Resilient-Seated Gate Valves
Initial publication
Showing changes from Initial revision
to Rev 1
in Resilient-Seated Gate Valves.
+---
+title: Resilient-Seated Gate Valves
+category: Process / Valves
+description: >
+ When to use: Gate valves furnished for isolation of water, wastewater, reclaimed water, and industrial process lines inside the fence of a water treatment plant, a wastewater treatment plant, a pump station, or an industrial process facility, exposed in galleries, buildings, and vaults or buried in yard piping, read together with [[sync/common-work-results-process]]. Covers the resilient-seated valve under AWWA C509 and AWWA C515, the metal-seated double-disc valve under AWWA C500 where a metal seat is still specified, and the cast iron gate valve under MSS SP-70 for process lines outside the AWWA standards; the body, bonnet, and bolting, the encapsulated wedge and its elastomer, the stem, stem nut, and stem seals, non-rising and outside screw and yoke stems, end connections and flange drilling, the rated working pressure, the direction of opening, the manual operator furnished with the valve, gear operators and bypass valves on large sizes, tapping valves and tapping sleeves as a conditional article, the mounting interface and thrust data a power actuator is sized from, the valve box and extension stem of a buried valve, AWWA C550 coating, proof-of-design and production tests, installation orientation, and field testing. A gate valve on a site water main outside the plant fence is furnished under [[sync/water-distribution-piping]] or [[sync/site-utilities]] unless the drawings designate this standard for it.
+ Not intended for: Rubber-seated butterfly valves (see [[sync/butterfly-valves]]); eccentric plug valves for wastewater, sludge, and other solids-bearing service (see [[sync/eccentric-plug-valves]]); process check valves (see [[sync/process-check-valves]]); air release, air/vacuum, and combination air valves (see [[sync/air-release-and-vacuum-valves]]); electric, pneumatic, and hydraulic actuators on isolation valves, with their controls and contacts, and floor stands, bench stands, and the extension stems and stem guides of exposed valves operated from a floor above (see [[sync/valve-and-gate-actuators]]); gate valves that modulate in a control loop (see [[sync/control-valves-and-actuators]]); slide gates and stop logs (see [[sync/slide-gates-and-stop-logs]]); general-duty gate valves in building domestic water piping (see [[sync/plumbing-piping-valves]]) and in hydronic and steam piping (see [[sync/hvac-piping-valves]]); gate valves, indicator posts, and control valves in fire service (see [[sync/fire-protection-piping]], [[sync/underground-fire-service-mains]], and [[sync/fire-pumps]]); the isolation valves furnished inside a packaged lift station (see [[sync/packaged-pump-stations]]) and inside a building sewage ejector package (see [[sync/sump-and-sewage-pumps]]); backflow prevention assemblies and their shutoff valves (see [[sync/backflow-prevention]]); the hydrant auxiliary valve on a site main (see [[sync/fire-hydrants]]); irrigation mainline isolation valves (see [[sync/landscape-irrigation]]); the piping the valve sits in, its flange bolting and gaskets, its thrust restraint, and its pressure test (see [[sync/ductile-iron-process-piping]], [[sync/steel-and-stainless-process-piping]], and [[sync/plastic-process-piping]] inside the plant, [[sync/water-distribution-piping]] and [[sync/site-utilities]] for buried site water mains, and [[sync/sanitary-sewer-systems]] for sewage force mains outside the station); the field-applied finish coat over the shop coating (see [[sync/high-performance-coatings]]); and steel gate valves under API 600 and API 602 for industrial pressure piping, thermoplastic process valves, and pressure relief and regulating valves, which are not yet owned by a SynC standard.
+---
+
+# Scope {toc}
+
+## This standard covers gate valves furnished for isolation of water, wastewater, reclaimed water, and industrial process lines inside the fence of a water or wastewater treatment plant, a pump station, or an industrial process facility, whether exposed in a gallery, a building, or a vault or buried in yard piping between plant structures. {note}
+
+## The boundary of the work is the valve as a shop-assembled unit: the body, bonnet, and bolting, the wedge or discs and the seats, the stem, stem nut, and stem seals, the end connections, the manual operator or the mounting interface for a power actuator, the shop coating, and the tests that prove the unit before it ships, together with the valve box and extension stem of a buried valve and the installation and field tests that prove the valve in the line. {note}
+
+## This standard is read with [[sync/common-work-results-process]], the umbrella for the process discipline, which carries the submittal register and procedures, the factory test witnessing policy, the manufacturer's field services, the equipment nameplates, the spare parts basis, the anchorage basis, and the vibration and noise limits for every process valve; nothing here restates them. {note}
+
+## A gate valve closes by lowering a wedge across the full bore, so an open gate valve passes a pig, a cleaning tool, and the full flow of the line with no obstruction in the waterway, and a closed resilient-seated gate valve seals in either direction with the elastomer on the wedge pressed into a smooth iron body that has no seat pocket. That combination is why the resilient-seated gate valve is the water-side isolation valve of the plant and of the site. In a sludge, scum, or grit line the same wedge closes onto whatever has settled in the body, and the eccentric plug valve under [[sync/eccentric-plug-valves]] is specified instead because its plug swings clear of the solids; the choice of valve type for each line is recorded on the valve schedule, not in this standard. {note}
+
+## The AWWA standards describe three gate valves. AWWA C509 describes the resilient-seated valve with full body wall thickness, in gray iron or ductile iron. AWWA C515 describes the resilient-seated valve with a reduced body wall, in ductile iron only, whose thinner section is carried by the higher strength of that material and which is the valve most manufacturers now build in every size. AWWA C500 describes the metal-seated double-disc valve, bronze mounted, with a seat pocket below the discs, which is the gate valve the industry built before the resilient wedge and the one some utilities still specify to match an inventory of parts. MSS SP-70 describes the cast iron, bronze-mounted gate valve of industrial piping, which this standard admits for process lines outside the water supply standards; steel gate valves under API 600 and API 602 for industrial pressure piping are not yet owned by a SynC standard. {note}
+
+## Valves shall conform to one of the design standards admitted in the datasheet of this standard and shall be rated for the working pressure indicated for each valve.
+
+## Valves in potable water service, including the wedge encapsulation, the shop coating, and the stem lubricant, shall carry the NSF/ANSI/CAN 61 and NSF/ANSI/CAN 372 certification required under [[sync/common-work-results-process]].
+
+## A gate valve on a site water main outside the plant fence, from the plant connection to the public main or to the buildings served, shall be furnished under [[sync/water-distribution-piping]] or [[sync/site-utilities]], as the drawings assign that main, unless [[drawing: the valve schedule]] designates this standard for the valve.
