1 Scope
NOTE This specification covers the automated final control element of a process control loop: the modulating control valve, the actuator that positions it, the positioner that commands the actuator, and the accessories that complete the assembly, for industrial, process, and water and wastewater treatment facilities. (1.1)
NOTE Equipment covered includes the control-valve body and trim, the actuator (pneumatic spring-diaphragm, pneumatic piston, or electric), the valve positioner (analog, HART, or digital/fieldbus), and the mounted accessories — I/P transducer, air set and filter regulator, solenoid valve, limit switches, position transmitter, and volume booster — furnished and calibrated as a coordinated valve assembly. (1.2)
NOTE The final control element is the muscle of the control loop: the controller computes a demand, but the valve assembly is what actually changes the process, and a loop is only as good as the valve that executes it. (1.3)
NOTE The boundary of work under this standard is the assembled control valve from its inlet and outlet pipe connections, through the actuator and positioner, to the instrument-air supply connection and the field signal terminations. (1.4)
NOTE This standard also covers electric (motorized) actuators applied to isolation valves — motor-operated valves (MOVs) — where the actuator is the controls interface that opens, closes, or modulates the valve and reports position to the supervisory system, because the actuator and its controls are I&C scope even when the valve body is an isolation valve. (1.5)
NOTE This standard does not cover general isolation and service piping valves selected for shutoff rather than throttling, nor the body and material standards that govern them; those are piping valves governed by AWWA, MSS, and API standards and belong to a Mechanical/Plumbing piping-valve standard. (1.6)
NOTE The distinction between a throttling control valve and an isolation valve determines which standard applies: a valve selected to modulate flow against a process variable is in scope; a valve selected to fully open or fully close for isolation is out of scope except through its electric actuator. (1.7)
1.8Control valve sizing shall comply with ANSI/ISA-75.01.01 (IEC 60534-2-1 Mod).
1.9Seat leakage classification shall comply with ANSI/FCI 70-2.
2 Referenced Standards
NOTE Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited. (2.1)
2.2Where conflicts exist between referenced standards, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
| Standard |
Title |
| ANSI/ISA-75.01.01 (IEC 60534-2-1 Mod) |
Industrial-Process Control Valves — Flow Equations for Sizing Control Valves |
| IEC 60534-2-1 |
Industrial-Process Control Valves — Sizing Equations for Fluid Flow Under Installed Conditions |
| IEC 60534-2-3 |
Industrial-Process Control Valves — Flow Capacity — Test Procedures |
| ANSI/ISA-75.08.01 |
Face-to-Face Dimensions for Integral Flanged Globe-Style Control Valve Bodies (Classes 125, 150, 250, 300, 600) |
| ANSI/ISA-75.08.02 |
Face-to-Face Dimensions for Flanged and Flangeless Rotary Control Valves |
| ANSI/FCI 70-2 |
Control Valve Seat Leakage |
| ISA-RP75.23 |
Considerations for Evaluating Control Valve Cavitation |
| IEC 60534-8-3 |
Control Valves — Noise Considerations — Aerodynamic Noise Prediction Method |
| IEC 60534-8-4 |
Control Valves — Noise Considerations — Prediction of Noise Generated by Hydrodynamic Flow |
| ANSI/ISA-75.19.01 |
Hydrostatic Testing of Control Valves |
| ANSI/ISA-75.13.01 |
Method of Evaluating the Performance of Positioners with Analog Input Signals and Pneumatic Output |
| ASME B16.34 |
Valves — Flanged, Threaded, and Welding End (pressure-temperature ratings — factual body reference) |
| ASME B16.5 |
Pipe Flanges and Flanged Fittings (end-connection reference) |
| AWWA C540 / C541 / C542 |
Power-Actuating Devices / Cylinder and Vane Actuators / Electric Motor Actuators for Valves and Slide Gates (water/wastewater MOVs) |
| ISO 15848-1 / -2 |
Industrial Valves — Measurement, Test and Qualification Procedures for Fugitive Emissions |
| NACE MR0175 / ISO 15156 |
Materials for Use in H2S-Containing Environments in Oil and Gas Production (sour service) |
| NAMUR NE 107 |
Self-Monitoring and Diagnosis of Field Devices (status signal) |
| IEC 61508 / IEC 61511 |
Functional Safety of Safety Instrumented Systems (where the valve is a safety final element) |
| IEC 60529 |
Degrees of Protection Provided by Enclosures (IP Code) |
| NEMA 250 |
Enclosures for Electrical Equipment (1000 V Maximum) |
| NEMA ICS 2 |
Industrial Control and Systems: Controllers, Contactors, and Overload Relays (electric actuator controls) |
| NFPA 70 |
National Electrical Code (NEC) — area classification and wiring methods |
3 Submittals
3.1 Action Submittals
3.1.1The Contractor shall submit the following for the Engineer's review and approval prior to procurement:
