1. Why an industrial valve is never just a valve

An industrial valve sits in the middle of a piping system. To install, operate and maintain it you need compatible pipe fittings (elbows, tees, reducers), bolted pipe flanges or butt-weld ends, a matched gasket, and the right stud bolt and nut grade. When those components are sourced from one mill-direct partner, you eliminate mismatched certificates, lead-time gaps and warranty finger-pointing between suppliers.

A midstream gas plant, a desalination skid and a coal-fired boiler island all use valves — but the metallurgy, the API specification, the face-to-face dimension, the fire-safe certification and even the hand-wheel orientation change with the service. The 7 valve types below cover roughly 95% of what a procurement team will ever order.

2. The 7 valve types every buyer should recognise

2.1 Gate valve — the full-bore workhorse

A gate valve lifts a wedge or slab out of the flow path. In the fully open position the bore matches the pipe, so pressure ｄｒｏｐ is the lowest of any valve type — perfect for mainline isolation in water, steam, oil and gas service. It is not a control valve: partial throttling will erode the seats.

• API 600 — the refinery standard, NPS 1 and above, ASME Class 150 to 2500, carbon and alloy steel, up to 538°C
• API 602 — forged small-bore gate valves, NPS ½ to 4, Class 150 to 1500 (including Class 800), screwed or socket-weld ends
• API 603 — corrosion-resistant gate valves in stainless or nickel alloy, lighter wall, Class 150/300/600

2.2 Ball valve — the 90° quarter-turn shut-off

Rotate the stem a quarter turn and the ball either lines up with the pipe (open) or blocks it (closed). Quick operation, bubble-tight shut-off and a compact face-to-face make ball valves the default isolation device on gas, hydrocarbon, water and chemical lines.

• API 608 — the dedicated ball-valve standard, Class 150 to 800, full / single-reduced / double-reduced bore
• Floating-ball design for small-bore and lower pressure; trunnion (fixed-ball) design for NPS 6 and above or Class 600 and above
• Soft seats (PTFE, RPTFE, PEEK) for tight shut-off; metal seats hard-faced with Stellite or Inconel for high temperature and abrasive service

2.3 Globe valve — the precision throttling valve

A globe valve moves a disc perpendicular to the seat, producing an S-shaped flow path. The flow restriction gives a globe valve excellent throttling and shut-off control — ideal for feedwater regulation, bypass lines around control valves and instrument isolation.

• API 602 for small-bore globe valves up to NPS 4
• API 623 for NPS 2 to NPS 24, Class 150 to 2500
• Install strictly in the direction of the cast arrow on the body

2.4 Check valve — the silent backflow preventer

A check valve closes automatically when flow reverses. It protects pumps from back-rotation, prevents water hammer, and isolates parallel pumps from each other. No handwheel, no external actuation — but the right style matters.

• API 594 — wafer, lug and double-flanged Type A (single-disc or dual-disc) and Type B (bolted-bonnet swing)
• API 602 — piston, ball and swing check for small-bore forged valves up to NPS 4
• Avoid installing swing checks on the bottom of vertical lines; dual-disc wafer checks handle vertical-up service best

2.5 Butterfly valve — the lightweight large-bore solution

A disc rotates 90° on a shaft inside the pipe. The compact body and low weight make butterfly valves the most cost-effective shut-off device for large-bore water, HVAC and low-pressure gas service. High-performance variants handle hydrocarbon and offshore duties.

• API 609 — covers both Category A (concentric, resilient seated, water and utility service, Class 125/150) and Category B (eccentric, double-eccentric and triple-eccentric, Class 150/300/600)
• Triple-eccentric metal-seated butterfly valves are increasingly specified as a lighter alternative to gate and ball valves in high-temperature hydrocarbon service

2.6 Plug valve — the rugged slurry and chemical shut-off

A cylindrical or tapered plug with a bore through it rotates 90° to open or close. The large seating area resists debris and gives tight shut-off in slurries, viscous chemicals and crude oil. Lubricated and lined (PTFE / FKM) versions are common.

• API 599 — covers lubricated and non-lubricated plug valves, NPS ½ to NPS 24, ASME B16.34 pressure-temperature ratings
• Sleeved plug valves dominate chemical and pharmaceutical service where elastomer or PTFE lining protects the metal body from corrosion

2.7 Diaphragm valve — the hygienic and corrosive-service specialist

A flexible diaphragm isolates the working parts from the fluid. Nothing touches the media except the body and the diaphragm — making diaphragm valves the go-to shut-off in pharmaceuticals, food and beverage, ultrapure water, acids and chlorine service. Not for high temperature or high pressure.

• Weir-type diaphragm valves for throttling; straight-through type for on/off duty
• Lined diaphragms in PTFE, EPDM, FKM or butyl — chosen for chemical compatibility, not pressure

3. API standards at a glance

Each valve type has its own dominant API specification. The table below summarises the standards you will see most often on a valve data sheet and the dimensions or testing they govern.

