Control Valves

Valves Process plants consist of hundreds, or even thousands, of control loops all networked together to produce a product to be offered for sale. Each of these control loops is designed to keep some important process variable such as pressure, flow, level, temperature, etc. within a required operating range to ensure the quality of the end product. Each of these loops receives and internally creates disturbances that detrimentally affect the process variable, and interaction from other loops in the network provides disturbances that influence the process variable.

To reduce the effect of these load disturbances, sensors and transmitters collect information about the process variable and its relationship to some desired set point. A controller then processes this information and decides what must be done to get the process variable back to where it should be after a load disturbance occurs. When all the measuring, comparing, and calculating are done, some type of final control element must implement the strategy selected by the controller.

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Globe Control Valve

Angle Control Valves

Three-Way Control Valve

V-Notch Control valve

Butterfly Control valve

Pressure Regulator

Desuperheater

Actuators

Accessories

Design and Manufacturing

• ANSI/ISA-75.01.01 (60534-2-1 MOD): Industrial-Process Control Valves - Part 2-1: Flow capacity - Sizing equations for fluid flow under installed conditions

This standard includes equations for predicting the flow of compressible and incompressible fluids through control valves. The equations for incompressible flow are based on standard hydrodynamic equations for Newtonian incompressible fluids. They are not intended for use when non-Newtonian fluids, fluid mixtures, slurries or liquid-solid conveyance systems are encountered. The equations for incompressible flow may be used with caution for non-vaporizing multi-component liquid mixtures. Refer to Clause 6 for additional information.

• ANSI/ISA-75.05.01: Control Valve Terminology

This document contains terminology for control valves.

• ISA-75.17: Control Valve Aerodynamic Noise Prediction

This standard establishes a method to predict the noise generated in a control valve of standard design by the flow of compressible fluid and the resulting noise outside of the pipe and downstream of the valve. The transmission loss (TL) equations are based on a rigorous analysis of the interaction between the sound waves that exist in the pipe and the many coincidence frequencies in the pipe wall. Commercial pipe specifications allow a relatively wide tolerance in pipe wall thickness. This limits the value of the very complicated mathematical methods required for a rigorous analysis; calculations prove that a simplified expression is justified.

The equations in this standard make use of the valve sizing factors defined in ANSI/ISA-S75.01 and ANSI/ISA-S75.02. This method was developed from the fundamental principles of acoustics, fluid mechanics, and mechanics.

Assembly and Inspection

• ANSI FCI 70.2: Control valve Seat Leakage

This standard establishes a series of seat leakage classes for control valves and defines the test procedures.

Selection of a leakage class is not restricted as to valve design, but acceptable values for various commercially available designs are suggested for each class under Section

• IEC 60534.4: Inspection and routine testing

This part of IEC 60534 specifies the requirements for the inspection and routine testing of control valves manufactured in conformity with the other parts of IEC 60534.

This standard is applicable to valves with pressure ratings not exceeding Class 2500. The requirements for actuators apply only to pneumatic actuators.

This standard does not apply to the types of control valves where radioactive service, fire safety testing, or other hazardous service conditions are encountered. If a standard for hazardous service conflicts with the requirements of this standard, the standard for hazardous service should take precedence.

• ANSI/ISA-75.19.01: Hydrostatic Testing of Control Valves

This standard applies to control valves having bodies, bonnets, cover plates, and bottom flanges made of carbon steel, low alloy and high alloy (stainless) steel, nickel-base alloy, cast iron, and ductile iron.

• ASTM E 165: Standard Test Method for Liquid Penetrant Examination

This practice2 covers procedures for penetrant examination of materials. Penetrant testing is a nondestructive testing method for detecting discontinuities that are open to the surface such as cracks, seams, laps, cold shuts, shrinkage, laminations, through leaks, or lack of fusion and is applicable to in-process, final, and maintenance testing. It can be effectively used in the examination of nonporous, metallic materials, ferrous and nonferrous metals, and of nonmetallic materials such as nonporous glazed or fully densified ceramics, as well as certain nonporous plastics, and glass.

• ISA 75.02.01: Control valve Capacity Test Procedure

This test standard utilizes the mathematical equations outlined in ANSI/ISA-75.01.01 (IEC 60534-2-1 Mod)-2007, Flow Equations for Sizing Control Valves, in providing a test procedure for obtaining the following:

a) Valve flow coefficient, C (Cv, Kv)

b) Liquid pressure recovery factors, FL and FLP

c) Reynolds Number factor, FR

d) Liquid critical pressure ratio factor, FF

e) Piping geometry factor, FP

f) Pressure drop ratio factor, xT and xTP

g) Valve style modifier, Fd

This standard is intended for industrial process control valves used in flow control of Newtonian fluids. See 4.2 for more information regarding specific valve styles.