- Control valve sizing calculation per ANSI/ISA-75.01.01 / IEC 60534-2-1 for each valve, showing the process data set (flow rate, inlet and outlet pressure, temperature, fluid properties, and specific gravity or molecular weight) at minimum, normal, and maximum flow cases, with the required and selected Cv, the percent of rated Cv at each case, and the resulting valve travel
- Cavitation and flashing evaluation per ISA-RP75.23 for liquid service, identifying the service sigma versus the manufacturer's sigma limits, and the predicted aerodynamic or hydrodynamic noise per IEC 60534-8-3 or IEC 60534-8-4
- Inherent flow characteristic (linear, equal-percentage, or quick-open) and rangeability for each valve, with justification for the characteristic against the installed pressure-drop ratio
- Valve body and trim data: body style, size, end connection, pressure class and pressure-temperature rating, body and trim materials, packing type, and bonnet type (standard, extended, or bellows)
- Seat leakage class per ANSI/FCI 70-2 for each valve
- Actuator data: type (spring-diaphragm, piston, or electric), available thrust or torque versus the required seating and dynamic thrust or torque, bench-set range (pneumatic), fail-safe action, and stroking speed
- Positioner data: signal input, communication protocol (analog 4-20 mA, HART, FOUNDATION Fieldbus, PROFIBUS PA), diagnostic capability, and NAMUR NE 107 status support
- Accessory schedule: I/P transducer, air set/filter regulator, solenoid valve, limit switches, position transmitter, and volume booster, with the function of each
- Electric actuator data (where applicable): motor rating, duty class (on-off, modulating S4, or continuous), torque switches and limit switches, network interface, local controls, and enclosure rating per NEMA 250 / IEC 60529
- Area classification compliance documentation where the valve assembly is installed in a classified location per NFPA 70
- Instrument-air consumption (steady-state and transient) for pneumatic assemblies, for coordination with the instrument-air system
- Dimensioned assembly drawings showing face-to-face dimension per ANSI/ISA-75.08, weight, and required service clearances
☐ Sizing calculation per ISA-75.01.01 / IEC 60534-2-1
☐ Cavitation/flashing and noise evaluation
☐ Flow characteristic and rangeability with justification
☐ Body and trim data (materials, class, packing)
☐ Seat leakage class per ANSI/FCI 70-2
☐ Actuator data with thrust/torque margin and fail action
☐ Positioner data and protocol
☐ Accessory schedule
☐ Electric actuator data and enclosure rating (MOVs)
☐ Area classification compliance
☐ Instrument-air consumption
☐ Dimensioned assembly drawings
3.1.2Fabrication and shipment shall not proceed until action submittals have been reviewed and returned.
3.2 Closeout Submittals
3.2.1At substantial completion, the Contractor shall provide the following before the control valves are accepted:
- Operation and maintenance manuals for each valve assembly, including disassembly, trim replacement, packing adjustment, and calibration procedures
- Factory hydrostatic shell test certificate per ANSI/ISA-75.19.01 and seat leakage test record per ANSI/FCI 70-2 for each valve
- As-calibrated positioner records, including the configured characteristic, span, zero, and the as-left signature (valve signature and step/ramp response) for digital positioners
- Loop checkout and stroke test records (full stroke and, where applicable, partial stroke) coordinated with Control Systems Integration
- Bench-set verification record (pneumatic) or torque-switch and limit-switch setting record (electric)
- Diagnostic baseline captured by digital positioners or electric actuators at commissioning, for future comparison
- Fugitive-emission packing certification per ISO 15848 where specified
- Warranty documentation
- Spare parts inventory list with manufacturer part numbers
☐ Operation and maintenance manuals
☐ Factory hydrostatic and seat-leakage test records
☐ As-calibrated positioner records and signatures
☐ Loop checkout and stroke test records
☐ Bench-set or torque/limit-switch setting record
☐ Commissioning diagnostic baseline
☐ Fugitive-emission packing certification (where specified)
☐ Warranty documentation
☐ Spare parts inventory list with part numbers
4 Quality Assurance
4.1 Manufacturer Qualifications
4.1.1Control valves and actuators shall be the products of a manufacturer with a minimum of ten years of continuous experience designing and producing modulating control valves of the type specified.
4.1.2The manufacturer shall maintain an ISO 9001 certified quality management system.
4.1.3Replacement trim, packing, and actuator parts shall be available for a minimum of fifteen years from the date of manufacture.
4.2 Sizing Responsibility
4.2.1The valve manufacturer shall perform and stamp the final sizing calculation for each valve using the process data set provided by the Engineer.
4.2.2The manufacturer shall not substitute a different valve size or trim from that calculated without the Engineer's written approval.
