The Ultimate Buyer's Guide for Purchasing Hard Chrome Plating Valve Balls

Ball valves may be small, but they are critical components in many industrial applications. Because ball valves control the flow of fluids, they see extensive use across just about every industry. It’s important to know how to tell which industrial ball valves are best for different applications, especially those involving hazardous chemicals, which can easily destroy some types of valves.

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Corrosion poses serious financial risks to any industry, as well as obvious structural risks. According to the National Association of Corrosion Engineers and the U.S. Federal Highway Administration, the total annual cost of corrosion in the United States across all industries is approximately $276 billion, or about 3% of the United States’ GDP. Your company can reduce your risk of financial loss from corrosion, though, by using chemical-resistant ball valves.

At RG Group, our Parker ball valves offer heavy-duty durability to fight against chemical corrosion. The premium quality and reliability of this brand of ball valve make it stand out from the rest. Our Parker valves function reliably in temperatures ranging from 0 to 360 degrees Fahrenheit, and they can withstand pressures of up to 6,000 psi. They come in a variety of styles, materials and diameters optimized for different industries and applications.

The wide variety of valve types on the market means finding the right ball valve can be tricky. Fortunately, we’ve put together this handy ball valve buying guide. Below, we’ll explain the benefits of chemical-resistant ball valves and help you figure out how to choose the ball valve that’s right for your application.

Types of Ball Valve Body Styles

Ball valves come in a few different styles:

1. Trunnion-Mounted Ball Valves

Trunnion-mounted ball valves contain a pivoting point where a shaft rotates inside part of a cylinder. This construction allows for shutoff and switching through the use of upper and lower bearings. The additional top-and-bottom anchoring of trunnion-style valves also keeps the ball from floating in the fluid. This construction allows for larger valves that function at peak performance in high-pressure operations and with higher flow capacity because the ball has more support, which reduces the friction against it.

RG Group’s trunnion-mounted ball valves can withstand pressures of up to 10,000 psi and provide dependable switching and shutoff capabilities. The design of the upper and lower bearing in these high-pressure ball valves helps provide seizure resistance and extend the valve’s lifespan, even in rigorous applications.

2. Floating Ball Valves

Floating ball valves are one of the most common types of ball valves. Their free-floating ball design allows for strong performance even under challenging pressure and temperature conditions. Unlike the balls in trunnion-mounted valves, the balls in floating ball valves are attached only to the valve stem. The advantage of this construction is that the ball can float in the liquid and press against the seat of the valve, creating a positive seal. A positive seal is useful because it allows for zero leakage from the valve, an essential quality in many gas operations, among others.

These ball valves are designed for process and instrumentation applications and can streamline fluid flow to enhance those operations. They offer rapid on-off control and can withstand pressures of up to 6,000 psi and temperatures of up to 450 degrees Fahrenheit.

These valves are useful in facilities such as chemical plants, refineries, power plants and petrochemical plants. They provide a range of functionalities, including flow diversion and flow selection, and are often critical parts of quick-fill systems, process-mixing systems, instrument panels and remote shutoff with actuation. They are also typically less expensive than trunnion designs.

RG Group’s floating ball valves are generally available in stainless steel and brass, with specific alloys available upon request. The ball bearings feature microfinishes for a positive seal, and the valves allow for a straight flow path that reduces pressure drop. Our products also offer optional features such as pneumatic and electric actuation, live-loaded PTFE stem seals, nonadjustable O-ring stem seals, upstream and downstream drain models and stainless steel and extended handles.

3. Rising-Stem Ball Valves

Rising-stem ball valves contain a stem that allows the ball to tilt within the valve. When the valve is closed, the ball nestles snugly against the seat – the disc-shaped material designed to provide a watertight seal. When the valve is open, the ball moves away from the seat, allowing liquid to flow around it. This capacity for repositioning prevents the ball from rubbing against the seat and causing the valve to fail. It decreases wear and minimizes the need for maintenance.

Ball Valve Port Styles

In addition to their different body types, ball valves also come with different port configurations. The ball of a ball valve typically contains a port, or a bored opening, through its center. When the bore is aligned with the valve body, liquid can flow through. When the valve is rotated 90 degrees and the bore is perpendicular to the valve body, liquid can no longer pass through. These ports are designed in different ways for optimization in a variety of applications.

1. Full-Port Ball Valves

A full-bore ball valve has a sizeable ball with a large bore diameter—often the same size as the valve pipe itself. This large orifice allows for a higher flow of liquid, thus reducing friction and pressure loss. The large bore diameter is also ideal for valves that may clog and require pigging to remove the blocked material.

2. Reduced-Port Ball Valves

Reduced-port ball valves have smaller ports to restrict the flow of liquid within a narrower path. These valves are typically smaller and less expensive, and they are useful in applications where pressure loss is a minimal concern.

3. V-Port Ball Valves

In a V-port ball valve, either the ball or the seat of the ball contains a V shape. The advantage of the V shape is that it allows the valve to open and close more easily. When the valve is closed, the smaller, V-shaped end typically opens first, allowing for greater stability and control of liquids’ velocities. For this reason, V-port ball valves often function as control valves, especially in industries such as the paper, chemical and power industries. However, because they require more stability to function, these valves are not suitable for use in all applications.

Ball Valve Body Materials

Ball valve bodies come in a few different types of materials. The three most popular materials we offer at RG Group are brass, carbon steel and stainless steel, but many other possibilities exist as well.

1. Brass and Chrome-Plated Brass

Brass ball valves offer the virtue of reliable performance at an economical price. They typically feature a brass body with a chrome-plated brass ball, and they provide superior corrosion resistance over plastic valves while remaining feasible for most budgets. Our brass ball valves offer long-lasting operation and come with a variety of options to suit different applications. In addition to being corrosion-resistant, they are heat-resistant as well. They function well at temperatures ranging from -50 degrees Fahrenheit up to 450 degrees Fahrenheit.