+
+## The power actuator on an isolation gate valve, whether electric under AWWA C542 or pneumatic or hydraulic under AWWA C541, with its integral controls, its open, closed, and position contacts, and its network interface, is furnished under [[sync/valve-and-gate-actuators]], which also furnishes floor stands, bench stands, and the extension stems and stem guides of exposed valves operated from a floor above. A gate valve that modulates in a control loop is a control valve and is furnished under [[sync/control-valves-and-actuators]]. This standard furnishes the valve body such an actuator is mounted on, the mounting interface, and the thrust and torque data the actuator is sized from. {note}
+
+## The following are outside this scope and are governed by the companion standards named. {note}
+- Rubber-seated butterfly valves: [[sync/butterfly-valves]]
+- Eccentric plug valves for raw water, wastewater, sludge, scum, and grit: [[sync/eccentric-plug-valves]]
+- Knife gate valves for sludge, slurry, grit, screenings, and dry solids: [[sync/knife-gate-valves]]
+- Process check valves: [[sync/process-check-valves]]; air release, air/vacuum, and combination air valves: [[sync/air-release-and-vacuum-valves]]
+- Electric, pneumatic, and hydraulic actuators on isolation valves and gates, and the manual operators bought separately from the valve: [[sync/valve-and-gate-actuators]]
+- Modulating control valves of every body style: [[sync/control-valves-and-actuators]]
+- Slide gates and stop logs: [[sync/slide-gates-and-stop-logs]]
+- General-duty gate valves in building domestic water piping: [[sync/plumbing-piping-valves]]; in hydronic and steam piping: [[sync/hvac-piping-valves]]
+- Gate valves, indicator posts, and control valves in fire service: [[sync/fire-protection-piping]], [[sync/underground-fire-service-mains]], and [[sync/fire-pumps]]
+- The isolation valves inside a packaged lift station: [[sync/packaged-pump-stations]]; inside a building sewage ejector package: [[sync/sump-and-sewage-pumps]]
+- Backflow prevention assemblies and their shutoff valves: [[sync/backflow-prevention]]; the hydrant auxiliary valve: [[sync/fire-hydrants]]; irrigation mainline isolation valves: [[sync/landscape-irrigation]]
+- The process piping, its flange bolting and gaskets, its thrust restraint, and its pressure test: [[sync/ductile-iron-process-piping]], [[sync/steel-and-stainless-process-piping]], and [[sync/plastic-process-piping]]
+- Buried site water mains and the valves and valve boxes on them: [[sync/water-distribution-piping]] and [[sync/site-utilities]]; sewage force mains outside the station: [[sync/sanitary-sewer-systems]]
+- Field-applied finish coat systems: [[sync/high-performance-coatings]]
+- Valve tags and piping identification: [[sync/mechanical-identification]]
+
+## Knife gate valves are governed by [[sync/knife-gate-valves]], water storage tanks by [[sync/water-storage-tanks]], and cathodic protection of buried valves and piping by [[sync/cathodic-protection]]. Steel gate valves under API 600 and API 602, thermoplastic process valves, and pressure relief and regulating valves are not yet owned by a SynC standard. {note}
+
+# Referenced Standards {toc}
+
+## Valves, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
+
+## Where the Contract Documents, the adopted codes, or a referenced standard conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+
+| Standard | Title |
+|----------|-------|
+| AWWA C509 | Resilient-Seated Gate Valves for Water Supply Service |
+| AWWA C515 | Reduced-Wall, Resilient-Seated Gate Valves for Water Supply Service |
+| AWWA C500 | Metal-Seated Gate Valves for Water Supply Service |
+| AWWA C550 | Protective Interior Coatings for Valves and Hydrants |
+| AWWA C105 / A21.5 | Polyethylene Encasement for Ductile-Iron Pipe Systems |
+| AWWA C111 / A21.11 | Rubber-Gasket Joints for Ductile-Iron Pressure Pipe and Fittings |
+| AWWA C606 | Grooved and Shouldered Joints |
+| AWWA C541 | Hydraulic and Pneumatic Cylinder and Vane-Type Actuators for Valves and Slide Gates |
+| AWWA C542 | Electric Motor Actuators for Valves and Slide Gates |
+| ASME B1.20.1 | Pipe Threads, General Purpose (Inch) |
+| ASME B16.1 | Gray Iron Pipe Flanges and Flanged Fittings: Classes 25, 125, and 250 |
+| ASME B16.42 | Ductile Iron Pipe Flanges and Flanged Fittings: Classes 150 and 300 |
+| MSS SP-25 | Standard Marking System for Valves, Fittings, Flanges, and Unions |
+| MSS SP-60 | Connecting Flange Joints Between Tapping Sleeves and Tapping Valves |
+| MSS SP-61 | Pressure Testing of Valves |
+| MSS SP-70 | Gray Iron Gate Valves, Flanged and Threaded Ends |
+| MSS SP-102 | Multi-Turn Valve Actuator Attachment: Flange and Driving Component Dimensions and Performance Characteristics |
+| ISO 5210 | Industrial Valves: Multi-Turn Valve Actuator Attachments |
+| ASTM A126 | Gray Iron Castings for Valves, Flanges, and Pipe Fittings |
+| ASTM A276 / A276M | Stainless Steel Bars and Shapes |
+| ASTM A536 | Ductile Iron Castings |
+| ASTM B584 | Copper Alloy Sand Castings for General Applications |
+| ASTM F593 | Stainless Steel Bolts, Hex Cap Screws, and Studs |
+| ASTM D429 | Rubber Property: Adhesion to Rigid Substrates |
+| ASTM D2000 | Classification System for Rubber Products in Automotive Applications |
+| ASTM D2240 | Rubber Property: Durometer Hardness |
+| NSF/ANSI/CAN 61 | Drinking Water System Components: Health Effects |
+| NSF/ANSI/CAN 372 | Drinking Water System Components: Lead Content |
+
+# Submittals {toc}
+
+## Action Submittals {toc}
+
+### The Contractor shall submit the following for the Engineer of Record's review and return before any gate valve is released for manufacture:
+
+- Product data for each valve size, design standard, end connection, and service, identifying the rated working pressure, the body, bonnet, wedge, stem, stem nut, and bolting materials with their ASTM designations, the wedge elastomer, the stem seal arrangement, the stem type, and the laying length
+- Dimensioned drawings for each valve showing the end connections and flange drilling, the bonnet and stem orientation, the operator or actuator mounting position, the handwheel or nut location, the position indicator where furnished, and the height of the stem at full open on outside screw and yoke valves
+- Operator data for each manually operated valve, identifying the operator type, the gear ratio where geared, the number of turns to close, the input torque at the rated working pressure, and, for buried valves, the operating nut and the extension stem length
+- Thrust and torque data for each valve to be power actuated, stating the stem thrust and torque to seat and unseat the wedge at the rated working pressure, the number of turns, the stem diameter and thread, the maximum thrust and torque the stem and wedge withstand, and the actuator mounting interface
+- Proof-of-design test certification for each valve design in accordance with the governing design standard
+- Coating system product data, including the AWWA C550 compliance statement, the dry film thickness, and the NSF/ANSI/CAN 61 listing where the valve is in potable water service
+- Elastomer compound data for the wedge encapsulation, stating the compound, the durometer hardness per ASTM D2240, and the service fluid and temperature range the manufacturer rates it for
+- Bypass valve and piping arrangement drawings for each valve furnished with a bypass
+- Tapping sleeve and tapping valve product data for each tap, with the sleeve test pressure and the cutter clearance through the valve
+- Valve box and extension stem product data for buried valves, identifying the box type, the adjustment range, the lid marking, and the stem guide arrangement
+- A field test plan identifying the operating test, the leakage observation during the piping pressure test, and the record form
+
+```datasheet
+label: Action Submittals Required
+type: checkbox
+options:
+ - "Valve product data by size, design standard, end connection, and service"
+ - "Dimensioned valve drawings with stem height at full open"
+ - "Manual operator data"
+ - "Thrust and torque data and actuator mounting interface for power-actuated valves"
+ - "Proof-of-design test certification"
+ - "Coating system product data"
+ - "Wedge elastomer compound data"
+ - "Bypass valve arrangement drawings"
+ - "Tapping sleeve and tapping valve product data"
+ - "Valve box and extension stem product data"
+ - "Field test plan"
+default:
+ - "Valve product data by size, design standard, end connection, and service"
+ - "Dimensioned valve drawings with stem height at full open"
+ - "Manual operator data"
+ - "Thrust and torque data and actuator mounting interface for power-actuated valves"
+ - "Proof-of-design test certification"
+ - "Coating system product data"
+ - "Field test plan"
+constraint: all_of
+```
+
+### Manufacture of a valve shall not begin until the submittal covering that valve has been returned by the Engineer of Record.
+
+### Each valve submittal shall be internally consistent across the valve, the operator, the coating, and the mounting interface, and the Contractor shall bear the cost of resubmission caused by internal inconsistency in its own submittal.
+
+## Closeout Submittals {toc}
+
+### The Contractor shall submit the following at substantial completion, before the gate valves are accepted:
+
+- Certified factory test reports for every valve, identified by serial number, recording the hydrostatic shell test, the seat leakage test in each direction, and the operational test with their pressures, durations, and results
+- Signed and dated field operating test records for every valve, recording the number of turns to close, the input torque or rim pull, the position indicator agreement where furnished, and the direction of opening
+- The leakage observation record for every valve that bounded a piping pressure test section
+- Record drawings locating every buried valve by tie dimensions to permanent surface features, with the depth to the operating nut, the number of turns to close, and the direction of opening
+- Operation and maintenance data for each valve size and operator type, including stem seal replacement, wedge and bonnet removal, and operator lubrication
+- Coating inspection records for shop coatings, recording the dry film thickness and the holiday test result for each valve
+- Spare parts receipt signed by the Owner's representative
+- Warranty documentation
+
+```datasheet
+label: Closeout Submittals Required
+type: checkbox
+options:
+ - "Certified factory test reports by serial number"
+ - "Field operating test records"
+ - "Leakage observation record during piping pressure tests"
+ - "Record drawings with buried valve ties, depth, turns, and direction"
+ - "Operation and maintenance data"
+ - "Shop coating inspection records"
+ - "Spare parts receipt"
+ - "Warranty documentation"
+default:
+ - "Certified factory test reports by serial number"
+ - "Field operating test records"
+ - "Leakage observation record during piping pressure tests"
+ - "Record drawings with buried valve ties, depth, turns, and direction"
+ - "Operation and maintenance data"
+ - "Warranty documentation"
+constraint: all_of
+```
+
+# Quality Assurance {toc}
+
+## Proof of Design {toc}
+
+### Each resilient-seated valve design furnished shall have passed the proof-of-design tests the governing design standard prescribes for its size and rated working pressure, and the proof-of-design certification shall be furnished as indicated in the datasheet.
