Valves control everything that flows through a piping system — starting, stopping, throttling and preventing backflow. For pipe, fitting and flange suppliers, valves are a natural add-on that increases order value. But buyers expect you to know the difference between the main industrial valve types and the standards behind them.

1. Gate valve

A gate valve uses a flat or wedge-shaped gate that moves up and down across the flow path.

  • Function: on/off isolation. Fully open gives almost no pressure drop.
  • Not for: throttling — a partly open gate vibrates and erodes.
  • Common standards: API 600 (bolted bonnet steel gate valves), API 602 (compact forged valves, small sizes), API 6D (pipeline valves).
  • Uses: water, oil, gas, steam isolation in refineries and utilities.

2. Globe valve

A globe valve has a disc that moves onto a seat inside a spherical body, forcing flow to change direction.

  • Function: throttling and regulating flow, with good shut-off.
  • Trade-off: higher pressure drop than gate or ball valves.
  • Common standards: BS 1873, API 602 (small forged), ASME B16.34.
  • Uses: steam control, feed water, cooling water, fuel oil lines.

3. Ball valve

A ball valve uses a rotating ball with a bore through it. A quarter turn opens or closes it.

  • Function: fast on/off with tight shut-off.
  • Types: floating ball (smaller sizes) and trunnion-mounted (large sizes and high pressure).
  • Common standards: API 608 (metal ball valves), API 6D, ISO 17292.
  • Uses: oil and gas, chemicals, water — anywhere quick, tight shut-off is needed.

4. Butterfly valve

A butterfly valve has a disc mounted on a shaft in the flow path. A quarter turn rotates the disc.

  • Function: isolation and moderate throttling, especially in large sizes.
  • Advantages: lightweight, compact, low cost in big diameters.
  • Body styles: wafer, lug and double-flanged; high-performance double- and triple-offset designs for demanding service.
  • Common standards: API 609, EN 593.
  • Uses: water treatment, HVAC, cooling water, large process lines.

5. Check valve (non-return valve)

A check valve opens with forward flow and closes automatically to prevent backflow.

  • Types: swing check, lift check, dual-plate (wafer) check, piston check.
  • Common standards: BS 1868, API 594 (wafer and dual-plate), API 602.
  • Uses: pump discharge, compressor outlets, any line where reverse flow would cause damage.

6. Plug valve and others

  • Plug valve: a tapered or cylindrical plug rotates a quarter turn; used for slurry, gas and on/off service.
  • Needle valve: fine flow control in instrumentation.
  • Diaphragm valve: hygienic and corrosive service.
  • Knife gate valve: slurries and pulp.

Quick comparison

Valve Operation On/off Throttling Pressure drop
Gate Multi-turn Excellent Poor Very low
Globe Multi-turn Good Excellent High
Ball Quarter-turn Excellent Limited Very low
Butterfly Quarter-turn Good Moderate Low
Check Automatic Prevents backflow — Low–moderate

Valve materials

Valve bodies are usually cast or forged:

  • Cast carbon steel: ASTM A216 WCB.
  • Cast stainless: ASTM A351 CF8 (304), CF8M (316), CF3M (316L).
  • Low-temperature cast steel: ASTM A352 LCB/LCC.
  • Forged: ASTM A105, A182 F316L, F51 (see ASTM A182 grades explained).

Trim (stem, seat, disc) is often specified by API trim numbers — for example, trim 8 means 13Cr with hardfaced seats.

Pressure ratings and testing

  • ASME B16.34 defines pressure–temperature ratings for valves by class (150 to 2500), similar to flanges. See flange pressure class ratings.
  • ASME B16.10 gives face-to-face and end-to-end dimensions.
  • API 598 sets inspection and pressure testing — shell and seat tests.

Quoting valves correctly

A complete valve line includes: type, size, class, end connection (flanged RF, BW, SW, threaded), body material, trim, operator (lever, gear, actuator) and standard. For example:

"Gate valve, 6" Class 300, RF flanged, A216 WCB body, trim 8, gear operated, API 600, tested to API 598."

Bundling valves with pipes, fittings and flanges makes you a one-stop supplier. QuoteMitra handles long multi-product quotations easily.

Frequently asked questions

Which valve is best for throttling?

Globe valves are best for precise throttling. Butterfly valves can throttle moderately in large sizes. Gate valves should not be used for throttling.

What is the difference between floating and trunnion ball valves?

In a floating ball valve, the ball is held by the seats and moves slightly downstream to seal. In a trunnion valve, the ball is fixed on trunnions, reducing operating torque — ideal for large sizes and high pressure.

What does WCB mean?

WCB is a grade of cast carbon steel under ASTM A216, widely used for valve bodies in water, oil and gas service.

What is API 598?

API 598 is the standard for valve inspection and testing, covering shell, backseat and seat leakage tests.

Key takeaways

  • Gate for isolation, globe for throttling, ball for fast tight shut-off, butterfly for large sizes, check for backflow prevention.
  • Body materials include WCB, CF8M, LCC and forged A105/A182.
  • ASME B16.34 sets ratings; API 598 sets testing.
  • Specify every detail in quotations to avoid wrong deliveries.

Adding valves to your range can lift average order value significantly — and buyers love fewer suppliers to manage.