Factors to Consider When Choosing Between Aluminum and Stainless Steel Slide Gate Valves for Your Water Facility

In water treatment plants and distribution systems, regulating water flow is essential. The slide gate valve is a type of gate valve specifically designed for this purpose. In general, Slide gate valves are made from aluminum or stainless steel. Various factors, including the specific application, budget, and environmental conditions, influence the choice between these materials.  But first, let's list the roles of slide gate valves in the water industry:

1. Flow Regulation: The primary purpose of a slide gate valve is to regulate the flow of water. By opening or closing the gate, the operator can control the amount of water that passes through the system.
2. Isolation: These valves can act as an isolation mechanism, allowing the shutdown of specific sections of the treatment or distribution system for maintenance, repairs, or emergencies.
3. Level Control in Reservoirs and Basins: In water treatment plants, certain processes require maintaining water at specific levels in tanks, basins, or reservoirs. Slide gate valves can control these levels by adjusting the flow in or out.
4. Backflow Prevention: In some configurations, slide gate valves prevent backflow, protecting treated water from potential contamination.

Next, let's look into the construction and application differences between aluminum and stainless steel slide gate valves:

Aluminum Slide Gate Valves:

• Lightweight: Aluminum is less dense than stainless steel, making aluminum slide gate valves relatively light, simplifying installation, particularly in scenarios where weight can be a limiting factor.
• Corrosion Resistance: Aluminum forms a protective oxide layer naturally when exposed to air, giving it a degree of corrosion resistance. However, it may be more susceptible to corrosion in specific environments than stainless steel, especially in saline or highly alkaline conditions.
• Cost-Effective: Aluminum slide gate valves are generally less expensive than their stainless steel counterparts.

Stainless Steel Slide Gate Valves:

• Strength: Stainless steel is more robust than aluminum, allowing these valves to handle higher pressures and stresses.
• High Corrosion Resistance: Stainless steel's corrosion resistance is greater than aluminum's, particularly when the material is exposed to aggressive chemicals or saline environments.
• Durability: Due to its strength and resistance to corrosion, stainless steel slide gate valves tend to have a longer service life than aluminum valves, especially in challenging conditions.
• Higher Cost: Stainless steel materials generally cost more than aluminum, leading to a higher price point for these slide gate valves.

Aluminum Slide Gate Valve Application:

• General Water Treatment: Suitable for standard water treatment applications where the water's pH and salinity do not pose significant corrosion risks.
• Distribution Systems: Useful in systems where lightweight components are preferred for ease of installation or maintenance.
• Stormwater Management: Employed in systems that don't expose the valve to particularly aggressive conditions.

Stainless Steel Slide Gate Valve Applications:

• Wastewater Treatment: Particularly effective in wastewater treatment plants where the water might contain a range of chemicals, which can be corrosive.
• Desalination Plants: Given the saline nature of the input water, stainless steel's superior resistance to salt-induced corrosion makes it the material of choice in desalination facilities.
• Chemical Dosing Areas: In sections of water treatment facilities where chemicals are added, stainless steel valves can better resist potential chemical corrosion.
• High-Pressure Scenarios: Due to their strength, stainless steel slide gate valves are suitable for applications requiring the handling of high pressures.

While aluminum and stainless steel slide gate valves have their merits, the choice between them often boils down to the application's specific needs and the environment in which the valve will operate. Careful consideration of factors like corrosion potential, pressure requirements, and budget constraints will help select the most suitable material for a given setting in the water industry. Automatic Controls of Virginia offers expert guidance in selecting the optimal material for your specific valve application. Numerous businesses rely on their proven engineering methodologies and extensive experience in the valve industry, ensuring a technically sound and efficient valve solution for your operational needs.

For more information, contact:
Automatic Controls of Virginia
https://acva.com
(804) 752-1000

Protecting Drinking Water Pipelines with Inflow Prevention

Protecting Drinking Water Pipelines with Inflow Prevention was written to assist water distribution system design engineers in reducing the risk to public health from contaminated drinking water by understanding the use of inflow preventer assemblies in water distribution systems.