+
+```datasheet
+label: Proof-of-Design Certification
+type: radio
+options:
+ - "Certified report of proof-of-design testing previously performed on the same design, size, and pressure rating"
+ - "Proof-of-design testing performed on a valve of this contract and witnessed by the Engineer of Record"
+default: "Certified report of proof-of-design testing previously performed on the same design, size, and pressure rating"
+```
+
+### AWWA C509 and AWWA C515 each require a valve design to be proven once, by a cycling test under pressure followed by a leakage test, and each allows a certified report of that earlier testing to stand for every later valve of the same design. Nearly every project accepts the report, because the test proves the design rather than the unit. Witnessing a fresh test on a contract valve is chosen where a design is new to the Owner or where the size is at the top of the manufacturer's range. {note}
+
+### The manufacturer's experience, reference installations, and replacement parts commitment shall be as required under [[sync/common-work-results-process]].
+
+## Single-Source Responsibility {toc}
+
+### Gate valves of each design standard furnished under this standard shall be the product of a single manufacturer.
+
+### Each valve, its manual operator, its bypass where furnished, and the mounting of any power actuator shall be furnished, assembled, adjusted, and tested by the valve manufacturer as a unit.
+
+### The valve manufacturer is the only party who knows the thrust its own wedge needs to seat at the rated pressure, so the operator, the gearing, and the actuator stops are set where that number is known. A valve shipped bare and fitted with an operator in the field arrives with nobody responsible for the torque match or the turn count. {note}
+
+## Marking {toc}
+
+### Each valve shall carry the markings the governing design standard requires, cast on the body or bonnet or on a permanently attached corrosion-resistant nameplate, including the manufacturer, the size, the rated working pressure, the design standard, the body material, and the year of manufacture.
+
+### Valve markings shall conform to MSS SP-25.
+
+### The direction of rotation to open shall be marked on the handwheel or the operator housing of every exposed valve and on the operating nut or the nut collar of every buried valve.
+
+# Service Conditions {toc}
+
+## Valve Schedule {toc}
+
+### The size, service fluid, location, exposed or buried installation, and method of operation of each valve shall be as indicated on [[drawing: the valve schedule]].
+
+### Valves designated for power actuation shall be as indicated on [[drawing: the valve schedule]], and their actuators shall be furnished under [[sync/valve-and-gate-actuators]].
+
+### Size, pressure rating, and end connection are properties of each location on a project, and a standard that asserts any of them has decided the hydraulics and the piping. The valve schedule carries them per tag, and this standard carries what every valve of a given design standard has in common. {note}
+
+## Isolation Duty and Solids Service {toc}
+
+### Valves under this standard are isolation valves and shall be operated to the fully open or fully closed position, and a gate valve shall not be used for throttling unless [[drawing: the valve schedule]] designates it for fixed-position throttling and the manufacturer rates the wedge for that duty.
+
+### A gate valve held partly open puts the full velocity of the line across the lower edge of the wedge, which erodes the encapsulation at the one place it seals and vibrates the wedge in its guides. A valve that is closed and opened a few times a year lasts for decades; the same valve throttled for a season needs a new wedge. {note}
+
+### Where [[drawing: the valve schedule]] designates a gate valve for a line that carries sludge, scum, grit, or screenings, the valve shall be installed with the stem horizontal under the Installation section of this standard, and the manufacturer shall confirm in writing that the wedge and guides are rated for that service.
+
+### The eccentric plug valve is what a solids line normally carries, and the valve schedule records the choice per line. A gate valve appears in solids service where a full round waterway is needed to pass a cleaning tool or where the Owner's inventory is gate valves, and it survives there only if the solids cannot settle in the wedge's path. {note}
+
+## Exposed and Buried Service {toc}
+
+### Valves in exposed service are those installed in a building, a gallery, a vault, or above grade, where the operator is reachable by hand; valves in buried service are those installed in a trench and operated through a valve box. The datasheets of this standard carry a selection for each where the product differs between them. {note}
+
+### Each valve shall be furnished for exposed or buried service as indicated for its location on [[drawing: the valve schedule]].
+
+### Gear operators on valves installed outdoors shall be furnished with a lubricant rated by its manufacturer for continuous service at [[parameter: site-ambient-temperature-minimum]] and at [[parameter: site-ambient-temperature-maximum]].
+
+### Operators and stem seals on buried valves, and gear operators on valves in vaults whose floor is below [[parameter: seasonal-high-groundwater-elevation]], shall be sealed for continuous submergence.
+
+### A vault below the water table floods, and a gear operator that was sealed for rain rather than for immersion fills with water on the first flood and seizes on the second. The groundwater elevation is a project fact, and the seal rating follows it. {note}
+
+# Design Standard and Pressure Rating {toc}
+
+## Admitted Design Standards {toc}
+
+### Gate valves shall be manufactured to a design standard admitted in the datasheet.
+
+```datasheet
+label: Admitted Design Standards for Gate Valves
+type: checkbox
+options:
+ - "AWWA C509, full-wall resilient-seated"
+ - "AWWA C515, reduced-wall resilient-seated"
+ - "AWWA C500, metal-seated double-disc"
+ - "MSS SP-70, gray iron bronze-mounted"
+default:
+ - "AWWA C509, full-wall resilient-seated"
+ - "AWWA C515, reduced-wall resilient-seated"
+constraint: any_of
+```
+
+### Where a particular valve is designated on the valve schedule for one of the admitted design standards, that valve shall conform to the designated standard.
+
+### Nearly every water and wastewater specification accepts a resilient-seated valve to either AWWA C509 or AWWA C515, because the two standards describe the same wedge, the same seals, and the same tests on bodies of different wall thickness, and a manufacturer's catalog line is usually certified to both; that is why the default admits both. Admitting C509 alone buys the heavier body for a utility that has standardized on it. Admitting C515 alone buys the lighter, ductile iron body with the higher small-size rating and the full range to the largest sizes. AWWA C500 is admitted where an Owner stocks double-disc parts or where a metal seat is required by the service temperature or an abrasive fluid that would cut an elastomer. MSS SP-70 is admitted for industrial process lines whose size, flange class, or fluid falls outside the water supply standards, and it carries a Class 125 or Class 250 rating rather than an AWWA working pressure. {note}
+
+### Where a valve manufactured to AWWA C500 is furnished, it shall also conform to the Metal-Seated Double-Disc Valves section of this standard, and where a valve manufactured to MSS SP-70 is furnished, it shall also conform to the MSS SP-70 Gray Iron Gate Valves section of this standard.
+
+## Rated Working Pressure {toc}
+
+### Each valve shall carry the rated working pressure indicated in the datasheet.
+
+```datasheet
+label: Rated Working Pressure
+type: range
+unit: psi
+derived: "the valve size, per the rating of the admitted design standard, and the design pressure of the connected piping including surge"
+options:
+ min: 150
+ max: 300
+ setpoints: [150, 200, 250, 300]
+default: derived
+constraint: min
+```
+
+### Each valve shall carry a rated working pressure not less than the rating the governing design standard assigns to its size.
+
+### Each valve shall carry a rated working pressure not less than the design pressure of the connected piping, including the surge allowance that piping is designed for under the standard governing it.
+
+### Each resilient-seated valve shall seal drip-tight at its rated working pressure with the pressure applied from either side of the closed wedge.
+
+### AWWA C509 rates its valves at 200 psi. AWWA C515 rates valves 12 in. and smaller at 250 psi and 14 in. and larger at 150 psi, with manufacturers offering 250 psi in the larger sizes. AWWA C500 rates valves 12 in. and smaller at 200 psi and 14 in. and larger at 150 psi. Those ratings cover nearly every plant line, and the field is derived from the size and the piping design pressure rather than fixed, so that a high-head pump discharge or a surge-prone force main gets the heavier valve the manufacturers offer without a conversation about every other valve on the project. {note}
+
+### Where a valve is installed in a dead-end position, at a blind flange, or where the downstream piping is to be removed while the upstream side remains pressurized, the valve shall be rated for its full working pressure with the downstream flange or pipe removed.
