What is API 609 Butterfly Valve - ZFA Valves Manufacturer

API 609 is the butterfly valve standard established by the American Petroleum Institute. The API 609 standard specifies the design, manufacturing, material and testing requirements for butterfly valves to ensure certain performance and reliability of butterfly valves in industrial applications.

In short, as long as the butterfly valve complies with the API609 standard, it is called API609 butterfly valve.

Table of Contents

what a butterfly valve is

Butterfly valves usually consist of a valve body, valve disc (butterfly plate), valve stem and seals. The valve plate is located inside the pipe and can rotate along the axis of the pipe to control the flow of fluid. When the valve plate touch the valve seat, it can effectively prevent the flow of fluid.

The Content of API609 Standard

1) API609 regulations on butterfly valve FTF dimensions.

API609 Standard covers the design and manufacturing of butterfly valves, including the connection type with the pipeline, structural form, structural length, etc.

Connection form: wafer butterfly valve, flange butterfly valve, lug butterfly valve, grooved butterfly valve, welded butterfly valve, etc.
Structural form: center line butterfly valve, eccentric butterfly valve (double eccentric butterfly valve, triple eccentric butterfly valve).
Structural length(FTF): divided into A series and B series. A series covers clamp and lug types, and B series covers clamp lug and flange types. The flange type is divided into long structure and short structure.

Face-to-face Dimensions, Category A Valves (Lug and Wafer type):

Face-to-face Dimensions, Category A Valves (Lug and Wafer type)
DN(INCH)	mm	in.
2	43	1.69
2 1/2	46	1.81
3	46	1.81
4	52	2.06
5	56	2.19
6	56	2.19
8	60	2.38
10	68	2.69
12	78	3.06
14	78	3.06
16	102	4.00
18	114	4.50
20	127	5.00
24	154	6.06
30	165	6.50
36	200	7.88
42	251	9.88
48	276	10.88

Face-to-face Dimensions, Category B Valves:

Face-to-face Dimensions, Category B Valves
Lug and Wafer type							Double-flanged Long type						Double-flanged Short type
DN (inch)	150lb		300lb		600lb		150lb		300lb		600lb		150lb		300lb		600lb
DN (inch)	mm	in.	mm	in.	mm	in.	mm	in.	mm	in.	mm	in.	mm	in.	mm	in.	mm	in.
3	48	1.88	48	1.88	54	2.12	203	8.00	282	11.12	356	14	114	4.50	180	7.09	180	7.09
4	54	2.12	54	2.12	64	2.50	229	9.00	305	12.00	432	17	127	5.00	190	7.48	190	7.48
6	57	2.25	59	2.31	78	3.06	267	10.50	403	15.88	559	22	140	5.50	330	8.27	210	8.27
8	64	2.50	73	2.88	102	4.00	292	11.50	418	16.50	660	26	152	6.00	350	9.06	230	9.06
10	71	2.81	83	3.25	117	4.62	330	13.00	457	18.00	787	31	165	6.50	250	9.84	250	9.84
12	81	3.19	92	3.62	140	5.50	356	14.00	502	19.75	838	33	270	7.00	178	10.63	270	10.63
14	92	3.62	117	4.62	155	6.12	381	15.00	762	30.00	889	35	190	7.50	290	11.42	290	11.42
16	102	4.00	133	5.25	178	7.00	406	16.00	838	33.00	991	39	216	8.50	310	12.20	310	12.2
18	114	4.50	149	5.88	200	7.88	432	17.00	914	36.00	1092	43	222	8.75	210	12.99	330	12.99
20	127	5.00	159	6.25	216	8.50	457	18.00	991	39.00	1194	47	229	9.00	230	13.78	350	13.78
24	154	6.06	181	7.12	232	9.13	508	20.00	1143	45.00	1397	55	267	10.50	390	15.35	390	15.35
26	—	—	—	—	—	—	559	22.00	1245	49.00	1448	57	292	11.50	410	16.14	—	—
28	—	—	—	—	—	—	610	24.00	1346	53.00	1549	61	292	11.50	430	16.93	—	—
30	—	—	—	—	—	—	610	24.00	1397	55.00	1651	65	318	12.52	450	17.72	—	—
32	—	—	—	—	—	—	660	26.00	1524	60.00	1778	70	318	12.52	470	18.50	—	—
36	—	—	—	—	—	—	711	28.00	1727	68.00	2083	82	330	12.99	510	20.80	—	—
38	—	—	—	—	—	—	—	—	—	—	—	—	410	16.14	530	20.87	—	—
40	—	—	—	—	—	—	—	—	—	—	—	—	410	16.14	550	21.65	—	—
42	—	—	—	—	—	—	—	—	—	—	—	—	410	16.14	570	22.44	—	—
48	—	—	—	—	—	—	—	—	—	—	—	—	470	18.50	630	24.80	—	—

