Instrumentation · Valves · Engineering Drawings
Valve Abbreviations Explained: A Complete Guide for Instrumentation and Process Engineers
A searchable, categorised reference to all common valve abbreviations used in P&IDs, piping isometrics, valve datasheets and engineering drawings, with plain-English explanations for every term.
Searchable Table
60+ Abbreviations
Grouped by Category
Plain English Explanations
Open any valve datasheet, piping isometric or P&ID drawing and you will immediately encounter a string of abbreviations: BB, RF, NPS, BW, OS&Y, FP, CWP, IBBM. To an experienced engineer these are instantly readable. To a first-year technician or a new graduate on their first plant project, they can be completely opaque.
Valve abbreviations appear on valve body markings, purchase order specifications, material requisitions, valve schedules and piping class documents. Misreading them can lead to ordering the wrong valve, specifying the wrong connection type or misinterpreting a pressure rating. Understanding what each abbreviation means, and more importantly why it matters, is an essential foundation skill for anyone working in process, piping or instrumentation engineering.
This guide covers over 60 of the most common valve abbreviations used in process industry engineering drawings and valve specifications, organised into logical groups with a plain-English explanation of each term. Use the search box below to find any abbreviation instantly. For background on how valves appear in process diagrams, see our guide on how to read a P&ID diagram.
What this guide covers
All major valve body and bonnet abbreviations · Process connection types: threaded, flanged, butt weld, socket weld · Stem types: rising, non-rising, inside screw, outside screw · Flange face types: raised face, flat face, ring type joint · Pressure rating abbreviations: CWP, WOG, OWG, SWP · Pipe size abbreviations: NPS, IPS · Material abbreviations: DI, IBBM, SB · Valve type abbreviations: BV, GV, CV, SOV, PRV.
Advertisement
Advertisement
Searchable Valve Abbreviation Lookup Table
Type any abbreviation or keyword into the search box below to find it instantly in the table. The table contains all abbreviations covered in this guide.
Search valve abbreviations
Showing all 63 abbreviations
| Abbr. | Full term | Meaning and use | Category |
|---|---|---|---|
| BB | Bolted Bonnet | A valve bonnet (the top cover enclosing the valve stem) that is secured to the valve body using bolts and nuts. The most common bonnet design in process valves. Allows the bonnet to be removed for maintenance without cutting the valve out of the line. | Valve Body |
| BC | Bolted Cap | A cap that is bolted onto the valve body, typically at the end opposite the bonnet. Used in certain globe and check valve designs to provide access to the internals. | Valve Body |
| TB | Threaded Bonnet | A valve bonnet that screws onto the valve body rather than being bolted. Common in smaller valves and lower-pressure applications. Simpler construction than a bolted bonnet but harder to remove for maintenance on large valves. | Valve Body |
| UB | Union Bonnet | A bonnet secured by a union nut, allowing the bonnet to be rapidly removed and reinstalled without tools. Common in instrumentation valves and small process valves requiring frequent maintenance access. | Valve Body |
| PB | Pressure Seal Bonnet | A bonnet design where the bonnet is held in place by the internal process pressure. The higher the pressure, the tighter the seal. Used in high-pressure power plant and hydrocarbon service valves above Class 600. | Valve Body |
| TC | Threaded Cap | A cap threaded onto the valve body end. Used in instrument root valves and small process isolations where a simple threaded connection is sufficient. | Valve Body |
| UC | Union Cap | A cap held by a union nut, similar to Union Bonnet design. Allows quick removal for inspection or cleaning without requiring spanners on the body itself. | Valve Body |
| HF | Hard Faced | Indicates the seating surfaces of the valve (the areas that contact each other to form a seal) have been hard-faced with a wear-resistant alloy such as Stellite. Used in valves handling abrasive, erosive or high-temperature service where soft seats would quickly wear out. | Valve Body |