+
+# Body, Bonnet, and End Connections {toc}
+
+## Body and Bonnet Material {toc}
+
+### The body and bonnet material shall be as indicated in the datasheet.
+
+```datasheet
+label: Body and Bonnet Material
+type: radio
+options:
+ - "Ductile iron, ASTM A536"
+ - "Gray cast iron, ASTM A126 Class B"
+default: "Ductile iron, ASTM A536"
+```
+
+### Ductile iron carries the AWWA working pressure at a lighter section and survives the bolting stress, the trench load, and the impact that crack a gray iron body, and it is the only body AWWA C515 permits, which is why it is the body of nearly every resilient-seated gate valve made today. Gray iron remains a permitted body under AWWA C509, AWWA C500, and MSS SP-70 and is specified where a utility's inventory is gray iron and interchangeability matters. {note}
+
+### The body shall have a smooth, unobstructed waterway of the full nominal diameter, with no seat pocket, groove, or recess below the wedge in which solids can collect.
+
+### The bonnet shall be bolted to the body with a gasket or an O-ring retained in a machined recess, and the wedge, the stem, the stem nut, and the stem seals shall be serviceable through the bonnet without removing the body from the line.
+
+### The waterway of a resilient-seated gate valve is the part the old double-disc valve did not have: a plain round bore the wedge presses into, with nowhere for grit to sit. A pocket below the wedge is where the double-disc valve collects the stone that keeps it from closing, and the absence of one is the single feature that lets the resilient wedge seal after years in raw water. {note}
+
+## Bonnet and Gland Bolting {toc}
+
+### The bonnet and gland bolting material shall be as indicated in the datasheet.
+
+```datasheet
+label: Bonnet and Gland Bolting
+type: select
+options:
+ - "Zinc-plated or coated carbon steel"
+ - "Type 304 stainless steel"
+ - "Type 316 stainless steel"
+```
+
+### Carbon steel bolting shall be plated or coated as the governing design standard permits, and stainless steel bolting shall conform to ASTM F593, Alloy Group 1 for Type 304 and Alloy Group 2 for Type 316.
+
+### Bolting on buried, submerged, and vault-installed valves shall be stainless steel regardless of the datasheet selection.
+
+### Stainless steel bolting shall be assembled with an anti-seize compound on the threads.
+
+### Plated carbon steel is the bolting a valve ships with and is adequate in a dry, heated gallery where it is inspected and painted with the valve. Type 304 holds up in the damp atmosphere of a wet well or a below-grade gallery, where plated steel rusts within a few years and a seized bonnet bolt turns a seal replacement into a body replacement. Type 316 adds resistance to chlorides and is selected in a chlorinated water gallery, near the coast, or wherever the plant standardizes on it. The decision follows the atmosphere the valves sit in, which the project knows and the standard does not. {note}
+
+## End Connections {toc}
+
+### The end connection of each valve shall be as indicated in the datasheet.
+
+```datasheet
+label: End Connection
+type: select
+drawing_ref: "the valve schedule"
+options:
+ - "Flanged"
+ - "Mechanical joint"
+ - "Push-on"
+ - "Flanged by mechanical joint"
+ - "Grooved end"
+ - "Threaded"
+default: deferred
+```
+
+### Flanged ends bolt the valve between flanges it can be unbolted from for service and are the connection of exposed plant piping in every size. Mechanical joint ends take the gasket and gland of AWWA C111/A21.11, tolerate the deflection a trench imposes, and are assembled without the face alignment a flange needs, which is why they are the buried connection on nearly every main. Push-on ends take the same gasket in a bell cast on the valve, cost less than a mechanical joint, and cannot be restrained without a separate device. A flanged by mechanical joint valve bolts to a flanged tee or a vault wall pipe on one side and joins the trench pipe on the other, and it is the usual valve at a buried tee. Grooved ends join to grooved piping under AWWA C606 without flanges where the piping system is grooved throughout. Threaded ends are available only in the small sizes and suit a threaded drain or seal water line where a flange would not fit. The connection follows the piping at each location, so the valve schedule carries it. {note}
+
+### Flanged valves shall be flat faced, with laying lengths conforming to the governing design standard.
+
+### Mechanical-joint and push-on ends shall conform to AWWA C111/A21.11, and the glands, gaskets, and bolts of a mechanical joint shall be furnished with the valve.
+
+### Grooved ends shall conform to AWWA C606 and shall be rated for the valve's working pressure with the coupling the piping standard furnishes.
+
+### Threaded ends shall conform to ASME B1.20.1 and shall be furnished only on valves 2 in. and smaller.
+
+### Thrust restraint at a buried valve, whether by restrained joint or by thrust block, shall be provided under the standard governing the buried piping.
+
+## Flange Drilling {toc}
+
+### The flange drilling of flanged valves shall be as indicated in the datasheet.
+
+```datasheet
+label: Flange Drilling
+type: radio
+options:
+ - "ASME B16.1 Class 125"
+ - "ASME B16.1 Class 250"
+default: "ASME B16.1 Class 125"
+```
+
+### Flanges on ductile iron bodies drilled to the Class 125 template shall conform to ASME B16.42 Class 150, and flanges drilled to the Class 250 template shall conform to ASME B16.42 Class 300.
+
+### Class 125 drilling matches the flanges of every ductile iron fitting, flanged pipe, and cast iron valve in a plant, and an AWWA valve carries its 200 psi or 250 psi rating on a Class 125 flange, which is why that drilling is what the valve is bolted to on nearly every project. Class 250 drilling is selected where the connected piping is Class 250 or Class 300 for a pressure above what the Class 125 flange carries. {note}
+
+# Wedge, Seat, and Stem {toc}
+
+## Resilient Wedge {toc}
+
+### The wedge of each resilient-seated valve shall be a one-piece gray iron or ductile iron casting, fully encapsulated in elastomer bonded or vulcanized to it, with no iron exposed to the line fluid.
+
+### The wedge encapsulation elastomer shall be as indicated in the datasheet.
+
+```datasheet
+label: Wedge Encapsulation Elastomer
+type: select
+options:
+ - "SBR"
+ - "EPDM"
+ - "Nitrile (Buna-N)"
+ - "Neoprene"
+ - "Natural rubber"
+```
+
+### The encapsulation is the only part of the valve that seals, so its compound is matched to the fluid first. SBR is the compound the resilient wedge was developed around and the one most manufacturers mold as standard for potable and raw water, and it is attacked by oils and by chloramine over years of contact. EPDM resists chlorine, chloramine, ozone, and the hot water of a wash cycle, which makes it the usual choice downstream of chloramination and in reclaimed water, and it is attacked by petroleum oils and greases. Nitrile resists oils, grease, and hydrocarbons and is selected for wastewater and industrial sewers that carry them. Neoprene sits between EPDM and nitrile on oil resistance and is specified where a utility's stock is neoprene. Natural rubber has the best abrasion resistance of the group and is selected for grit-laden water at the cost of ozone and oil resistance. No compound is the norm across the water, wastewater, and process services this standard covers, so none is defaulted. {note}
+
+### The wedge encapsulation shall be rated by its manufacturer for the service fluid and the service temperature range indicated for the valve on the valve schedule, and shall conform to ASTM D2000 for the elastomer selected.
+
+### The bond of the encapsulation to the wedge casting shall be not less than the adhesion the governing design standard requires when tested in accordance with ASTM D429.
+
+### Encapsulation hardness shall be within the range the valve manufacturer publishes for the compound when tested in accordance with ASTM D2240, and the durometer value shall be stated on the elastomer compound data submitted.
+
+### The wedge shall seal in either direction of pressure, shall be guided in the body so that the encapsulation does not rub the seating surface during travel, and shall be symmetrical so that it can be installed in the body in either orientation.
+
+### The wedge nut shall be bronze conforming to ASTM B584, shall be cast or molded into the wedge so that it cannot turn in the wedge, and shall be replaceable with the wedge.
+
+## Stem and Stem Nut {toc}
+
+### The stem material shall be as indicated in the datasheet.
+
+```datasheet
+label: Stem Material
+type: select
+options:
+ - "Low-zinc bronze"
+ - "Type 304 stainless steel, ASTM A276"
+ - "Type 316 stainless steel, ASTM A276"
+default: "Low-zinc bronze"
+```
+
+### Bronze stems shall contain not more than 16 percent zinc and not more than 2 percent aluminum, as AWWA C509 and AWWA C515 require, so that the stem does not dezincify in service.
