{"id":14507,"date":"2026-09-14T11:03:29","date_gmt":"2026-09-14T03:03:29","guid":{"rendered":"https:\/\/raymonvalve.com\/?p=14507"},"modified":"2026-09-14T11:08:25","modified_gmt":"2026-09-14T03:08:25","slug":"fail-open-vs-fail-close-control-valve","status":"publish","type":"post","link":"https:\/\/raymonvalve.com\/pt\/fail-open-vs-fail-close-control-valve\/","title":{"rendered":"Fail Open vs Fail Close Control Valve: Process Safety, Air Failure, Actuator Action and Specification"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-post\" data-elementor-id=\"14507\" class=\"elementor elementor-14507\" data-elementor-post-type=\"post\">\n\t\t\t\t<div class=\"elementor-element elementor-element-212e4a18 e-flex e-con-boxed e-con e-parent\" data-id=\"212e4a18\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-2e60b2cf elementor-widget elementor-widget-text-editor\" 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border-right:0;\n}\n\n.raymonvalve-blog-page tbody tr:last-child td{\n  border-bottom:0;\n}\n\n.raymonvalve-blog-page th{\n  background:var(--rv-navy);\n  color:#fff;\n  font-weight:700;\n}\n\n.raymonvalve-blog-page tbody tr:nth-child(even) td{\n  background:#f9fbfc;\n}\n\n.raymonvalve-blog-page .rv-cta{\n  margin:48px 0;\n  padding:32px;\n  border-radius:14px;\n  background:var(--rv-navy);\n  color:#fff;\n}\n\n.raymonvalve-blog-page .rv-cta h2{\n  margin:0 0 14px;\n  color:#fff;\n}\n\n.raymonvalve-blog-page .rv-cta p,\n.raymonvalve-blog-page .rv-cta strong{\n  color:#eef4f9;\n}\n\n.raymonvalve-blog-page .rv-button{\n  display:inline-block;\n  margin-top:8px;\n  padding:13px 20px;\n  border:2px solid #fff;\n  border-radius:7px;\n  background:#fff;\n  color:var(--rv-navy);\n  font-weight:700;\n  line-height:1.35;\n  text-decoration:none;\n}\n\n.raymonvalve-blog-page .rv-button:hover,\n.raymonvalve-blog-page .rv-button:focus{\n  background:transparent;\n  color:#fff;\n}\n\n.raymonvalve-blog-page .rv-faq{\n  margin-top:22px;\n}\n\n.raymonvalve-blog-page details{\n  margin:12px 0;\n  padding:0 18px;\n  border:1px solid var(--rv-border);\n  border-radius:10px;\n  background:#fff;\n}\n\n.raymonvalve-blog-page summary{\n  cursor:pointer;\n  padding:17px 4px;\n  color:var(--rv-navy);\n  font-weight:700;\n  line-height:1.45;\n}\n\n.raymonvalve-blog-page details p{\n  margin:0;\n  padding:0 4px 17px;\n}\n\n@media(max-width:767px){\n  .raymonvalve-blog-page{\n    padding:16px 14px 44px;\n    font-size:16px;\n  }\n\n  .raymonvalve-blog-page h2{\n    margin-top:44px;\n    font-size:26px;\n  }\n\n  .raymonvalve-blog-page h3{\n    margin-top:28px;\n    font-size:21px;\n  }\n\n  .raymonvalve-blog-page .rv-answer,\n  .raymonvalve-blog-page .rv-note,\n  .raymonvalve-blog-page .rv-warning{\n    padding:18px;\n  }\n\n  .raymonvalve-blog-page .rv-keyline{\n    grid-template-columns:1fr 1fr;\n    gap:10px;\n  }\n\n  .raymonvalve-blog-page .rv-keyline div{\n    min-height:76px;\n    padding:13px 10px;\n    font-size:14px;\n  }\n\n  .raymonvalve-blog-page table{\n    min-width:700px;\n    font-size:14px;\n  }\n\n  .raymonvalve-blog-page th,\n  .raymonvalve-blog-page td{\n    padding:12px;\n  }\n\n  .raymonvalve-blog-page .rv-cta{\n    padding:24px 20px;\n  }\n\n  .raymonvalve-blog-page .rv-button{\n    display:block;\n    width:100%;\n    text-align:center;\n  }\n}\n\n@media(max-width:420px){\n  .raymonvalve-blog-page .rv-keyline{\n    grid-template-columns:1fr;\n  }\n}\n<\/style><\/p>\n<article class=\"raymonvalve-blog-page\">\n<div class=\"rv-content\">\n<div class=\"rv-answer\">\n<p><strong>Fail open and fail close describe where a control valve should move after a defined failure, but neither position is inherently safer.<\/strong> The correct choice depends on the process consequence of losing instrument air, electrical power, control signal or a shutdown command. Define the failure and required process-safe state first, then specify the actuator, solenoid, positioner, shutoff requirement and functional verification needed to achieve it.<\/p>\n<\/div>\n<figure><img fetchpriority=\"high\" decoding=\"async\" title=\"Fail Open vs Fail Close Control Valve Comparison\" src=\"https:\/\/raymonvalve.com\/wp-content\/uploads\/2026\/09\/fail-open-vs-fail-close-control-valve-comparison.webp\" alt=\"Fail open, fail close and fail in place control valve comparison\" width=\"1600\" height=\"900\" data-image-status=\"live-verified\" data-source-type=\"generated-engineering-schematic\" \/>\n<figcaption>Engineering schematic comparing fail-open, fail-close and fail-in-place behavior under a defined failure condition. It is a decision aid, not a project-specific safety analysis.<\/figcaption>\n<\/figure>\n<div class=\"rv-keyline\">\n<div>Define the failure<\/div>\n<div>Assess the consequence<\/div>\n<div>Specify the package action<\/div>\n<div>Verify the response<\/div>\n<\/div>\n<h2>Fail Open vs Fail Close Control Valve: What Is the Actual Difference?<\/h2>\n<p>A <strong>fail-open control valve<\/strong> moves toward its specified open position when the defined failure occurs. A <strong>fail-close control valve<\/strong> moves toward its specified closed position. A <strong>fail-in-place<\/strong> or project-defined fail-lock arrangement is intended to keep the valve near a specified position when a defined failure occurs.<\/p>\n<p>The abbreviation alone is not a complete engineering requirement. Writing only <strong>FC<\/strong> does not tell a supplier whether the valve must close on loss of instrument air, loss of electrical power, loss of control signal, solenoid de-energization, emergency shutdown demand or another project-defined event.