Ball Valve Glossary


Following is a glossary of valve terms and serves as both a ball valve and control valve glossary.


1 Piece (ball valve) Design
Inexpensive and having few potential leak paths (end connections and stem), they are a light-weight and difficult to repair.  Often a reduced port design, typical of OEM and commercial-duty ball valves. 

2 Piece (ball valve) Design
Industrial standard for flanged ball valves, having only one body joint (potential leak path), they are easier to repair but are more expensive than 1 piece designs due to the increased complexity of the design.

3 Piece (ball valve) Design
Industrial standard for threaded and welded connections, the central body can be removed without removing the end connections from the pipeline, thus repair is easier.  They can also be supplied with different end configurations.  Having two body joints (potential leak paths), some designs utilize through bolts and others studs with nuts.


Actuator Mounting Pad

The manual valve operator can be removed and an electric or pneumatically actuated valve actuator can be installed for automation.  The industry standard is ISO 5211.


Adjustable Stem Packing

A stem seal is used to seal between the shaft of the handle stem and the valve body. This seal is then compressed around the stem by means of a packing gland, which forms a watertight seal around the handle stem assembly.  Over time, due to various environmental conditions, the seal material may expand or contract; thereby affecting the quality of this seal. To combat this (if a leak should occur) you can adjust the packing gland by tightening it slightly.


ANSI FCI-70-2-1976

Establishes Testing procedures and associated acceptable leakage rates for industrial control valves. There are different seat leakage classifications defined by ANSI/FCI 70-2 2006 (European equivalent standard IEC 60534-4).  The most commonly used are:



Anti-static device (ball valve feature)
Ensures an electrical continuity between valve ball, stem, and body thereby reducing static electricity which may exist in the ball or stem of the valve.


API 598
This standard covers inspection, examination, and testing requirements for resilient-seated, non-metallic-seated, and metal-to-metal-seated gate, glove, plug, ball, check, and butterfly valves. It is relevant to examination and testing by the valve manufacturer, supplementary examinations performed at the valve manufacturer’s plant and pressure tests performed at either the plant or another mutually agreed-upon facility.


API 607 (fire tested)
Fire Test for Soft-Seated Quarter Turn Valves. The standard covers the requirements for testing and evaluating the performance of straightway, soft-seated quarter-turn valves when the valves are exposed to certain fire conditions defined in this standard. The procedures described in this standard apply to all classes and sizes of such valves that are made of materials listed in ASME B16.34.

API 608
A valve standard which is actually an additional set of requirements beyond those mentioned in the ASME B16.34 standard, and compliance to the latter is a prerequisite. This standard has been developed by the API to be used by “downstream” refineries and chemical plants for the selection and approval of ball valves.

Some of these additional requirements for a ball valve to comply with API 608 are:

API 609
This standard covers design, materials, face-to-face dimensions, pressure-temperature ratings, and examination, inspection and test requirements for gray iron, ductile iron, bronze, steel, nickel-based alloy, or special alloy butterfly valves.

An adoption of ISO 14313:1999, Petroleum and Natural Gas Industries-Pipeline Transportation Systems-Pipeline Valves. This International Standard specifies requirements and gives recommendations for the design, manufacturing, testing and documentation of ball, check, gate and plug valves for application in pipeline systems.

A company level certification based on the standard developed and published by the American Petroleum Institute (API) titled "Specification for Quality Management System Requirements for Manufacturing Organizations for the Petroleum and Natural Gas Industry".


ASME B1.20.1

Standard on Pipe Threads, General Purpose, Inch covers dimensions and gaging of the world’s most common pipe threads:  NPT, NPSC, NPTR, NPSM, and NPSL


ASME B16.10

Standard covers face-to-face and end-to-end dimensions of straightway valves, and center-to-face and center-to-end dimensions of angle valves. Its purpose is to assure installation interchangeability for valves of a given material, type, size, rating class, and end connection.


ASME B16.11

This Standard covers ratings, dimensions, tolerances, marking and material requirements for socket-welding and threaded forged fittings.


ASME B16.34

Valve standard accepted worldwide by end-users, engineering contractors and manufacturers as the fundamental basis for valve design, testing and performance. It covers pressure-temperature ratings, dimensions, tolerances, materials, nondestructive examination requirements, testing, and marking for cast, forged, and fabricated flanged, threaded, and welding end and wafer or flangeless valves of steel, nickel-base alloys, and other alloys.