• ISA-75.25.01: Test Procedure for Control Valve Response Measurement from Step Input

This standard defines the testing and reporting of step response of control valves that are used in throttling closed loop control applications. A control valve consists of the complete, ready-to-use assembly of the control valve body, actuator, and any required accessories. The most probable accessory is a valve positioner. For background, refer to technical report ISA-TR75.25.02-2000 (R2010), Control Valve Response Measurement from Step Inputs.

Flange Dimension

• ASME B 16.5: Pipe Flanges and Flanged Fittings.

This Standard establishes requirements for wrought copper and wrought copper alloy braze-joint seamless fittings designed for use with seamless copper tube conforming to ASTM Standard Specification, B88 (Water and General Plumbing Systems), B280 (Air Conditioning and Refrigeration Service), and B819 (Medical Gas Systems). This Standard covers joints assembled with brazing materials conforming to ANSI/AWS A5.8.

This Standard is allied to ASME standards B16.18 and B16.22. It provides requirements for fitting-ends suitable for brazing. This Standard covers

(a) pressure–temperature ratings

(b) abbreviations for end connections (c) size and method of designating openings of fittings

(d) marking

(e) material

(f) dimensions and tolerances

(g) testing

• ANSI B16.10: Face to Face & End to End Dimensions of Valves

This 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 ensure installation interchangeability for valves of a given material, type, size, rating class, and end connection.

• ASME B16.47: large diameter steel flanges: nps 26 through nps 60 This Standard covers pressure–temperature ratings, materials, dimensions, tolerances, marking, and testing for pipe flanges in sizes NPS 26 through NPS 60.

Included are flanges with rating class designations 75, 150, 300, 400, 600, and 900 with requirements given in both SI (Metric) and U.S. Customary units, with diameter of bolts and flange bolt holes expressed in inch units. This Standard is limited to

(a) flanges made from cast or forged materials (b) blind flanges made from cast, forged, or plate materials. Also included in this Standard are requirements and recommendations regarding flange bolting, flange gaskets, and flange joints.

Face To Face

• ISA S75.12: Face-to-Face and End-to-End Dimensions of Valves

This standard applies to socket weld-end globe-style control valves, sizes 1/2 in (15 mm) through 4 in (100 mm), and screwed-end globe-style control valves, sizes 1/2 in (15 mm) through 2 1/2 in (65 mm), having top, top and bottom, port, or cage guiding.

• ANSI/ISA-75.08.01: Face-to-Face Dimensions for Integral Flanged Globe-Style Control Valve Bodies (Classes 125, 150, 250, 300, and 600)

This standard applies to integral flanged globe-style control valves, sizes 15 mm (1/2 inch) through 400 mm (16 inches), having top, top and bottom, port, or cage guiding.

• ANSI/ISA-75.08.02: Face-to-Face Dimensions for Flanged and Flangeless Rotary Control Valves (Classes 150, 300, and 600, and PN 10, PN 16, PN 25, PN 40, PN 63 and PN 100)

This standard applies to flanged and flangeless rotary control valves using a full ball or a segment of a ball and other rotary-stem control valves, sizes (20 mm) 3/4 inch through (600 mm) 24 inches for Classes 150 through 600, and for PN 10, PN 16, PN 25, PN 40, PN 63, and PN100.

• ANSI/ISA-75.08.03: Face-to-Face Dimensions for Socket Weld-End and Screwed-End Globe-Style Control Valves (Classes 150, 300, 600, 900, 1500, and 2500)

This standard applies to socket weld-end globe-style control valves, sizes 1/2 inch (15 mm) through 4 inches (100 mm), and screwed-end globe-style control valves, sizes 1/2 inch (15 mm) through 2 1/2 inches (65 mm), having top, top and bottom, port, or cage guiding.

• ANSI/ISA-75.08.08: Face-to-Centerline Dimensions for Flanged Globe-Style Angle Control Valve Bodies (Classes 150, 300, and 600) This standard aids user in their piping design by providing Classes 150, 300, and 600 raised-face flanged globe-style angle control valve face-to-centerline dimensions without giving special considerations to the equipment manufacturer to be used.