<\/p>\n<p>The distinction matters because the same valve and actuator package can respond differently to different failures. Instrument air can be lost while an electrical signal remains present; a control signal can disappear while air remains available; and an ESD command can intentionally override normal control while both utilities remain healthy.<\/p>\n<h2>Define the Failure Before Defining the Fail Position<\/h2>\n<p>A fail position should always be tied to a specific failure scenario. The engineering sequence is not \u201cchoose FC, then select an actuator.\u201d It is <strong>define the failure \u2192 assess the process consequence \u2192 define the required safe state \u2192 configure the valve and actuator package to achieve that state<\/strong>.<\/p>\n<div class=\"raymonvalve-table-wrap\">\n<table>\n<thead>\n<tr>\n<th scope=\"col\">Failure Scenario<\/th>\n<th scope=\"col\">What Changes?<\/th>\n<th scope=\"col\">Questions to Confirm<\/th>\n<th scope=\"col\">Required Specification<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Loss of instrument air<\/td>\n<td>Pneumatic energy is lost or falls below the usable pressure.<\/td>\n<td>Spring return or double acting? Is stored air or lock-up provided?<\/td>\n<td>Required valve position at the stated minimum or lost-air condition.<\/td>\n<\/tr>\n<tr>\n<td>Loss of electrical power<\/td>\n<td>Electrical energy to the positioner, solenoid or electric actuator may be lost.<\/td>\n<td>Which components lose power? Does pneumatic energy remain available?<\/td>\n<td>Required response to the defined power-failure condition.<\/td>\n<\/tr>\n<tr>\n<td>Loss of control signal<\/td>\n<td>The command signal becomes unavailable or invalid.<\/td>\n<td>Does instrument air remain? What is the configured positioner fault action?<\/td>\n<td>Open, close, hold or another project-defined response.<\/td>\n<\/tr>\n<tr>\n<td>Solenoid de-energization<\/td>\n<td>The solenoid valve changes state.<\/td>\n<td>Is the SOV energized during normal operation? How is air routed when de-energized?<\/td>\n<td>Required trip position and pneumatic routing.<\/td>\n<\/tr>\n<tr>\n<td>Emergency shutdown demand<\/td>\n<td>Shutdown logic intentionally overrides normal control.<\/td>\n<td>What process-safe state, stroke direction and response time are required?<\/td>\n<td>ESD position, accessory logic and verification requirement.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<figure><img decoding=\"async\" title=\"Control Valve Failure Scenario Matrix\" src=\"https:\/\/raymonvalve.com\/wp-content\/uploads\/2026\/09\/control-valve-failure-scenario-matrix.webp\" alt=\"Control valve failure scenario matrix for air, signal, power and ESD conditions\" width=\"1200\" height=\"900\" data-image-status=\"live-verified\" data-source-type=\"generated-decision-matrix\" \/>\n<figcaption>Example decision matrix separating instrument-air failure, signal failure, electrical-power failure and shutdown demand.<\/figcaption>\n<\/figure>\n<div class=\"rv-note\">\n<p><strong>Specification rule:<\/strong> FO, FC or fail-in-place is not complete until the initiating failure condition and required final response are defined together.<\/p>\n<\/div>\n<h2>Good vs Bad Fail-Action Specification<\/h2>\n<p>The quality of a control-valve fail-action specification depends on whether different failure cases are explicit enough for every bidder to quote the same functional requirement.<\/p>\n<div class=\"raymonvalve-table-wrap\">\n<table>\n<thead>\n<tr>\n<th scope=\"col\">Specification Level<\/th>\n<th scope=\"col\">Example<\/th>\n<th scope=\"col\">Assessment<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Weak<\/td>\n<td><strong>Fail Action: FC<\/strong><\/td>\n<td>Does not identify which failure must drive the valve closed or how signal failure, power failure and ESD should behave.<\/td>\n<\/tr>\n<tr>\n<td>Better<\/td>\n<td><strong>Required position on loss of instrument air: Closed<\/strong><\/td>\n<td>Defines one failure condition and the required response.<\/td>\n<\/tr>\n<tr>\n<td>Project-ready direction<\/td>\n<td>Loss of instrument air: closed. ESD solenoid de-energization: closed. Signal-loss response: per approved control philosophy. Shutoff leakage specified separately.<\/td>\n<td>Separates failure scenarios, package action and sealing requirement so quotations can be normalized.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p><strong>A recurring RFQ problem<\/strong> is that two suppliers both write \u201cFC\u201d but propose different solenoid and positioner philosophies. The label looks identical while the package behavior is not. The practical prevention is to issue the same failure-scenario matrix to every bidder and require each supplier to identify valve action, actuator action, SOV state, positioner fault behavior and technical deviations.<\/p>\n<h2>How Process Safety Determines Fail Open or Fail Close<\/h2>\n<p>There is no universal rule that fail close is safer than fail open. The required position depends on the consequence of continued flow compared with interrupted flow during the defined failure.<\/p>\n<p><strong>The decision question is: Which valve position places this specific process in the safer state for the event being evaluated?<\/strong><\/p>\n<p>The answer should come from the approved process design, hazard review, cause-and-effect logic, shutdown philosophy and project requirements rather than from the valve name or service label alone.