| HW | Handwheel | Indicates the valve is operated by a handwheel rather than a lever or other actuator. Handwheels are standard on gate, globe and needle valves. The abbreviation appears on valve schedules to indicate manual operation. | Valve Body |
| BV | Ball Valve | A quarter-turn valve using a spherical ball with a hole through its centre. When the hole aligns with the pipe, the valve is open. A 90-degree turn closes it. Fast operation, tight shutoff, low pressure drop. Extremely common in process plants. | Valve Type |
| GV | Gate Valve | A valve using a sliding gate disc to start or stop flow. Suitable for fully open or fully closed operation only, not for throttling. Very low pressure drop in the open position. Standard isolation valve in water, oil and gas piping. | Valve Type |
| CV | Check Valve | A non-return valve that allows flow in only one direction. The disc or ball opens under forward flow pressure and closes when flow reverses. Used to prevent backflow from pressurised systems into suction lines, tank vent lines and compressor discharge lines. | Valve Type |
| SOV | Shut Off Valve | A valve used specifically to isolate a section of pipework. The term is generic and applies to any valve type used for isolation rather than flow control. On P&IDs, SOV often appears on drain, vent and instrument isolation valves. | Valve Type |
| PRV | Pressure Reducing Valve | A self-actuated valve that automatically maintains a constant downstream pressure regardless of upstream pressure variations. Used to reduce high-pressure supply to a lower working pressure required by the downstream system. Common on utility steam and air systems. | Valve Type |
| PSV | Pressure Safety Valve | A spring-loaded valve that opens automatically when the upstream pressure exceeds a set value, then reseats when the pressure falls below the set point. The primary overpressure protection device in pressure vessels and piping systems. Governed by ASME Boiler and Pressure Vessel Code. | Valve Type |
| RV | Relief Valve | Similar to a PSV but specifically for liquid service. Opens proportionally to overpressure rather than popping fully open. Used on liquid lines where a sudden full-open release would cause problems. The term PSV is often used generically to cover both. | Valve Type |
| NV | Needle Valve | A valve with a tapered needle-shaped plug allowing very fine flow adjustment. Used for instrumentation impulse lines, small-bore instrument isolation and precise flow control in laboratories. Provides much finer control than a globe valve at low flow rates. | Valve Type |
| BFV | Butterfly Valve | A quarter-turn valve using a circular disc that rotates on a central shaft. Compact, lightweight and inexpensive relative to other valve types at large pipe sizes. Common in water treatment, HVAC and large-diameter process lines. Can be used for throttling in some designs. | Valve Type |
| DD | Double Disc | A gate valve design that uses two independent disc plates instead of a single wedge. The double disc design provides a tighter seal as each disc seats independently against its own seat ring. Common in gas service gate valves. | Valve Body |
| SW | Solid Wedge Disc | The most common gate valve disc design. A single rigid wedge-shaped disc that seats against two angled seat rings inside the valve body. Simple, strong and suitable for most general service applications. Less forgiving of pipe misalignment than a flexible wedge design. | Valve Body |
| FW | Flexible Wedge | A gate valve disc with a single piece but incorporating a groove around the rim that allows the disc to flex slightly. This flexibility allows the disc to conform better to the seat faces even when the valve body is distorted by pipe strain or thermal movement. Better sealing than a solid wedge under adverse installation conditions. | Valve Body |
| RWD | Resilient Wedge Disc | A gate valve disc design with the metal disc encapsulated in an elastomer (rubber) coating. The rubber provides an extremely tight shutoff and is used in water distribution valves, wastewater and municipal water services. Not suitable for hot water or hydrocarbon service as the elastomer may be damaged. | Valve Body |