4. Body and trim material selection by service

A valve is only as good as the alloy on the wetted surfaces. Use this short matrix as a starting point; for combined corrosion, temperature and pressure cases always request a corrosion-engineering review.

4.1 Carbon steel — the default for hydrocarbons and steam

ASTM A216 WCB cast carbon steel is the workhorse for oil, gas, steam and water up to 425°C. For sour service (NACE MR0175) specify A216 WCC with controlled hardness below 22 HRC and full NACE-compliant heat treatment.

4.2 Low-temperature carbon steel — for LNG, LPG and ammonia

ASTM A352 LCB (-46°C) and LC1 (-59°C) are the standard low-temperature cast carbon steel grades. Impact-tested at the design temperature per ASME B16.34.

4.3 Stainless steel — for corrosion and clean service

ASTM A351 CF8M (316 equivalent) is the most common stainless valve body. For low-carbon version specify CF3M (316L) to avoid carbide precipitation during welding. Duplex (A890 4A / 5A) and super-duplex (6A) bridge the gap when 316 is no longer enough in chloride-bearing or sour service.

4.4 Nickel alloy — for seawater, acid and aerospace

Monel (ASTM A494 M-35-1, Cu-Ni 70/30) and Inconel (A494 CW-6MC, N06600 / N06625) are specified for seawater cooling, hydrofluoric acid alkylation, nuclear safety-related service and aerospace propulsion. Our copper nickel alloy line covers the equivalent tube and pipe alloys when the upstream piping also needs to match.

4.5 Trim — the seat, disc, stem and seal surfaces

13Cr, 17Cr, Stellite 6 and Inconel 625 are common hard-facing alloys. For sour service insist on NACE MR0175-compliant trim. For high-temperature steam above 500°C, request 17Cr or Stellite 6 seats with graphite packing.

5. Matching connections: flange, thread, weld or wafer

A valve is useless if it does not bolt to the right face. Specify the connection type up front — it determines the matching steel flanges, the gasket and the stud bolt grade.

• Flanged ends (RF, FF, RTJ) — the default for in-line maintenance; pair with RF raised-face pipe flanges and spiral-wound gaskets
• Butt-weld ends — the preferred choice for high-pressure and high-temperature service; pair with matched butt weld fittings
• Socket-weld ends — NPS ½ to NPS 2 high-pressure forged valves (API 602 territory)
• Threaded (NPT / BSP) ends — utility and small-bore, limited to Class 800
• Wafer / lug / double-flanged — for butterfly and check valves; the lug pattern allows dead-end service with single-side bolting removed

6. Why bundled procurement wins on industrial projects

A typical 100-valve skid package needs roughly 200 flanges, 400 gaskets, 1,600 stud bolts, 300 butt-weld elbows, 100 tees and 50 reducers — and several kilometres of pipe. When every component comes from one mill-direct partner with a single EN 10204 3.1 / 3.2 mill test certificate chain, you save weeks of certification review and remove the risk of one mismatched component holding up hydrotest or PMI.

Our portfolio covers:

• Industrial valves across the 7 types in this guide, with body and trim alloys matched to your line pipe
• Pipe fittings in butt-weld, socket-weld and threaded execution
• Pipe flanges in carbon, stainless, alloy and copper-nickel
• Gaskets, stud bolts and nuts in B7/2H, B16, B8/8M and B8M/8M matched to the flange class and service
• Stainless steel pipe and carbon steel pipe that mechanically and chemically match the valve body alloys

7. 10-point RFQ checklist before you sign the PO

• Service fluid, full composition, operating temperature range and design pressure
• Valve type and API standard (e.g. API 600 gate, API 608 ball, API 609 Category B butterfly)
• Body and trim material (e.g. WCB + 13Cr, CF8M + Stellite 6, LCB + 13Cr)
• End connections (flanged RF, butt-weld, socket-weld, threaded, wafer, lug)
• Pressure class (ASME Class 150 / 300 / 600 / 900 / 1500 / 2500)
• Special requirements: NACE MR0175, fire-safe API 607, low-emission ISO 15848, low-temperature impact, double block and bleed
• Actuator interface (ISO 5211 mounting platform) and hand-wheel / gear / motor / pneumatic preference
• Testing and certification: API 598 hydrostatic and pneumatic, EN 10204 3.1 or 3.2 MTC, PMI, NDE scope
• Painting, marking and packaging (e.g. SSPC-PA1, export sea-worthy crating)
• Quantity, size schedule, delivery window and Incoterms

8. Closing thoughts

The cheapest valve on the market is rarely the lowest-cost valve on the project. A 5% saving on the unit price disappears fast if the body alloy does not match the line pipe, the face-to-face does not match the pipe flanges, or the fire-safe certification is missing. Specifying to the right API standard, matching trim to the service, and sourcing the valve together with its pipe fittings, flanges, gaskets and bolts keeps the system coherent and the schedule on track.