NOTE A control valve sized only on the line size — rather than on the process data set and the required Cv — is the single most common control-valve error, producing a valve that operates near the seat at normal flow with poor controllability and accelerated trim wear. (4.2.3)
4.3 Single-Source Responsibility
4.3.1For each control valve, the body, trim, actuator, positioner, and accessories shall be furnished, assembled, and calibrated by or through a single supplier as a coordinated assembly.
NOTE Field-assembling a valve body from one supplier with an actuator and positioner from others transfers the responsibility for thrust margin, bench set, and characterization to the field, where it is frequently done incorrectly. (4.3.2)
4.4 Listing and Area Classification
4.4.1Electrical components of the valve assembly — positioner, solenoid, limit switches, position transmitter, and electric actuator — shall be listed by a Nationally Recognized Testing Laboratory for the area classification of their installed location per NFPA 70.
4.4.2In classified (hazardous) locations, the protection method (explosionproof, intrinsically safe, or increased safety) shall be as required for the area class, division or zone, and gas group.
5 Environmental and Service Conditions
5.1 Installation Environment
Indoor — heated process building or control building
Indoor — unheated process area
Outdoor — exposed (rain, sun, wind-driven dust)
Below-grade vault or wet well (WTP/WWTP)
Submerged or intermittently flooded
5.1.1Valve assemblies shall be selected and rated for the conditions at the installation site, including ambient temperature extremes, humidity, precipitation, and airborne contaminants.
5.1.2Outdoor and below-grade assemblies shall protect the positioner, solenoid, and electrical accessories against water ingress to the rating specified for the location.
5.2 Enclosure Protection Rating
NEMA 4 / IP66 — outdoor, hose-directed water (standard for WTP/WWTP outdoor)
NEMA 4X / IP66 — corrosive or coastal outdoor
NEMA 6 / IP67 — occasional submersion (vaults, wet wells)
NEMA 6P / IP68 — prolonged submersion
NEMA 7 / explosionproof — Class I Division 1 hazardous
NEMA 12 / IP54 — indoor industrial, dust and dripping
5.2.1Positioners, solenoids, limit switches, position transmitters, and electric actuator housings shall meet the enclosure rating specified for the installation environment per NEMA 250 and IEC 60529.
NOTE Water and wastewater service routinely exposes valve electrics to washdown, condensation, and flooding; an underrated enclosure admits moisture that corrodes the positioner and fails the loop. (5.2.2)
5.3 Ambient Temperature
-20°F to 120°F (verify project location and indoor/outdoor)
°F5.3.1The valve assembly, including the positioner, solenoid, and actuator diaphragm or seals, shall be rated for the project ambient temperature range without loss of function.
5.3.2In cold climates, freeze protection of instrument air (dryness/dewpoint), valve cavities holding stagnant liquid, and below-grade assemblies shall be coordinated with the project mechanical design.
6 Application and Loop Role
6.1 Final Control Element Function
NOTE The control valve shall be selected to modulate the controlled process variable (flow, pressure, level, or temperature) in response to the loop demand signal from the controller. (6.1.1)
NOTE The valve assembly shall accept the controller output and position the valve so that the installed flow tracks the demand across the required operating range. (6.1.2)
6.2 Controlled Variable
Flow
Pressure
Level
Temperature
pH or analytical setpoint
Differential pressure
6.3 Service Type
NOTE The service fluid and its phase determine the sizing equations, the trim selection, and the material requirements. (6.3.1)
Clean liquid (water, treated water, clear process liquid)
Dirty or solids-bearing liquid (raw water, sludge, slurry)
Gas or vapor
Steam
Two-phase or flashing liquid
Corrosive chemical (acid, caustic, oxidant)
6.3.2The service fluid, composition, and any solids or abrasive content shall be as indicated on the P&IDs and process datasheets. 7 Valve Body Style
7.1 Body Style Selection
NOTE The body style shall match the service, the required rangeability, the available pressure drop, and the cleanliness of the fluid. (7.1.1)
NOTE Globe (sliding-stem) valves provide precise throttling, high rangeability, and ready accommodation of anti-cavitation and low-noise trim, and are the default for clean modulating service where tight control matters. (7.1.2)
NOTE Segmented-ball valves provide high capacity and high rangeability with good shutoff, tolerate fiber and solids, and are common in pulp, sludge, and high-turndown liquid service. (7.1.3)
NOTE Eccentric rotary-plug valves combine rotary economy with globe-like control and good shutoff, and resist coating and scaling. (7.1.4)
NOTE High-performance (eccentric-disc) butterfly valves provide high capacity in large line sizes at low cost and are used for modulating control where the pressure drop is modest, including large water and wastewater flow control. (7.1.5)
○ Globe — sliding stem, single or balanced cage trim
○ Segmented ball (V-notch) — high capacity, high rangeability
○ Eccentric rotary plug — globe-like control, anti-coating
○ High-performance butterfly (eccentric disc) — large line, modulating
7.1.6The body style shall not be a quarter-turn isolation valve repurposed for throttling unless it is specifically the high-performance modulating type with a control-quality actuator and positioner.