| FP | Full Port | Indicates a ball valve whose bore (internal hole) is the same diameter as the connecting pipe bore. A full port valve has no restriction to flow and therefore has essentially zero pressure drop. Preferred where pressure drop must be minimised or where a pig (pipeline inspection gauge) must pass through. | Valve Body |
| RP | Reduced Port | A ball valve whose bore is smaller than the connecting pipe bore. Reduced port valves are smaller and less expensive than full port equivalents but create a pressure drop. Acceptable in most isolation and on/off applications where flow restriction is not critical. | Valve Body |
| BWE | Butt Weld End | A valve end connection where the pipe end and valve end are bevelled and welded together using a full-penetration circumferential weld (butt weld). The strongest and most leak-proof connection type. Required for high-pressure, high-temperature and toxic service. Produces a flush internal bore with no restriction at the joint. | Connection |
| BW | Butt Weld | Shorthand for Butt Weld End. Same meaning as BWE. Appears on piping isometrics and valve schedules to indicate the end connection type. | Connection |
| SWE | Socket Weld End | A valve end connection where the pipe slides into a socket (counter-bore) in the valve body and is then fillet-welded at the outside. Used for small bore pipe (typically DN50/2 inch and below) in high-pressure service. Creates a stronger connection than a threaded end but with a small internal crevice at the pipe-socket interface. | Connection |
| SW | Socket Weld | Shorthand for Socket Weld End. Note: SW is also used for Solid Wedge Disc in some valve specifications. Context determines the correct meaning. When SW appears in the "End Connection" column it means Socket Weld. When it appears in the "Disc" column it means Solid Wedge. | Connection |
| TE | Threaded End | A valve end connection using male or female pipe threads. The most economical connection type. Used in lower-pressure service (typically Class 150 to Class 300). NPT (National Pipe Taper Thread) is the standard for threaded connections in North American process industry. BSP is used in European and Asian installations. | Connection |
| FLG | Flange | A flanged end connection. The valve has a flange at each end that bolts to a mating flange on the piping. Flanged connections are the standard for most process plant valves above DN15 (0.5 inch). The flange rating (Class 150, 300, 600, 900, 1500, 2500) determines the pressure and temperature capability. | Connection |
| FE | Flange End | Same meaning as FLG. The valve end connection type is flanged. Appears interchangeably with FLG in different piping specifications and valve schedules. | Connection |
| MJ | Mechanical Joint | A flexible pipe connection using a bolted gland that compresses a rubber gasket around the pipe end to form a seal. Used extensively in water distribution pipework, especially for large diameter buried water mains where some angular deflection between pipes is needed. | Connection |
| SE | Solder End | A valve end connection designed to be soldered (brazed) to copper pipe. Used in plumbing, HVAC and domestic water systems. The pipe slides into a socket and is sealed with solder or brazing material heated to the required temperature. | Connection |
| SB | Silver Brazed | Indicates the valve connection is joined using silver brazing alloy rather than ordinary solder. Silver brazed joints are stronger than soft-soldered joints and suitable for higher temperatures. Used on refrigeration valves and high-specification copper pipework. | Connection |
| DWV | Drain, Waste, Vent | A classification for valves, fittings and pipes used in sanitary drainage, waste and vent systems. DWV fittings have smoother internal contours to promote self-cleaning flow and are thinner-walled than pressure-rated pipe. Not rated for pressure service. | Connection |
| FTTG | Fitting | Abbreviation for fitting, used on piping isometrics and bills of material to denote a piping component other than a valve or pipe (e.g. elbow, tee, reducer, coupling). Appears in material take-off documents and purchase requisitions. | Connection |
| RF | Raised Face | The most common flange face type in process industry. A circular raised ring on the flange face, around the bore, that forms the sealing surface. The gasket sits on this raised area only, concentrating the bolt load on a smaller area for better sealing. Standard for ANSI/ASME Class 150 to Class 2500 flanges in most services. | Flange Face |