<\/p>\n<h3>When Fail Close May Be Considered<\/h3>\n<p>Fail close may be considered when continued flow increases the process consequence\u2014for example, when stopping additional feed or isolating a source is part of the defined safe-state philosophy. This remains a preliminary direction until the relevant process and shutdown logic are confirmed.<\/p>\n<h3>When Fail Open May Be Considered<\/h3>\n<p>Fail open may be considered when maintaining flow reduces the consequence of an upset, such as a service where loss of cooling, quench or circulation creates the more severe condition. The application name alone is not enough: redundancy, downstream consequences, shutdown sequence and available utilities still need review.<\/p>\n<h3>When Fail in Place May Be Considered<\/h3>\n<p>Fail in place may be considered when sudden travel toward either fully open or fully closed could worsen the process condition. The intended behavior may require lock-up devices, stored pneumatic energy or other project-specific arrangements.<\/p>\n<div class=\"rv-warning\">\n<p><strong>Important:<\/strong> A double-acting actuator does not automatically provide fail-in-place behavior. The actual result depends on the pneumatic circuit, solenoid arrangement, lock-up devices, stored energy, valve forces and the defined failure.<\/p>\n<\/div>\n<figure><img decoding=\"async\" title=\"Control Valve Fail-Position Selection Matrix\" src=\"https:\/\/raymonvalve.com\/wp-content\/uploads\/2026\/09\/control-valve-fail-position-selection-matrix.webp\" alt=\"Control valve fail-position selection matrix based on process consequence\" width=\"1200\" height=\"900\" data-image-status=\"live-verified\" data-source-type=\"generated-selection-matrix\" \/>\n<figcaption>Preliminary engineering matrix for considering fail-open, fail-close or fail-in-place from the process consequence. It does not replace project-specific hazard or cause-and-effect review.<\/figcaption>\n<\/figure>\n<p>For the broader actuator decision\u2014including required torque or thrust, stroke time, available power and fail action\u2014see Raymon Valve&#8217;s <a href=\"https:\/\/raymonvalve.com\/valve-drive-mode\/\">valve actuation and drive mode selection guide<\/a>.<\/p>\n<h2>Air-to-Open vs Air-to-Close: How Actuator Action Relates to Fail Position<\/h2>\n<p>Air-to-open and air-to-close describe how pneumatic actuator pressure moves the valve. They are related to fail position in common spring-return arrangements, but they are not interchangeable with the final failure specification.<\/p>\n<h3>Air-to-Open<\/h3>\n<p>In a conventional spring-return arrangement, increasing pneumatic pressure moves an air-to-open actuator toward the open direction. If instrument air is lost, spring force may drive the assembly toward closed.<\/p>\n<p>This commonly produces <strong>Air-to-Open \u2192 Fail Close<\/strong>, but the relationship must be confirmed from the actual valve action, actuator mounting and accessories.<\/p>\n<h3>Air-to-Close<\/h3>\n<p>In a conventional spring-return arrangement, increasing pneumatic pressure moves an air-to-close actuator toward the closed direction. Loss of air may allow the spring to drive the valve toward open.<\/p>\n<p>This commonly produces <strong>Air-to-Close \u2192 Fail Open<\/strong>. It is not a substitute for checking the complete assembled package.<\/p>\n<figure><img loading=\"lazy\" decoding=\"async\" title=\"Air-to-Open vs Air-to-Close Actuator Action\" src=\"https:\/\/raymonvalve.com\/wp-content\/uploads\/2026\/09\/air-to-open-vs-air-to-close-actuator-action.webp\" alt=\"Air-to-open and air-to-close pneumatic actuator action schematic\" width=\"1200\" height=\"900\" data-image-status=\"live-verified\" data-source-type=\"generated-engineering-schematic\" \/>\n<figcaption>Engineering schematic showing typical spring-return air-to-open and air-to-close relationships. Actual package behavior must be confirmed from the valve, actuator, mounting, positioner, solenoid and pneumatic accessories.<\/figcaption>\n<\/figure>\n<p>For integrated package considerations, see Raymon Valve&#8217;s <a href=\"https:\/\/raymonvalve.com\/actuated-valves\/\">actuated valve package guidance<\/a>.<\/p>\n<h2>Fail Position Is Not the Same as Positioner or Controller Action<\/h2>\n<div class=\"rv-note\">\n<p><strong>Process Variable \u2192 Controller \u2192 Positioner \u2192 Actuator \u2192 Valve<\/strong><\/p>\n<\/div>\n<p><strong>Valve fail position<\/strong> defines the required mechanical position after the specified failure.<\/p>\n<p><strong>Actuator action<\/strong> describes how the actuator moves in response to pneumatic pressure, electrical power or another motive-energy source.<\/p>\n<p><strong>Positioner action<\/strong> describes how the positioner converts its input signal into actuator output and how it is configured to react to signal faults.<\/p>\n<p><strong>Controller action<\/strong> defines how controller output changes as the measured process variable changes. Direct or reverse controller action does not by itself determine the valve&#8217;s mechanical fail position.<\/p>\n<h2>Loss of Air vs Loss of Signal vs Loss of Power<\/h2>\n<p>Loss of air, signal, power and an ESD demand are different events and should not automatically share one fail-action statement.<\/p>\n<div class=\"raymonvalve-table-wrap\">\n<table>\n<thead>\n<tr>\n<th scope=\"col\">Condition<\/th>\n<th scope=\"col\">Air Available?