Unlike other types of ball valves made of materials such as bronze, brass ball valves contain very little lead, so they are safer for use in applications where lead contamination is a concern.

Brass is also a key component of Parker brass compression fittings. These utilize a brass compression piece to compact around the pipe and hold the valve securely in place.

2. Carbon Steel

Carbon steel ball valves are exceptionally rugged and durable. They typically consist of carbon steel bodies with steel balls, and they are designed for demanding applications in which valves must stand up over time to harsh working conditions. They are often used in heavy-duty truck manufacture and agricultural, construction and industrial applications.

Carbon steel ball valves are useful for fuel line shutoffs in gasoline- and diesel-powered equipment and are also common features of hydraulic lines and in plant design plumbing that requires complete shutoff capability. They can function effectively in temperatures ranging from -20 degrees Fahrenheit to 425 degrees Fahrenheit.

3. Stainless Steel

Stainless steel ball valves are well suited for all-purpose industrial use because of their excellent chemical resistance. They provide the best corrosion resistance of any of the ball valves we offer. They can stand up to the harshest chemical conditions and are particularly recommended for use in marine environments because they resist the corroding effects of saltwater as well.

Stainless steel ball valves are often used in industries such as petrochemical, steel, agricultural and food processing. They are also common components of fuel lines, chemical lines, washdowns and plant plumbing that requires complete shutoff capability.

4. Bronze

Bronze ball valves are resistant to cracking because of the high malleability and ductility of bronze. Bronze ball valves also resist corrosion very well and are relatively inexpensive, providing beneficial cost savings to many industries when compared to valves made of materials like brass. They are often used for direction control, flow shutoff and a variety of other functions.

5. Chrome

Chrome is useful for making ball valves because it provides strong resistance against wear over time. It also helps the ball move smoothly as the valve opens and closes and allows for excellent corrosion resistance. Chrome is more porous than many other materials, though, so if a chrome valve contains chrome plating over another metal, the porous nature of the chrome can sometimes allow water to seep through and corrode the underlying ball structure.

Many ball valves have a protective coating made of materials like chrome. A chrome coating can make a ball valve as hard and resistant as stainless steel. It is susceptible to corrosion by seawater and chlorine, however.

6. Titanium

Titanium provides a high level of corrosion resistance and abrasion resistance for ball valves. It is an ideal material for ball valves that will be used in high-pressure acid leaching (HPAL) scenarios, which make use of highly corrosive acids, often 98% sulfuric acid. Titanium ball valves are also ideal in pressure oxidation (POX) applications, such as in autoclave plants for steam sterilization. They are optimal for use in plant maintenance and emergency shutdown applications.

7. Nylon

Nylon valves are common across a range of industries. They are inexpensive to produce and have good chemical and mechanical qualities.

One of the nylon-bodied ball valves RG Group offers is the mini ball valve. The nylon construction of this ball valve makes it lightweight and ideal for use in compact operations and where quick installation times are a priority. These valves offer full flow capacity and stable performance. They are often used in pneumatic applications, as well as in factory and process automation, packaging, petrochemical facilities, semiconductors, machine tools, robotics, vacuum lines and textile operations.

8. PVC

Plastic ball valves like PVC valves are useful because of their high corrosion resistance. Because they are plastic rather than metal, they provide superior resistance to rust and corrosion, and they are also more inexpensive to manufacture than many metal ball valves. Because of their light weight, they are also economical to ship. They are not suitable for certain demanding industries because they cannot stand up to the same temperatures and pressures that metal valves can. But in many applications, such as in swimming pools or irrigation systems, they make an excellent cost-effective alternative to metal valves.

9. Polypropylene

Polypropylene ball valves, also made from plastic polymers instead of metal, provide extreme resistance against harsh chemicals and corroding agents. These ball valves are ideal for applications such as water filtration units, coffeemakers, cold beverage machines and other applications whose parts need to stay in pristine condition.

Chemical Resistance of Ball Valve Seals

The seal is one of the most important ball valve components. The seal forms a tight connection between the ball and the seat material to prevent liquids from passing through when the valve is closed. The right seal can make an enormous difference in functionality, maintenance time and costs.

Common ball valve seal materials include the following:

• EPDM: EPDM rubber is a type of synthetic rubber made of ethylene, propene and a diene monomer. It is one of the best-performing types of seal materials and provides a particularly effective seal in hot water and steam. It is also optimal for use with alcohols, low concentrations of acids and alkaline substances and more. It has limited resistance to grease, oils and solvents, however.
• FKM: FKM is a fluoroelastomer that provides more heat and chemical resistance than most rubbers. It offers resistance to a broad spectrum of chemicals and is also resistant to many oils. It does not perform as well with hot water and steam, though, because it tends to expand at high temperatures.
• PTFE: PTFE — commonly known as Teflon — is hard and rigid, unlike EPDM and FKM. It is resistant to many chemicals, though, and its hardness allows it to withstand extreme temperatures and pressures.
• NBR: NBR is nitrile rubber. It provides strong resistance to compression and wear, and it stands up well to alcohols, oils and nonpolar solvents. It is sensitive to fluctuations in weather and temperature, though.

Ball Valve Applications

Ball valves find uses in a number of different industries and applications, from gas processing and oil refining to fuel lines, flowing systems on ships and many more. The rugged performance of chemical-resistant ball valves makes them incredibly well suited to demanding manufacturing and industrial environments.