| FF | Flat Face | A flange face machined flat across the entire face, with no raised ring. Full-face gaskets span the entire flange face. Used when connecting valves with flanges made from brittle materials (cast iron, ductile iron) to avoid cracking the flange from the bending stress created by a raised-face connection. | Flange Face |
| RJ | Ring Type Joint | A flange face design using a metal ring gasket seated in a machined groove on the flange face. The ring gasket is crushed into the groove when the flange bolts are tightened, creating an extremely reliable metal-to-metal seal. Used in high-pressure and high-temperature service, particularly in oil and gas exploration and production. More expensive and more difficult to disassemble than RF connections. | Flange Face |
| RTJ | Ring Type Joint | Alternative abbreviation for Ring Type Joint. Same meaning as RJ. RTJ is more commonly used in British and European specifications while RJ is more common in North American specifications. | Flange Face |
| RS | Rising Stem | A valve stem that moves upward (rises) when the valve is opened. The stem threads through the handwheel or actuator. Provides a visual indication of valve position: when the stem is raised the valve is open, when flush with the bonnet the valve is closed. Standard on gate valves and globe valves. | Stem Type |
| NRS | Non-Rising Stem | A valve stem that does not rise when the valve is opened. The stem threads into the disc and rotates in place while the disc travels up and down. Requires less headroom above the valve than a rising stem design. Used where overhead clearance is limited, such as in underground valve boxes and confined plant rooms. | Stem Type |
| OS&Y | Outside Screw and Yoke | A rising stem design where the threads are outside the valve body and the stem rises through a yoke. The threads are never in contact with the process fluid, eliminating corrosion of the threads from the process fluid. The standard stem design for fire protection gate valves (where OS&Y provides visible open/closed indication) and many process gate valves. A locked-open OS&Y valve is a standard fire system indicator. | Stem Type |
| ISRS | Inside Screw Rising Stem | A valve where the stem threads are inside the valve body (in contact with the process fluid) but the stem still rises as the valve opens. The threads are exposed to the process fluid, so material compatibility must be checked. Less common than OS&Y in process plants but found in older installations and utility services. | Stem Type |
| RWD | Resilient Wedge Disc | See Valve Body section. A rubber-encapsulated gate valve disc providing tight shutoff in water service. | Stem Type |
| NPS | Nominal Pipe Size | The North American standard system for designating pipe and valve sizes. The NPS number is a nominal (approximate) designation, not an actual measurement. For NPS 1/4 to NPS 12, the NPS number approximates the pipe outside diameter in inches. Above NPS 12, the NPS number equals the outside diameter in inches. NPS sizes run from NPS 1/8 to NPS 80 and larger. | Pipe Size |
| IPS | Iron Pipe Size | The traditional designation system for pipe sizes that preceded NPS. IPS uses the same nominal sizes as NPS (they are numerically identical) but the terminology IPS is used in older specifications and certain industries including plastics and gas distribution piping. | Pipe Size |
| DN | Diameter Nominal | The international (metric) equivalent of NPS under ISO and EN standards. The DN number approximates the pipe bore in millimetres. Common conversions: NPS 1 = DN25, NPS 2 = DN50, NPS 4 = DN100, NPS 6 = DN150, NPS 8 = DN200. DN is used in European, Asian and most international engineering specifications. | Pipe Size |
| NPT | National Pipe Taper Thread | The North American standard for tapered pipe threads, defined by ANSI/ASME B1.20.1. The taper (1 in 16 on the diameter) creates a pressure-tight seal as the threads engage without requiring a gasket or sealant, though thread sealant (PTFE tape or pipe dope) is always used in practice. NPT is the dominant threaded connection standard in North American process plants. | Thread |