7.2 Body Size and End Connection
0.548
0.50.7511.5234681012162024303648
Default: 4 in. (NPS)
Flanged — ASME B16.5 raised face
Flanged — flat face (cast iron / lined systems)
Flangeless (wafer) — between-flange rotary
Lug — between-flange, tapped
Butt-weld
Threaded (NPT) — small valves only
Grooved (WTP/WWTP yard piping)
7.2.1The body size shall be the size determined by the sizing calculation, which is frequently smaller than the line size; the valve shall be installed with reducers as required.
7.2.2The valve body size shall not be selected to match the line size by default.
NOTE Selecting the valve to match the line size oversizes most control valves, forcing them to operate near the seat where control is poor and trim wears rapidly. (7.2.3)
7.3 Pressure Class
ASME Class 150
ASME Class 300
ASME Class 600
ASME Class 900
ASME Class 1500
ASME Class 2500
AWWA / cast-iron rating (WTP/WWTP low-pressure)
7.3.1The body pressure-temperature rating shall equal or exceed the maximum service conditions per ASME B16.34, and the body and end connections shall match the connected piping class.
8 Sizing and Flow Coefficient
8.1 Required Flow Coefficient
NOTE The required flow coefficient (Cv) shall be calculated per ANSI/ISA-75.01.01 / IEC 60534-2-1 for the minimum, normal, and maximum flow cases using the process data set. (8.1.1)
8.1.2The valve shall be sized so that at the maximum flow case the required Cv does not exceed approximately 80% of the valve's rated Cv, and at the minimum flow case the valve travel is not so low that control becomes unstable.
8.1.3The selected valve travel shall fall within the controllable range of the trim — typically between about 20% and 80% of rated travel across the normal operating cases.
8.1.4Sizing shall account for piping geometry factors (reducers and expanders) and, for compressible flow, for the gas expansion factor and the pressure-drop ratio.
☐ Minimum, normal, and maximum flow cases provided
☐ Inlet and outlet pressure at each case
☐ Temperature and fluid properties at each case
☐ Piping geometry factor (reducers/expanders) applied
☐ Required Cv and percent of rated Cv at each case
☐ Resulting valve travel at each case
8.2 Process Data Set
As indicated on the P&IDs and instrument datasheets (with units)
As indicated on the process datasheets
psigAs indicated on the process datasheets
psiNOTE The pressure drop across the valve shall be the actual drop at each flow case, not an assumed fixed value; using an arbitrary fixed drop produces a mis-sized valve when the system curve is pump- or elevation-dominated. (8.2.2)
9 Flow Characteristic and Rangeability
9.1 Inherent Flow Characteristic
NOTE The inherent flow characteristic relates flow capacity to valve travel at constant pressure drop, and shall be selected so that the installed characteristic — the relationship of flow to travel under the actual, varying system pressure drop — is approximately linear. (9.1.1)
NOTE Equal-percentage trim produces equal proportional changes in Cv for equal increments of travel and is the most common selection, because it compensates for the falling valve pressure drop as flow rises in systems where the valve takes a small share of the total system drop. (9.1.2)
NOTE Linear trim produces flow proportional to travel and is appropriate where the valve pressure drop is a large and relatively constant share of the system drop. (9.1.3)
NOTE Quick-open trim produces large flow change for small initial travel and is not used for modulating control; it suits on-off and some self-acting service only. (9.1.4)
○ Equal-percentage (most modulating service)
○ Linear (valve drop a large, constant share of system drop)
○ Quick-open (on-off only — not for modulating control)
○ Modified parabolic (intermediate, manufacturer-specific)
9.1.5The characteristic shall be selected against the pressure-drop ratio (valve drop divided by system drop) at maximum flow: equal-percentage where that ratio is low, linear where it approaches unity.
NOTE Specifying linear trim on a system where the valve takes only a small share of the pressure drop yields an installed characteristic that behaves like quick-open — most of the control occurs in the first portion of travel, and the loop is difficult to tune. (9.1.6)
9.2 Rangeability
NOTE Rangeability is the ratio of the maximum to the minimum controllable flow coefficient over which the valve holds its characteristic. (9.2.1)
NOTE Higher rangeability lets one valve control a wider flow range without losing characterization at low travel. (9.2.2)
30:1 (globe, standard)
50:1 (globe, high-performance trim)
100:1 or greater (segmented ball, special trim)
20:1 (rotary, standard)
9.2.3The valve rangeability shall equal or exceed the turndown required by the process operating cases.