Industries that involve hazardous chemicals need the right kind of valves to ensure that their processes run efficiently and effectively. Chemical-resistant valves have the durable construction to withstand harsh, hazardous substances and keep performance high and maintenance requirements minimal.

Contact RG Group for Chemical-Resistant Metric Ball Valves

In any industry, it’s important to choose the right ball valves, and it’s also important to have the facts you need to make an informed decision. The consequences of choosing the wrong ball valves can have a dramatic impact on your business, so it’s always best to get the decision right the first time.

Partner with RG Group for the best motion control and fluid handling solutions and quality products. We can help you figure out how to find the right ball valve for your specific application. And the technical expertise of our engineers means we can answer your questions about choosing chemical-resistant ball valves and give you the highly functional and long-lasting products you need.

“Realize now the power that your words command if you simply choose them wisely.” – Tony Robbins

Valve Terminology & Glossary

Accumulator – A vessel in which a gas is trapped and compressed by the liquid in a hydraulic system, thus storing energy to supply liquid under pressure to the system when needed.

ACME Thread – A flat-topped screw thread for power transmission. This thread has a 29- degree included angle between adjacent thread faces compared with the 60-degree angle of the US standard V thread.

Actuator – Used to operate a valve using electric, pneumatic or hydraulic means. Often used for remote control or sequencing of valve operations.

(AISI) American Iron and Steel Institute – An association of steelmakers that sets standards for the chemical and physical properties of steel and iron in various shapes and forms – pipe, tubing, sheet, strip, and wire.

Alloy steel – A steel consisting primarily of iron with some percentage of one or more other elements such as chromium, nickel, manganese, or vanadium deliberately added to enhance its properties.

Ambient Temperature – The prevailing temperature of the environment immediately surrounding an object.

Angle Valve – A variation of the globe valve in which the end connections are at right angles to each other, rather than being in-line.

(ANSI) American National Standard Institute – The principle organization in the US that oversees the creation, promulgation and use of standards for a wide variety of items, including the design, fabrication, and testing of pressure piping, systems, and components for various pipeline services.

(API) American Petroleum Institute – The principal US oil company trade association.

It has some standards and specification writing functions, such as wellhead components and pipeline valves.

(ASME) American Society of Mechanical Engineers – This professional society publishes technical books, papers, codes, and standards. Of principal interest is the ASME Boiler and Pressure Vessel Code which is referenced for many aspects of valve making.

(ASTM) American Society for Testing and Materials – A professional society governing the detailed physical and chemical analysis of all basic metals and alloys used in construction. The valves of most manufacturers have components whose materials correspond to ASTM standards.

Atmospheric Pressure – The external pressure exerted on a body by the atmosphere: 14.7 psi (absolute) at sea level.

Austenitic stainless steel – The common stainless steel, where the primary microstructure is austenite and the composition primarily iron but also includes both chromium and nickel. The steels are designated as 300 series such as 304, 316, CF8M, etc.

(AWS) American Welding Society – A society which sets guidelines and standards for all welds.

BBL (bbl) – An abbreviation for “barrel”. Used to express liquid volume. One barrel of oil is equal to 42 US gallons.

Back seat – A shoulder on the stem of a gate or globe valve which seals against a mating surface inside the bonnet to prevent leakage of media through the bonnet stuffing box when the valve is fully opened.

Ball – The closure element of a ball valve.

Ball valve – A valve using a spherical closure element which is rotated through 90° to open and close the valve.

Bar – A metric unit of pressure. One bar equals 14.5 psi.

Belleville Spring – A spring resembling a dished washer, used in some ball valves to push the seats against the ball. They also are used to provide live-load to packing systems on globe and wedge gate valves.

Bevel – A chamfer. The angle between two adjacent surfaces (other than 90 degrees). The word “bevel” is used in describing weld-end preparations. See “End Bevel”.

Bevel Gear Operated (or Operator) – The actuation of a valve by means of a set of bevel gears having the axis of the pinion gear at right angles to that of the larger ring gear. The reduction ratio of this gear set determines the multiplication of torque achieved. Used on gate valves.

Body – The principle pressure containing part of a valve in which the closure element and seats are located.

Bolt – A fastener that normally has a square or hex head and is threaded on the opposite end to receive a nut. Sometimes used to make up a flanged connection.

Bolt Circle – The circle on which bolt holes are located.

Bolted bonnet – A bonnet which is connected to a valve body with bolts or studs and nuts.

Bonnet – The top part of a valve, attached to the body, that guides the stem and adapts to extensions or operators.

Bore (or port) – The inside diameter of the smallest opening through a valve, e.g., inside diameter of a seat ring, diameter of hole through ball in a ball valve.

Brinell Hardness Number – A number indicating metal hardness using the Brinell scale. Can be converted to Rockwell B and C hardness by reference to conversion tables.

Bubble-Tight Shutoff – A phrase used in describing the sealing ability of a valve.

During air pressure testing of a new valve in the closed position, leakage past the seats is collected and bubbled through water. To qualify as bubble- tight, no bubbles should be observed in a prescribed time span.

Butt weld end – The end connection of a valve suitably prepared for butt welding to a connecting pipe.

Butterfly Valve – A short face-to-face valve that has a movable vane, in the center of the flow stream, which rotates 90 degrees as the butterfly valve opens and closes.

Bypass – A system of pipes and valves permitting the diversion of flow or pressure around a line valve.

Carbon steel – Iron containing carbon in the form of carbides, about 0.1 to 0.3 percent carbon with no other alloying elements other than the sulfur, phosphorus, and other elements present in almost all steels.

Cast iron – The common term for cast gray iron or iron containing flake carbon in the range of 1% to 2%. Cast iron is brittle, exhibiting very little ductility before fracturing.

