Ball Valve Selection

Ball valve selection starts with three parameters: medium, temperature and pressure. The first section of our instructions for use sets out the points to be considered in selection under seven headings.

Questions that determine selection

Medium: Type, body and seat material

Temperature: Seat and body material

Pressure: Pressure rating (PN / Class)

Size and flow rate: DN, bore type

Connection: Flanged, welded, threaded

Standard: Product family

Selection steps

Step	Question	Determines
1	What is the medium? Liquid, gas or steam; does it contain solid particles; is it corrosive; is it flammable?	Valve type, body and seat material, fire-safe requirement
2	What are the minimum and maximum operating temperatures?	Seat material, body material, O-ring
3	What is the maximum operating pressure?	Pressure rating (PN / Class), floating or trunnion
4	What is the pipe size or the hourly flow rate?	DN, full bore or reduction bore
5	How will it be connected to the line?	Connection type, flange facing, face-to-face dimension
6	Which standard is required?	Product family
7	Where will it be installed? Underground, above ground, confined space?	Body design
8	How will it be operated?	Lever, gearbox, actuator
9	Is additional safety required?	Double isolation, drain and vent, optional features

Responsibility for the correct selection, sizing, installation, operation and maintenance of the valve rests with the end user. Our technical team is available where support is needed in selection.

Medium

Property of the medium	Effect on selection
Flammable (oil, LPG, natural gas)	Fire-safe and antistatic design
Containing abrasive particles	Metal-to-metal seat
At temperatures PTFE cannot withstand	Metal-to-metal seat
Containing H₂S (sour gas)	Material in accordance with NACE MR0175 / ISO 15156
Asphalt, certain foodstuffs and chemicals	Jacketed valve
Contaminated line (rust, slag, scale)	Strainer upstream of the valve
Steam	Steel or cast valve; steam trap for condensate
Corrosive chemical	Stainless steel body and trim; chemical compatibility chart for suitability

Pressure

The pressure rating is expressed as PN in Europe and as Class in the American standard: Class 150 = PN 20, Class 300 = PN 50, Class 600 = PN 100. The Batu Valve production range extends from PN 6 to Class 2500.

PN and Class pressure ratings

Size, flow rate and bore type

Full bore: the ball bore equals the pipe diameter; pressure drop is at its minimum. It is mandatory where a pig is to pass through the line.
Reduction bore: the bore is one size smaller; the valve is smaller and lighter.

The size is selected according to the required flow rate and the permissible flow velocity. For this purpose the recommended flow velocities table and the pipe flow diagram are used.

Connection

Connection	When used
Flanged — RF	General service; removable
Flanged — RTJ	High pressure classes
Butt welded (BW)	Lines that will not be dismantled; where leak points are to be avoided
Socket weld (SW)	Small sizes
Threaded	Small sizes, low and medium pressure
Wafer	Confined space

When allowing space for the valve, the face-to-face dimension and the gasket thickness are taken into account together.

Standard and product family

Standard required by the project	Product family
API 6D / ASME (oil, gas, pipeline)	API 6D split body, DBB, pig, fully welded
EN / DIN (European industrial piping)	EU, steel, high pressure European norm, mono-block
TS EN 331 / TS 9809 (natural gas distribution and building installations)	Natural gas ball valve
TS 3148 (water, heating)	Cast iron and sphero ball valve

Body design and location

Condition	Selection	Reason
Maintenance required; must be dismantlable	Split body	Bolted; seats and seals can be replaced
Underground; transmission and distribution line	Fully welded	Light, durable, compact
Confined piping; between two flanges	Burak type mono-block	One-piece body; short and light
Line to be pigged but no space for a station	Pig ball valve	Launcher, receiver and shut-off in a single body
Two separate shut-offs with a bleed in between	DBB ball valve	Reduces the number of valves and the space required
Flow to be divided or mixed	3 way (L or T)	The L type changes direction by 90°; the T type mixes

Routine maintenance cannot be carried out on underground valves; an annual preventive maintenance and inspection programme is required.

Operation

Operation	When used
Lever	Small sizes. 4″ and below in the API 6D series.
Gearbox (handwheel)	Large sizes. Above 4″ in the API 6D series.
Pneumatic, hydraulic or electric actuator	Remote or automatic operation

The top of the body is machined to ISO 5211; an actuator can also be fitted at a later date.

Information to provide when requesting a quotation

Medium: name, state, clean or contaminated, corrosive or not, flammable or not
Minimum and maximum temperature
Maximum operating pressure or required pressure rating
Size (DN / inch) and bore type (full / reduction)
Connection: flange standard and facing, weld or thread
Standard (API 6D, EN, TSE) and required certificates
Body design (split body, fully welded, mono-block); underground or not
Seat type (soft / metal) and isolation arrangement
Operation (lever, gearbox, actuator)
Additional requirements: drain and vent, injection, locking device, special paint, special material

Frequently asked questions

When is a full bore ball valve mandatory?Which ball valve is used on an underground line?Can an actuator be fitted at a later date?How is a ball valve protected on a contaminated line?

A full bore valve is mandatory where a pig is to pass through the line. In full bore the ball bore equals the pipe diameter and pressure drop is at its minimum.

A fully welded ball valve. It is light, durable and compact; it is used below and above ground on transmission and distribution lines.

Yes. The mounting flange on top of the body is to ISO 5211 dimensions; an actuator can also be fitted at a later date.

A strainer is installed upstream of the valve. Fitting strainers on main lines extends the service life of the valve.