+
+### The stem is the part that carries the full operator thrust into the wedge and that corrodes at the thrust collar where it is loaded and wetted. Low-zinc bronze is the stem AWWA C509 and C515 are written around and the one nearly every manufacturer ships as standard, and it resists dezincification in water that a high-zinc brass would not. A stainless steel stem is selected where the water is aggressive to copper alloys, where the Owner standardizes on stainless wetted parts, or on a power-actuated valve whose thrust is at the top of the bronze stem's capacity, with Type 316 chosen over Type 304 where chlorides are present. {note}
+
+### Non-rising stems shall be of one piece with an integral thrust collar, and the thrust collar shall bear on bearings or washers above and below it so that the stem turns freely under full thrust.
+
+### The stem nut shall be bronze conforming to ASTM B584, independent of the wedge nut on a non-rising stem valve, and shall be of a design that lets the wedge be removed without disturbing the stem seals.
+
+### Stem threads shall be of a form and pitch that hold the wedge in position under line pressure in either direction with no load on the operator.
+
+## Stem Seals {toc}
+
+### Non-rising stem valves shall be sealed with not fewer than two O-rings, of which at least one shall be above the thrust collar and replaceable with the valve fully open and under pressure, without removing the bonnet or the operator.
+
+### Outside screw and yoke valves shall be sealed with a stuffing box and an adjustable gland, with packing that can be replaced with the valve fully open and under pressure by backseating the stem.
+
+### Where a stem seal or packing gland is below a gear operator and is not accessible with the operator mounted, the valve shall be furnished with an extension between the bonnet and the operator that exposes the seal.
+
+### The seal a crew replaces is the one above the thrust collar, because the collar holds the line pressure off it while the valve is open, and a valve whose upper seal can be changed under pressure stays in the line through its whole life. A seal that can be reached only by pulling the bonnet is replaced the day the line is drained for something else, which on a plant main is years away. {note}
+
+## Stem Type for Exposed Service {toc}
+
+### Valves in exposed service shall be furnished with the stem type indicated in the datasheet.
+
+```datasheet
+label: Stem Type, Exposed Service
+type: radio
+options:
+ - "Non-rising stem (NRS)"
+ - "Outside screw and yoke (OS&Y) rising stem"
+```
+
+### A non-rising stem turns in place, keeps its threads inside the bonnet where the line fluid wets them, and needs no clearance above the handwheel, so it is the valve of a vault, a pit, and a gallery with low headroom. An outside screw and yoke stem rises as the wedge lifts and shows its position at a glance from across the gallery, its threads stay dry and greased above the packing, and it needs the full stem travel in clear height above the valve. Water plants that read their valves by eye specify OS&Y in the galleries; plants whose valves sit under piping or in pits specify NRS with a position indicator. Neither is the norm across the plants this standard covers. {note}
+
+### Non-rising stem valves in exposed service shall be furnished with a position indicator that shows the wedge position continuously from fully open to fully closed and that is visible from the operating position.
+
+### Outside screw and yoke valves shall be installed with clear height above the handwheel for the full rise of the stem, and the stem height at full open shall be shown on the dimensioned drawings submitted.
+
+### Valves in buried service shall be non-rising stem valves.
+
+# Metal-Seated Double-Disc Valves {toc}
+
+## Requirements in this section apply where a valve manufactured to AWWA C500 is furnished under the Admitted Design Standards article of this standard.
+
+## Metal-seated valves shall be of the double-disc, parallel-seat design, with a bronze-mounted body and discs and with seat rings and disc faces of bronze conforming to ASTM B584, pressed or threaded into the body and the discs.
+
+## The discs shall be of the same iron as the body, shall be spread against the seats by a wedging mechanism at the closed position, and shall be free to seat independently of each other.
+
+## Metal-seated valves 16 in. and larger installed with the stem horizontal shall be furnished with the disc tracks, rollers, or scrapers the governing design standard requires for that orientation.
+
+## Metal-seated valves shall seal at their rated working pressure with the pressure applied from either side of the closed discs, to the leakage the governing design standard permits.
+
+## A double-disc valve seals metal on metal, so it tolerates a fluid temperature and an abrasive solid that would cut an elastomer, and it holds the leakage rate AWWA C500 allows rather than the drip-tight seal of a resilient wedge. Its seat pocket collects whatever settles, which is why a double-disc valve in raw water is flushed before it is closed. It is the valve an Owner specifies to match thirty years of spare discs and seat rings, and the one an engineer specifies where the service is outside what an elastomer serves. {note}
+
+# MSS SP-70 Gray Iron Gate Valves {toc}
+
+## Requirements in this section apply where a valve manufactured to MSS SP-70 is furnished under the Admitted Design Standards article of this standard.
+
+## MSS SP-70 valves shall be Class 125 or Class 250 as the rated working pressure of the valve requires, with the pressure and temperature rating of that class not less than the design pressure of the connected piping.
+
+## MSS SP-70 valves shall be of the bolted-bonnet, outside screw and yoke design, bronze mounted, with a solid or flexible wedge and renewable seat rings, and with flanged ends drilled to ASME B16.1 for the class or threaded ends conforming to ASME B1.20.1.
+
+## MSS SP-70 valves shall be shell and seat tested in accordance with MSS SP-61, and that test shall satisfy the production tests of this standard.
+
+## An MSS SP-70 valve is the iron gate valve of industrial piping: its flanges, its bronze trim, and its MSS SP-61 test match the AWWA valves closely enough that one procurement covers both, which is why this standard admits it rather than sending a plant's industrial lines to another document. Its class rating is a pressure and temperature rating rather than a cold working pressure, and it is the valve selected for a process line that runs hot or outside the sizes and services the water supply standards cover. A steel gate valve under API 600 belongs to industrial pressure piping with its own trim and test regime and is not admitted here. {note}
+
+# Manual Operators {toc}
+
+## Operator Type for Exposed Service {toc}
+
+### Manual operators on valves in exposed service shall be of the type indicated in the datasheet.
+
+```datasheet
+label: Manual Operator, Exposed Service
+type: select
+options:
+ - "Handwheel"
+ - "Handwheel with 2 in. square operating nut"
+ - "2 in. square operating nut"
+ - "Chainwheel"
+ - "Bevel-gear or spur-gear operator with handwheel"
+default: "Handwheel"
+```
+
+### A handwheel on the stem is the operator of nearly every exposed gate valve at an operating floor, because a gate valve is a multi-turn valve whose stem thread already multiplies the operator's effort. A handwheel fitted with a nut lets the same valve be operated by hand at the floor and by a portable actuator when the pull is heavy or the turn count is long. A 2 in. square nut in place of the handwheel suits a valve in a pit or a chamber that is reached with a key or a tee handle, and it removes a handwheel that would be in the way. A chainwheel replaces the handwheel where the valve is overhead and the operator is reached from the floor by a chain. A gear operator is the operator of the large sizes, where the stem thrust at the rated pressure exceeds what a person applies through a handwheel, and the Gear Operators article sets the size at which it is furnished regardless of this selection. {note}
+
+### Handwheels shall be of a diameter that closes the valve against the rated working pressure within the input effort limit the governing design standard sets, shall be marked with the direction of opening, and shall be secured to the stem or the stem nut so that they cannot be removed without a tool.
+
+### Chainwheel operators shall have the chain looped to within 3 ft of the operating floor and guided so that it cannot leave the wheel.
+
+### Manual operators on exposed valves shall be furnished with the position indicator the Stem Type for Exposed Service article requires on non-rising stem valves.
+
+## Gear Operators {toc}
+
+### Valves of the size indicated in the datasheet and larger shall be furnished with a totally enclosed bevel-gear or spur-gear operator regardless of the operator type selected for exposed service, and every buried valve of that size and larger shall be furnished with a gear operator under its operating nut.
+
+```datasheet
+label: Smallest Valve Size Furnished with a Gear Operator
+type: range
+unit: in.
+options:
+ min: 12
+ max: 30
+ setpoints: [12, 14, 16, 18, 20, 24, 30]
+constraint: exact
+```
+
+### The stem thrust to seat a resilient wedge rises with the square of the valve size and with the rated pressure, and somewhere between 14 in. and 20 in. it exceeds what a person applies through a handwheel or a key within the input limits the design standards set. Utilities set the threshold their crews work to, and manufacturers fit gearing as standard from a size that differs between them, which is why the size is not defaulted. A lower threshold buys an easier valve at the cost of a higher turn count and a gear case on every mid-size valve. {note}
+
+### Gear operators shall be totally enclosed, grease packed, self-locking, and sealed against the entry of water and dust, with a position indicator on exposed valves and with the gear case on an outdoor or vault valve sealed as the Exposed and Buried Service article requires.