<\/th>\n<th scope=\"col\">Electrical Power?<\/th>\n<th scope=\"col\">Control Signal?<\/th>\n<th scope=\"col\">Final Response Depends On<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Instrument-air failure<\/td>\n<td>No or below the stated usable pressure<\/td>\n<td>Possibly<\/td>\n<td>Possibly<\/td>\n<td>Spring, actuator construction, pneumatic circuit and accessories<\/td>\n<\/tr>\n<tr>\n<td>Signal failure<\/td>\n<td>Usually yes<\/td>\n<td>Usually yes<\/td>\n<td>No or invalid<\/td>\n<td>Positioner configuration and control philosophy<\/td>\n<\/tr>\n<tr>\n<td>Power failure<\/td>\n<td>Possibly yes<\/td>\n<td>No<\/td>\n<td>May also be unavailable<\/td>\n<td>Solenoid, positioner, electric actuator and stored energy<\/td>\n<\/tr>\n<tr>\n<td>ESD trip<\/td>\n<td>Often available<\/td>\n<td>Often available<\/td>\n<td>Normal command overridden<\/td>\n<td>Shutdown logic, SOV arrangement and required safe state<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h2>Fail Close Does Not Mean Tight Shutoff<\/h2>\n<p>Fail direction and leakage performance are separate requirements. A fail-close valve is required to move toward the specified closed position after the defined failure, but that statement does not establish the allowable leakage at the seat.<\/p>\n<p>Shutoff performance depends on the selected valve and trim design, seat construction, differential pressure, actuator force or thrust, condition of the sealing surfaces and the stated acceptance criterion.<\/p>\n<p>The official <a href=\"https:\/\/webstore.iec.ch\/en\/publication\/31136\" target=\"_blank\" rel=\"noopener noreferrer nofollow\">IEC 60534-4:2021 control-valve inspection and routine-testing publication<\/a> provides a relevant testing framework within its stated scope. It should not be interpreted as evidence that a valve specified as fail closed automatically satisfies a particular leakage requirement.<\/p>\n<div class=\"rv-note\">\n<p>A project datasheet may therefore require both <strong>Fail Position: Closed<\/strong> and a separately defined <strong>allowable leakage or shutoff acceptance requirement<\/strong>.<\/p>\n<\/div>\n<h2>How Actuator Type Changes Fail-Safe Behavior<\/h2>\n<h3>Spring-Return Pneumatic Actuator<\/h3>\n<p>A spring-return pneumatic actuator stores mechanical energy in the spring. When pneumatic pressure can no longer oppose the spring, the actuator can move toward its spring position. Final sizing still requires manufacturer-specific valve force or torque, maximum relevant differential pressure, minimum available air pressure, seat construction, stroke time and the required fail direction.<\/p>\n<h3>Double-Acting Pneumatic Actuator<\/h3>\n<p>A double-acting pneumatic actuator normally uses air pressure for movement in both directions. After loss of air, the final position depends on the pneumatic circuit, trapped pressure, lock-up devices, reservoirs, solenoids, external valve forces and other accessories.<\/p>\n<h3>Electric Actuator<\/h3>\n<p>An electric actuator uses electrical motive power. If movement is required after normal power is lost, the package requires an appropriate stored-energy, emergency-power or other engineered arrangement. The required response must be specified rather than assumed.<\/p>\n<p><strong>A common actuator-selection mistake<\/strong> is to match the actuator only from valve size and fail direction. A package can still be inadequate if the actuator output was not checked against the relevant differential-pressure load at the minimum available air or power condition. Technical review should therefore compare manufacturer valve load data with actuator output over the required travel and failure case rather than infer suitability from nominal size.<\/p>\n<h2>How to Specify Fail Action on a Control Valve Datasheet<\/h2>\n<p>A useful fail-action datasheet identifies the process duty, the failure event and the complete package response. For the broader control-valve product and configuration context, see the <a href=\"https:\/\/raymonvalve.com\/control-valves\/\">Raymon Valve control valve range<\/a>.<\/p>\n<div class=\"raymonvalve-table-wrap\">\n<table>\n<thead>\n<tr>\n<th scope=\"col\">Datasheet Field<\/th>\n<th scope=\"col\">What Should Be Defined<\/th>\n<th scope=\"col\">Why It Matters<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Valve tag and service<\/td>\n<td>Equipment identification and controlled process duty<\/td>\n<td>Connects the fail-action requirement to the correct process function.<\/td>\n<\/tr>\n<tr>\n<td>Defined failure<\/td>\n<td>Loss of air, signal, power, ESD or another stated event<\/td>\n<td>Prevents one generic fail label from covering different scenarios.<\/td>\n<\/tr>\n<tr>\n<td>Required safe position<\/td>\n<td>Open, closed, hold\/fail-in-place or project-defined position<\/td>\n<td>Defines the intended mechanical result.<\/td>\n<\/tr>\n<tr>\n<td>Actuator type<\/td>\n<td>Spring-return pneumatic, double acting, electric, hydraulic or other<\/td>\n<td>Determines the motive-energy and stored-energy arrangement.<\/td>\n<\/tr>\n<tr>\n<td>Actuator action<\/td>\n<td>ATO \/ ATC or equivalent action where applicable<\/td>\n<td>Defines travel direction under motive power.<\/td>\n<\/tr>\n<tr>\n<td>Instrument-air supply<\/td>\n<td>Normal and minimum available pressure<\/td>\n<td>Actuator output must be evaluated at the stated minimum supply.<\/td>\n<\/tr>\n<tr>\n<td>Positioner<\/td>\n<td>Type, input signal and fault-response requirement<\/td>\n<td>Signal-loss behavior may differ from air-failure behavior.