Every industrial valve on a pipeline is a decision about pressure, temperature, fluid, frequency of operation and the standard that the inspector will hold you to. A ball valve that works perfectly in a water service line can become a leak source the moment it lands in a sour gas manifold. The goal of this guide is to give procurement engineers, project buyers and EPC specifiers a single decision path from datasheet to quote — grounded in the standards and material logic that EZ STEEL INDUSTRIAL has been applying to oil, gas, power and marine projects since 1994.

Step 1: Lock the Service Envelope Before You Pick a Type

Valve selection always starts with the service envelope, not the catalog page. Before shortlisting gate, ball, globe, check, butterfly or plug, capture the following four parameters in writing:

• Fluid and phase — crude oil, natural gas, steam, seawater, condensate, LNG, sour service (H₂S), or chemical media.
• Design pressure and temperature — both the normal operating point and the design maximum / minimum.
• Function — isolation, throttling, check / backflow prevention, safety relief, or diverting.
• Duty cycle — how often the valve will be operated in a year, and whether it will be used in a partially open (throttling) position.

These four parameters determine the valve type, the pressure class, the body / trim material, and which international standard you must call out on the purchase order. Skipping this step is the most common reason RFQs bounce back and forth between buyer and supplier.

Step 2: Match Valve Type to Function

Once the envelope is fixed, the next decision is the type itself. Each type has a natural fit — and a natural penalty if you misapply it:

Gate Valves for High-Pressure Isolation

Gate valves are the workhorse of crude oil and natural gas transmission. They offer a very low pressure ｄｒｏｐ when fully open and a bi-directional seal, but they are not designed for throttling. For ASME Class 600+ pipelines, a gate valve is usually the most economical and standard-compliant isolation choice.

Ball Valves for Quick Shut-Off and Pigging

Ball valves deliver quarter-turn shut-off, tight sealing and low maintenance. For high-pressure pipelines, the trunnion-mounted design (per API 6D) is the default. Floating ball valves are typically reserved for low and medium pressure services. In LNG and sour gas lines, ball valves can also be specified in corrosion-resistant alloys.

Globe Valves for Throttling and Metering

When the function is flow regulation, not just on/off, a globe valve is the correct tool. The disc moves perpendicular to flow, giving precise control at the cost of a higher pressure ｄｒｏｐ. Globe valves are widely used at pressure control and metering stations, and in fuel gas and cooling water systems.

Check Valves for Backflow Protection

Check valves (non-return valves) protect pumps, compressors and subsea pipelines from reverse flow. Swing, lift and dual-plate designs each answer a different problem. Dual-plate check valves built to API 6D are a compact, fast-closing option for high-pressure service — but the closing characteristic must be reviewed to control water hammer risk.

Butterfly and Plug Valves for Compact Service

Wafer and lug butterfly valves are a low-cost, compact choice for low-pressure gas, water and fire protection lines. Plug valves — cylindrical or conical — handle slurry, corrosive fluids and wellhead multi-port duty. Neither should be pushed into the high-pressure, high-temperature envelope where ball and gate valves belong.

Pressure Relief and Safety Valves for Overpressure Protection

Every pressure vessel, storage tank and compressor station needs a pressure relief or safety valve sized to the worst credible overpressure scenario. Spring-loaded and pilot-operated designs both belong on the datasheet; the choice depends on set pressure, capacity and the required blow-down characteristic.

Step 3: Call Out the Right Standard on the PO

For oil and gas buyers, the standard you write into the purchase order is the standard the inspector will verify against. The most frequently referenced documents are:

• API 6D — pipeline valves (gate, ball, check) for transmission service.
• API 600 — bolted bonnet steel gate valves, the long-standing refinery specifier reference.
• API 6A — wellhead and Christmas tree valves for upstream service.
• API 598 — valve inspection and testing, including shell, seat and backseat tests.
• ASME B16.34 — pressure / temperature ratings for steel valves; pairs with ASME B16.10 face-to-face dimensions.
• ISO 14313 — the international equivalent of API 6D for pipeline valves.
• ISO 5208 — industrial valve leakage classification for seat testing.
• NACE MR0175 / MR0103 — mandatory call-out for sour (H₂S) service.
• EN 593 and EN 12516 — European norms for butterfly valves and pressure shell design.