+
+### Gear operators shall be furnished with adjustable mechanical stops at the fully open and fully closed positions that carry the full operator output without transmitting it to the wedge or the seat.
+
+### Gear operators shall be mounted so that the handwheel, nut, or chainwheel is in the position shown on the accepted dimensioned drawings, and the gearing shall be oriented so that the valve opens in the direction selected under the Direction of Rotation article.
+
+## Operator for Buried Service {toc}
+
+### Valves in buried service shall be furnished with a non-rising stem terminating in a 2 in. square operating nut conforming to the dimensions of the governing design standard, with the direction of opening cast or stamped on the nut or on a collar at its base.
+
+### Buried-service operators shall be furnished with a stem guide or a stuffing box at the operating nut that keeps soil from entering the stem seals, and the seals shall be rated for continuous submergence under the Exposed and Buried Service article.
+
+### Where the operating nut of a buried valve is driven through a gear operator, the gear case shall be totally enclosed, packed with grease, and sealed with O-rings or an equivalent seal at every shaft and cover for continuous submergence.
+
+## Direction of Rotation {toc}
+
+### Valves shall open in the direction of rotation indicated in the datasheet.
+
+```datasheet
+label: Direction of Rotation to Open
+type: radio
+options:
+ - "Counterclockwise (open left)"
+ - "Clockwise (open right)"
+default: "Counterclockwise (open left)"
+```
+
+### Most North American utilities open their valves counterclockwise, and a plant whose valves open the other way from the distribution system around it has an operator closing a valve that was meant to be opened on the day it matters. A minority of utilities, often whole regions, open clockwise, and a project in their territory follows the owning utility's practice without exception. The direction is set once for a project and is cast on every operator. {note}
+
+### Every valve on the project shall open in the same direction of rotation, and the direction shall match the practice of the utility that will operate the valves.
+
+## Operator Sizing {toc}
+
+### Each manual operator shall be sized to seat and unseat the wedge at the rated working pressure applied to either side of the closed wedge, with an input torque at the operating nut, the handwheel rim, or the chain not exceeding the limits the governing design standard sets.
+
+### The valve manufacturer shall publish, for each valve size and operator, the number of turns of the handwheel or nut from fully open to fully closed, and that number shall be stated on the operator data submitted.
+
+### Operators sized to the rated pressure rather than to the project's operating pressure are what let a valve be closed on the day the pressure is at its highest, which is the day a main breaks and the pressure on the closed wedge is the full static head of the system. An operator sized to the normal operating pressure is sized to the one condition under which nobody needs to close the valve. {note}
+
+### An operator that cannot seat or unseat the valve at the rated working pressure within the published input limit shall be replaced by the Contractor with an operator that can, at the Contractor's cost.
+
+# Bypass Valves {toc}
+
+## Valves designated for a bypass on [[drawing: the valve schedule]] shall be furnished with a bypass valve and bypass piping connected to tapped and flanged bosses cast on the body on each side of the wedge, assembled and tested on the valve by the valve manufacturer.
+
+## Bypass valves shall be resilient-seated gate valves conforming to an admitted design standard of this standard, of the same rated working pressure as the main valve, in the size the valve manufacturer publishes for the main valve size, with the same stem type and operator arrangement as the main valve.
+
+## Bypass piping shall be bronze, stainless steel, or flanged ductile iron rated for the working pressure of the main valve, and shall be supported from the body of the main valve.
+
+## A large gate valve closed against the full static head of a system needs the thrust to lift the wedge off the seat against that head, and an operator sized for it is a gear case a crew turns for a long time. A bypass equalizes the pressure across the wedge before the main valve is opened, so the wedge lifts under no differential, and it also lets a drained section be refilled slowly through a small valve rather than through a crack in the main one, which is what keeps air and surge out of a main being returned to service. The valves that get a bypass are the ones that isolate a reservoir, a transmission main, or a pump station discharge, and the schedule designates them because the decision belongs to each location rather than to a size. {note}
+
+# Tapping Valves and Sleeves {toc}
+
+## Requirements in this section apply where a tapping sleeve and tapping valve are designated for a live tap on [[drawing: the process mechanical plans]].
+
+## Tapping valves shall be resilient-seated gate valves conforming to an admitted design standard of this standard, with a flanged inlet conforming to MSS SP-60 for alignment with the tapping sleeve and with the outlet end connection the connected piping requires.
+
+## The seat opening of a tapping valve shall be oversized so that the shell cutter of a full-size tapping machine passes through the open valve without touching the wedge, the seat, or the encapsulation.
+
+## The tapping sleeve shall be of the type indicated in the datasheet, of a size and a pressure rating that match the main tapped and the tapping valve, with a flanged outlet conforming to MSS SP-60.
+
+```datasheet
+label: Tapping Sleeve Type
+type: select
+options:
+ - "Ductile iron mechanical-joint sleeve"
+ - "Stainless steel full-circle sleeve with stainless steel flange"
+ - "Fabricated steel sleeve, epoxy coated"
+```
+
+## A ductile iron mechanical-joint sleeve bolts around the main with the gaskets and glands of a mechanical joint, holds its own thrust, and matches the ductile iron main it is nearly always used on. A stainless steel full-circle sleeve seals with a full gasket around the pipe, fits the outside diameter of ductile iron, cast iron, PVC, and steel mains of the same nominal size, and resists soil corrosion without a coating, which is why it has become the sleeve many utilities specify on every tap. A fabricated steel sleeve is made to order for a main whose diameter or wall is outside the catalog of the other two, and it depends on its coating in the ground. The sleeve follows the main it is tapping, which the project knows and the standard does not. {note}
+
+## The tapping sleeve shall be fitted with a test plug, and the assembled sleeve and tapping valve shall be hydrostatically tested at the test pressure of the main for not less than fifteen minutes with no leakage before the main is cut.
+
+## The tap shall be made with a tapping machine through the open tapping valve, with the main under pressure, and the tapping valve shall be closed and the machine removed without draining the main.
+
+## A sleeve that leaks is found while the plug is still in and the main is still whole, which is the only time it can be fixed without an outage; a sleeve that was never tested is found when the coupon comes out and the leak cannot be stopped. The oversized seat is what keeps the cutter from carving the encapsulation off a new valve on its first use. {note}
+
+# Power Actuation Interface {toc}
+
+## Electric actuators under AWWA C542 and pneumatic and hydraulic cylinder actuators under AWWA C541 on gate valves under this standard, with their integral controls, their open, closed, and position contacts, and their network interface, are furnished under [[sync/valve-and-gate-actuators]], and the actuator on a gate valve that modulates in a control loop is furnished under [[sync/control-valves-and-actuators]]. This standard furnishes the valve, the mounting interface, and the thrust and torque data. {note}
+
+## For each valve designated for power actuation, the valve manufacturer shall furnish the stem thrust and torque to seat and to unseat the wedge at the rated working pressure applied to either side, the running thrust and torque, the number of turns from fully open to fully closed, the stem diameter, thread form, and lead, and the maximum thrust and torque the stem, the stem nut, and the wedge withstand.
+
+## The thrust and torque data furnished shall be the basis on which the actuator is sized under [[sync/valve-and-gate-actuators]], and the valve manufacturer shall confirm in writing that the selected actuator's rated output and torque switch settings do not exceed the maximum thrust and torque of the valve.
+
+## The actuator mounting flange and the drive connection on the valve shall conform to ISO 5210 or MSS SP-102, with a thrust base on the valve or the actuator that carries the full stem thrust, or shall be of the valve manufacturer's design where the valve size exceeds the range of those standards.
+
+## Each power actuator shall be mounted on its valve by the valve manufacturer, with the torque and limit switches set and the assembly cycled through full travel before shipment.
+
+## Valves designated for power actuation shall be furnished with a declutchable handwheel on the actuator so that the valve can be operated with the actuator de-energized.
+
+## A multi-turn actuator that reaches its closed limit by torque rather than by position drives the wedge into the seat until the torque switch trips, and a switch set above what the stem and wedge nut withstand bends the stem or strips the nut on the first close. The valve manufacturer is the only party who knows where that limit is, and the written confirmation is what puts the number in front of the actuator supplier before the switch is set. {note}
+
+# Coatings and Linings {toc}
+
+## Shop Coating System {toc}
+
+### Ferrous interior and exterior surfaces of each valve body, bonnet, and wedge casting, except machined flange faces, seating surfaces of metal-seated valves, and bearing and seal surfaces, shall be coated at the factory in accordance with AWWA C550 with the system indicated in the datasheet.