<\/td>\n<\/tr>\n<tr>\n<td>Solenoid valve<\/td>\n<td>Normal energized\/de-energized state and trip philosophy<\/td>\n<td>Determines pneumatic routing during a shutdown command.<\/td>\n<\/tr>\n<tr>\n<td>Differential pressure<\/td>\n<td>Relevant operating, shutoff and failure load cases<\/td>\n<td>Directly affects required valve force or actuator torque\/thrust.<\/td>\n<\/tr>\n<tr>\n<td>Shutoff requirement<\/td>\n<td>Allowable leakage and applicable acceptance basis<\/td>\n<td>Separates sealing performance from fail direction.<\/td>\n<\/tr>\n<tr>\n<td>Stroke time<\/td>\n<td>Required opening and closing response<\/td>\n<td>Excessively fast or slow movement may affect the process transient.<\/td>\n<\/tr>\n<tr>\n<td>Reset behavior<\/td>\n<td>Required response after air, power or signal is restored<\/td>\n<td>Reduces the risk of unintended restart movement.<\/td>\n<\/tr>\n<tr>\n<td>Functional verification<\/td>\n<td>Required failure simulation, observations and records<\/td>\n<td>Confirms the behavior of the assembled package rather than individual components alone.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h2>Fail-Action Engineering Decision Gate<\/h2>\n<p>Before a fail-open, fail-close or fail-in-place requirement is released for quotation, use the following gate to identify where a project decision is still missing.<\/p>\n<div class=\"raymonvalve-table-wrap\">\n<table>\n<thead>\n<tr>\n<th scope=\"col\">Decision Question<\/th>\n<th scope=\"col\">If Yes<\/th>\n<th scope=\"col\">If No<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Is the failure scenario clearly defined?<\/td>\n<td>Continue to consequence review.<\/td>\n<td>Do not finalize FO \/ FC \/ fail-in-place.<\/td>\n<\/tr>\n<tr>\n<td>Is the consequence of continued versus stopped flow understood?<\/td>\n<td>Identify the required process-safe state.<\/td>\n<td>Return the decision to process or safety engineering.<\/td>\n<\/tr>\n<tr>\n<td>Is the required final valve position confirmed?<\/td>\n<td>Translate it into actuator and accessory requirements.<\/td>\n<td>Do not select actuator action yet.<\/td>\n<\/tr>\n<tr>\n<td>Are air, signal, power and ESD cases separated where necessary?<\/td>\n<td>Specify the required response for each relevant case.<\/td>\n<td>Separate the failure scenarios before RFQ issue.<\/td>\n<\/tr>\n<tr>\n<td>Is the valve \/ actuator \/ positioner \/ SOV logic known?<\/td>\n<td>Proceed to package-level verification.<\/td>\n<td>Request the supplier configuration and pneumatic\/control schematic.<\/td>\n<\/tr>\n<tr>\n<td>Is shutoff leakage specified independently?<\/td>\n<td>Review trim, seat and available actuator force.<\/td>\n<td>Define the acceptance requirement before technical approval.<\/td>\n<\/tr>\n<tr>\n<td>Is reset or utility-restoration behavior defined?<\/td>\n<td>Include it in the functional verification procedure.<\/td>\n<td>Clarify the restart philosophy before commissioning.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"rv-warning\">\n<p><strong>Engineering stop point:<\/strong> If the process consequence or required safe state has not been confirmed, a valve supplier should not be expected to determine the final fail position from the service name alone.<\/p>\n<\/div>\n<h2>What Should Be Verified During Functional Testing?<\/h2>\n<p>Fail-action requirements should ultimately be checked on the assembled valve, actuator and accessory package against an approved project procedure.<\/p>\n<ul>\n<li>Confirm normal actuator and valve travel direction.<\/li>\n<li>Confirm the mechanical spring position where applicable.<\/li>\n<li>Verify SOV energized and de-energized behavior.<\/li>\n<li>Verify the configured response to loss of control signal.<\/li>\n<li>Verify the defined air-failure response where the approved procedure permits the simulation.<\/li>\n<li>Confirm final valve position and indicated feedback.<\/li>\n<li>Check required mechanical stops and travel limits.<\/li>\n<li>Measure stroke time where it is a specified acceptance item.<\/li>\n<li>Restore air, electrical power or signal and verify the required reset\/restart behavior.<\/li>\n<li>Record the tested configuration and any approved deviations.<\/li>\n<\/ul>\n<figure><img loading=\"lazy\" decoding=\"async\" title=\"Control Valve Fail-Action Functional Verification Flowchart\" src=\"https:\/\/raymonvalve.com\/wp-content\/uploads\/2026\/09\/control-valve-fail-action-functional-test-flowchart.webp\" alt=\"Control valve fail-action functional verification flowchart\" width=\"1200\" height=\"900\" data-image-status=\"live-verified\" data-source-type=\"generated-engineering-flowchart\" \/>\n<figcaption>Example engineering verification flow from the defined failure to final valve response and utility restoration. Final FAT, SAT and commissioning procedures remain project-specific.<\/figcaption>\n<\/figure>\n<p><strong>A recurring commissioning risk<\/strong> occurs when the fail position is specified but the restoration behavior is not. A valve may reach the intended safe state during the failure yet move unexpectedly when air, power or signal returns. The prevention is to include restoration and reset behavior in the control philosophy and functional-test acceptance criteria, not only the initial fail movement.<\/p>\n<h2>What Technical Evidence Should the Supplier Provide?