ASME B16.42

This Standard covers minimum requirements for Classes 150 and 300 cast ductile iron pipe flanges and flanged fittings. The requirements covered are as follows: (a) pressure-temperature ratings (b) sizes and method of designating openings of reducing fittings (c) marking (d) material (e) dimensions and tolerances (f) bolts, nuts, and gaskets (g) tests.


ASME B16.5

Covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing, and methods of designating openings for pipe flanges and flanged fittings.


ASME B31.1

Prescribes minimum requirements for the design, materials, fabrication, erection, test, inspection, operation, and maintenance of piping systems typically found in electric power generating stations, industrial and institutional plants, geothermal heating systems, and central and district heating and cooling systems.


ASME B31.3

Requirements for piping typically found in petroleum refineries; chemical, pharmaceutical, textile, paper, semiconductor, and cryogenic plants; and related processing plants and terminals. It covers materials and components, design, fabrication, assembly, erection, examination, inspection, and testing of piping.



An international standard developed as an aid for the design and construction of equipment intended for use in the manufacturing of biopharmaceuticals.


Ball Valve
A ¼ turn valve using a hollow sphere used to close, open or control fluid flow.


Blow Out Proof Stem

Ensures the top packing rings can be replaced while the valve is under pressure, without the stem being pushed out.


BS 2080
British specification for face-to-face, center-to-face, end-to-end and center-to-end dimensions of valves.


BS 6755 PART 2
British fire test standard, similar to API 607, although API 607 4th edition is considered more stringent.


Bubble Tight Design

A phrase 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.


Butterfly Valve
Enables quick shut-off of pipeline flow similar to a ball valve, except they typically cost less and more compact than comparable ball valves.


Requires 51% of the components or value of the final product to be made in the U.S.A.; thus qualifies for a U.S.A. certificate of origin.


CE per PED97/23/EC
European standards for the design and fabrication of steam boilers, pressure vessels, piping, safety valves and other components and assemblies subject to pressure loading. It also sets the administrative procedures requirements for the "conformity assessment" of pressure equipment, for the free placing on the European market without local legislative barriers.  The standards and regulations regarding pressure vessels and boilers safety is very similar to the US standards defined by the ASME.


Chain Wheel

Type of manual actuator for difficult to reach (typically high) valves.  The chain wheels can be supplied in a variety of materials.


CIP/SIP Purge Ports

Valve bodies and ends can be modified with additional ports to facilitate draining of the valve body cavity or for flushing the valve; enabling clean-in-place (CIP) or steam-in-place (SIP).


Control Valve
A valve used to control fluid flow by varying the size of the flow passage, which is accomplished via manual or automated actuation, thus enables the direct control of flow rate and the consequential control of process quantities such as pressure, temperature, and liquid level.


Stands for Canadian Registration Number, a number issued by each province or territory in Canada by an authorized safety authority for any boiler, pressure vessel or fitting that operates at a pressure greater than 15 psig.


Cryo-Tek Valve Seats

A modified PTFE material having a temperature operational range from -400ºF to 400ºF.


Cv (Flow Coefficient)

Refers to a scientific standard for volume of water at 60ºF which can pass through a pipe, valve or other pipeline fitting and have a loss or differential pressure drop of 1 PSI.  Therefore the higher the Cv value for a given flow rate, the lower the pressure drop will be across the valve/fitting.


Double Acting Pneumatic Valve Actuator

This type of valve actuator has two compressed air ports; when air is applied to one port and vented by the other, it causes the internal pinion assembly to rotate clockwise.  Just the opposite occurs when air is applied to the other port with the rotation being counter-clockwise.

double acting pneumatic valve actuator double acting pneumatic actuator port b

Double Offset Butterfly Valve
Refers to the position of the valve stem in relation to the centerline of the disc and bore, they are used for higher pressures and fluids with particulate, reduces contact between the valve disc and seat, prolonging the seat life.



An electro-chemical process to remove surface material and provide an extremely smooth surface that is easier to clean.


The inherent benefits of Electropolishing subsequent to mechanical polishing are as follows:


Image resultEpicyclical Gearing

A type of concentric gear assembly with the center of one gear revolving around the center of the other which increases the efficiency and transfer of torque to the valve operator.


FDA Compliance
The FDA (Food and Drug Administration) is the government agency primarily responsible for determining how food products may be affected by exposure to various materials. The code of Federal Regulations (CFR) Title 21 is the agency's relevant guidelines for all materials intended for food contact.


