Model: D343H Series | Pressure: PN2.5 / PN4 / PN6 / PN10 / PN16 / PN25 / PN40 | Connection: Flanged | Medium: Steam, Oil, Gas, Water, Acid

Gaoshan Valve — D343H Bidirectional Triple Eccentric Hard-Seal Butterfly Valve (Flanged)

Gaoshan D343H triple-offset hard-seal butterfly valve is designed for high-temperature and high-pressure service where soft-seat valves cannot perform. The triple-offset geometry ensures the disc lifts completely clear of the seat throughout the stroke, eliminating rubbing contact and reducing operating torque. The laminated metal disc seal withstands continuous service up to 425°C. Flanged end connections conform to GB/T 9113, with worm gear standard and pneumatic or electric actuator options.

Nominal Pressure

PN2.5 – PN40

Size Range

DN50 – DN2000

Design Type

Triple Eccentric

Max Temperature

Up to 425 °C

End Connection

Flanged (GB/T 9113)

Operation

Worm Gear / Pneumatic / Electric

Product Overview

Gaoshan D343H series triple-offset hard-seal butterfly valve is engineered for high-temperature and high-pressure applications where elastomer-seated valves reach their limits. The triple-offset design ensures the disc surface lifts completely clear of the seat throughout the entire stroke, eliminating rubbing contact and reducing operating torque. The laminated stainless-steel and flexible graphite disc seal handles continuous service up to 425°C. Flanged end connections are standard, with worm gear handwheel as standard and pneumatic or electric actuator options available.

Model Designation Guide

Model Code	Pressure	Size Range	End Connection	Drive
D343H-10C / 16C	PN10 / PN16	DN50 – DN2000	Flanged (GB/T 9113)	Worm gear handwheel
D343H-25C / 40C	PN25 / PN40	DN50 – DN1600	Flanged (GB/T 9113)	Worm gear handwheel
D643H (Pneumatic)	PN10 – PN40	DN50 – DN600	Flanged	Pneumatic actuator
D943H (Electric)	PN10 – PN40	DN50 – DN1600	Flanged	Electric actuator 380V/220V

Triple Eccentric (Triple Offset) Principle

Gaoshan D343H uses three independent offsets to achieve zero-friction, pressure-assisted sealing across the full pressure range:

Triple Eccentric Principle Diagram

Offset 1 — Shaft Behind Disc Centreline

The valve stem is positioned behind the disc sealing face, so that when the disc closes it contacts the seat ring with uniform circumferential pressure. This geometry ensures tight shut-off around the full seat circumference.

Offset 2 — Shaft Off Pipeline Centreline

The stem centerline is offset from the pipeline centerline. This eliminates interference between the disc and body during opening, preventing the rubbing wear that conventional butterfly valves suffer in the 10°–80° open range.

Offset 3 — Conical Seat Axis

The seat cone axis is set at an angle to the pipeline centerline. This makes the disc sealing surface a true cone: as it rotates into the seat, contact pressure is applied evenly around the full circumference, avoiding localised stress and seat damage.

The result is simple: the disc never touches the seat during most of the stroke. Contact happens only in the final few degrees before full closure. This reduces operating torque and eliminates wear on the seat ring. The valve achieves bidirectional tight shut-off that meets Gaoshan’s zero-leakage standard throughout its service life.

Triple Eccentric Principle Diagram

Triple Eccentric Principle Diagram — replace YOUR-IMAGE-URL with actual image

Laminated Flexible Metal Seat Disc

The D343H disc sealing face uses a laminated metal construction developed by Gaoshan, which gives better high-temperature performance than solid metal or elastomer seats:

High-Temperature Capability — up to 538 °C

The laminated disc assembly is built with thin stainless steel rings separated by flexible graphite gaskets. Because the graphite is not adhesively bonded to the steel rings, the disc can handle much higher temperatures than any bonded rubber seat design.

Low Stem Seal Leakage — 10–20 ppm

Gaoshan D343H stem packing is finished to 8 RMS on the shaft and 32 RMS on the gland bore, achieving shaft-seal leakage of 10–20 ppm. The packing can be replaced on-site without removing the valve from the pipeline.

Anti-Blowout Shaft Protection

Gaoshan D343H is designed with dual anti-blowout protection.The bottom stem is retained by an internal collar; the top stem uses a shoulder that bears against the body bore. Both features prevent stem ejection if packing fails or pressure surges occur.