<\/h2>\n<p>A fail-action requirement should be supported by package-level technical evidence. A procurement team should be able to trace the proposed failure response from the datasheet through the actuator and accessory configuration to the functional test.<\/p>\n<div class=\"raymonvalve-table-wrap\">\n<table>\n<thead>\n<tr>\n<th scope=\"col\">Technical Item<\/th>\n<th scope=\"col\">Supplier Should Confirm<\/th>\n<th scope=\"col\">Why It Matters<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Valve action<\/td>\n<td>Actual stem, shaft or plug movement for opening and closing<\/td>\n<td>Prevents reversed package configuration.<\/td>\n<\/tr>\n<tr>\n<td>Actuator construction<\/td>\n<td>Spring-return, double-acting or another arrangement<\/td>\n<td>Defines how motive and stored energy are provided.<\/td>\n<\/tr>\n<tr>\n<td>Spring action<\/td>\n<td>Spring-to-open or spring-to-close where applicable<\/td>\n<td>Confirms mechanical response when air is lost.<\/td>\n<\/tr>\n<tr>\n<td>Minimum utility condition<\/td>\n<td>Minimum air pressure or electrical basis used for selection<\/td>\n<td>Provides the basis for available actuator output.<\/td>\n<\/tr>\n<tr>\n<td>Maximum relevant differential pressure<\/td>\n<td>Opening, closing and shutoff load case used for actuator review<\/td>\n<td>Affects required torque or thrust.<\/td>\n<\/tr>\n<tr>\n<td>Positioner configuration<\/td>\n<td>Configured response to lost or invalid command signal<\/td>\n<td>Separates signal-failure response from air failure.<\/td>\n<\/tr>\n<tr>\n<td>Solenoid logic<\/td>\n<td>Energized\/de-energized condition and pneumatic routing<\/td>\n<td>Defines shutdown and trip behavior.<\/td>\n<\/tr>\n<tr>\n<td>Stroke time<\/td>\n<td>Opening and closing response under the stated conditions<\/td>\n<td>Can affect process transients and shutdown behavior.<\/td>\n<\/tr>\n<tr>\n<td>Allowable leakage<\/td>\n<td>Specified shutoff acceptance requirement<\/td>\n<td>Separates sealing performance from fail direction.<\/td>\n<\/tr>\n<tr>\n<td>Functional test<\/td>\n<td>Failure simulation, observed response and recorded result<\/td>\n<td>Confirms assembled-package behavior.<\/td>\n<\/tr>\n<tr>\n<td>Reset behavior<\/td>\n<td>Response when utilities or command are restored<\/td>\n<td>Reduces the risk of unexpected post-failure movement.<\/td>\n<\/tr>\n<tr>\n<td>Technical deviations<\/td>\n<td>Any difference from the issued datasheet, control philosophy or purchase specification<\/td>\n<td>Prevents an alternative package philosophy from being accepted without review.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h2>How to Normalize Supplier Quotations<\/h2>\n<p>Two quotations can use the same fail-position abbreviation while offering different technical packages. Technical bid evaluation should therefore compare a common engineering basis rather than the FO\/FC label or price alone.<\/p>\n<div class=\"raymonvalve-table-wrap\">\n<table>\n<thead>\n<tr>\n<th scope=\"col\">Bid Comparison Field<\/th>\n<th scope=\"col\">Required Comparison Basis<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Defined failure<\/td>\n<td>All suppliers use the same air, power, signal and trip scenarios.<\/td>\n<\/tr>\n<tr>\n<td>Required fail position<\/td>\n<td>The same final position is quoted for each relevant scenario.<\/td>\n<\/tr>\n<tr>\n<td>Actuator type<\/td>\n<td>Spring-return, double-acting, stored-energy or alternative arrangements are compared against the same functional requirement.<\/td>\n<\/tr>\n<tr>\n<td>Minimum utility condition<\/td>\n<td>All suppliers use the same minimum air-pressure or electrical-power basis.<\/td>\n<\/tr>\n<tr>\n<td>Maximum differential pressure<\/td>\n<td>Actuator selection is based on the same relevant valve load case.<\/td>\n<\/tr>\n<tr>\n<td>Accessories<\/td>\n<td>Positioner, solenoid, lock-up, tank, switches and feedback scope are normalized.<\/td>\n<\/tr>\n<tr>\n<td>Stroke time<\/td>\n<td>Opening and closing response requirements are identical.<\/td>\n<\/tr>\n<tr>\n<td>Shutoff<\/td>\n<td>All bidders use the same allowable-leakage requirement independently of fail position.<\/td>\n<\/tr>\n<tr>\n<td>Functional verification<\/td>\n<td>The same failure simulation and documentation scope is included.<\/td>\n<\/tr>\n<tr>\n<td>Technical deviations<\/td>\n<td>Every exception is stated explicitly rather than embedded in the vendor configuration.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h2>RFQ Checklist for a Fail-Safe Control Valve Package<\/h2>\n<p>For a meaningful technical quotation, provide enough process and package data to evaluate both control-valve duty and fail-action behavior.<\/p>\n<ul>\n<li>Valve tag and service description<\/li>\n<li>Medium, composition, phase and solids where relevant<\/li>\n<li>Minimum, normal and maximum flow conditions<\/li>\n<li>Upstream and downstream pressures for relevant operating cases<\/li>\n<li>Normal and design pressure<\/li>\n<li>Normal and design temperature<\/li>\n<li>Line size and piping information<\/li>\n<li>Maximum relevant differential pressure<\/li>\n<li>Control objective and normal operating position where relevant<\/li>\n<li>Defined loss-of-air, loss-of-signal, loss-of-power and trip scenarios<\/li>\n<li>Required process-safe state for each relevant scenario<\/li>\n<li>Required fail position<\/li>\n<li>Actuator type and action<\/li>\n<li>Minimum available instrument-air pressure or electrical supply<\/li>\n<li>Positioner type and control signal<\/li>\n<li>Solenoid configuration and trip philosophy<\/li>\n<li>Allowable leakage or shutoff requirement<\/li>\n<li>Required