10 Cavitation, Flashing, and Noise
10.1 Cavitation and Flashing Evaluation
NOTE Liquid service shall be evaluated for cavitation and flashing per ISA-RP75.23 using the sigma (σ) method, comparing the service sigma to the manufacturer's sigma limits for the selected valve and trim. (10.1.1)
NOTE Cavitation occurs when the local pressure at the vena contracta falls below the fluid vapor pressure and then recovers, collapsing vapor bubbles against trim and body surfaces and causing severe erosion, noise, and vibration. (10.1.2)
NOTE Flashing occurs when the outlet pressure remains below vapor pressure so the fluid stays partly vaporized downstream, eroding the body by high-velocity two-phase flow. (10.1.3)
None expected — service sigma well above incipient
Incipient cavitation — monitor, standard trim acceptable
Cavitation expected — anti-cavitation (multi-stage) trim required
Flashing service — hardened body and erosion-resistant trim required
10.1.4Where the evaluation predicts damaging cavitation, anti-cavitation trim that stages the pressure drop (multi-stage, multi-path, or tortuous-path) shall be provided to keep each stage above the cavitation threshold.
10.1.5Where the service flashes, the valve body and trim shall be selected for the resulting two-phase erosion, with a hardened or hardfaced trim and an erosion-resistant body, and the body style shall direct the expanding flow away from the body wall.
NOTE Cavitation cannot be eliminated by trim material alone; if the pressure profile is not staged, even hardened trim erodes — the pressure drop must be managed, not merely resisted. (10.1.6)
10.2 Predicted Noise
NOTE Predicted valve noise shall be calculated per IEC 60534-8-3 for compressible (aerodynamic) flow and IEC 60534-8-4 for liquid (hydrodynamic) flow. (10.2.1)
75110
80859095100105110
Default: 85 dBA
10.2.2Predicted sound pressure level at 1 m from the valve shall not exceed the limit specified for the area.
10.2.3Where predicted noise exceeds the limit, low-noise trim, downstream diffusers or resistance plates, heavier-wall downstream pipe, or path attenuation shall be provided.
NOTE Aerodynamic valve noise above approximately 100 dBA also indicates high trim velocity that mechanically damages the trim; noise control and trim longevity are linked. (10.2.4)
11 Trim, Materials, and Seat Leakage
11.1 Trim Materials
NOTE Trim materials shall be selected for the service: erosion, corrosion, temperature, and any abrasive solids. (11.1.1)
Type 316 stainless steel (standard clean service)
316 SST with hardened (hardfaced) seat and plug (cavitation/erosion)
Stellite or tungsten-carbide trim (severe erosion/cavitation)
Alloy 20, Hastelloy, or titanium (aggressive chemical service)
NACE MR0175-compliant trim (sour / H2S service)
11.1.2Trim for cavitating, flashing, or solids-bearing service shall be hardened or hardfaced.
11.1.3Trim for sour (H2S-containing) service shall comply with NACE MR0175 / ISO 15156.
11.2 Body Material
Carbon steel (WCB) — general clean service
Cast iron / ductile iron — WTP/WWTP low-pressure water service
Stainless steel (CF8M / 316) — corrosive or clean process
Alloy (Alloy 20, Hastelloy, titanium) — aggressive chemical
Lined (PTFE, PFA, rubber) — corrosive or abrasive
11.2.1The body material shall match the service fluid, the pressure-temperature rating, and the connected piping material.
11.3 Packing
PTFE V-ring (standard, low friction)
Graphite (high temperature)
Live-loaded (spring-energized, low maintenance)
Low-emission / fugitive-emission certified (ISO 15848)
11.3.1Stem packing shall be selected for the service temperature and the emission requirement.
11.3.2Where fugitive-emission control is required, the packing shall be certified to ISO 15848 to the specified emission class.
NOTE Packing friction directly degrades positioning resolution; over-tightened or high-friction packing causes deadband and limit-cycling in the loop, so packing selection is a control-performance decision, not only a sealing decision. (11.3.3)
11.4 Seat Leakage Class
NOTE The seat leakage class per ANSI/FCI 70-2 shall be specified for each valve according to how tightly the valve must shut off when fully closed. (11.4.1)
NOTE Class IV (metal seat) is the standard for most metal-seated modulating valves; Class V is for critical metal-seat shutoff under high differential; Class VI (bubble-tight, soft seat) is for applications requiring near-zero leakage. (11.4.2)
○ Class IV — metal seat, standard modulating shutoff
○ Class V — metal seat, tight shutoff under high differential
○ Class VI — soft seat, bubble-tight
○ Class II or III — general (where tight shutoff not required)
11.4.3A modulating control valve shall not be relied upon as the process isolation point; where positive isolation is required, a dedicated isolation valve (outside this standard) shall be provided in series.
