Industrial Valves

The key difference is in how the ball is supported and how the sealing load is created:

• Floating Ball Valve: The ball is not mechanically fixed — it "floats" on its trunnion pins and is pushed laterally by line pressure against the downstream seat ring to create the seal. The sealing load is directly proportional to line pressure. Simple design, lower cost. Limited to smaller sizes (typically up to 6″ NPS) and lower pressure classes (up to Class 600) because at higher pressures, the force on the downstream seat becomes too high, causing excessive operating torque and seat damage.
• Trunnion Mounted Ball Valve: The ball is mechanically fixed to trunnion supports at top and bottom. The seat rings are spring-loaded to press against the ball from both sides — creating a bi-directional seal independent of line pressure. This means operating torque remains low even at high pressures and large bore sizes. Trunnion valves are heavier and more expensive but are required for Class 900+, large bore (8″+ NPS), and anywhere that low operating torque is critical (e.g. actuated valves, emergency shutdown valves).

A "fire safe" valve is designed to maintain a minimum level of sealing integrity if the soft (polymer or elastomeric) seat and stem seals are destroyed by an external fire. The valve achieves this through metallic backup seats that take over sealing duty if the soft seats are burned away. The valve is tested per API 607 (quarter-turn — ball and butterfly) or API 6FA / ISO 10497 (all valve types including gate and globe) by exposing the valve to a controlled external fire at 750°C–1000°C for 30 minutes while under pressure, then measuring body leakage and seat leakage after the fire.

When is fire-safe required? For all valves handling flammable hydrocarbons on offshore platforms and FPSOs, onshore oil and gas facilities, refineries and petrochemical plants, and any area classified as a hazardous zone. Many national and international standards (NORSOK, Shell DEP, ADNOC specifications) mandate fire-safe valves for all hydrocarbon service. If you are unsure whether your project requires fire-safe valves, specify them — it is better to over-specify than to use a non-fire-safe valve in a fire-risk environment.

API 600 covers bolted bonnet steel gate valves for petroleum and chemical plant service — specifically process plant gate valves (inside the plant boundary) in Class 150 to 2500. API 600 valves have a wedge gate (solid, flexible, or split) with an OS&Y (rising stem) design. The stem rises visually through the yoke as the valve opens — providing a clear visual position indicator.

API 6D covers valves for pipeline service (transmission and gathering pipelines). API 6D gate valves are typically through-conduit (slab gate) or expanding gate types — designed so that when fully open, the bore is completely clear with no metal protruding into the flow path (important for pigging service). API 6D valves are typically higher quality with more stringent testing requirements than API 600 — including anti-static device, fire-safe design, and seat-leakage testing to tighter limits.

In summary: if your gate valve is in a pipeline that may be pigged, or in mainline transmission service, specify API 6D. If your gate valve is in a process plant, specify API 600.

Fugitive emissions are unintentional leaks of process gas or volatile liquid from valve stem packing, flange connections, or other valve sealing points — directly to the atmosphere. In oil and gas service, these emissions are primarily VOCs (volatile organic compounds) and methane, which contribute to air quality issues and greenhouse gas emissions. Fugitive emission testing measures the amount of gas leaking from the valve stem packing under pressurised conditions.

Valves are tested to ISO 15848-1 (or API 641 for ball valves) to quantify stem leakage — with Class BH being the most common requirement (leakage less than 50 ppm by volume). Low-emission (LE) valves typically use graphite or PTFE injection-type packing with double packing sets.

Fugitive emission certified valves are now required by environmental regulations in many jurisdictions — including the EU IED (Industrial Emissions Directive), US EPA regulations, LDAR (Leak Detection and Repair) programmes, ADNOC and Saudi Aramco environmental standards, and NORSOK M-630. If your project requires compliance with environmental regulations or operator standards referencing fugitive emissions, specify ISO 15848-1 Class BH or API 641 in your valve RFQ.

Seawater is one of the most corrosive environments for valve materials — containing chloride ions, biological agents, and oxygen that rapidly attack carbon steel and even standard austenitic stainless steel (TP316L). The correct valve material selection for seawater service depends on the specific application:

• Super Duplex Stainless Steel (S32750 / CF3M cast equivalent): The preferred body material for seawater lift valves, seawater injection, and FPSO seawater systems. PREN >40 provides excellent pitting resistance in high-chloride environments.
• Duplex SS (S31803): Suitable for less aggressive seawater applications and where cost is a factor — lower PREN than super duplex but still much better than 316L.
• Gunmetal / Bronze: Traditional seawater valve material for marine applications — copper-based alloy with good seawater corrosion resistance. Used for sea chest valves and overboard valves on vessels.
• Titanium: Ultimate seawater resistance for the most aggressive environments — high cost but zero corrosion. Used in some desalination plant and defence applications.
• Carbon Steel with Cathodic Protection: CS body with sacrificial anode CP system and fusion-bonded epoxy (FBE) internal coating — used for large bore seawater pipeline isolation valves where duplex is not economical.

Please specify the seawater temperature, flow velocity, and whether the fluid is de-oxygenated (injection water) or oxygenated (lift water) in your RFQ — these factors affect the corrosion rate and optimal material selection.

API 598 is the standard testing specification for all valve types — it defines the required hydrostatic and leakage tests for gate, globe, check, ball, plug, and butterfly valves. Every valve supplied by Naftaar is factory-tested in accordance with API 598 as standard. API 598 requires three tests:

• Shell (Body) Hydrostatic Test: The valve body and bonnet are hydrostatically tested at 1.5× the rated working pressure (at room temperature) with water. No visible leakage through body, bonnet, or any pressure-containing part is permitted. Test duration is typically 2 minutes for NPS ≤2″ and longer for larger valves.
• Seat Closure Test (Low Pressure): Each seat is tested at a low pressure (5–7 bar) — typically air or nitrogen — to check for any gross seat leakage. Maximum allowable leakage rates are defined per valve size and class in API 598 Table 3.
• Seat Closure Test (High Pressure — Water): Each seat is tested at 110% of the rated working pressure with water. Maximum allowable leakage rates per API 598 Table 3 apply. For metal-seated valves, higher leakage is permitted than for soft-seated valves (which should be effectively bubble-tight).

All test certificates are included in Naftaar's standard documentation package for every valve supplied.

Yes. Naftaar can supply complete actuated valve packages — the valve body with a matched actuator and all associated accessories. We supply:

• Pneumatic Actuators: Scotch-yoke or rack-and-pinion types for quarter-turn valves (ball and butterfly); spring-return (fail-open or fail-closed) or double-acting configurations. Air supply typically 4–7 bar. Includes solenoid valve, limit switches, manual handwheel override, and junction box.
• Electric Actuators: Part-turn (quarter-turn) electric actuators for ball and butterfly valves; multi-turn actuators for gate and globe valves. Single-phase or three-phase power. Modulating or on/off control. ATEX/IECEx rated for hazardous areas available.
• Hydraulic Actuators: For large bore, high-torque applications — subsea, remote pipeline ESD stations, and large trunnion ball valves where pneumatic torque is insufficient. Linear or rotary hydraulic actuators.
• Emergency Shutdown (ESD) Packages: Complete ESD valve packages with solenoid valve, hydraulic accumulator, pressure switch, and reset mechanism — for fail-closed pipeline isolation and process plant safety systems.

Please specify the valve type, size, class, fail position (fail-open, fail-closed, fail-in-place), power supply, area classification (safe area or ATEX Zone 1/2), and control signal (on/off or modulating) in your RFQ for actuated packages.