• ANSI/ISA-75.08.09: Face-to-Face Dimensions for Sliding Stem Flangeless Control Valves (Classes 150, 300, and 600)

1.1 This standard applies to sliding stem flangeless control valves, sizes 20 mm (3/4 inch) through 600 mm (24 inches) for Classes 150, 300, and 600.

1.2 The face-to-face dimensions listed apply only to control valves that will be bolted between flanges.

1.3 This standard is not intended to include rotary valves, such as butterfly valves.

• ANSI/ISA–75.15: Face-to-Face Dimensions for Buttweld-End Globe-Style Control Valves (ANSI Classes 150, 300, 600, 900, 1500, and 2500)

This standard applies to buttweld-end globe-style controls valves, sizes 15 mm (1/2 inch) through 450 mm (18 inches) for ANSI Classes 150 through 2500, having top, top and bottom, port, or cage guiding.

• ANSI/ISA–75.16: Face-to-Face Dimensions for Flanged Globe-Style Control Valve Bodies (ANSI Classes 900, 1500, and 2500) This standard applies to flanged control valves, sizes 15 mm (1/2 inch) through 450 mm (18 inches), having top, top and bottom, port, or cage guiding.

Body Material

Forged carbon Steel valves: ASTM A105/ A105M Forged carbon Steel valves For low Temprature Service: ASTM A350/ A350M (LF1, LF2, LF3, LF5, LF6, LF9, LF 787)

Forged Alloy Steel and Stainless Steel valves For High Temprature Service: ASTM A182/ A182 M-98ª(F 304, F 304H, F 304L, F 304N, F304 LN, F 309H, F310, F 310H, F 310 MoLN, F 316, F 316H, F 316L, F 316N, F 316LN, F 317, F 317L, F 347, F 347 H, F 348, F 348 H, F 321, F321 H)

Forged Duplex Steel valve : ASTM A182 (F 50, F 51, F 52, F 53M F 54, F 55, F 57, F 59, F 60, F 61, F 904L)

ASTM A352/ A352M (LCA, LCB, LCC, LC1, LC2, LC2-1, LC3,LC4, LC9(J31300), CA6NM),

ASTM A351/ A351 M (CF8(F304), CF3(F304L), CF3M(F316L), CF8M(F316))

ASTM A217/ A217 M-98a( WC1, WC4, WC5, WC6, WC9, WC11, C5, C12, C12A,

ASTM A351/ A351 M (CN7M, CD4MCu, CG8M, CK3MCuN)

SA-494/ SA-494 M(UNS N02100, UNS N24135, UNS N04020, UNS N24030, UNS N24025, UNS N24130, UNS N30012, UNS N30007, UNS N30003, UNS N06040, UNS N30002, UNS N30107, UNS N26455, UNS N26625, UNS N26055, UNS N30003, UNS N26022, UNS N08826, UNS N26059)

Body Standard

API 6D, API 600, API 599, API 598, API 608, API 602, ASME B16.10, ASME B16.5, ASME B16.47 (Serie A and Serie B) and MSS SP44 are the key specifications covering the dimensions and the manufacturing tolerances of Control valves body.

API 6D

Specification for Pipeline Valves. API Specification 6D is 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.

API 600

Bolted Bonnet Steel Gate Valves for Petroleum and Natural Gas Industries - Modified National Adoption of ISO 10434:1998.

API 599

Metal Plug Valves - Flanged, Threaded and Welding Ends. A purchase specification that covers requirements for metal plug valves with flanged or butt-welding ends, and ductile iron plug valves with flanged ends, in sizes NPS 1 through NPS 24, which correspond to nominal pipe sizes in ASME B36.10M. Valve bodies conforming to ASME B16.34 may have flanged end and one butt-welding end. It also covers both lubricated and no lubricated valves that have two-way coaxial ports, and includes requirements for valves fitted with internal body, plug, or port linings or applied hard facings on the body, body ports, plug, or plug port.

API 598

The API STANDARD 598: VALVE INSPECTION AND TESTING, covers the testing and inspection requirements for gate, globe, check, ball, plug & butterfly valves. It has acceptable leakage rates for liquid as well as gas testing. All valves built to the various API standards are required to meet API-598 leakage criteria prior to shipment from the manufacturer or supplier.

API 608

Metal Ball Valves - Flanged and Butt-Welding Ends. The standard covers Class 150 and Class 300 metal ball valves that have either butt-welding or flanged ends and are for use in on-off service.