Casting – A product or the act of producing a product made by pouring molten metal into a mold and allowing it to solidify, thus taking the shape of the mold.

Capscrew – A fastener with a head whose shank is normally threaded throughout its entire length. It is not used with a nut, but rather engagement is made with a female thread in the piece to be joined.

Cavitation – The rapid formation and collapse of vapor pockets in a flowing liquid in localized regions of very low pressure – often a cause of erosive damage to pumps, throttling type valves and the piping itself. Can be the cause of excessive noise.

Charpy Test – A mechanical test conducted on a precisely machined coupon of the steel to be tested. The coupon is clamped in a special machine and subjected to a lateral hammer blow. This test provides a relative measure of the toughness of the steel or its resistance to shock or impact loads. Often required for low temperature applications where testing is done at the expected minimum service temperature. (Refer to requirements ISO .)

Chevron Packing – A type of packing used in packing boxes consisting of a nest of V cross-section rings.

Cladding – A method of coating metals by which the coating becomes an integral part of the material. This normally is done by welding. It is generally done on valves where special trims are required for difficult applications.

Class – A pressure rating expressed as a dimensionless number. The class rating charts give actual pounds per square inch maximum allowable pressure at a given temperature.

Clevis – A U-shaped connecting yoke at the end of a stem or rod, between the ends of which a gate or other part may be pinned or bolted.

Concentric – Having the same centers.

Contaminant – A particle or material which is foreign to the fluid media.

Control Valve – A valve that controls a process variable, such as pressure, flow or temperature, by modulating its opening in response to a signal from a controller. See “Controller”.

Controller – A device that measures a controlled variable, compares it with a predetermined setting and signals the actuator to readjust the opening of the valve in order to re-establish the original control setting.

Corrosion – The deterioration of a material due to chemical action.

Corrosion Allowance (CA) – An additional amount of wall thickness that is added by calculation to account for planned corrosion over the lifetime of a pressure vessel.

Crude Oil – Unrefined oil. Oil as it comes directly from the well.

Cryogenic Temperature – Any temperature below about -240° F (-151° C).

CV – The capacity factor of a valve, also called the valve coefficient; specifically, the number of gallons of water per minute that will flow through a valve with a pressure drop of 1 psi.

CWP – Cold Working Pressure

Cycle – A single complete operation or process returning to the starting point. A valve, stroked from full open to full closed and back to full open, has undergone one cycle.

Cycle Test – A procedure whereby a valve is put through an interval of time during which a test process is completed. This can be a set number of events or it can be a continuous operation until something in the product fails.

Delta (DP) – See “Differential Pressure”, “Pressure Drop”.

Diaphragm – A round, thin, flexible sealing device secured and sealed around its outer edge – and sometimes around a central hole in the diaphragm – with its unsupported area free to move by flexing.

Differential Pressure – The difference in pressure across a valve in a pressurized line. The difference in pressure between any two points in a pressurized system under flowing conditions.

Drain plug – A fitting at the bottom of a valve, the removal of which permits draining and flushing the body cavity.

Durometer – An instrument for determining the hardness of synthetic rubber or elastomeric materials, usually on the Shore A scale. Also the unit of hardness: e.g., 90Durometer Shore A.

Dye Penetrant Inspection –“Liquid Penetrant Inspection”.

Eccentric – Not having the same center.

Elastomer – A natural or synthetic material. Used in synthetic rubber parts such as O- rings.

Electroless Nickel Plating – A plating process that requires no external electrical power and is the result of a chemical reaction between the part and the plating solution. A uniform consistent deposit and plating rate can be produced by controlling and adjusting the chemistry of the plating bath.

End Bevel – Weld end preparations for butt welding. Governed by ASME B31.4 and B16.25.

End Connection – The type of connection supplied on the end of a valve that allows it to be installed in a pipeline. Weld end, flanged end, screwed end.

Erosion – The mechanical wearing away of a metal surface or part due to fluid impingement. The presence of entrained solid particles accelerates this process.

ESV Emergency Shutdown Valve – A valve or a system of valves that, when activated, initiate a shutdown of the plant, process, or platform they are tied to.

Explosion Proof – A statement associated with a design that is capable of passing certain specified tests after exposure to a potentially explosive environment. Generally, these tests must be referenced to a particular specification. This is especially important for electrical devices, such as solenoids and switches.

External Coating – Coating applied to protect valves against various environments – sea air, salt water, earth burial, and normal air exposure.

Face-to-Face – The overall dimension from the inlet face of a valve to the outlet face of the valve (one end to the other).

Facing – The finish of the contact surface of flanged fittings.

Fail-Safe Valve – A valve designed to operate to a preferred position (open or closed) in order to avoid an undesirable consequence in a piping system. Refer to ESDV and BDV.

Female Thread – An internal screw thread designed to mate with a component having male (external) threads of the same size and type.

(FEA) Finite Element Analysis – Computerized method of analyzing complex shapes by organizing the shapes into a series of smaller elements that can be more accurately analyzed to determine whether or not components are suitable for their intended purpose.

Field Serviceable – A statement indicating that normal repair of the valve or replacement of operating parts can be accomplished in the field without returning the valve or part to the manufacturer.

Flange – A formed pipe fitting consisting of a projecting radial collar with bolt holes to provide a means of attachment to piping components having a similar fitting. The end piece of flanged end valves.

Flat Face (FF) – A flange surface in which the gasket sealing area is the entire surface from the ID to the outside edge. Usually used for class 125 cast iron valves.

Flow – A fluid in motion in a conducting line.

Flow Coefficient – The number of gallons of water per minute that will flow through a valve with a pressure drop of 1 psi. Also referred to as the CV of the valve.

