind design choices for stem packing, bonnet bolting, and the ability to replace seals without removing the entire valve from the line.