Industrial Valves: A Procurement Guide to the 7 Main Types, Standards, and Bundled Project Sourcing

Walk through any oil refinery, gas treatment plant, or thermal power station, and you will see industrial valves doing four different jobs. Some simply turn flow on and off. Some regulate it precisely. Some stop reverse flow before it damages a pump. Others protect the entire system from overpressure. Most procurement mistakes happen not because the buyer picked a "wrong" brand, but because the wrong type of valve was specified for the service — or the supporting documentation (MTR, NACE certificate, fire test report) was not on the RFQ in the first place.

This guide walks through the seven valve types that show up most often in oil and gas, petrochemical, and power piping projects, the international standards that govern them, and the practical questions a procurement team should ask before signing a purchase order. It is written from the buyer's side, drawing on three decades of EZ Steel Industrial experience as a manufacturer and integrated supplier of carbon & carbon alloy steel piping packages.

1. The Seven Valve Types You Will See on Most RFQs

Whether the RFQ comes from a midstream gas operator or a downstream petrochemical plant, the shortlist almost always comes down to the same seven valve families. Each is built around a different operating principle, and each is matched to a specific service profile.

A. Gate Valve — for full-bore isolation, not throttling

A gate valve uses a wedge or knife that slides up and down to block flow. When fully open, the bore is unobstructed, which makes it the lowest-pressure-ｄｒｏｐ isolation valve in the lineup. That is why gate valves dominate high-pressure transmission lines (ASME Class 600 and above) and crude oil / natural gas trunk lines. The trade-off: operation is slow, the seats erode if the valve is left partially open, and the body is taller and heavier than a ball valve of the same class. For most pipeline isolation duty, specify API 600 (bolted bonnet) or API 6D (pipeline).

B. Ball Valve — for quick, tight shut-off

A ball valve rotates a quarter-turn to align or block a machined bore. The two main constructions are floating ball (suited to low and medium pressure, typically Class 150–300) and trunnion-mounted ball (the standard for high-pressure, large-diameter pipeline service, designed to API 6D). Ball valves are the workhorse of LNG, sour gas, and pigging stations because they seal tightly, operate fast, and need little maintenance. Watch for cavitation on high differential pressure drops — a soft seat or multi-stage trim usually solves it.

C. Globe Valve — for throttling and flow regulation

If a service line needs to control flow precisely — metering stations, fuel gas regulation, cooling water modulation — a globe valve is the correct choice. A plug or disc moves perpendicular to flow, giving a linear relationship between stem travel and flow area. The cost is a relatively high pressure ｄｒｏｐ and a heavier body, which is why globe valves are not used for general line isolation. Standards to look for: API 600 (steel globe), ASME B16.34 (pressure-temperature rating), and ISO 10434.

D. Check Valve (Non-Return Valve) — passive backflow prevention

A check valve has no external handle; it reacts to flow. The three common constructions are swing check (simple, hinged disc — best for clean low-to-medium service), lift check (vertical disc, better for high pressure), and dual plate check (compact, fast-closing, designed to API 6D — the typical choice for pump discharge, compressor stations, and subsea pipelines). The key risk is water hammer: if the disc closes too slowly, the reverse slug can damage pumps, meters, and pipe supports. For critical service, request a fast-closing dual-plate or nozzle-type check.

E. Butterfly Valve — compact and economical for large diameters

A butterfly valve rotates a disc inside the flow path. Wafer-type bodies clamp between pipe flanges; lug-type bodies are bolted for dead-end service. The advantage is obvious: low cost, light weight, quick operation. The limitation is sealing and pressure/temperature ceiling — butterfly valves are typically specified for low-pressure gas, water, fire protection, and HVAC service rather than high-pressure hydrocarbon lines. European water and HVAC projects often reference EN 593.

F. Plug Valve — for slurry, corrosive, and diverting service

A plug valve rotates a cylindrical or conical plug with a bored passage. Because the plug can have multiple ports, plug valves are commonly used where flow needs to be diverted between three or four lines — wellhead control, slurry lines, and certain chemical services. Lubricated and sleeved plug valves still appear in legacy oilfield applications, but most new EPC specs lean toward ball or gate valves unless a specific diverting or slurry duty justifies the plug.

G. Pressure Relief Valve (PRV) / Safety Valve — system protection

The seventh type is a different category: pressure relief valves (spring-loaded, adjustable set pressure) and pilot-operated safety valves protect storage tanks, boilers, and compressor stations from overpressure events. PRVs are not a flow-control device; they are a code-required safety device. Sizing follows ASME Section VIII (pressure vessels) or ASME Section I (power boilers), and the set pressure, capacity, and relieving media must be declared on the RFQ. EZ Steel supplies PRV bodies in carbon, stainless, and alloy steels; the trim and certification are typically engineered by a dedicated PRV manufacturer.

2. The Standards That Actually Matter on an RFQ

The valve standards landscape looks intimidating at first, but most RFQs are governed by a small set of documents. Knowing which one applies keeps the data sheet tight and avoids paying for certifications the project does not require.

A practical rule of thumb: for an oil and gas pipeline, write the RFQ against API 6D + ASME B16.34 + API 598 + (if sour) NACE MR0175. For a refinery or petrochemical plant, switch the gate and globe references to API 600, keep API 598 for testing, and add ASME B16.10 for face-to-face. For a power plant boiler feedwater line, ASME B16.34 + ASME B16.10 + ISO 10434 is a clean combination. Adding more standards to a data sheet is not safer — it just inflates cost and lead time.