A datasheet that names the standard, the pressure class, the material and the test plan up front removes most of the back-and-forth that delays an RFQ. EZ STEEL INDUSTRIAL supports the full set above and can review specifications line by line before quotation.

Step 4: ｓｅｌｅｃｔ the Material to Match the Fluid

Material selection is where safety and lifecycle cost are decided. The wrong body or trim material turns a perfectly specified valve into a maintenance liability within months. The four families most specifiers work with are:

For marine and shipbuilding buyers, copper-nickel flanges and 90/10 or 70/30 Cu-Ni pipe are the default pairing for seawater systems because of their proven resistance to biofouling and chloride pitting. For nuclear and aerospace service, ASTM B163, B165, B407 and RCC-M II call-outs need to be visible on the datasheet from day one. Our copper-nickel flange and pipe range is documented on the copper nickel flanges and copper nickel alloy pages.

Step 5: Don't Forget the Flange, Bolt and Gasket Bundle

A valve is rarely delivered alone. Every flanged valve on a pipeline arrives with a flange face, a gasket, a stud bolt and a nut — and the joint only performs as well as the weakest component in that bundle. The most common project failure is not the valve itself; it is a mixed-origin bundle where one component was downgraded to save cost. Three things to verify before the PO is released:

• Flange standard match — ASME B16.5, ASME B16.47, EN 1092-1, GOST or JIS must match the mating pipe flange; mixing rating classes is the most common leak path.
• Bolt specification — stud bolt material and length must match the flange class, gasket type and operating temperature. B7 / 2H studs with A194 nuts are typical for ASME Class 150–600 service.
• Gasket type — spiral-wound and RTJ gaskets are the workhorse for oil and gas lines; non-asbestos sheet gaskets are for utility service. The full set is available on the gasket, stud bolt & nut page.

For carbon steel line pipe projects, the matching steel flanges and ASTM A106 / A53 pipe are kept in aligned inventory so that material certificates, heat numbers and dimensions follow one continuous documentation trail — rather than three different certificates from three different mills.

Step 6: Specify the Test Plan Before the Order

Standard hydrostatic shell and seat tests, defined in API 598 and ISO 5208, are the baseline. For critical service, additional tests should be written into the PO so they are scheduled in the shop — not negotiated after delivery:

• Shell test at 1.5× rated pressure to verify body and bonnet integrity.
• Seat test at the rate defined by the soft / metal seat classification, with double block-and-bleed verification for DBB valves.
• Backseat test to confirm stem sealing when the valve is fully open.
• Fire test (API 607 / API 6FA) for hydrocarbon service where soft seats may be exposed to flame.
• Cryogenic test (BS 6364 / ISO 28921) for LNG and ethylene service.
• Fugitive emissions test (ISO 15848, API 624) for VOC-sensitive service and environmental compliance.
• NDT — dye penetrant, magnetic particle, ultrasonic and radiographic tests as applicable to the casting / forging route.

A written test plan is also the basis for the mill test report, the NACE certificate (where applicable) and the third-party inspection arrangement. It is far cheaper to agree these documents in the RFQ stage than after the valves have been machined.

Step 7: Bundle the Valve with the Rest of the Pressure Boundary

Industrial valve projects rarely succeed or fail on the valve alone. They succeed or fail on whether the valve, the pipe, the fittings, the flanges and the bolting arrive from one documented supply chain. EZ STEEL INDUSTRIAL has been built around that idea since 1994. With 500+ employees, an annual capacity of more than 480,000 tons, and inventory aligned to ASTM A106, A53, A312, API 5L and the EN / GOST / JIS families, the company can ship a valve order with the matching pipe, butt weld fittings, pipe fittings and flanges from one documentation bundle.