Flow, Laminar – The flow of a viscous fluid in which the fluid moves in parallel layers with a fixed velocity gradient from the centerline to the containing walls of the conduit.

Sometimes referred to as “streamline” flow.

Flow Rate – The volume or weight of a fluid passing through a pipeline or conductor per unit of time, e.g., b/d of oil; 4 MMcf/hr of gas.

Flow, Turbulent – The random flow of a fluid in which the velocity at a certain point in the fluid varies irregularly.

Fluid – Any non-solid substance that can be made to flow. Both liquids and gases are fluids.

Force – The intensity of an influence tending to produce motion, distortions, or change of shape. The product of unit force (psi) and the area over which it acts. Usually expressed in pounds.

Forging – A part that is formed by heating followed by hammering, rolling, or applying other compressive forces to create a specific shape.

Friction – The resistance to motion between two contacting surfaces or substances. Friction also is developed between a flowing fluid and the inner wall of the conducting pipe, resulting in a drop of pressure.

Full Bore – Describes a valve whose bore (port) is nominally equal to the bore of the connecting pipe. See “Venturi Valve”.

Full-Penetration Weld – Describes the type of weld wherein the weld metal extends across the entire wall thickness of the joint.

Galling – The tearing of metal when two elements rub against each other. Usually caused by lack of lubrication or extreme contact pressure.

Gas – A compressible fluid such as air, hydrogen, nitrogen, etc.

Gasket – A seal or packing placed between mechanical joints (such as flanges) to prevent the escape of the flowing medium.

Gland (or Gland Bushing) – That part of a valve which retains or compresses the stem packing in a stuffing box (where used) or retains a stem O-ring, lip seal, or stem O-ring bushing.

Sometimes manually adjustable. See “Packing”, “Stuffing Box”.

Graphite – Flexible carbon material used to make gaskets and packing. The gaskets may be flat graphite sheet or have metal inserts for added strength. The packing is a combination of lattice braided rings used as anti-extrusion or wiper rings and dieformed rings which are compressed to affect the seal.

Grease Fitting – A fitting through which lubricant or sealant is injected.

Hard Facing – A surface preparation, such as detonation gun or high velocity oxygen flow (HVOF), in which an alloy is deposited on a metal surface, usually by weld overlay, to increase abrasion and/or corrosion resistance.

Head – The height of an open column of liquid above a given datum, expressed in linear units; e.g., feet of water, inches of mercury, etc. It is another way of expressing pressure.

Heat Analysis – A chemical analysis, conducted by the foundry immediately prior to pouring, which measures the exact chemical composition of a particular batch of molten metal. Does not include analysis of physical properties. See “Mill Test”.

Heat-Treatment – Describes any process or procedure by which the internal structure of steel is altered by heating to produce desired physical characteristics. This is usually accomplished by furnace heating followed by controlled cooling.

Holiday – An imperfection or bare spot in a coating or plating.

Hot tears – A defect occurring in castings caused where partially solidified or weak, newly solidified sections are subjected to a pull resulting from the contraction of thinner parts that have solidified earlier. A hot tear is an intergranular failure.

Hubs – The end connection tubes on a valve.

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Hydraulic – Pertaining to, or using, water, oil, or other liquids.

Hydraulic Actuator (or Operator) – A device by which rotation of a hydraulically powered motor is converted into mechanical motion.

Hydrostatic Test (or Shell Test) – A test in which a valve is completely filled with water and pressure tested. Used for conducting proof pressure testing.

(ID) Inside Diameter – The measurement of the inner diameter of a circular part.

Inertia – The property of a body or mass which resists a change in velocity.

Inlet Port – The end of a valve which is connected to the upstream pressure zone of a fluid system.

In Situ Maintenance – To maintain or repair a product in its original place, such as a top entry ball valve or regulator.

(ISO) International Standards Organization – An organization that sets minimum international standards for a wide variety of items manufactured and used in pipeline services.

(LNG) Liquefied Natural Gas – Natural gas in the liquid state. For the gas to remain liquefied, the temperature must be maintained in the cryogenic region.The liquid occupies far less volume than an equivalent volume of gas and it can be readily transported by

ship and stored ashore in insulated tanks to await regasification.

(LPG) Liquid Petroleum Gas – Gases such as butane or propane in the liquid state. LPG, under relatively low pressure, remains a liquid at normal ambient temperature.

Lifting Lugs – Lugs provided on larger ball, gate, and check valves, for lifting and positioning valves. Also called lifting eyes.

Line – A pipe, tube, or hose for conducting fluids.

Liquid Penetrant Inspection – An NDE method of detecting the presence of surface cracks and surface imperfections in welds or castings through use of a special red dye.

Locking Device – A mechanism provided on valve operators to prevent unauthorized operation or tampering.

(MAOP) Maximum Allowable Operating Pressure – Determined in accordance with piping codes, DOT regulations, etc.

Magnetic Particle Inspection – An inspection procedure for detecting surface cracks in welded areas through the use of fine iron particles in an electrical field.

Male Thread – The external thread on pipe, fittings, or valves used in making a connection with mating female (internal) threaded parts.

Manifold (or Header) – A common pipe or chamber having several lateral outlets.

(MDS) Material Data Sheets – The material data sheets define the minimum requirements for the required materials, i.e., chemical requirements, manufacturing, qualification of supplier, mechanical testing and properties, non-destructive examination, repair, marking, and certification.

Mechanical Seal – In a valve, a shutoff that is accomplished by a mechanical means rather than with fluid or line pressure. The wedging action of a gate against the seats or the seat springs pushing the seat against the ball or gate are examples of mechanical seals in a valve.