Federal Specifications WW-V-35B

This federal specification includes military specifications MIL-V-3 (packaging) and MIL-STD-105 (testing/inspection procedures) and Manufacturers Standardization Society of the Valve and Fittings Industry standard MSS SP-72.


Fire Safe
A valve design that is capable of passing a fire test with specified limits  on  leakage  to  the  atmosphere  and  downstream  after  being  closed subsequent  to  fire  exposure.


Flanged (full body butterfly) Valve
Has a separate inlet and outlet flange connection and thus, like a Lug butterfly valve, either end of the pipeline can be removed without affecting the sealing.


Floating (ball valve) Design (ball moves to seat)
Its diverting ball is not anchored to the valve body; rather it floats against the seat to form a seal.  Compared to a Trunnion Valve the sealing is improved and its design is more compact, however they generally have higher torque requirements and thus used for lower pressure applications.


FM Approved
Independent testing arm of international insurance carrier, FM Global. FM approvals uses scientific research and testing to make sure products conform to the highest standards for safety and property loss prevention.


full port ball valveFull Port (Bore)
The bore or ID of the valve matches the ID of the pipe it is connected to, minimizing differential pressure drop.


Fusible Link (ball valve feature)
Feature for fire service valves to enable the valve to fail closed in the event of fire based upon a pre-determine temperature the customer specifies. 


ISO 5211
Refers to standard dimensions for actuator mounting flanges.

ISO 5211 mounting pattern


ISO 5752
Specifies the dimensions for two-way valves. Each basic series of these dimensions may be used as required with flanges of mating dimensions conforming to ISO 2084 or ISO 2229.


ISO 9001
A quality management systems having standards designed to help organizations ensure that they meet the needs of customers while meeting statutory and regulatory requirements related to a product.


Low Cv Trim Design

Special ball valve design for throttling low flow rates with accuracy


Low Noise Trim

Special ball valve design for throttling gas, steam and applications where cavitation related noise.


Lug (Butterfly) Valve
Has threaded flange holes to enable removing piping from one side of the valve without affecting its sealing.


Media Containment
Prevents fugitive emissions, protection from extreme temperatures and hazardous fluids via secondary containment of the valve stem.


Metal Name Plates

Identifies all soft parts for easy replacement if required.


Metal Seat
The valve ball or disc interfaces directly against a metal seat.  This style of valve requires periodic operation and maintenance to ensure a leak-free seal.  These types of valves are better for high pressures, extreme temperatures, sanitary/pure fluids and applications with a high percentage of particulates in the fluid.  Metal seats are commonly used for control valves due to higher fluid velocities and related erosion.  Special alloys can be used for enhanced fluid compatibility

MSS - Manufacturers Standardization Society of the Valve and Fittings Industry


Multi-Port (ball valve) Design
Valves which have more than one inlet or outlet, used for diverting flow. 


NACE MR 0175/ISO 15156
Specifies requirements and provides recommendations for the selection and qualification of carbon and low-alloy steels, corrosion-resistant alloys, and other alloys for service in equipment used in oil and natural gas production and natural gas treatment plants in H2S-containing environments.


As relates to our valve actuators, is an industry standard for air port and mounting configurations  for solenoid valves.

NAMUR solenoid mountingNAMUR air porting


NSF Certified

An accredited, independent third-party certification body that tests and certifies products to verify they meet these public health and safety standards.


PED 97/23/EC
European legislation relating to the safety of pressure equipment throughout Europe.


Devices sent through pipelines for cleaning and inspection purposes.  Cleaning could be maintenance or process (cross contamination ) related.  Pigging devices are often used during production and only full port ball valves are compatible with pigging processes. 


Pressure Balanced Ball

A safety feature within the ball to prevent excessive pressure build-up in the cavity from trapped liquid when the valve is in the open position.


PTFE (valve seat material)
Made from Virgin Teflon, this is the most common sealing material; its chemical compatibility is excellent for almost all media. Temperature -50°F to 400°F.

PTFE Cavity filled Seats
Available on request (CF), suitable for filling the void between the body and ball eliminating product build up. Cavity filled seats are standard on our sanitary line of ball valves in both two and three way.


Rated for Vacuum Service

Standard valves to 25 torr; Custom assembled valves to 20 microns.


Resilient Seat Butterfly Valve (zero offset, concentric)
Has an elastomeric material between the valve body and valve ball/disc, providing the following advantages:

  1. The seat is deformable, meaning it will still seal if some debris becomes caught between the valve disc and seat.

  2. The body can be made of a less expensive materials such as ductile iron because it is not in contact with the process fluid

  3. The disc stem O-ring seal eliminate maintenance prone packing gland seals.

  4. The elastomeric seal generally requires less torque for actuation, which reduces the actuator size/complexity and thus reduces initial cost.