opening and closing stroke time<\/li>\n<li>Reset \/ restart behavior<\/li>\n<li>Hazardous-area and environmental requirements<\/li>\n<li>Required inspection, testing and documentation scope<\/li>\n<li>Applicable project specification and approved standards\/editions<\/li>\n<li>Relevant P&amp;ID, cause-and-effect or control-philosophy documents where available<\/li>\n<\/ul>\n<figure><img loading=\"lazy\" decoding=\"async\" title=\"Control Valve Fail-Action RFQ Checklist\" src=\"https:\/\/raymonvalve.com\/wp-content\/uploads\/2026\/09\/control-valve-fail-action-rfq-checklist.webp\" alt=\"Control valve fail-action RFQ and datasheet checklist\" width=\"1200\" height=\"900\" data-image-status=\"live-verified\" data-source-type=\"generated-rfq-checklist\" \/>\n<figcaption>Example RFQ checklist covering process data, failure definition, actuation, accessories, performance and verification requirements.<\/figcaption>\n<\/figure>\n<p>Fail action is only one part of control-valve engineering. If a liquid service also has a significant pressure drop, the RFQ may need separate review of vapor formation, pressure recovery and downstream two-phase behavior. See the related guide to <a href=\"https:\/\/raymonvalve.com\/control-valve-cavitation-vs-flashing\/\">control valve cavitation vs flashing<\/a>.<\/p>\n<p>Final control-valve sizing must not be inferred from fail position, nominal line size or pressure class alone. It requires confirmed flow conditions, upstream and downstream pressures, temperature, fluid properties, piping data and the required control objective. Final actuator sizing likewise requires manufacturer-specific valve force or torque, differential pressure, seat construction, minimum available utility and required stroke time.<\/p>\n<h2>Fail Open vs Fail Close: Final Engineering Takeaway<\/h2>\n<p><strong>The correct fail position is the position that moves the specific process toward its defined safer state for the failure being evaluated.<\/strong><\/p>\n<ol>\n<li>Define the initiating failure.<\/li>\n<li>Assess the consequence and define the required process-safe state.<\/li>\n<li>Specify the valve, actuator, solenoid, positioner and accessory behavior needed to achieve it.<\/li>\n<li>Separate fail direction from shutoff leakage and actuator sizing requirements.<\/li>\n<li>Verify the assembled package and its reset behavior under the approved project procedure.<\/li>\n<\/ol>\n<p>For safety instrumented functions, the official <a href=\"https:\/\/webstore.iec.ch\/en\/publication\/61289\" target=\"_blank\" rel=\"noopener noreferrer nofollow\">IEC 61511-1:2016+AMD1:2017 consolidated publication<\/a> addresses specification, design, installation, operation and maintenance of safety instrumented systems used to achieve or maintain a safe process state. A valve&#8217;s FO\/FC label, actuator type or spring action alone does not establish SIL capability for the complete safety function.<\/p>\n<div class=\"rv-cta\">\n<h2>Request Control Valve Fail-Action Review<\/h2>\n<p>Send your control-valve datasheet or RFQ with the service medium, flow cases, upstream and downstream pressures, temperature, maximum relevant differential pressure, defined air \/ signal \/ power \/ trip scenarios, required process-safe state, fail position, actuator requirement, minimum utility condition, positioner, solenoid philosophy, stroke time, allowable leakage and reset behavior.<\/p>\n<p>Where available, also provide the relevant <strong>P&amp;ID, cause-and-effect document, control philosophy, existing valve datasheet and actuator datasheet<\/strong>. These inputs allow the valve, actuator and accessory configuration to be reviewed on a consistent technical basis before quotation.<\/p>\n<a class=\"rv-button\" href=\"https:\/\/raymonvalve.com\/contact\/\">Submit Your Valve Datasheet for Review<\/a><\/div>\n<h2>Frequently Asked Questions<\/h2>\n<div class=\"rv-faq\"><details>\n<summary>What is the difference between fail open and fail close control valves?<\/summary>\n<p>A fail-open control valve moves toward its specified open position when the defined failure occurs, while a fail-close valve moves toward its specified closed position. The failure condition must also be identified because loss of air, signal, power and an ESD demand can produce different package responses.<\/p>\n<\/details><details>\n<summary>Does air-to-open always mean fail close?<\/summary>\n<p>No. In a conventional spring-return pneumatic arrangement, air-to-open commonly corresponds to spring-driven fail-close behavior when air is lost. The actual response still depends on valve action, actuator mounting, spring arrangement, positioner, solenoid and other accessories.<\/p>\n<\/details><details>\n<summary>What happens to a control valve when instrument air fails?<\/summary>\n<p>The result depends on the actuator and pneumatic circuit. A spring-return actuator may move toward its spring position, while a double-acting package may respond according to trapped air, lock-up devices, reservoirs, solenoid logic and external valve forces.<\/p>\n<\/details><details>\n<summary>Is loss of control signal the same as loss of instrument air?<\/summary>\n<p>No. The control signal can be lost while instrument air remains fully available. The valve response then depends on the configured positioner and control philosophy rather than on air-failure behavior alone.<\/p>\n<\/details><details>\n<summary>Does fail close mean a control valve provides tight shutoff?