Wafer

Flange

Lug

2 Offset

3 Offset

2) API609 regulations on butterfly valve materials.

Cast iron is the earliest material used for valves. Its biggest advantage is that it is easy to cast and has a low price. The disadvantage is that it has a weak pressure bearing capacity and cannot be used for medium and high pressure.
Ductile iron is one of the most commonly used materials for valves now. It has high tensile strength and can be used for medium and high pressure pipelines. It is very cost-effective. Therefore, it is generally the first choice for use in media that are not strong acids or strong alkalis.
But in any case, it also complies with the API609 regulations ASME B16.41.
WCB: The biggest feature of WCB is that it can be welded, especially for butterfly valves with extra large diameters. The cost of welding is much lower than that of casting. And it has better high temperature resistance. And it also includes low-temperature resistant LCB materials, which can be used in extremely cold areas.
But at the same time, it also has advantages and disadvantages, such as poor corrosion resistance compared to ductile iron.
Api609 stipulates that WCB must comply with ASME B16.34,
Stainless steel: Stainless steel is famous for its corrosiveness, and it is not easy to produce sand holes during the casting process. Common stainless steel grades include 304, 316 and 316L. In valves, it becomes CF8, CF8M, CF3, CF3M.
Duplex stainless steel: has higher strength and corrosion resistance than stainless steel, and the most common ones are 2205, 2507, etc.
Aluminum bronze: used in applications that require corrosion resistance and low friction. It can be used as a ship valve as a whole, or for components such as valve stems, valve seats and shaft sleeves.
Aluminum bronze and other materials comply with ASME B16.24.

3) API609 regulations on butterfly valve inspection.

API 609 is a butterfly valve standard formulated by the American Petroleum Institute (API), which contains regulations on butterfly valve inspection. According to API 609 standard, the inspection of butterfly valves should include the following aspects:

Appearance: including the smoothness of the surface, whether there are blisters, whether there is damage, etc.
Dimensions: including valve diameter, structural length, etc., to ensure compliance with design requirements.
Sealing: including static sealing and dynamic sealing, water sealing and air sealing, sealing tests are conducted under different pressures and different media to ensure that the valve has no leakage in the closed state.
Pressure: In accordance with API598 standards, check the pressure resistance performance of the butterfly valve under the design pressure.

The main features and applications of API 609 butterfly valve

1. Simple structure

Compared with other valves, the butterfly valve has a relatively simple structure, light weight and small size.

2. Quick opening and closing

The disc of the butterfly valve only needs to rotate 90 degrees, so it can be opened or closed quickly.

3. Low flow resistance

Since the valve disc of the butterfly valve rotates on the axis within the pipe, when it is fully opened, the resistance of the fluid is relatively small and has a lower pressure drop than most other valves.

4. High flow capacity

Butterfly valves usually have larger diameters, and ZFA valves can reach DN3000, which can control large flows.

5. Wide range of applications

Butterfly valves are suitable for low-pressure and medium-pressure systems, and are usually used to control media such as liquids, gases, and powders. The temperature range is usually based on the material and design of the butterfly valve.

6. Operation method

API 609 butterfly valve is usually operated by manual, pneumatic, electric or hydraulic methods.

Advantages of API 609 butterfly valve from ZFA Valves

1. We provide OEM services for many well-known valve brands around the world.
2. In the past 17 years, our production lines have been gradually improved. We have more than 30 machines that produce parts, processing, assembly. Furthermore, we have professional technicians and sales team, to ensure the comminication and product quality.
3. We have more than ten sets of molds on hand, including valve bodies, valve plates, handles, etc.