This paper is not intended to provide all of the information necessary for specifying these devices, but rather to explain their function and performance criteria along with common engineering parameters associated with the application of air valves and cross connection control devices. Successful system design should consider the functions of the air valves and vents together with the need to protect the system from contamination and loss of efficiency.

With this knowledge, the design engineer can better apply American Water Works Standard C514 and American Society of Sanitary Engineering (ASSE) Standard 1063 Inflow Preventers and understand the application, sizing, installation guidelines and code applications that affect their use. The rating information provided is based on generally accepted products and standards which offer valuable information for predicting performance.

---

DOWNLOAD THE FULL WHITE PAPER FROM THIS ACVA WEB PAGE

---

For more information about the proper application of pressure instrumentation, contact Automatic Controls of VA by visiting https://acva.com or by calling (804) 752-1000.

American Water Works Association Valve Standards and Descriptions

The American Water Works Association (AWWA), the leading non-profit, scientific and educational association dedicated to water management and treatment. AWWA members include water utilities, treatment plant operators and managers, and manufacturers. The AWWA maintains and regulates the design and performance standards of valves and actuators used in municipal water treatment and distribution systems.  The following are the standards with links for additional information:

AWWA C500-09 Metal-Seated Gate Valves for Water Supply Service

This standard describes iron-body, brass-mounted, non-rising stem (NRS) gate valves, including tapping gate valves, 3-in. (75-mm) NPS through 48-in. (1,200-mm) NPS, and outside screw and yoke (OS&Y) rising-stem gate valves, 3-in. (75-mm) NPS through 24-in. (600-mm) NPS, with either double-disc gates having parallel or inclined seats, or solid-wedge gates. These valves are suitable for use in approximately level settings in water systems. These valves are intended for applications where fluid velocities do not exceed 16 ft/sec (4.9 m/sec) when the valve is in the fully open position. The major revisions in this edition of ANSI/AWWA C500 include the following: editorial changes to conform to current AWWA form and content; permitting the use of stainless-steel stems and reduced-thickness ductile-iron flanges; addition of stainless steel as a stem material; addition of a "non-integral thrust collar" for stems in NRS valves; addition of aluminum-bronze and silicon-bronze copper alloys; provision for reduced flange thickness for end flanges of ductile-iron flanged valves; addition of 14-in. and 18-in. valve sizes; and, addition of metric fasteners and socket head fasteners.

AWWA C510-07 Double Check Valve Backflow Prevention Assembly

This standard describes the double check valve back flow prevention assembly. The assembly shall be for operation on hot or cold water lines and capable of withstanding a working water pressure of at least 150 psi (1,034 kPa) without damage to working parts or impairment of function. This standard describes hot- and cold-water double check valve back flow prevention assemblies. Assemblies shall be designed to operate at a minimum temperature range of 33ºF to 140ºF (1ºC to 60ºC). Hot water assemblies shall be designed to operate, at a minimum, in water at a temperature range of 33ºF to 180ºF (1ºC to 82ºC). A complete assembly consists of two internally loaded, independently operating check valves, located between two tightly closing resilient-seated shutoff valves, with four properly placed resilient-seated test cocks (see Sec. 4.3.1.3). Major revisions made to the standard in this revision include the following: AWWA standard materials statement has been added (Sec. III.A.2 and Sec. 4.1); synthetic coating of ferrous bodies has been removed (Sec. 4.1.2); the material callouts have been updated (Sec. 4.1.3); the identification of nominal size of the assembly has been revised (4.2.1.1); the requirements for structural capability and operational capability have been revised (Sec. 4.2.2.1 and Sec. 4.2.2.2); the sections on area of waterways, clearance of moving parts, facing rings for poppet-type valves, facing rings for swing-type valves, and bushings have been removed (former Sec. 4.3.1.2 through Sec. 4.3.1.6); the requirements for shutoff valves have been updated (Sec. 4.3.1.6); requirements for operational cycle testing have been added (Sec. 4.3.2.3); and, requirements for replacement parts have been added (Sec. 4.3.4).