| BSP | British Standard Pipe Thread | The thread standard used in Europe, Asia, Australia and most of the world outside North America. Comes in two forms: BSPP (parallel thread, requires a gasket) and BSPT (tapered thread, similar to NPT). NPT and BSP threads are NOT interchangeable despite being close in size. Mixing them causes leaks. Always verify which thread standard is specified before ordering valves or fittings. | Thread |
| CWP | Cold Working Pressure | The maximum allowable working pressure of a valve at ambient temperature (typically 100°F / 38°C). CWP is the baseline pressure rating and will be lower at elevated temperatures. Always check the pressure-temperature rating table for the actual service conditions, not just the CWP figure. | Pressure |
| WOG | Water, Oil, Gas Pressure | A pressure rating designation for valves approved for use with water, oil and gas service at the stated pressure. WOG is an older designation still commonly found on bronze and iron valves. It does not specify the temperature, so the actual safe working pressure must be confirmed from the pressure-temperature rating tables. | Pressure |
| OWG | Oil, Water, Gas Pressure | Same meaning as WOG. The terms are interchangeable. OWG and WOG both appear on older valve body markings and specifications to indicate the valve is suitable for these three fluid types. Modern specifications use ASME pressure class ratings (Class 150, 300, etc.) instead. | Pressure |
| SWP | Steam Working Pressure | The maximum working pressure of a valve in steam service. Steam service ratings are always lower than cold water ratings for the same valve because steam operates at elevated temperature, and valve materials lose strength as temperature increases. Always check the SWP rating separately from the CWP or WOG rating when using valves in steam service. | Pressure |
| WWP | Water Working Pressure | The maximum allowable working pressure of a valve specifically in water service. Appears on valves used in water distribution, fire protection and HVAC applications. Similar to CWP but specifically stated for water service conditions. | Pressure |
| DI | Ductile Iron | A type of cast iron with a modified microstructure (spheroidal graphite instead of flake graphite) that gives it much higher tensile strength and impact resistance than grey cast iron. Ductile iron is widely used for valve bodies in water distribution (gate valves, butterfly valves) because it is stronger and less brittle than grey cast iron while still being cost-effective. | Material |
| IBBM | Iron Body Bronze Mounted | A valve construction where the body is cast iron but the internal wetted components (seats, disc, stem) are made from bronze. The bronze internals provide better corrosion resistance and tighter seating than iron-on-iron construction. Very common in older water service and general utility valves. | Material |
| WCB | Cast Carbon Steel (ASTM A216 Grade WCB) | The most common carbon steel used for valve bodies in process plant service. WCB (Weldable Cast B) is a general-purpose cast carbon steel suitable for temperatures from -29°C to +427°C (-20°F to +800°F). Specified in ASTM A216. The first choice for most oil, gas and chemical service valves. | Material |
| CF8M | Cast 316 Stainless Steel (ASTM A351 Grade CF8M) | The cast stainless steel equivalent of wrought 316L SS. Contains molybdenum which gives excellent resistance to chloride pitting corrosion. Used for valve bodies in corrosive chemical service, seawater, acid and pharmaceutical applications. | Material |
| CF8 | Cast 304 Stainless Steel (ASTM A351 Grade CF8) | The cast stainless steel equivalent of wrought 304 SS. Good general corrosion resistance but without the molybdenum of CF8M, so less resistant to chloride pitting. Used in less aggressive corrosive service applications. | Material |
| RP | Reduced Port | See Valve Body section. Ball valve bore smaller than the connecting pipe bore. | Misc |
No abbreviations found matching your search. Try a different keyword.
Advertisement
Advertisement
Valve Abbreviations by Category
The abbreviations below are grouped by category to help you understand the logical structure of valve specifications. When you read a valve datasheet or purchase order, each column in the specification corresponds to one of these categories.