Metal-to-Metal Seal – The seal produced by metal-to-metal contact between the sealing face of the seat ring and the closure elements, without benefit of a synthetic seal.

Meter Run – A section of pipeline in which a meter is installed to measure the volume of fluid passing through the line.

Manual Gear Operator – A gear operator that operates manually (with a hand wheel).

Mill Certificates – Certificates, provided by the steel mill, indicate the chemical analysis and physical properties of a specific batch of steel. “Mill Certs” are usually required only for pressure containing parts. The customer’s need for such “Mill Certs” must be made known when the order is first placed, otherwise is it not possible to trace a valve part back to the mill.

Mill Test – All tests required by the material specification. Usually includes both the heat analysis (chemical) and the physical properties, and sometimes impact tests.

MMCF – An abbreviation for “million cubic feet” used to designate gas volume and gas flow rates in pipelines (MMcf/d or MMcf/hr).

Mold – A hollow cavity (frequently in packed sand) for giving a desired shape to a material in a molten or plastic state. Used in making metal castings.

(MSS) Manufacturers Standardization Society of the Valve and Fitting Industry – A technical association of valve, fitting, and actuator manufacturers that writes standards and practices for the valve and fitting industry. Recommendations of this society are advisory only.

(MWP) Maximum Working Pressure (or CWP – Cold Working Pressure) – The maximum working pressure (pounds per square inch) at which a valve can be operated.

The maximum working pressure for various pressure classes are defined by ASME B16.34 or API 6A.

(NACE) National Association of Corrosion Engineers – This technical association publishes papers, articles, and standards on all aspects of corrosion and has written the definitive standard for valve materials for sour gas service.

NDE – Non-Destructive Examination

Nipple – A short length of small size pipe, threaded on both ends. Used on end connections of screwed-end valves and in small size piping systems.

Nitrogen/Helium Test – A pressure test conducted using nitrogen or helium (inert gases) instead of air, water, or other gases to prevent any danger of fires or explosions.

Generally specified by the purchaser when buying a valve or regulator product.

Non-Destructive Tests – Inspection tests that are not destructive to the valve structure or function. See “Radiographic Inspection”, “Liquid Penetrant Inspection”, “Magnetic Particle Inspection”, “Ultrasonic Inspection”.

Non-Rising Stem – A gate valve having its stem threaded into the gate. As the stem turns, the gate moves but the stem does not rise. Stem threads are exposed to line fluids.

(NPS) Nominal pipe size – Dimensionless number used to indicate sizes of pressure pipe and valves – used interchangeably with valve size in inches.

(NPT) National Pipe Tapered – A uniform standard governing the dimensions of tapered pipe threads.

(OD) Outer Diameter – The measurement of the outermost diameter of a circular part. O-Ring – An elastomeric or synthetic seal ring of circular cross section.

Operator – A device that converts manual, hydraulic, pneumatic, or electrical energy into mechanical motion to open and close a valve.

PSI (psi) – An abbreviation for “pounds per square inch”. The force per unit area exerted against a resisting body.

Packing – The deformable sealing material inserted into a valve stem stuffing box, which, when compressed by a gland, provides a tight seal about the stem. See “Gland”, “Stuffing Box”.

Pattern – A duplicate or copy, usually wooden, of a part to be cast. Used to form the mold into which molten metal is poured.

Phenolic Coating- A thermo-setting resin applied to valve interiors and/or exteriors to inhibit corrosion. A plastic material.

PIG (Pipeline Inspection Gauge) – A device, closely conforming to the pipe bore, which is forced through a pipeline to clean the pipe of all foreign material and debris.

The valves in a pipeline that will be pigged must be through- conduit, full port; otherwise the pig will not pass through them.

Pilot – A spring-loaded pressure regulator used to control the pressure and flow of other larger pressure regulators or instruments.

Pilot-Operated Regulator – A regulator that is controlled by a second small- volume, high- accuracy regulator or pilot. This arrangement has the advantages of improving performance reducing the effects of unbalanced pressure and droop. The number of possible applications also are increased since a wide range of pilot configurations are feasible.

Pinhole – Numerous small gas holes at the surface or just below the surface of castings, generally occurring in the thicker parts of the casting as a reduction in the solubility of gases in the metal as the metal cools.

Piston Effect – The sealing principle involved in utilizing line pressure to affect a seal across the floating seats of some valves.

(PMI) Positive material identification – a method for cross checking the identity of a piece of material, often using a portable spectrometer, usually with x-rays (TN , nuclear analyzer) or a welding arc (Arc Met 900, optical spectrometer).

Pneumatic – Pertaining to, or using, air or gas.

Porosity – A defect found in castings or welds consisting of gas bubbles or voids in the solidified metal.

Position Indicator – Any external device that visually indicates the open and closed position of a valve.

Pressure Drop – Decrease in pressure along the direction of flow in a piping system caused by fluid friction, restrictions, and change-of direction fittings. Pressure drop is related to velocity, specific gravity, viscosity, and the size and roughness of the pipe interior.

Pressure-Temperature Ratings – The maximum allowable working pressures at specified temperatures. For steel valves, the ratings are defined by “classes”

and found in ASME B16.34. For iron and bronze valves, the ratings are defined in the applicable MSS specifications.

Pressure Test – A test using specified pressures of liquid or gases, which can be used to check the sealing, integrity, design standards, etc., of a particular product.

Product Analysis – A verification conducted by the steel manufacturer to assure that the chemical composition of received material coincides with the heat analysis and with requirements of the applicable specification.

Proof Pressure – A hydrostatic test pressure, usually 1-1/2 times the rated working pressure, applied to an assembled valve to verify the structural integrity of the pressure containing parts. Synonymous with hydrostatic shell test.

