Industrial valves are mechanical devices used to control, regulate and open/close the flow and/or the pressure of a pipeline and/or a piping system. Valves are highly critical and expensive components and one of the determining factors for oil & gas pipelines reliability, safety, and performance. Valves are available with a cast (A216, A351) or forged steel (A105, A350, A182) body materials, depending on bore size and pressure rating, and in several shapes: gate, globe, check, ball, the butterfly is the most common.
The valves’ market is worth approximately 70 billion USD per year in 2018, and major manufacturers are located in the US, Europe (Italy, Germany, France, and Spain), Japan and China.
Industrial valves are used to:
- Start/stop the flow of the fluid (hydrocarbons, oil & gas, steam, water, acids) through the pipeline (example: gate valve or plug valve)
- Modulate the flow of the fluid through the pipeline (example: globe valve)
- Control the flow of the fluid (control valve)
- Change the direction of the flow (for example a 3-way ball valve)
- Regulate the pressure of a process (pressure reducing valve)
- Protect a piping system or a device (pump, motor, tank) from overpressures (safety or pressure relief) or back-pressures (check valve)
- Filter debris flowing through a pipeline, to protect equipment that may be damaged by solid parts (y and basket strainers)
(Source: Spirax Sarco)
Industrial valves can be classified according to multiple criteria, the main ones are:
BY DISC TYPE
- LINEAR MOTION: gate, globe, diaphragm, pinch, and check valves
- ROTARY MOTION: butterfly, ball, plug, eccentric- and swing check valves
- QUARTER TURN: devices that require approximately a quarter turn motion, from 0 to 90° of the stem to move from fully close to a fully open position or vice versa.
BY BODY MATERIAL
- CAST (the body is obtained by casting steel). The main casting materials for valves are listed in this article.
- FORGED (the body is manufactured by forging steel)
BY VALVE OPERATION
- MANUAL: the valve is operated manually, via levers, wheels and/or gears;
- ACTUATED: the valve is actioned via electromechanical devices, called actuators, that may be electric, pneumatic, hydraulic and gas over oil
TYPES OF VALVES
The most used valves in the oil and gas industry are listed below. More details for each type are available by clicking on the link.
ORDERING OIL AND GAS VALVES
To specify a valve to suppliers correctly, the following details have to be provided:
- Valve family (example ball valve), subfamily (example ball/trunnion) and exact type (ball/trunnion/top entry)
- Bore size, generally expressed in NPS or DN (main bore and reducing bore, if applicable)
- Valve rating/class (class range from 150# to 4500#)
- Manufacturing norm (example API 6D)
- Body material/trim material/packing etc
- Testing requirements
- Type of connection (flanged, threaded, butt weld, lug and others)
- Fluid in the pipeline (>oil, gas, water, steam, solids)
- Working temperature
- Working pressure
- Delivery time
- Origin restrictions (Chinese valve manufacturers / Indian valve manufacturers allowed or not)
EXAMPLE HOW TO ORDER GATE, GLOBE, CHECK VALVES
Each manufacturer has own valves ordering sheets that map the valve configuration parameters that user has to consider:
GS – F – 6″ / 150 – 316 – B
1 2 3 4 5
|1. Valve type||2. End type||3. Size / Class||4. Body Material||5. Options|
|C: Check Valve
CL: Lift Check Valve
CS: Check pressure Sealed Valve
CW: Swing Check Valve
G: Gate Valve
GG: Forged Gate Valve
GL: Light Type Gate Valve (API 603)
GS: Gate Pressure Sealed Valve
O: Globe Valve
OB: Globe Bellowed Sealed Valve
OS: Globe Pressure Sealed Valve
|F: Flanged End
T: Threaded End
W: Butt Weld End
S: Socket Weld End
|Size: NPS 1/2 – 80″
10K: JIS 10K
|GG: Forged Gate Valve
316: Casting S.S CF8M
304: Casting S.S CF8
F316: Forgings S.S F316
F304: Forgings S.S F304
WCB: Steel WCB
LCB: Steel LCB
HB: Hastelloy B
G: Gear Operator
ASME B16.34: VALVE COMPLIANCE
The ASME valve standard B16.34 is a globally accepted standard to design, manufacture and test valves. ASME B16.34 is also mentioned in the more general ASME spec ASME B31.1, “Power Piping Design”. Back in 1988, the scope of this standard was modified to include threaded-end and weld-end valves in addition to flanged-end valves. A valve complies with ASME B16.34 when the following conditions are met:
- The valves body & shell materials comply with ASME and ASTM material standards for chemistry and strength
- Body & shell materials are heat-treated to ensure proper grain structure, corrosion resistance, and hardness.
- Wall thicknesses of body and other pressure-containing components meet ASME B16.34 specified minimum values for each pressure class.
- NPT and SW end connections comply with ASME B1.20.1 or ASME B16.11.
- Stems are internally loaded and blowout proof.
- All bolting will be ASTM grade with maximum applied stress controlled by B16.34.
- Each valve is shell tested at 1,5x rated pressure for a specific test time duration.
- Each valve is tested for seat leakage in both directions for a specific test time duration.
- Each valve is permanently tagged with materials of construction, operating limits and name of the manufacturer.