Valve Type Abbreviations
These abbreviations identify what kind of valve it is: what it does and how it moves.
| Abbreviation | Full Term | Key point |
|---|---|---|
| BV | Ball Valve | Quarter-turn, full or reduced port, tight shutoff, very common |
| GV | Gate Valve | Fully open or closed only. Rising stem standard. Zero throttling. |
| BFV | Butterfly Valve | Quarter-turn, wafer or lugged body, large bore, low cost |
| CV | Check Valve | Non-return. Allows flow one way only. No manual operation. |
| NV | Needle Valve | Fine flow adjustment. Small bore instrument and lab service. |
| SOV | Shut Off Valve | Generic isolation valve. Any type used for on/off service. |
| PRV | Pressure Reducing Valve | Self-actuated. Maintains constant downstream pressure. |
| PSV | Pressure Safety Valve | Overpressure protection. Opens at set pressure, reseats below. |
Body and Bonnet Abbreviations
These describe how the valve is constructed and how the bonnet (top cover) is attached to the body.
| Abbreviation | Full Term | Key point |
|---|---|---|
| BB | Bolted Bonnet | Most common. Bolts hold bonnet to body. Easy to remove for maintenance. |
| TB | Threaded Bonnet | Screws onto body. Small valves and lower-pressure service. |
| UB | Union Bonnet | Union nut secures bonnet. Quick removal for maintenance. |
| PB | Pressure Seal Bonnet | Internal pressure holds bonnet. High-pressure power plant service. |
| HF | Hard Faced | Stellite or similar hard-facing on seats. Abrasive/erosive service. |
| HW | Handwheel | Manual operation by handwheel as opposed to lever or actuator. |
| FP | Full Port | Ball valve bore = pipe bore. Zero pressure drop. Piggable. |
| RP | Reduced Port | Ball valve bore smaller than pipe. Creates pressure drop. |
| DD | Double Disc | Gate valve with two independent discs. Better sealing than solid wedge. |
| SW | Solid Wedge Disc | Single rigid wedge gate disc. Most common gate valve disc type. |
| FW | Flexible Wedge | Single flexible wedge. Handles pipe strain and thermal distortion better. |
| RWD | Resilient Wedge Disc | Rubber-coated disc. Tight shutoff in water distribution service. |
End Connection Abbreviations
These describe how the valve connects to the piping. This is one of the most critical specifications on a valve purchase order.
| Abbreviation | Full Term | Key point |
|---|---|---|
| BWE / BW | Butt Weld End | Strongest. Full penetration weld. Required for high-pressure and toxic service. |
| SWE / SW | Socket Weld End | Pipe slides into socket then fillet welded. Small bore high-pressure only. |
| TE | Threaded End | NPT or BSP threads. Lower pressure service. Most economical connection. |
| FLG / FE | Flanged End | Standard for most process valves. Bolted to pipe flanges. |
| MJ | Mechanical Joint | Rubber gasket + gland. Water distribution buried service. |
| SE | Solder End | Copper pipe systems. Plumbing and HVAC service. |
Stem Type Abbreviations
| Abbreviation | Full Term | Key point |
|---|---|---|
| RS | Rising Stem | Stem rises when valve opens. Visual position indication. |
| NRS | Non-Rising Stem | Stem stays in place. Saves headroom. Underground and confined installations. |
| OS&Y | Outside Screw and Yoke | Threads outside body. Required on fire protection gate valves (visible open/closed). |
| ISRS | Inside Screw Rising Stem | Threads inside (in contact with fluid). Stem still rises. Older installations. |
Flange Face Type Abbreviations
| Abbreviation | Full Term | Key point |
|---|---|---|
| RF | Raised Face | Standard for Class 150 to 2500 process service. Gasket on raised ring only. |
| FF | Flat Face | Required with brittle materials (cast iron). Full-face gasket across entire flange. |
| RJ / RTJ | Ring Type Joint | Metal ring in groove. High pressure and temperature. Oil and gas upstream. |
Pressure Rating Abbreviations
| Abbreviation | Full Term | Key point |
|---|---|---|
| CWP | Cold Working Pressure | Maximum pressure at ambient temperature. Reduces with temperature. |