+
+```datasheet
+label: Shop Coating System on Ferrous Surfaces
+type: radio
+options:
+ - "Fusion-bonded epoxy, AWWA C550"
+ - "Two-part liquid epoxy, AWWA C550"
+default: manufacturer
+```
+
+### Fusion-bonded epoxy is applied as a powder to a heated casting and cures into a hard, holiday-free film that bonds to blast-cleaned iron better than any liquid coating, and it is the interior and exterior coating of nearly every resilient-seated gate valve made today. Two-part liquid epoxy to the same standard is applied by spray in any coating shop and is the system a manufacturer uses where its castings are too large to heat. Both meet AWWA C550, both are certified to NSF/ANSI/CAN 61 by the manufacturers that offer them, and the choice follows the manufacturer's process rather than the project. {note}
+
+### Shop coatings shall be applied over a surface prepared and to a dry film thickness in accordance with AWWA C550, and shall be holiday tested in accordance with that standard before shipment.
+
+### Coating that is damaged in shipment or installation shall be repaired with the coating manufacturer's repair material in accordance with the coating manufacturer's written procedure, and a repair that cannot restore a holiday-free film shall be cause for rejection of the valve.
+
+### Buried valves shall be polyethylene encased in accordance with AWWA C105/A21.5 where the connected main is encased, and the encasement shall be continuous over the valve body, the bonnet, and the joints and shall be sealed around the stem below the valve box.
+
+## Exterior Finish on Exposed Valves {toc}
+
+### The exterior finish on valves in exposed service shall be as indicated in the datasheet.
+
+```datasheet
+label: Exterior Finish, Exposed Valves
+type: radio
+options:
+ - "Shop epoxy as the finished coating"
+ - "Shop epoxy as the primer for a field-applied finish coat"
+```
+
+### The shop epoxy is a complete corrosion barrier on its own and is the finished exterior on a valve in a vault or a gallery where nobody looks at it. In a plant whose piping is color-coded or finished to a scheme, the valve exterior is topcoated in the field to match the pipe, and the shop epoxy becomes the primer that topcoat has to bond to. The decision follows the plant's finish scheme rather than the valve. {note}
+
+### Where the datasheet selects a field-applied finish coat, the shop epoxy shall be compatible with the finish coat system furnished under [[sync/high-performance-coatings]], and the valve manufacturer shall state the surface preparation the finish coat requires over its epoxy.
+
+### Where the datasheet selects a field-applied finish coat, the gear case, yoke, and handwheel shall be finished in the field under [[sync/high-performance-coatings]] in the color the finish scheme assigns to valve operators, and the stem of an outside screw and yoke valve shall not be painted.
+
+# Buried Service Provisions {toc}
+
+## Valve Boxes {toc}
+
+### Each buried valve shall be furnished with a valve box of the type indicated in the datasheet, extending from the valve to finished grade, except where the valve is installed on a site distribution main whose valve box is furnished under [[sync/water-distribution-piping]] or [[sync/site-utilities]].
+
+```datasheet
+label: Valve Box Type
+type: select
+options:
+ - "Cast-iron two-piece slide-type box"
+ - "Cast-iron three-piece screw-type box"
+ - "Precast concrete valve vault with access cover"
+```
+
+### A two-piece slide box telescopes to grade and is set without threading, so it adjusts in the trench and again at final grading, and it carries no load to the valve if the lower section sits on a base plate clear of the bonnet. A three-piece screw box is adjusted by turning the upper section and holds its setting against traffic and frost better than a slide box, and it is the box of utilities that have standardized on it. A precast vault gives a crew room to reach the operator, the stem seals, and a power actuator, and it is used on large valves, on valves with a bypass, on valves that are operated often, and wherever a valve is to be actuated electrically. {note}
+
+### Valve boxes shall be cast iron, of a two-piece or three-piece adjustable design, with a base section that bears on the soil or on a base plate and not on the valve body, the bonnet, or the operator, and with a lid marked for the service.
+
+### The valve box shall be set plumb and centered over the operating nut, and the upper section shall be adjusted to finished grade after final grading.
+
+### The valve box lid shall be marked "WATER" for potable and raw water, "SEWER" for wastewater and sludge, and "RECLAIMED" for reclaimed water, in letters cast into the lid.
+
+### Buried valves shall be installed at the depth of the main they are set in, whose depth of cover is set below [[parameter: frost-depth]] by the standard governing the main.
+
+### A valve box that bears on the valve transfers the weight of every vehicle that drives over the lid into the bonnet, and the bonnet bolts loosen or the stem binds in the first winter. The base section sits on the soil, on a base plate, or on a concrete collar poured around the bonnet, never on the valve. {note}
+
+## Extension Stems {toc}
+
+### Where the operating nut of a buried valve would otherwise be deeper below finished grade than the depth indicated in the datasheet, an extension stem shall be furnished that brings the operating nut to within that depth of grade.
+
+```datasheet
+label: Operating Nut Depth Below Finished Grade
+type: range
+unit: in.
+options:
+ min: 12
+ max: 72
+ setpoints: [12, 18, 24, 36, 48, 60, 72]
+constraint: max
+```
+
+### An operating key reaches a nut a few feet down without trouble and loses its purchase as the depth grows, and a crew that cannot find or seat the key on a deep nut leaves the valve as it found it. Utilities set the depth their crews work to, commonly within a few feet of grade, and a deeper main gets an extension stem that brings the nut up. The depth is the utility's practice rather than the valve's, which is why it is not defaulted. {note}
+
+### Extension stems shall be of steel or stainless steel, sized to carry the full operator input torque through the number of turns the valve requires, fitted with a 2 in. square operating nut at the top and a socket that engages the valve nut at the bottom, and held centered in the valve box by a stem guide.
+
+### Extension stems shall be pinned or bolted to the valve operating nut so that the stem cannot lift off the nut when the key is withdrawn.
+
+### The extension stems, stem guides, and floor stands that operate exposed valves from a floor above are furnished under [[sync/valve-and-gate-actuators]]; this article covers extension stems inside valve boxes on buried valves only. {note}
+
+# Factory Testing {toc}
+
+## Each valve shall be hydrostatically shell tested at the factory in accordance with the governing design standard, with the wedge open, at the pressure and for the duration that standard prescribes for its rated working pressure, with no leakage through the body, the bonnet joint, or the stem seals.
+
+## Each resilient-seated valve shall be seat tested at the factory with the wedge closed and the rated working pressure applied to each side of the wedge in turn, for the duration the governing design standard prescribes, with no leakage past the wedge.
+
+## Each metal-seated valve shall be seat tested at the factory with the discs closed and the rated working pressure applied to each side in turn, and the leakage shall not exceed the rate the governing design standard permits.
+
+## Each valve shall be operationally tested at the factory by cycling it through full travel with its manual operator or its mounted actuator, and the turn count, the stops where furnished, the position indicator where furnished, and the direction of opening shall be verified during that cycle.
+
+## The design standards set the shell test at twice the rated working pressure and the seat test at the rated working pressure, and the seat test is performed in each direction because an isolation valve is closed from whichever side the pressure happens to be on. A resilient wedge that seals in one direction and weeps in the other is sitting off center in its guides, and the test finds it before the trench does. {note}
+
+## A valve that fails any factory test shall be corrected and retested, and the Contractor shall bear the cost of the correction and the retest.
+
+## Certified test reports identifying each valve by serial number shall be furnished for every valve before shipment, and no valve shall be shipped without one.
+
+## Factory tests shall be witnessed on the basis selected under [[sync/common-work-results-process]], and the valves designated for a witnessed test, where that basis designates by valve, shall be as indicated on [[drawing: the valve schedule]].
+
+# Delivery, Storage, and Handling {toc}
+
+## Valves shall be shipped with the wedge closed, with the end openings covered to keep debris off the seating surfaces, and with the covers left in place until the valve is set in the line.
+
+## Valves shall be lifted by the body, by lifting lugs the manufacturer provides, or by slings around the body, and shall not be lifted by the operator, the actuator, the handwheel, the stem, or the bypass piping.
+
+## Valves shall be stored off the ground on timbers or pallets, under cover, with the operator or actuator protected from weather, and valves with resilient wedges shall be stored out of direct sunlight and away from ozone sources such as motors and welding equipment.