AWWA C507-11 Ball Valves, 6 in. through 60 in. (150 mm through 1,500 mm) 

This standard covers gray-iron, ductile-iron, and cast-steel, flanged-end, low-leakage, shaft- or trunnion-mounted, full-port, double- and single-seated ball valves for pressures up to 150 psi (1,050 kPa) in sizes 6-in. through 60-in. (150-mm through 1,500-mm) diameter and pressures up to 300 psi (2,100 kPa) in sizes from 6-in. through 48-in. (150-mm through 1,200-mm) diameter for use in water, wastewater, and reclaimed water systems having water with a pH greater than 6 and less than 12 and with temperatures greater than 32ºF (0ºC) and less than 125ºF (52ºC). Design fluid velocity - the valve assembly shall be structurally suitable for a port fluid velocity of 35 ft/sec (10.7 m/sec) at design pressure and shall be within the allowable stresses noted in Sec. 4.3.1. Pressure class and rated/design pressure - the classes of valves discussed in this standard shall be designed for the maximum rated pressure. Rated pressure is defined as the design pressure at 100ºF (38ºC). The major changes made in this revision of the standard include the following: added sizes 54 in. and 60 in. (1,350 mm and 1,500 mm); added paragraph 25 in Section III regarding the consideration of requiring pulls less than 80 lb (356 N) for hand-wheels and chainwheels; added paragraphs 1.4 on Valve Construction and 1.5 on Description of Operation to Sec. 1, General; revised Table 1 in Sec. 4.3, Port diameter and minimum body shell thickness, to require that the wall thicknesses of ductile-iron construction be the same wall thicknesses as cast steel construction; added paragraph 4.3.9.4 on design methodology for the valve shafts; revised the metal-seat leakage requirements in Sec. 5.1.2.3; revised coating requirements in Sec. 4.4.3; added actuator pressure rating and actuator flow rating to nameplate requirements; and, added Appendix A on Installation, Operation, and Maintenance of Ball Valves.

AWWA C509-09 Resilient-Seated Gate Valves for Water Supply Service

This standard describes iron-body, resilient-seated gate valves with non-rising stems (NRS) and outside screw-and-yoke (OS&Y) rising stems, including tapping gate valves, for water supply service having a temperature range of 33º-125ºF (0.6º- 52ºC). These valves are intended for applications where fluid velocity does not exceed 16 ft/sec when the valve is in full open position. Major revisions made to the standard in this edition include the following: editorial changes to conform to current AWWA form and content; addition of reduced-thickness ductile-iron flanges; addition of stainless-steel alloys for use as a stem material; permitting the use of non-integral thrust collars for stems in NRS valves; addition of aluminum-bronze and silicon-bronze copper alloys; addition of 14-, 18-, and 36-in. valve sizes; addition of socket head and metric fasteners; requirement to use an anti-seize compound with stainless-steel bolts and nuts; and, removal of maximum phosphorus content.

AWWA C515-09 Reduced-Wall, Resilient-Seated Gate Valves for Water Supply Service

This standard describes reduced-wall, resilient-seated gate valves with non-rising stems (NRS) and outside screw-and-yoke (OS&Y) rising stems, including tapping gate valves, for water supply service having a temperature range of 33º to 125ºF (0.6º to 52ºC). These valves are intended for applications where fluid velocity does not exceed 16 ft/sec (4.9 m/sec) when the valve is in the fully open position. Major revisions made to the standard in this edition include the following: revised to cover 42-in. NPS and 48-in. NPS sizes; revised to include integral and non-integral thrust collar stem designs; revised to include reduced flange thickness for flanged-end valves; revised to include socket head and metric fasteners; added additional copper alloys to Table 5; and, revised to include the use of stainless-steel components (Sec. 4.2.3.5).