| WOG | Water, Oil, Gas Pressure | Older rating. Suitable for water, oil and gas at stated pressure. |
| OWG | Oil, Water, Gas Pressure | Same as WOG. Older nomenclature. |
| SWP | Steam Working Pressure | Steam service rating. Always lower than CWP due to elevated temperature. |
| WWP | Water Working Pressure | Maximum pressure specifically in water service. |
Material Abbreviations
| Abbreviation | Full Term | Key point |
|---|---|---|
| DI | Ductile Iron | Stronger than grey cast iron. Standard for water distribution gate and butterfly valves. |
| IBBM | Iron Body Bronze Mounted | Cast iron body, bronze internals. Better corrosion resistance. Older utility valves. |
| WCB | Cast Carbon Steel (A216 Gr. WCB) | Standard process plant valve body material for most oil, gas and chemical service. |
| CF8M | Cast 316 Stainless Steel | Corrosive chemical, seawater and pharmaceutical service. |
| CF8 | Cast 304 Stainless Steel | General corrosive service. Less chloride resistance than CF8M. |
| SB | Silver Brazed | High-quality brazed joint. Refrigeration and high-spec copper systems. |
Advertisement
Advertisement
The Most Commonly Confused Valve Abbreviations
CV: Check Valve or Control Valve?
On the reference article from Inst Tools, CV is listed as Check Valve. In instrumentation and P&ID practice, CV is most commonly used for Control Valve. The correct meaning depends entirely on context. On a valve schedule or piping specification, CV = Check Valve. On an instrument index or P&ID tag, CV = Control Valve. Always check the document type before interpreting CV.SW: Socket Weld or Solid Wedge?
SW appears in two completely different columns on valve specifications. In the "End Connection" column, SW means Socket Weld. In the "Disc" column, SW means Solid Wedge. This is one of the most common sources of confusion on valve datasheets. Always read SW in the context of which column or field it appears in.BV: Ball Valve or Butterfly Valve?
In the reference article, BV = Ball Valve. However, BFV or BUV is the more specific abbreviation for Butterfly Valve. Some older specifications use BV for both. In ambiguous cases, check the valve body drawing number or the nominal pipe size. Ball valves are more common in smaller sizes (DN15 to DN300) while butterfly valves are more common in large sizes (DN300 and above).How Valve Abbreviations Appear in Engineering Documents
Understanding where each type of abbreviation appears on engineering documents helps you use this reference correctly. The same valve can be described using a combination of many of these abbreviations simultaneously. For example, a valve specification might read:
Example: Reading a typical valve specification line
8" GV, WCB, BB, OS&Y, RS, RF, BW, Class 300, CWP 720 psi
Reading this in sequence: 8 inch (NPS 8) Gate Valve, Cast Carbon Steel body (WCB), Bolted Bonnet (BB), Outside Screw and Yoke stem (OS&Y), Rising Stem (RS), Raised Face flanges (RF), Butt Weld Ends (BW), ASME Pressure Class 300, Cold Working Pressure 720 psi.
This one specification line tells a procurement engineer exactly what valve to order without any ambiguity. Every abbreviation eliminates one degree of freedom in the specification.
Further Reading and External Resources
Trusted external resources on valve terminology and abbreviations
- MSI Valves: Complete Valve Glossary. Comprehensive valve terminology reference from a specialist valve manufacturer covering body types, trim types, actuators and standards.
- Flowserve: Control Valve Handbook. The industry-standard reference for control valve engineering, selection and terminology from one of the world's leading valve manufacturers.
- ASME B16.34: Valves: Flanged, Threaded and Welding End. The governing ASME standard for valve pressure-temperature ratings, end connections and dimensions.
- ISA 5.1: Instrumentation Symbols and Identification. The ISA standard covering valve symbols and tag identification as they appear on P&ID drawings.
Frequently Asked Questions: Valve Abbreviations
What does BB mean on a valve?