NOTE Specifying Class VI bubble-tight shutoff on a valve whose only duty is throttling adds soft-seat cost and limits temperature and erosion tolerance for a shutoff that the loop never requires. (11.4.4)
12 Actuators
12.1 Actuator Type
NOTE The actuator shall be sized and selected to position the valve against the maximum dynamic and seating forces at the available supply pressure or motor rating, with margin. (12.1.1)
NOTE Pneumatic spring-diaphragm actuators provide inherent fail-safe action from the spring, smooth modulation, and are the default for modulating service where instrument air is available. (12.1.2)
NOTE Pneumatic piston actuators provide higher thrust and faster stroking for large valves and high differential pressure, and are double-acting (requiring a separate fail-safe means) or spring-return. (12.1.3)
NOTE Electric actuators are used where instrument air is unavailable or undesirable, and are required for most water/wastewater MOVs and for remote sites. (12.1.4)
○ Pneumatic spring-diaphragm (modulating, fail-safe spring)
○ Pneumatic piston — spring-return (high thrust, fail-safe)
○ Pneumatic piston — double-acting (with fail-safe accumulator/SOV)
○ Electric — modulating duty (S4 / continuous rated)
○ Electric — on/off or open/close (MOV isolation)
12.2 Actuator Sizing
NOTE The actuator output (thrust for sliding-stem, torque for rotary) shall equal or exceed the maximum required seating and dynamic force, including the unbalance force at maximum differential pressure, the packing friction, and the seat load, with a minimum 25% margin at the minimum available air supply pressure. (12.2.1)
25% minimum margin at minimum supply pressure (standard)
50% margin (high differential or critical service)
Per manufacturer maximum-shutoff dP rating
NOTE Actuator output shall be verified against the valve's published maximum shutoff differential pressure rating; an undersized actuator cannot close against the process and stalls. (12.2.2)
12.3 Bench Set (Pneumatic)
NOTE The pneumatic actuator bench set shall be specified to preload the spring so the actuator overcomes the seat load and unbalance force and delivers full travel within the diaphragm pressure range. (12.3.1)
3-15 psig (standard diaphragm range)
6-30 psig (high-seat-load applications)
Per positioner output (positioner-driven, bench set selected for thrust)
12.3.2Where a positioner is provided, the bench set shall be selected for thrust and seating rather than for direct signal-range correspondence, and the positioner shall characterize the signal-to-travel relationship.
12.4 Fail-Safe Action
NOTE The fail-safe action on loss of signal, loss of air, or loss of power shall be specified for each valve based on the process safe state. (12.4.1)
○ Fail closed (FC) — spring closes valve on loss of air/power
○ Fail open (FO) — spring opens valve on loss of air/power
○ Fail last (FL) — valve holds last position (requires lock-up or motor brake)
12.4.3Fail-last action shall be provided only with a positive holding means — a pneumatic lock-up relay with an air reservoir for pneumatic actuators, or a self-locking gear train or brake for electric actuators — because a plain double-acting or electric actuator does not hold position when its motive power is lost.
NOTE Choosing the wrong fail action is a safety error, not a preference: a feedwater or coolant valve that fails closed when it should fail open can damage equipment or endanger personnel. (12.4.4)
12.5 Stroking Speed
Standard modulating speed (no special requirement)
Fast stroke — volume booster or piston actuator (surge/anti-water-hammer)
Slow stroke — controlled closure to prevent water hammer (WTP/WWTP)
12.5.1Where rapid closure would induce water hammer in a liquid line, the closure speed shall be limited; where rapid action is required for surge or trip duty, a volume booster or piston actuator shall be provided.
13 Electric Actuators on Isolation Valves (MOVs)
13.1 Scope of Electric Actuation
NOTE Electric actuators applied to isolation valves (MOVs) are in this standard because the actuator and its controls are the I&C interface that opens, closes, or modulates the valve and reports its position to the supervisory system, even though the valve body is an isolation valve governed elsewhere. (13.1.1)
NOTE The valve body, end connections, and body materials of an MOV isolation valve are governed by the applicable piping-valve standard (AWWA, MSS, or API) and are outside this standard; this standard governs only the electric actuator and its controls. (13.1.2)
13.1.3Electric actuators for water and wastewater valves and slide gates shall comply with AWWA C542.
13.2 Duty Rating
○ On/off (open-close) — Class A/B duty
○ Inching/positioning — Class C duty
○ Modulating — Class D (S4) continuous-rated for high starts/hour
13.2.1The electric actuator duty rating shall match the operating frequency: open/close isolation duty for valves that operate occasionally, and a modulating-rated (S4, continuous) actuator with a high permissible starts-per-hour rating for valves that throttle continuously.