AWWA C504-10 Rubber-Seated Butterfly Valves, 3 In. (75 mm) through 72 In. (1,800 mm)

This standard establishes minimum requirements for rubber-seated butterfly valves, 3 in. (75 mm) through 72 in. (1,800 mm) in diameter, with various body and end types, for fresh water having a pH range from 6-12 and a temperature range from 33º-125ºF (0.6º-52ºC). This standard covers rubber-seated butterfly valves suitable for a maximum steady-state fluid working pressure of 250 psig (1,723 kPa), a maximum steady-state differential pressure of 250 psi (1,723 kPa), and a maximum fully open fluid velocity of 16 ft/sec (4.9 m/sec) based on nominal valve size. The major revisions made to the standard in this edition include the following: permeation language was moved to the Foreword under Special Issues, Sec. II.C; and, new requirements were provided for mechanical-joint-end valves.

AWWA C542-09 Electric Motor Actuators for Valves and Slide Gates

This standard describes electric motor actuators for valves and slide gates in water, wastewater, and reclaimed water utility systems. Electric motor actuators are designed to produce a multi-turn rotary motion output to actuate a multi-turn valve or gate, or to actuate an external gear head for quarter-turn valves. Electric motor actuators not requiring external gear heads for quarter-turn valves are defined in Sec. 4.4.1.2. This is the first edition of this standard, and therefore, there are no revisions.

AWWA C508-09 Swing-Check Valves for Waterworks Service, 2-In. through 24-In. (50-mm through 600-mm) NPS

This standard describes only iron body, non-assisted, swing-check valves, 2-in. through 24-in. (50-mm through 600-mm) NPS, with mechanical-joint or flanged ends that are installed in approximately level settings in water systems. The manufacturer should be consulted for special conditions. Check valve sizes described in this standard are 2-, 2 1/2-, 3-, 4-, 6-, 8-, 10-, 12-, 14-, 16-, 18-, 20-, and 24-in. (50-, 65-, 75-, 100-, 150-, 200-, 250-, 300-, 350-, 400-, 450-, 500-, and 600-mm) NPS. Sizes refer to the nominal diameter of the waterway through the inlet and outlet connections and the seat ring. Major revisions made to the standard in this edition include the following: the pressure ratings were revised in Sec. 1.1.4; standard end-to-end dimensions were moved from the appendix to the body of the standard in Sec. 4.4.2 and Table 2; new ductile-iron flange thicknesses were added to Sec. 4.4.7.1 and Table 3; and, a new appendix titled "Installation, Operation, and Maintenance of Swing- Check Valves for Waterworks Service" was added.

AWWA C512-07 Air-Release, Air/Vacuum, and Combination Air Valves for Waterworks Service 

This standard describes 1/2 in. (13-mm) through 6 in. (150-mm) air-release valves and 1/2 in. (13-mm) through 20-in. (500-mm) air/vacuum and combination air valves having gray cast-iron or ductile-iron bodies and covers. The valves are designed for use in water systems with maximum working pressures of 300 psig (2,070 kPa [gauge]) and water temperatures ranging from above freezing to a maximum of 125ºF (52ºC). Major changes made to the standard in this revision include the following: added requirements for throttling devices in Sec. 4.3.3; and, added requirements for slow-closing devices in Sec. 4.3.4.

AWWA C517-09 Resilient-Seated Cast-Iron Eccentric Plug Valves

This standard describes resilient-seated cast-iron eccentric plug valves, 3 in. (75 mm) through 72 in. (1,800 mm) in diameter, with flanged, grooved, or mechanical-joint ends, for water, wastewater, and reclaimed water systems having a pH range from 6 to 12 and a temperature range from 33ºF to 125ºF (0.6ºC to 52ºC). The minimum design pressure shall be 175 psig (1,208 kPa) for 3 in. through 12 in. (75 mm through 300 mm) sizes and 150 psig (1,034 kPa) for 14 in. through 72 in. (350 mm through 1,800 mm) sizes. Major changes made to the standard in this revision include the following: expanded Scope and Purpose to include wastewater and reclaimed water service; added references to ANSI/AWWA Standards C541 and C542 for power actuator requirements; and, removed contractual language from the body of the standard.

AWWA C541-08 Hydraulic and Pneumatic Cylinder and Vane-Type Actuators for Valves and Slide Gates

This standard describes hydraulic and pneumatic cylinder and vane-type actuators for operation of valve and slide gates in utility systems. This is the first edition of this standard, and therefore, there are no revisions.