3. Material Selection: Match the Body, Trim, and Bolting to the Fluid

Material selection is where most project cost is won or lost. The body determines pressure containment; the trim (seat, disc, stem, sealing surfaces) determines sealing life; the bolting determines flange integrity. Get any one of these wrong and the valve fails early, even if the other two are perfect.

• Carbon steel (WCB, LCB): the default for general hydrocarbon, water, steam, and air service. Cheapest, easiest to weld and repair. Not suitable for corrosive or low-temperature (-46 °C) service.
• Stainless steel (CF8M, 316): the right call for corrosive chemicals, seawater, food/pharma, and high-temperature service. Specified frequently on stainless steel tube lines in copper & nickel alloy or stainless systems.
• Duplex / super duplex (UNS S31803, S32750): the standard for offshore, subsea, and sour service where chloride stress corrosion cracking is a risk.
• Alloy 20 (Carpenter 20): for sulfuric acid and other aggressive acidic media. Limited availability — confirm stock before locking the BOM.
• Monel, Inconel, nickel alloys: for hydrofluoric acid, hot alkaline solutions, and seawater; common in petrochemical facilities and marine piping.
• Titanium: for chlorides, wet chlorine, and certain seawater duties where neither stainless nor cupronickel survives.

4. What a Good RFQ Package Looks Like

A clean valve RFQ saves at least two rounds of clarification. The minimum data set the supplier needs:

• Valve type and function (gate, ball, globe, check, butterfly, plug, relief — and the intended duty: isolation, regulation, backflow prevention, safety)
• Size (NPS / DN), pressure class (ASME Class 150 / 300 / 600 / 900 / 1500 / 2500), and end connection (RF flange, RTJ, BW, SW, threaded, wafer, lug)
• Design standards (API 6D, API 600, ASME B16.34, ISO 14313, EN 593, etc.) and material standards (ASTM A216, A351, A182, etc.)
• Body, trim, and bolting material with any NACE / sour service requirement
• Service fluid, operating pressure and temperature, design pressure and temperature, and any required corrosion allowance
• Testing requirements (API 598 is the baseline; cryogenic, fire-safe, or fugitive emission tests are extra)
• Documentation required with shipment: MTC EN 10204 3.1, MTR, NACE certificate, hydrostatic test report, dimensional report, fire test / fugitive emission test report (where applicable)

When the RFQ is structured this way, the supplier can return a technically compliant quote in one pass, and the buyer's engineering team can compare offers apples-to-apples.

5. Why a Mill-Direct Integrated Supplier Reduces Project Risk

Most valve RFQs are issued by companies that are also buying pipe, fittings, flanges, gaskets, and stud bolts for the same line. Sourcing each commodity from a separate vendor creates three predictable problems: mismatched delivery schedules, fragmented MTC traceability, and a multiplied inspection burden.

EZ Steel Industrial has been operating as a mill-direct manufacturer and integrated project supplier since 1994. Today the company's three-facility network covers alloy and carbon steel pipe production in Yangzhou, alloy steel pipe inventory and custom pipe fittings in Cangzhou, and stainless steel plus copper-nickel corrosion-resistant materials in Lishui. The same quality system that governs the pressure tubes on the data sheet governs the industrial valves — ISO 9001, API 5L / API 5CT product certifications, PED compliance, and more than twelve documented quality checkpoints from raw material receiving to final pressure test.

For an EPC piping package, the practical benefit is a single point of accountability: one MTC trail covering the line pipe, the butt-weld fittings, the flanges, the gaskets, the stud bolts, and the valves. The buyer's QA team inspects one production schedule, not five.

6. Common Procurement Mistakes to Avoid

a. Treating a valve like a commodity

A 2-inch ASME Class 150 gate valve from a low-cost source can be identical on the outside to one from a qualified mill, and still differ in body wall thickness, stem alloy, seat hardness, and test depth. Buy on documented standards and traceability, not on visual appearance.

b. Skipping the seat test specification

API 598 seat leakage rates are tiered — soft-seated valves are typically zero-bubble, metal-seated valves have a defined allowable leak rate per minute. Without a written seat test acceptance, the supplier can default to the looser interpretation. State the seat test class on the data sheet.

c. Forgetting fugitive emission limits

For hydrocarbon, refinery, and chemical service, ISO 15848 Class AH or BH, API 624, or TA-Luft fugitive emission testing is increasingly mandated. Stem packing design and bellows seal upgrades both add cost, but only the bellows seal eliminates the leak path entirely. Decide before the RFQ.

d. Mixing sourcing channels for the same line

Buying pipe from one supplier and valves from another on the same project is the single most common reason for delivery slippage. The integrated package model — pipe, fittings, flanges, gaskets, stud bolts, and valves from one supplier with one schedule — is the most reliable way to keep an EPC line on its critical path.

7. Closing — How to Start an Inquiry

For a typical oil and gas or petrochemical project, the fastest path to a clean valve quote is to send a single RFQ file containing the data sheets for all seven valve types referenced in this guide, plus the line pipe, fittings, flanges, gaskets, and stud bolt specifications. EZ Steel Industrial can return a complete technical and commercial package from a single point of contact, with mill-direct traceability for every component.

To request a quotation, an MTC sample, or a factory audit, contact the export team at export@ezsteelpipe.com or call +86 731 8870 6116. The office is at No. 199 Xiangfu Road, Yuhua Industrial Zone, Changsha, China.