NOTE Applying an open/close-rated actuator to a continuously modulating duty overheats the motor and fails it prematurely; modulating duty requires an actuator specifically rated for the start frequency. (13.2.2)
13.3 Position Feedback and Controls
Discrete — open/close command and open/closed status (hardwired)
Analog — 4-20 mA command and 4-20 mA position feedback
Network — Modbus RTU/TCP
Network — PROFIBUS DP / PROFINET
Network — EtherNet/IP
Network — FOUNDATION Fieldbus
13.3.2The actuator shall include torque switches to protect the valve and actuator against overtorque at the seat and against jamming, and limit switches to define the open and closed positions.
13.3.3The actuator shall provide local open/close/stop controls and a local/remote selector, with the local controls lockable where required.
14 Positioner and Accessories
14.1 Valve Positioner
NOTE Each modulating control valve shall be furnished with a valve positioner that compares the demand signal to the measured stem or shaft position and adjusts the actuator until the position matches the demand. (14.1.1)
NOTE A positioner overcomes packing friction, actuator hysteresis, and dynamic load to deliver accurate, repeatable positioning, and is required on essentially all modulating valves. (14.1.2)
○ Analog (electro-pneumatic) — 4-20 mA input, no diagnostics
○ Digital with HART — 4-20 mA input plus HART diagnostics (standard)
○ Digital fieldbus — FOUNDATION Fieldbus or PROFIBUS PA
○ Pneumatic positioner — 3-15 psig input (legacy/no electrical)
14.1.3A positioner shall be provided on every modulating valve; relying on the bare actuator signal-to-pressure relationship without a positioner leaves the loop with the actuator's hysteresis and the packing friction uncorrected.
14.2 Positioner Diagnostics
NOTE Digital positioners shall capture and store diagnostic information for predictive maintenance, including valve signature, friction trend, travel histogram, cycle count, and response signatures. (14.2.1)
NOTE The positioner shall report device health using a NAMUR NE 107 status classification (failure, function check, out of specification, maintenance required) to the supervisory system. (14.2.2)
☐ Valve signature (capture at commissioning as baseline)
☐ Online friction and travel trending
☐ Travel histogram and cycle counter
☐ NAMUR NE 107 status reporting
☐ Partial stroke test (PST) — safety final elements
14.2.3Where the valve is a final element of a safety instrumented function, the positioner shall support partial stroke testing (PST) to improve the diagnostic coverage of the function per IEC 61508 / IEC 61511, and the safety requirement shall be coordinated with the safety system design.
14.3 Mounted Accessories
NOTE The valve assembly accessories shall be selected for the duty and mounted and tubed at the factory as part of the assembly. (14.3.1)
☐ Air filter regulator (air set) — conditions instrument air
☐ I/P transducer (where positioner is pneumatic-input)
☐ Solenoid valve — drives valve to fail position on trip
☐ Volume booster — speeds large-actuator stroking
☐ Limit switches — discrete open/closed position to SCADA
☐ Position transmitter — independent 4-20 mA position feedback
☐ Handwheel / manual override
14.3.2An air filter regulator (air set) shall be provided on every pneumatic assembly to condition the instrument air to the positioner and actuator.
14.3.3A solenoid valve shall be provided where the valve must be driven to its fail position on a trip independently of the modulating signal.
14.3.4A volume booster shall be provided where a large actuator must stroke faster than the positioner output alone can fill or exhaust it.
14.3.5A separate position transmitter shall be provided where the supervisory system requires position feedback independent of the positioner's internal feedback.
14.4 Instrument Air Supply
20150
2030406080100120150
Default: 80 psig
14.4.1The instrument-air supply pressure and quality (dryness/dewpoint and particulate per the instrument-air standard) shall be confirmed available at each pneumatic valve.
14.4.2The actuator sizing shall be based on the minimum guaranteed supply pressure, and the assembly air consumption shall be reported for coordination with the instrument-air system.
NOTE Wet or dirty instrument air is the leading cause of positioner and solenoid failure in the field; air quality is a prerequisite for valve reliability, not an optional refinement. (14.4.3)
15 Factory Testing
15.1 Hydrostatic and Seat Leakage Tests
NOTE Each valve body shall be hydrostatically shell-tested by the manufacturer per ANSI/ISA-75.19.01 to prove the structural integrity and leak-tightness of the pressure-retaining parts. (15.1.1)
15.1.2Each valve shall be seat-leakage tested to the specified ANSI/FCI 70-2 class.
☐ Hydrostatic shell test per ISA-75.19.01
☐ Seat leakage test per ANSI/FCI 70-2 (specified class)
☐ Stroke/calibration record (signal vs. travel)
☐ Actuator bench-set or torque-switch verification
☐ Fugitive-emission packing test (ISO 15848, where specified)
15.1.3Test certificates shall be furnished as closeout submittals.
15.2 Factory Calibration
15.2.1The manufacturer shall stroke and calibrate each assembled valve, verifying that the valve moves through full travel in the correct direction in response to the demand signal and that the positioner reports position accurately.