Pulsation – Rhythmical throbbing or vibrating. In pipelines, a flow or pressure oscillation that is identically repeated in every fixed time interval. Pulsation is an inherent characteristic of reciprocating gas compressors and reciprocating liquid pumps. Pressure and flow pulsations interact with piping systems to cause vibration, metering errors, and potential equipment damage.

Quality Assurance – Planned regular and/or preventive actions which are used to ensure that materials, products, or services will meet specified requirements.

Ra – Abbreviation for “arithmetic average roughness height” – the measure of the roughness of a surface expressed in microinches. The higher the number, the rougher the surface. Used to designate the desired surface finish for end flange raised faces.

Radiographic Inspection – An X-ray NDE procedure for locating flaws in welds, casting, and fabricated parts.

Regular Port Valve – A term usually applied to plug valves. The regular port of such a valve is customarily about 40% of the line pipe area. It corresponds to a Venturi or reduced-bore valve of the same nominal pipe size. Venturi ball valves often are a logical alternative to plug valves with advantages in price torque and low maintenance.

Regulator – A throttling valve that exercises automatic control over some variable (usually pressure). Not an on-off valve.

Resilient Seat – A valve seat containing a soft seal, such as an O-ring, to ensure tight shutoff.

(RF) Raised Face – The raised area of a flange face which affords a seal with a mating flange face by means of a flat gasket of the same diameter as the raised face.

Rim pull – The force required at the edge of the hand wheel to generate the required torque at the center of the hand wheel.

Rising Stem – A valve stem that rises as the valve is opened.

Rockwell Hardness Number – A numerical expression of the hardness of a metal as determined with a Rockwell Hardness Tester. There are several hardness scales. The most commonly used are the Rockwell B scale for soft metals and the Rockwell C scale for hard materials.

(RPM) Revolutions Per Minute – Rotational speed, turns per minute. For example, the RPM delivered by a power operator to the pinion shaft of a gear operator.

(RTJ) Ring-Type Joint – A flange connection using a specially shaped soft metal ring as a gasket. Generally used on high-pressure valves and not widely used in the pipeline industry.

Schedule – A system for indicating the wall thickness of pipe. The higher the schedule number, the thicker the wall for a certain pipe size.

Screwed Ends – Internally threaded end connections supplied on some valves. Usually tapered pipe threads

Seal, Dynamic – A sealing element used between parts that have relative motion, e.g., stem seals, seat seal O-rings, etc.

Seal, Static – A sealing element used as a gasket between two nonmoving parts, e.g., valve bonnet O-rings, ball valve body O-rings, flange gaskets, etc.

Seal weld – A weld that does not contribute anything to the mechanical integrity of an assembly, but is made purely to seal or prevent leakage from, for instance, a threaded joint.

Seat – The part of a valve against which the closure element (gate, ball) affects a tight shutoff. In many ball valves and gate valves, it is a floating member usually containing a soft seating element.

Separator – A special tank used to separate gas from oil in some crude oil gathering systems.

Shut-off Valve – A valve designed only for on/off service. Not a throttling valve. Sometimes referred to as a “block valve”.

Shrinkage – Internal defect in castings that are internal voids, irregular in shape, caused by volume contraction during solidification. Can be caused by not maintaining a fluid channel to the riser during solidification.

Slurry Service – An application involving a flow medium consisting of small solid particles suspended in a liquid. Coal slurry, consisting of about equal parts of coal and water, is transported by pipeline from coal mines to plants where the coal is dewatered and burned. A specially modified GROVE® B5 ball valve is offered for this service.

Socket End – An end connection in which a pipe or tube is inserted into a counter bored hole and then brazed or fillet-welded.

Sour Gas – Natural gas containing significant amounts of H2S. Requires special trim.

Specific Gravity – The ratio of the weight of a given volume of fluid to the weight of an equal volume of water (if the fluid is a liquid) or to the weight of an equal volume of air (if the fluid is a gas).

Stem – A rod or shaft transmitting motion from an operator to the closure element of a valve.

Stress – An engineering parameter used in the design of valves. The value of unit force (psi) produced within a material as the result of an applied force or load. Developed stress must be held well below the yield strength of the material.

Stud – A bolt, threaded on both ends, often used in bolting together two members, one of which has blind tapped bolt holes.

Stuffing Box – The annular chamber provided around a valve stem in a sealing system into which deformable packing is introduced. See “Packing”, “Gland”.

Surge – To rise suddenly to an excessive or abnormal value; a transient sudden rise of pressure in a pipeline. Pipeline surges can be positive or negative and are caused most frequently by the sudden closure of a block valve or emergency shutdown of a pump. Surge pressure in excess of the rated capacity of a pipeline can cause ruptures of the piping system.

Sweet Gas – Natural gas having no significant H2S content.

System Engineering – That engineering approach which deals with the design and integration of multiple components and controls into an assembled piping complex to accomplish a specified function or functions.

Tensile Strength – The highest tensile stress that a material can withstand before failure or rupture occurs with force being applied in a direction tending to elongate the material.

Tensile Test – A test performed on specially machined specimens taken from material in its delivered condition, to determine physical properties, e.g., yield strength, ultimate strength, and percent elongation.

Test Certificates – Documents provided by a manufacturer certifying that required tests were performed.

Throttling – The intentional restriction of flow by partially closing or opening a valve. A wide range of throttling is accomplished automatically in regulators and control valves.

Through-Conduit – An expression characterizing valves when in the open position, wherein the bore presents a smooth uninterrupted interior surface across seat rings and through the valve port, thus affording minimum pressure drop. There are no cavities or large gaps in the bore between seat rings and body closures or between seat rings and ball/gate. Consequently, there are no areas that can accumulate debris to impede pipeline cleaning equipment or restrict the valve’s motion.