API 602

Compact Steel Gate Valves - Flanged, Threaded, Welding, and Extended-Body Ends. The standard covers threaded-end, socket-welding-end, butt-welding-end, and flanged-end compact carbon steel gate valves in sizes NPS4 and smaller. BS 1873

BS 1873

British Standard Institute: Specification for steel globe and globe stop and check valves (flanged and butt-welding ends) for the petroleum, petrochemical and allied industries.

ASME B16.10

Face to Face & End to End Dimensions of Valves.

ASME B16.5

ASME B16.5 Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing, and methods of designating openings for pipe flanges and flanged fittings. Included are: flanges with rating class designations 150, 300, 400, 600, 900, and 1500 in sizes NPS 1/2 through NPS 24 and flanges with rating class designation 2500 in sizes NPS 1/2 through NPS 12.

ASME B16.47 (Serie A and Serie B), MSS-SP44

Large Diameter Steel Flanges, NPS 26 through NPS 60 Metric/Inch Standard, Weld Neck, Slip-On, Blind. Class 150 to Class 900.

ASTM A703/ A703M

This specification covers steel castings, general requirements, for pressure-containing parts. The steel shall be made by open-hearth or electric-furnace process, with or without separate refining such as argon-oxygen-decarburization (AOD), unless otherwise designated by the individual specification. Ferritic and martensitic steel shall be cooled after pouring to provide substantially complete transformation of austenite prior to heat treatment to enhance mechanical properties. The material shall conform to the specified chemical composition requirements. An analysis of each heat shall be made by the manufacturer to determine the percentages of the elements specified. The mechanical test methods and definitions are presented in details. One tension test shall be made from each heat, and shall conform to the tensile requirements specified. Test coupons shall be cast from the same heat as the castings represented, except that for investment castings, the test coupons shall be cast in the same type of mold as the castings. After machining, each casting shall be tested under specified hydrostatic shell test pressures in the applicable steel rating for which the casting is designed.

ASTM A487/ A703M

This specification covers low-alloy steel and martensitic stainless steels in the normalized and tempered, or quenched and tempered conditions, suitable for pressure-containing parts. All castings shall receive the specified heat treatment requirement: austenitizing temperature, medium, quenching cool, and tempering temperature. Preliminary heat treatment and multiple tempering are permitted. Recording-type pyrometers shall be used to control the furnace temperature. The steel shall conform to the required chemical composition for carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, vanadium, boron, and copper. Residual elements include: copper, nickel, chromium, tungsten, molybdenum, and vanadium. Tensile properties of the steel shall conform to the requirements for tensile strength, yield strength, elongation, reduction of area, hardness, and maximum thickness. Product analysis tolerance is specified. Repair by welding may be done.

ASTM A985/ A985M

This specification covers a group of common requirements that are mandatory for steel castings produced by the investment casting process for pressure-containing parts. Master heats shall be made by the electric furnace process with or without separate refining such as argon-oxygen-decarburization (AOD), vacuum-oxygen degassing (VOD), vacuum-induction-melting (VIM). Ferritic and martensitic steel shall be cooled after pouring to provide complete transformation of austenite prior to heat treatment to enhance mechanical properties. Chemical, heat, and product analyses shall be performed and the chemical composition thus determined shall conform to the prescribed values in carbon, manganese, silicon, phosphorus, sulfur, nickel, chromium, molybdenum, vanadium, tungsten, copper, and aluminum. Tensile testing shall be done on the castings and shall meet the required yield and tensile strength, elongation, and reduction of area. Each casting shall also be tested after machining to hydrostatic shell pressure test and shall not show any leaks.

API 6F

API 6F is About recommended practice for fire test for valves.

Valve Types and Typical Applications

Legend:

• DC = Directional Change

• IOS = Isolation or Stop

• PR = Pressure Relief

• TH = Throttling

Notes:

1. Only angle-globe valves can be used for a 90-degree change in direction of flow.

2. Check valves (other than the stop-check valves) stop flow only in one (reverse) direction. Stopcheck valves can be and are used as stop, block, or isolation valves, in addition to being used as a check valve.

3. Some designs of ball-and-plug valves (contact the valve manufacturer) are suitable for throttling service.

4. Multiport ball-and-plug valves are used for changing the direction of flow and mixing flows.

Control Valve Arrangement

The image below shows how a control valve can be used to control rate of flow in a line. The "controller" receives the pressure signals, compares them with pressure drop for the desired flow and if the actual flow is different, adjusts the control valve to increase or decrease the flow.

Comparable arrangements can be devised to control any of numerous process variables. Temperature, pressure, level and flow rate are the most common controlled variables.