15.2.2For digital positioners, the as-shipped configuration (characteristic, span, zero) and a baseline valve signature shall be recorded.
16 Installation
16.1 Orientation and Access
16.1.1Control valves shall be installed in the orientation recommended by the manufacturer, with the actuator accessible for calibration and maintenance and the flow direction matching the body arrow.
16.1.2Sufficient clearance shall be maintained above and around the valve for actuator removal, trim service, and packing replacement per the equipment arrangement and piping drawings. 16.1.3Sliding-stem globe valves should be installed with the stem vertical and the actuator above the line wherever practical, so the actuator weight is supported and condensate does not collect in the actuator.
16.2 Piping and Isolation
16.2.1Block-and-bypass valves and upstream and downstream isolation valves shall be provided around each control valve as indicated on the P&IDs so the control valve can be isolated and serviced without draining the system. 16.2.2The required straight pipe runs upstream and downstream and any reducers shall be installed as shown on the drawings, and the valve shall be installed free of pipe strain.
16.2.3Welding slag, scale, and construction debris shall be flushed from the line before the control valve is installed or, where the valve is installed first, a temporary spool shall be used during flushing to protect the trim.
NOTE Construction debris drawn through a new control valve cuts the seat and trim and is a frequent cause of early seat-leakage failure. (16.2.4)
16.3 Air and Signal Connections
16.3.1Instrument-air tubing shall be run to each pneumatic valve from the conditioned instrument-air supply, sloped and trapped to drain condensate, and connected through the air set.
16.3.2Signal and feedback wiring shall be installed and terminated per Conductors And Cables, with analog loops separated from power wiring and shields grounded at one end only. 17 Field Commissioning
17.1 Loop Checkout and Stroke Test
NOTE After installation, each valve shall be loop-checked and stroke-tested under
Control Systems Integration, verifying that the demand from the controller produces the correct travel and direction, that the position feedback to
Scada And Hmi Systems agrees with the actual position, and that the fail-safe action occurs on loss of signal, air, or power.
(17.1.1) ☐ Full-stroke test (0-100-0%) with travel vs. signal verified
☐ Fail-safe action verified (loss of signal/air/power)
☐ Position feedback to SCADA verified against actual travel
☐ Calibration of zero and span confirmed as-left
☐ Packing adjusted to eliminate deadband without binding
☐ Partial stroke test configured (safety final elements)
☐ Diagnostic baseline captured (digital positioner/actuator)
17.1.2Deadband and resolution shall be checked and the packing adjusted so the valve responds to small signal changes without binding or limit-cycling.
17.1.3The as-left calibration and the commissioning diagnostic baseline shall be recorded for each valve.
17.2 Coordination with the Loop
NOTE A valve with excessive packing friction, incorrect characterization, or an undersized actuator cannot be tuned out at the controller and shall be corrected at the valve. (17.2.2)
18 Delivery, Storage, and Handling
18.1Control valves shall be delivered with end-connection protectors in place and with the actuator, positioner, and accessories factory-mounted and protected.
18.2Valves shall be stored indoors, clean and dry, with electrical and pneumatic ports capped until connection.
18.3Valves shall be handled and rigged by the body or by manufacturer-designated lifting points, never by the actuator, positioner, tubing, or accessories.
NOTE Lifting or supporting a valve by its actuator or positioner bends linkages and damages the position feedback, throwing off the calibration before the valve is ever installed. (18.4)
19 Warranty
19.1 Warranty Terms
1 year from substantial completion (standard)
2 years from substantial completion
18 months from shipment or 12 months from startup, whichever first
19.1.1The manufacturer shall warrant each control valve assembly against defects in materials and workmanship for the period selected from the date of substantial completion.
19.1.2The warranty shall cover the body, trim, actuator, positioner, and factory-mounted accessories as a coordinated assembly.
20 Spare Parts
20.1 Spare Parts Package
20.1.1The Contractor shall furnish the manufacturer's recommended spare parts for the first year of operation.
- One trim repair kit (seat, plug or disc, and stem seals) for each valve size and trim type
- One packing set for each valve size
- One positioner repair/diaphragm kit for each positioner type
- One solenoid valve and one I/P transducer of each type used
- One diaphragm and one gasket set for each pneumatic actuator size
☐ Trim repair kit (each size/type)
☐ Packing set (each size)
☐ Positioner repair/diaphragm kit (each type)
☐ Spare solenoid valve (each type)
☐ Spare I/P transducer (each type)
☐ Actuator diaphragm and gasket set (each size)
20.1.2Common spare parts shall be stocked once per size/type rather than per valve where multiple identical valves are installed.
20.1.3The spare-parts list with manufacturer part numbers shall be included in the closeout documentation.