Thrust – Force applied to a part in a particular direction, e.g., thrust on a valve stem.

Top Entry – The design of a particular valve or regulator where the unit can be serviced or repaired by leaving its body in the line and accessing its internals by removing a top portion of the unit.

Torque – The turning effort required to operate a valve. Usually expressed in lb/ft and in reference to the stem nut, hand wheel, or operator pinion shaft.

Torque Switch – An electrical device on a motor operator that cuts off power to the operator when allowable torque is exceeded, thus preventing damage to the valve and/or the operator.

Transition Piece – A length of pipe that is welded to a valve hub or closure. Generally provided by the customer, it serves as a transition from the customer’s piping to the valve to compensate for differences in material or size.

Transmission Line – A main pipeline transporting oil or gas from wells or storage fields to refineries, loading docks, or distribution companies. Generally, the pipeline is bigger than 6″ and the pressure greater than 150 psi.

Trim – Commonly refers to the valve’s working parts and to their materials.

Turns to Operate – The number of complete revolutions of a hand wheel or the pinion shaft of a gear operator required to stroke a valve from fully open to fully closed or vice versa.

U-Cup (Ring Packing) – A U cross-section ring located in the tail end of certain ball valve seats to retain the grease in an emergency seat seal system.

(UL) Underwriters Laboratory – An impartial testing laboratory concerned with the safety of electrical components. Products surviving the tests are included on a certified listing of products by manufacturer. This does not imply UL approval.

Ultimate Strength – The stress at which a material will fail. See “Tensile Test”

Ultrasonic Inspection – An inspection procedure using high-frequency sound waves to detect voids and imperfections throughout the thickness of metal parts.

Union bonnet – A type of valve construction in which the bonnet is held on by a union nut with threads on the body.

Union Connection – A small three-piece fitting used to join two lengths of pipe. A female piece is installed on each of the two pipe ends and the connection is mechanically sealed by an external nut.

Vacuum – A space from which air or gas has been exhausted until its pressure is less than atmospheric pressure, e.g., any pressure below 14.7 psi absolute.

Valve – A device that controls the flow of a liquid or gas in a conduit or pipeline.

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Variable Orifice – A small variable profile valve put in a flow line and used with a pilot to restrict the flow into the pilot and make the pilot more or less sensitive to changing conditions.

(VDS) Valve Data Sheet – A data sheet defining the minimum level of a valve design, including the materials, testing, inspection, and certification requirements.

Velocity – The speed at which a fluid flows through a line in a specified direction. Usually expressed in ft./sec.

Vent Plug (or Vent Plug Assembly/Safety Vent Plug) – A special pipe plug having a small hex wrench-operated vent valve. These special plugs are located at the bottom of most ball valves. With the line valve closed (and under pressure), the body cavity pressure can be vented through this small valve to check the tightness of seat seals or to make minor repairs. Having vented the body pressure, the vent plug can be removed to blow out debris and foreign material or to flush the body cavity.

Venturi Valve – A reduced-bore valve. A valve having a bore smaller in diameter than the inlet or outlet. For example, an 8″ x 6″ x 8″ ball valve has 8″ inlet and outlet connections, while the ball and seats are 6″. The flow through a Venturi valve will be reduced because of the smaller port. Venturi valves often can be economically substituted for plug valves.

Viscosity – A measure of the internal friction of a fluid or the resistance of a flow. Two fluids of identical specific gravity may have quite different viscosities.

Wall Thickness – The thickness of the wall of a pressure vessel or the thickness of the wall of a pipe.

Water Hammer – The physical effect, often accompanied by loud banging, produced by pressure waves generated within the piping by a rapid change of velocity in a liquid system.

(WE) Weld End – The end connection of a valve which is to be installed by welding into the line.

To prepare the end bevel, it is necessary to know the wall thickness and specified minimum yield strength of the connecting pipe. See “End Bevel”. Wear Test – Verification of a component’s resistance under specific wear conditions.

Weld Neck Flange – A flanged piping element with a weld neck used in pipeline construction to provide a companion for installation of flanged valves. Also used to convert weld end valves to flanged valves or vice versa.

Weld Reducer – A reducing fitting used on weld end piping components to adapt from a large sized pipe to a smaller diameter pipe or vice versa.

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(WOG) Water-Oil-Gas – Used in connection with a pressure rating. Thus, 100 WOG indicates the rated pressure is 100 psi in water, oil, or gas service at normal ambient

(WP) Working Pressure – The maximum anticipated sustained operating pressure applicable to a pipe.

VALVE SPECIFICATIONS

Below is a listing of the basic specifications used in the design and manufacture of valves:

American Petroleum Institute

API Q1 Specification for quality programs API 6A Specification for Wellhead valves

API 598 Valve inspection and testing

API 607 Fire test for soft seated quarter turn valves

American Society of Mechanical Engineers/ American National Standards Institute ASME/ANSI B16.34 Valves – flanged, threaded and welding end

ASME/ANSI B16.5 Pipe flanges and flanged fittings

ASME/ANSI B16.10 Face-to-face and end-to-end dimensions of valves ASME/ANSI B16.11 Forged fittings, socket-welding and threaded ASME/ANSI B16.25 Butt-welding ends

MSS SP-25 Standard marking system for valves, fittings, flanges and unions

MSS SP-55 Quality standard for steel castings for valves, flanges, and fittings, and other piping components – visual method

MSS SP-79 Socket-welding reducer inserts National Association of Corrosion Engineers

NACE MR Standard material requirements for sulfide stress cracking resistant metallic materials for oilfield equipment.

ISO / Quality system – Model for Quality Assurance

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