Product Range
Select a series for detailed specifications, downloads and technical data.
油润滑旋塞阀
尺寸：2" - 24" (DN50 - DN600)
软密封旋塞阀
尺寸：1/2" – 12" (DN15 – DN300)
压力平衡式旋塞阀
尺寸：2"–24" (DN50–DN600)
提升式旋塞阀
1/2" – 4" (DN15 – DN100)
膨胀式旋塞阀
尺寸：2" – 24" (DN50 – DN600)
Expanding Plug Valve-Full Bore
Quick Specs 2" – 36" (DN50 – DN900) Class 150 – 600 / PN 10-100 API 6D, API 599, ASME B16.34, API 607 (fire-safe available) A216 WCB, A217 WC6/WC9, A351 CF8M, A351 CF8 Metal-to-metal, expanding plug mechanism — central core + expandable sealing elements for DBB sealing against full-diameter seat faces. Full-bore (full-port) flow passage. Body bore at the seat area matches nominal pipe diameter. Piggable when open. Zero pressure drop in open state. Everything the Venturi Gives You, Plus an Open Bore The full-bore expanding plug valve delivers the same DBB function as the venturi version — two independent sealing boundaries in a single valve body, expandable slips that seal simultaneously against upstream and downstream seat faces, a built-in bleed port between the seats. Same isolation capability. Same single-valve DBB package. What's different is the bore. Full bore means the body passage at the seat area matches the pipeline diameter. No constriction. No reduced cross-section. When the valve is open, the flow passage is the same diameter as the pipe on both sides. Two things change when you open up the bore. First: pigging. Pipeline pigs, cleaning tools, scraping tools, inspection pigs — they all need a full-diameter bore to pass through. A venturi constriction blocks the pig. Full-bore passage lets it go. If your pipeline specification requires piggable valves at isolation points, the full-bore expanding plug is the only plug valve design that gives you DBB isolation and piggable flow in one body. Second: pressure drop. In continuous-flow applications where the valve stays open most of the time, the venturi constriction adds a permanent pressure loss. Every hour, every day, that loss is there. Full-bore passage eliminates it. Open bore matches the pipe diameter, flow goes through unobstructed, and your pump or compressor doesn't have to compensate for a restriction that shouldn't be there. The Mechanical Cost of a Full-Diameter Seat Full-diameter seat faces are larger. The expanding slips have to seal against a seat circumference that matches the full pipe diameter — not a reduced venturi diameter. More circumference means more expansion travel, larger sealing elements, and a heavier mechanism. At 12 inches and below, the difference is modest. The full-bore mechanism is still compact enough to be straightforward. At 24 inches and 36 inches, the expanding elements are pushing outward against a seat circumference two or three feet across. The mechanism gets bigger, more complex, and more expensive to manufacture. That's the tradeoff. Full bore gives you piggable flow and zero pressure drop. It costs more — especially at large sizes — because the expanding mechanism has to work against a larger seat. When your specification demands pigging or zero open-state pressure drop, the cost is justified. When it doesn't, the venturi version gives you the same DBB function for less money and with a simpler mechanism. Where Full Bore Wins Transmission pipeline isolation at stations where pigs run through. That's the primary application. Pipeline operators run pigs regularly for cleaning, inspection, and integrity verification. Every isolation valve on a piggable section has to let the pig pass. A venturi valve blocks the pig — the crew has to remove the valve or install a bypass every time they run one. Full-bore expanding plug valves eliminate that problem. Continuous-flow isolation points — meter stations, compressor station block valves that sit open for months and only close for maintenance — also benefit from full bore. The open-state pressure drop through a venturi valve accumulates over time. In continuous service, eliminating that drop saves pumping energy and reduces operating cost. Fire-safe configurations are available. API 607 testing confirms both sealing boundaries hold after fire exposure, and the full-bore passage doesn't compromise fire-test performance. FAQ A: Standard cleaning pigs and inspection pigs pass through the full-bore open passage. Verify pig dimensions with the valve manufacturer — some expanding plug designs have minor internal features that may affect specific pig types. In general, full-bore expanding plug valves are piggable for standard pipeline pigging programs. A: Larger seat circumference requires larger expanding sealing elements and more expansion travel. The mechanism components — slips, wedges, core, seat faces — all scale with the bore diameter. At 24"–36", the mechanical package is substantially larger than the equivalent venturi design. A: Yes. The expanding mechanism creates two independent sealing boundaries against the full-diameter upstream and downstream seat faces. DBB function is the same — the only difference is the seat diameter the slips seal against. A: That's exactly where full bore delivers its pressure-drop advantage. The venturi version adds permanent flow restriction during those long open periods. Full bore eliminates that restriction. For isolation valves that rarely close but need DBB when they do, full bore is the better choice. A: 2" through 36" (DN50 through DN900). The most common sizes in pipeline service are 6" through 24". 30" and 36" are available for large-diameter transmission pipeline isolation but carry significant cost premiums due to the size of the expanding mechanism at those diameters.