D343H Structural Diagram

D343H Structural Diagram — replace YOUR-IMAGE-URL with actual image

Materials of Construction

Component	Standard	Optional
Body (阀体)	Cast Iron / Cast Steel (WCB)	Stainless Steel (CF8, CF8M)
Disc (蝶板)	Cast Steel	Stainless Steel; Duplex SS
Shaft (阀杆)	Cast Steel	Stainless Steel (316)
Seat Ring (阀座)	Carbon Steel	Stainless Steel; PTFE-lined; Rubber-lined
Laminated Disc Seal	Stainless steel + Flexible Graphite laminate	All-SS laminate (high-temp); PTFE laminate (chemical)
Stem Packing	Flexible Graphite	PTFE; PTFE + Graphite composite

Applicable Media

Steam (High Pressure)
High-Temperature Oil
Water / Seawater
Natural Gas
Air / Compressed Air
Acid / Alkali Solutions
Salt / Brine Solutions
Pharmaceutical Process
Food & Beverage
Wastewater / Slurry
Weak Corrosive Media

Design & Inspection Standards

Design / Manufacturing	Flange Connection	Face-to-Face Length	Pressure Test & Inspection
JB/T 8527	GB/T 9113	GB/T 12221	GB/T 13927

Connection Dimensions — D343H-10/16C (Flanged PN10/PN16, DN50–DN2000)

Unit: mm | D=flange OD, D1=bolt PCD, D2=bore, f=flange face width, b=flange thickness, Z-Φd=bolt quantity × diameter, H0=face-to-face, H=height, A=width, B=depth, G=gear handwheel diameter

1.0 MPa (PN10)

DN	L	D	D1	D2	f	b	Z-Φd	H0	H	A	B	G
50	100	165	125	102	3	18	4-Φ18	82.5	195	50	144	180
65	112	185	145	122	3	18	4-Φ18	92.5	215	50	144	180
80	120	200	160	138	3	20	8-Φ18	125	240	62	200	300
100	127	220	180	158	3	20	8-Φ18	110	235	50	144	220
125	140	250	210	188	3	22	8-Φ18	125	290	60	200	300
150	140	285	240	212	3	22	8-Φ22	100	310	63	200	300
200	152	340	295	268	3	22	8-Φ22	202	360	63	200	300
250	165	395	350	320	3	26	12-Φ22	235	395	80	230	350
300	178	445	400	378	4	26	12-Φ22	265	425	80	230	350
350	190	505	460	438	4	26	16-Φ22	305	475	115	260	400
400	216	565	515	490	4	26	16-Φ26	305	475	115	260	400
450	222	615	565	532	4	28	20-Φ26	365	550	125	260	400
500	229	670	620	585	4	28	20-Φ26	365	550	125	260	400
600	267	780	725	685	5	30	20-Φ30	445	655	160	398	500
700	292	895	840	800	5	32	24-Φ30	495	710	200	418	600
800	318	1015	950	905	5	36	24-Φ33	655	885	200	418	600
1000	410	1160	1110	1005	5	38	28-Φ36	715	950	263	510	700
1200	470	1340	1280	1160	5	40	32-Φ39	840	1125	263	510	700
1400	530	1675	1535	1480	5	48	36-Φ42	980	1275	333	550	800
1600	600	1930	1685	1630	5	54	40-Φ48	1125	1470	374	590	900
1800	670	2115	2020	1960	5	56	44-Φ48	1240	1585	374	590	900
2000	760	2230	2170	2150	5	70	48-Φ48	1380	1720	453	635	1000