Resilient seat valves have become an industry standard and are appropriate for most water and industrial fluid applications.  They are best suited for fluids with few particulates because the valve disc is in constant contact with the seat (creates wear).


RTFE (valve seat material)
15% glass reinforced PTFE, suitable for temperature -50°F to 450°F, chemical resistance is compatible to virgin PTFE with better wear factor. The standard in most all of our ball valves.


Screw Cap Valve BoltingScrew Cap Bolting

Reduces effects of linear thermal expansion and thus leakage from the valve body.  The screw cap bolting design uses twice the number of body bolts, each threaded to more than half of their length.


Seal Weld

Eliminates potential leakage at body joints to ensure pressure containment.  Accomplished using automatic welding equipment to create uniform weld penetrations; during the welding procedure a continuous water flow passes through the valve to protect the valve seats and seals from damage.


Solution Annealing

The process of heating an alloy to an elevated temperature to promote a homogenous chemistry and uniform mechanical properties to produce what is essentially stress free, or “soft” material; then quenched or rapidly cooled to minimize re-precipitation of carbides.


Spring Return Pneumatic Valve Actuators

Designed to ensure the actuator "fails safe", compressed air is used to compress springs and a counter-clockwise rotation.  Upon venting or loss of pressure, the spring forces clockwise rotation of the valve positioner.

spring return valve actuator counterclockwise spring return valve actuator clockwise


standard port ball valveStandard Port (Reduced Bore)
The bore or ID of the valve is one size smaller than the pipe it is connected to, which reduces the size and cost of the valve although would have a higher differential pressure drop compared to a Full Port Valve.  Likely only used when the pipeline is oversized for the flow rate such that the reduced bore size isn’t detrimental.


Surface Finish

The maximum level of roughness average (Ra) is expressed in micro inches (µ in), thus the average roughness for Ra 25-30 is 25-30 µ inches (0.635 to 0.762 microns) and for Ra 8-12 it is 8-12 µ inches (0.203 to 0.304 microns).


TFM Super-Tek (valve seat material)

Considered to be an upgrade from PTFE material, having an improved thermo-mechanical properties resulting in lower torque and less permeability, cold flow deformation.  In addition deformation recovery is enhanced.  The operational temperature range is -50ºF to 500ºF.


Triple Offset  Butterfly Valve (high pressure, dirty fluids, bubble tight performance)
Designed like a Double Offset butterfly valve with the addition of having a tapered shaped seat which matches the sealing disc, eliminating rubbing altogether and enables tight sealing with a metal-to-metal interface.  Due to their compact size, triple offset valves are sometimes a better choice than gate valves due to reduced weight, cost and ease of operation (ergonomics).


Trunnion (ball valve) Design (seat moves to ball)
Has a diverting ball which is physically connected to both the upper and lower parts of the valve body, utilizing line pressure to move the seat against the ball for sealing.  This is typical for larger valves and higher pressure valves.


Two-way/Bi-Directional (ball valve) design
Whichever side has the higher pressure, the seat or ball moves accordingly for sealing.


UL Listed

UL has tested representative samples of a product and determined that it meets UL's requirements. These requirements are often based on UL's published and nationally recognized Standards for Safety.


USP Class IV
The United States Pharmacopeia (USP) is a non-government organization concerned with the pharmaceutical and bio-technology industries, setting standards for quality, purity, strength and consistency. USP Class IV types of products go through a series of biological tests (Acute Systemic Toxicity Test, Intracutaneous Test, Implantation Test & Standard Temperatures and Times). The USP Class VI compounds must be made from ingredients with clear histories of biocompatibility that meet tight requirements for leachates.


Wafer (butterfly) Valve
Has smooth bore flange holes such that the valve is sandwiched between opposing pipe flanges and thus removing one side of the piping and leaving the valve in-place is not possible.


Weld-In-Place (WIP) Design

Patented WIP ball valve design reduces installation time for ball valves welded to their piping system.  Conventional designs require disassembly of the valve, welding the ends to the corresponding piping and then assembling the body onto the ends.  This is not only time consuming, but also repetitious because the valve with factory assembled and tested prior to shipment.  The WIP design lets the user weld the fully assembled and tested valve right into the piping and thus reducing both time and expense.