<\/summary>\n<p>No. Fail close defines the required movement direction after a specified failure. Allowable leakage is a separate requirement that depends on valve and trim design, seat construction, differential pressure, actuator force and the applicable acceptance criterion.<\/p>\n<\/details><details>\n<summary>Can a double-acting actuator be assumed to fail in place?<\/summary>\n<p>No. A double-acting actuator does not by itself establish the failure position. The actual response depends on the pneumatic circuit, solenoids, lock-up devices, stored air, valve forces and the specific failure being considered.<\/p>\n<\/details><details>\n<summary>What information should be included in a control valve fail-action specification?<\/summary>\n<p>Define the failure scenarios, process-safe state, required fail position, actuator type and action, minimum utility condition, positioner and solenoid configuration, relevant differential pressure, shutoff requirement, stroke time, reset behavior and functional-test requirement.<\/p>\n<\/details><\/div>\n<div class=\"rv-note\">\n<p><strong>Engineering Note:<\/strong> This article supports preliminary fail-action review, RFQ preparation and technical bid normalization. Final fail position should be confirmed against the approved process design, hazard review, cause-and-effect logic, shutdown philosophy and project specification. Final control-valve sizing and actuator sizing require complete process data and manufacturer-specific calculations. Functional-safety or SIL requirements require system-level review and cannot be established from a fail-open, fail-close, air-to-open or actuator label alone.<\/p>\n<\/div>\n<\/div>\n<\/article>\n<p><script type=\"application\/ld+json\">\n{\n  \"@context\":\"https:\/\/schema.org\",\n  \"@type\":\"TechArticle\",\n  \"headline\":\"Fail Open vs Fail Close Control Valve: Process Safety, Air Failure, Actuator Action and Specification\",\n  \"description\":\"Compare fail open vs fail close control valves, define air, signal and power failure scenarios, and prepare actuator, RFQ and verification requirements.\",\n  \"mainEntityOfPage\":{\n    \"@type\":\"WebPage\",\n    \"@id\":\"https:\/\/raymonvalve.com\/fail-open-vs-fail-close-control-valve\/\"\n  },\n  \"image\":[\n    \"https:\/\/raymonvalve.com\/wp-content\/uploads\/2026\/09\/fail-open-vs-fail-close-control-valve-comparison.webp\"\n  ],\n  \"author\":{\n    \"@type\":\"Organization\",\n    \"name\":\"Raymon Valve\"\n  },\n  \"publisher\":{\n    \"@type\":\"Organization\",\n    \"name\":\"Raymon Valve\",\n    \"url\":\"https:\/\/raymonvalve.com\/\"\n  }\n}\n<\/script> <script type=\"application\/ld+json\">\n{\n  \"@context\":\"https:\/\/schema.org\",\n  \"@type\":\"FAQPage\",\n  \"mainEntity\":[\n    {\n      \"@type\":\"Question\",\n      \"name\":\"What is the difference between fail open and fail close control valves?\",\n      \"acceptedAnswer\":{\n        \"@type\":\"Answer\",\n        \"text\":\"A fail-open control valve moves toward its specified open position when the defined failure occurs, while a fail-close valve moves toward its specified closed position. The failure condition must also be identified because loss of air, signal, power and an ESD demand can produce different package responses.\"\n      }\n    },\n    {\n      \"@type\":\"Question\",\n      \"name\":\"Does air-to-open always mean fail close?\",\n      \"acceptedAnswer\":{\n        \"@type\":\"Answer\",\n        \"text\":\"No. In a conventional spring-return pneumatic arrangement, air-to-open commonly corresponds to spring-driven fail-close behavior when air is lost. The actual response still depends on valve action, actuator mounting, spring arrangement, positioner, solenoid and other accessories.\"\n      }\n    },\n    {\n      \"@type\":\"Question\",\n      \"name\":\"What happens to a control valve when instrument air fails?\",\n      \"acceptedAnswer\":{\n        \"@type\":\"Answer\",\n        \"text\":\"The result depends on the actuator and pneumatic circuit. A spring-return actuator may move toward its spring position, while a double-acting package may respond according to trapped air, lock-up devices, reservoirs, solenoid logic and external valve forces.\"\n      }\n    },\n    {\n      \"@type\":\"Question\",\n      \"name\":\"Is loss of control signal the same as loss of instrument air?\",\n      \"acceptedAnswer\":{\n        \"@type\":\"Answer\",\n        \"text\":\"No. The control signal can be lost while instrument air remains fully available. The valve response then depends on the configured positioner and control philosophy rather than on air-failure behavior alone.\"\n      }\n    },\n    {\n      \"@type\":\"Question\",\n      \"name\":\"Does fail close mean a control valve provides tight shutoff?\",\n      \"acceptedAnswer\":{\n        \"@type\":\"Answer\",\n        \"text\":\"No. Fail close defines the required movement direction after a specified failure. Allowable leakage is a separate requirement that depends on valve and trim design, seat construction, differential pressure, actuator force and the applicable acceptance criterion.\"\n      }\n    },\n    {\n      \"@type\":\"Question\",\n      \"name\":\"Can a double-acting actuator be assumed to fail in place?\",\n      \"acceptedAnswer\":{\n        \"@type\":\"Answer\",\n        \"text\":\"No. A double-acting actuator does not by itself establish the failure position. 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