BB stands for Bolted Bonnet. It means the bonnet (the top cover that encloses the valve stem) is secured to the valve body using bolts and nuts. This is the most common bonnet construction in process industry valves because it allows the bonnet to be removed for maintenance without cutting the valve out of the pipeline.
What is the difference between WOG and CWP?
Both are pressure rating abbreviations. CWP (Cold Working Pressure) is the maximum allowable pressure at ambient temperature. WOG (Water, Oil, Gas) is an older designation indicating the valve is rated for those fluid types at the stated pressure. WOG ratings were used on older bronze and iron valves. Modern specifications use ASME pressure class ratings (Class 150, 300, etc.) which include temperature-dependent pressure ratings.
What does OS&Y mean on a gate valve?
OS&Y stands for Outside Screw and Yoke. It means the stem threads are outside the valve body and the stem rises through a yoke as the valve is opened. The threads are never in contact with the process fluid. A gate valve with a visibly raised OS&Y stem is open. When the stem is flush with the handwheel the valve is closed. OS&Y is the required design for fire protection gate valves because the open/closed position is visible from a distance.
What is the difference between RF and FF flanges?
RF (Raised Face) has a raised ring machined on the flange face where the gasket sits. FF (Flat Face) has the entire flange face machined flat with the gasket spanning the full face. RF is the standard for process plant flanges (Class 150 to 2500). FF is required when connecting to brittle material flanges like cast iron or ductile iron, because bolting a raised-face flange against a flat-face brittle flange can crack the brittle flange.
What does NPS mean and how does it differ from DN?
NPS (Nominal Pipe Size) is the North American pipe size designation system. DN (Diameter Nominal) is the international metric equivalent. They use different numbers but cover the same pipe sizes. Common equivalents: NPS 1 = DN25, NPS 2 = DN50, NPS 4 = DN100, NPS 6 = DN150, NPS 8 = DN200, NPS 12 = DN300. NPS is used in American, Canadian and some Middle Eastern specifications. DN is used in European, Asian and international specifications.
Why does CV sometimes mean Check Valve and sometimes Control Valve?
CV is an overloaded abbreviation used for both Check Valve (in piping and valve specifications) and Control Valve (in instrumentation and P&ID context). On a valve schedule, line list or piping specification CV almost always means Check Valve. On a P&ID or instrument index, CV almost always means Control Valve. Always read CV in the context of the document type. When specifying valves, use CHK or NRV for check valve to avoid ambiguity.
Advertisement
Advertisement
Related articles on this site
- How to Read a P&ID Diagram: Complete Guide
- What Is a Control Valve? Working Principle and Types
- Control Valve Positioner: Working Principle, Types and When to Use One
- What Is a Pressure Switch? Working Principle and Selection Guide
- Signals in Instrumentation: AI, AO, DI and DO Explained
- Instrument Loop Checking: A Complete Step-by-Step Procedure
What we learn today
- Valve abbreviations describe five key aspects of any valve: its type (GV, BV, CV, PRV), its body and bonnet construction (BB, TB, UB, HF), its end connection (BW, SW, TE, FLG), its stem design (RS, NRS, OS&Y) and its pressure rating (CWP, WOG, SWP). Understanding all five lets you read any valve specification line.
- SW means Socket Weld when it appears in the connection column and Solid Wedge when it appears in the disc column. CV means Check Valve in piping documents and Control Valve in instrumentation documents. Context always determines the correct meaning of ambiguous abbreviations.
- NPS (North American) and DN (international) are the two pipe size systems. NPT and BSP are the two threaded connection standards. They are not interchangeable. Always confirm which standard applies before ordering threaded valves or fittings.
- OS&Y (Outside Screw and Yoke) is the required stem design for fire protection gate valves because the raised or lowered stem gives a clear visual indication of open or closed position from a distance. A raised OS&Y stem always means the valve is open.
I hope you like above blog. There is no cost associated in sharing the article in your social media. Thanks for Reading !! Happy Learning