1.6 MPa (PN16)

DN	L	D	D1	D2	f	b	Z-Φd	H0	H	A	B	G
50	100	165	125	102	3	18	4-Φ18	82.5	195	50	144	180
65	112	185	145	122	3	18	4-Φ18	92.5	215	50	144	180
80	120	200	160	138	3	20	8-Φ18	125	240	62	200	300
100	127	220	180	158	3	20	8-Φ18	110	235	50	144	220
125	140	250	210	188	3	22	8-Φ18	125	290	60	200	300
150	140	285	240	212	3	22	8-Φ22	100	310	63	200	300
200	152	340	295	268	3	22	8-Φ22	202	360	63	200	300
250	165	395	350	320	3	26	12-Φ26	202	360	80	230	350
300	178	445	400	378	4	26	12-Φ26	202	360	80	230	350
350	190	505	460	438	4	28	16-Φ26	305	475	115	260	400
400	216	565	515	490	4	28	16-Φ30	305	475	115	260	400
450	222	615	565	532	4	28	20-Φ30	365	550	125	260	400
500	229	670	620	585	4	30	20-Φ30	365	550	125	260	400
600	267	780	725	685	5	32	20-Φ33	445	655	160	398	500
700	292	895	840	800	5	34	24-Φ33	495	710	200	418	600
800	318	1015	950	905	5	38	24-Φ36	655	885	200	418	600
1000	410	1160	1110	1005	5	40	28-Φ39	715	950	263	510	700
1200	470	1340	1280	1160	5	44	32-Φ42	840	1125	263	510	700
1400	530	1675	1535	1480	5	48	36-Φ48	980	1275	333	550	800
1600	600	1930	1685	1630	5	56	40-Φ48	1125	1470	374	590	900
1800	670	2115	2020	1960	5	62	44-Φ56	1240	1585	374	590	900
2000	760	2345	2230	2150	5	70	48-Φ62	1380	1720	453	635	1000

Connection Dimensions — D343H-25/40C (Flanged PN25/PN40, DN50–DN1600)

Unit: mm | Z-W = bolt size designation (ASME-style for high-pressure flanges)

2.5 MPa (PN25)

DN	L	D	D1	D2	f	b	Z-W	H0	H	A	B	G
50	108	165	125	102	3	20	4-Φ18	82.5	195	50	144	180
65	112	185	145	122	3	22	8-Φ18	92.5	215	50	144	180
80	120	200	160	138	3	24	8-Φ18	125	240	62	200	300
100	127	235	190	162	3	24	8-Φ22	110	235	50	144	220
125	140	270	220	188	3	26	8-Φ26	125	290	60	200	300
150	140	300	250	218	3	28	8-Φ26	100	310	63	200	300
200	152	360	310	278	3	30	12-Φ26	202	360	63	200	300
250	165	425	370	330	3	32	12-Φ30	235	395	80	230	350
300	178	485	430	395	4	34	12-Φ30	265	425	80	230	350
350	190	550	490	450	4	38	16-Φ33	305	475	115	260	400
400	216	620	560	505	4	40	12-Φ36	305	475	115	260	400
500	229	730	670	600	4	48	16-Φ36	365	550	125	260	400
600	267	845	770	685	5	57	16-Φ39	445	655	160	398	500
700	292	960	875	820	5	64	20-Φ42	495	710	200	418	600
800	318	1085	990	905	5	70	20-Φ48	655	885	200	418	600
900	368	1185	1090	1020	5	72	20-Φ48	715	950	263	510	700
1000	406	1320	1210	1140	5	76	24-Φ56	840	1125	263	510	700
1200	470	1530	1420	1355	5	84	32-Φ56	980	1275	333	550	800
1400	530	1755	1640	1565	5	93	36-Φ62	1125	1470	374	590	900
1600	600	1975	1795	1686	5	100	40-Φ62	1380	1720	453	635	1000

Key Features & Advantages

Zero-Friction Open / Close

The third eccentricity makes the disc lift completely clear of the seat during the whole stroke. No rubbing occurs at any opening angle, which greatly extends service life in frequent-cycle duty.

Pressure-Assisted Seal

Line pressure pushing on the disc cone increases seat contact force. The higher the pressure difference, the tighter the seal. Gaoshan D343H achieves zero-leakage performance in both flow directions.

High-Temperature Metal Seat

Gaoshan D343H uses a laminated stainless-steel and flexible graphite disc seal rated for continuous service up to 425°C, suitable for superheated steam and thermal oil applications.

Flanged End Connection

D343H uses flanged ends conforming to GB/T 9113. Flange drilling matches PN2.5 through PN40 bolt patterns. Companion flanges and fasteners are available as accessories.

Uniform Seat Compression

The inclined cone seat geometry applies even contact pressure around the full seat ring, avoiding localised stress that causes soft-seat valves to leak at the disc edges.

Wide Actuator Compatibility

Gaoshan D343H has an ISO 5211 top flange for direct mounting of worm gear, pneumatic, or electric actuators without extra brackets.

Request a Quote or Technical Consultation

Gaoshan D343H flanged triple eccentric hard-seal butterfly valve is available in PN2.5 to PN40, DN50 to DN2000. Custom body materials, seat options, and actuator configurations are available. Contact our engineering team for sizing, torque calculation, and certification support.

Get a Quote

D343H Triple Eccentric Hard-Seal Butterfly Valve (Flanged)