+
+## A resilient wedge is shipped closed because the encapsulation is unloaded against a smooth bore rather than compressed against a seat ring, and a closed valve keeps construction debris off the surfaces it seals on. Ultraviolet light and ozone harden the elastomer on a wedge left open in the sun for a season, and the cover keeps the sun off it. {note}
+
+## Each valve shall be delivered with its certified test reports, its mechanical-joint accessories where furnished, its operating nut or handwheel, and its extension stem and valve box where furnished, and the Contractor shall verify the delivery against the approved submittal before the valve is moved to the trench or the piping.
+
+## The Contractor shall bear the cost of repairing or replacing a valve damaged in delivery, storage, or handling.
+
+# Installation {toc}
+
+## Exposed Valves {toc}
+
+### Flanged valves shall be installed with the mating flanges aligned, parallel, and concentric before the bolts are tightened, and the valve shall not be used to draw misaligned piping together.
+
+### Flange bolting and gaskets at each valve shall be furnished and installed under the standard governing the piping, shall be rated for the working pressure of the valve, and shall be full-face gaskets against the flat-faced valve flange, with no raised-face mating flange bolted to a cast iron or ductile iron valve.
+
+### The stem of each valve in horizontal piping shall be oriented as indicated in the datasheet.
+
+```datasheet
+label: Stem Orientation in Horizontal Piping
+type: select
+options:
+ - "Vertical, stem up"
+ - "Horizontal"
+ - "Vertical, stem down"
+default: "Vertical, stem up"
+```
+
+### With the stem up, the operator stands above the pipe where it is reached and read from the walkway, the bonnet drains back into the line, and the wedge closes downward into the waterway, which is the orientation nearly every exposed gate valve in water service is installed in. With the stem horizontal, the wedge closes sideways across the bore and the bonnet cavity sits beside the pipe rather than above it, so a solid that settles in the invert is pushed aside rather than closed upon, which is why a gate valve in a sludge or grit line is installed that way, at the cost of a side-mounted operator that needs a gear and a support. With the stem down, the bonnet hangs below the pipe and collects whatever settles, and the valve is installed that way only where headroom leaves no alternative and the manufacturer rates the valve for it. {note}
+
+### Valves in horizontal piping that carry sludge, scum, grit, or screenings shall be installed with the stem horizontal regardless of the datasheet selection.
+
+### Valves shall be installed with the stem down only where the manufacturer rates the valve for that orientation in writing and [[drawing: the valve schedule]] designates the valve for it.
+
+### Valves shall be supported independently of the piping so that no piping load, thrust, or vibration is carried into the valve body, and the supports shall be furnished under the standard governing the piping.
+
+### Each exposed valve shall be installed with clearance for the operator, the handwheel, the actuator, the full rise of an outside screw and yoke stem, and the removal of the bonnet and the wedge, and the clearance shall be not less than the manufacturer's published service clearance.
+
+### Each valve shall be cycled through full travel after the flanges are tightened and before the piping is tested, and a valve that binds at any position shall be removed and reinstalled with the cause corrected.
+
+## Buried Valves {toc}
+
+### Buried valves shall be set on compacted bedding of the same material and to the same depth as the bedding of the adjacent pipe, with the stem vertical and the operating nut centered under the valve box.
+
+### Each buried valve shall be operated through its valve box with an operating key, from fully open to fully closed and back, before backfill is placed above the valve and again after backfill is complete.
+
+### Backfill around a buried valve shall be placed and compacted under the standard governing the buried piping, and the valve box shall be held plumb and centered on the operating nut throughout backfill.
+
+### Where the valve box lid is in a pavement, the box shall be set so that the lid is flush with the finished pavement, and where it is in a landscaped area, the lid shall be set flush with the finished grade or raised as the Owner's standard requires.
+
+### Buried valves shall be located on the record drawings by not fewer than two tie dimensions to permanent surface features, with the depth from the lid to the operating nut and the number of turns to close.
+
+### A buried valve that cannot be found is a valve that does not exist on the day the main breaks. Two ties to features that will still be there in twenty years, and a depth and a turn count that tell the crew what they are reaching for, are what make the valve usable by someone who did not install it. {note}
+
+### Where a buried valve is on a site distribution main and the valve schedule designates this standard for it, the valve box, its setting, and the record ties shall be as required under [[sync/water-distribution-piping]] or [[sync/site-utilities]], and this article shall apply to the valve itself.
+
+## Field Testing {toc}
+
+### Each valve shall be operated through full travel after installation, and the Contractor shall record the number of turns to close, the input torque or rim pull at the handwheel, nut, or chain, the agreement of the position indicator with the wedge where an indicator is furnished, and the direction of opening.
+
+### A valve whose input effort exceeds the limit the governing design standard sets, whose turn count differs from the published count, or whose position indicator does not agree with the wedge shall be corrected by the Contractor before the piping is tested.
+
+### Each valve that bounds a section of piping under hydrostatic test shall be observed for leakage past the closed wedge during the test, and a valve that leaks past its wedge at the test pressure of the piping shall be removed, repaired or replaced, and retested.
+
+### The piping pressure test itself shall be performed under the standard governing the piping, and a gate valve shall not be used to isolate a test section at a test pressure exceeding the rated working pressure of the valve.
+
+### The field test shall be witnessed by the party indicated in the datasheet.
+
+```datasheet
+label: Field Test Witness
+type: select
+options:
+ - "Engineer of Record or the Engineer's representative"
+ - "Owner's operations representative"
+ - "Contractor's quality control representative"
+default: "Engineer of Record or the Engineer's representative"
+```
+
+### The Engineer of Record witnesses the test on most projects because the test record is the Engineer's evidence that the valve matches its submittal. An Owner's operator witnesses where the plant staff will operate the valves and wants to see each one work before it is handed over, which is common on a plant expansion. A contractor's quality control representative witnesses where the contract carries a quality control program and the Engineer reviews its records rather than attending. {note}
+
+### The Contractor shall give the witnessing party not less than five business days notice of a scheduled field test.
+
+### The Contractor shall bear the cost of correcting a valve that fails a field test and of the retest, including the cost of the witness's attendance at the retest.
+
+# Warranty {toc}
+
+## The Contractor shall warrant each gate valve, its operator, its bypass where furnished, and the mounting of any power actuator against defects in materials and workmanship for the period selected under [[sync/common-work-results-process]], measured from the date of substantial completion.
+
+## A valve that leaks past its wedge or discs at or below the rated working pressure beyond what its design standard permits, leaks through its stem seals, bonnet joint, or body, or cannot be operated within the input limits of the governing design standard within the warranty period shall be repaired or replaced by the Contractor at no cost to the Owner.
+
+## The Contractor shall bear the cost of excavating and backfilling to reach a buried valve for a warranted repair, of draining and refilling the piping the repair requires, of disinfecting a potable line the repair opened, and of repairing any other work damaged by the failure or by the repair.
+
+## The warranty term on a repaired or replaced valve, the assignment of the manufacturer's warranty, and the claim procedure shall be as required under [[sync/common-work-results-process]].
+
+## The cost that goes unassigned in a valve warranty is never the valve. It is the excavation to reach a buried one, the outage to drain the main it sits in, and the disinfection of a potable main that was opened. Naming those costs is what makes the warranty worth having on a valve that cost less than the trench around it. {note}
+
+# Spare Parts {toc}
+
+## The Contractor shall furnish the spare parts indicated in the datasheet, packaged, labeled with the valve size and design standard they fit, and delivered to the Owner before substantial completion, on the spare parts basis selected under [[sync/common-work-results-process]].
+
+```datasheet
+label: Spare Parts Furnished
+type: checkbox
+options:
+ - "One stem seal set for each valve size and stem type"
+ - "One packing set for each outside screw and yoke valve size"
+ - "One encapsulated wedge for each size of valve 16 in. and larger"
+ - "One gear operator repair kit for each gear operator size"
+ - "Two operating keys for the 2 in. square nut, sized for the deepest valve on the project"
+ - "One set of bonnet bolting for each valve size"
+default:
+ - "One stem seal set for each valve size and stem type"
+ - "Two operating keys for the 2 in. square nut, sized for the deepest valve on the project"
+constraint: all_of
+```
+
+## Spare parts shall be the products of the valve manufacturer and shall be interchangeable with the parts installed in the valves furnished.
+
+## A stem seal is the one wearing part every gate valve has and the one a crew replaces in place, so a set per size is the spare that is used. A replacement wedge for a large valve is a long-lead molded part that is worth holding where the valve isolates something the plant cannot do without. Operating keys are furnished because a buried valve without a key within reach is a valve nobody can close. {note}
+
+## The spare parts list, with the manufacturer's part numbers, shall be included in the operation and maintenance data.