Technical Overview
Plug valves rotate a cylindrical or tapered plug 90° inside the body bore to open or close the flow passage. The plug itself is the sealing element—its outer surface contacts the body seat surface directly, or through an intermediate seat insert, to achieve shutoff. That direct plug-to-seat interface is the fundamental characteristic that distinguishes plug valves from ball valves (where a separate seat ring contacts the ball) and gate valves (where a flat gate slides between two seat rings). FLOWKS manufactures six plug valve configurations spanning three seating philosophies and three mechanical motion types. Lubricated plug valves inject sealant through external fittings into internal distribution grooves on the tapered plug surface—the lubricant film creates both the primary sealing boundary and the rotational lubrication layer that prevents metal galling. Soft seated plug valves use PTFE, reinforced PTFE, Viton, EPDM, or NBR inserts bonded to the body bore or plug surface—soft seat compression fills surface irregularities for bubble-tight zero leakage, no external lubricant needed. Pressure balanced plug valves route line pressure to both sides of the plug through internal bypass passages—hydraulic forces cancel out, operating torque stays manageable at Class 600-900 and 12"-24" sizes where unbalanced torque would exceed manual or actuator capability. Lift type plug valves raise the plug off the seat before rotating—zero sliding contact during rotation eliminates seat wear, limited to 1/2"-4" sizes where the lift distance is short. Expanding plug valves (Venturi) use expandable sealing elements (slips/wedges) that move outward against reduced-diameter body seat faces—double-block-and-bleed sealing in a single valve body, with some open-state pressure drop through the venturi constriction. Expanding plug valves (Full Bore) apply the same expanding mechanism against full-diameter seat faces—DBB sealing plus piggable unrestricted flow passage, at higher mechanical complexity and cost than the venturi design.
FLOWKS plug valves provide quarter-turn shutoff through direct plug-to-body sealing contact across the widest range of pressure and seating requirements. Oil lubricated plug valves create a hydrostatic seal through injected lubricant film between tapered plug and body bore—specified for crude oil, natural gas, and refinery service where line media degrades elastomer seats. Soft seated plug valves achieve bubble-tight zero leakage through PTFE, reinforced PTFE, Viton, or EPDM seat inserts—no external lubricant, lower torque, ideal for chemical, water, and process isolation up to Class 300. Pressure balanced plug valves cancel hydraulic force on the plug face through internal bypass passages—manageable operating torque at Class 600-900 on 12" through 24" pipeline isolation where unbalanced torque exceeds actuator capability. Lift type plug valves raise the plug off the seat before rotation—zero sliding friction, zero seat wear, limited to 1/2"-4" sizes for instrument and sampling isolation. Expanding plug valves (Venturi) deliver double-block-and-bleed sealing in a single valve body through outward-expanding sealing elements against reduced-diameter seat faces—compact seat geometry, some open-state pressure drop. Expanding plug valves (Full Bore) provide DBB sealing plus piggable unrestricted flow passage through full-diameter expanding slips—zero open-state pressure drop, pigging-compatible, at higher mechanical complexity.
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Ball Valves
FLOWKS offers floating ball valve, trunnion mounted ball valve and top entry ball valve for oil & gas, petrochemical and power generation. Designed per API 6D, API 608 and ASME B16.34.
DBB Valves
FLOWKS Double Block & Bleed (DBB) valves provide dual isolation with bleed verification in a single compact body. Replacing traditional multi-valve installations, FLOWKS DBB valves reduce weight, space and potential leak paths. Available in bolted bonnet, all-welded and expanding gate designs per API 6D and API 607.
Gate Valves
FLOWKS gate valves for isolation service in piping systems. Flexible wedge, solid wedge, slab and expanding gate designs per API 600, API 602 and ASME B16.34.
Globe Valves
FLOWKS globe valves for throttling and isolation. Standard, angle, Y-pattern and bellows seal configurations per API 602 and BS 1868.