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The Ultimate Butterfly Valve Bolt Chart
The definitive, library-grade reference for butterfly valve bolting calculations. This exhaustive resource provides complete bolt quantity and size data for both Lug-Style (using cap screws) and Wafer-Style (using through-bolts), cross-referenced against all major global flange standards.
Lug vs. Wafer: Understanding the Bolting Difference
The fundamental difference between Lug and Wafer butterfly valves dictates their bolting method and application range, especially in critical dead-end service.
Wafer Style (Through-Bolts)
Wafer valves are "sandwiched" between two pipe flanges. They rely on long through-bolts (or studs with nuts on each end) that pass through both flanges and the valve body's unthreaded guide holes. The tension from these bolts clamps the entire assembly together.
Mechanism: Clamped by tension from long bolts passing through the entire assembly.
Key Feature: Valve cannot remain in the line if the downstream flange is removed (no dead-end service).
Advantage: Typically more cost-effective and lighter.
Lug Style (Cap Screws)
Lug valves feature threaded inserts ("lugs") in the valve body that align with the bolt holes of the flanges. Each flange is bolted to the valve body independently using shorter cap screws (bolts).
Mechanism: Each flange is independently bolted to the valve's threaded lugs.
Key Feature: Allows for dead-end service, where the downstream piping can be removed while the valve maintains a seal against upstream pressure.
Advantage: Essential for maintenance-heavy applications and end-of-line service.
LUG VS. WAFER BOLT COUNT
For a given flange standard, a Lug-style valve will use twice as many bolts as a Wafer-style valve. For example, a 6" Class 150 flange has 8 bolt holes. A wafer valve will use 8 long through-bolts, while a lug valve will use 16 shorter cap screws (8 for the upstream flange, 8 for the downstream flange).
Wafer Style Butterfly Valve Bolt Chart
Data below represents the required Through-Bolts for Wafer Style valves when installed between two flanges of the specified standard. The quantity is determined by the number of bolt holes in the corresponding flange.
Wafer Style: ASME / ANSI Flanges
Standard Note
ASME B16.5 covers sizes up to NPS 24. For sizes NPS 26 and larger, ASME B16.47 Series A (preferred for new construction) and Series B (often for retrofitting) are the governing standards.
Nominal Size (NPS)
Class 150
Class 300
Class 600
Class 900
B16.47 Ser. A
B16.47 Ser. B
Qty.
Size (in)
Qty.
Size (in)
Qty.
Size (in)
Qty.
Size (in)
Qty.
Size (in)
Qty.
Size (in)
2
4
5/8
8
5/8
8
5/8
8
3/4
-
-
-
-
2.5
4
5/8
8
3/4
8
3/4
8
7/8
-
-
-
-
3
4
5/8
8
3/4
8
3/4
8
7/8
-
-
-
-
4
8
5/8
8
3/4
8
7/8
8
1 1/8
-
-
-
-
5
8
3/4
8
3/4
8
1
8
1 1/4
-
-
-
-
6
8
3/4
12
3/4
12
1 1/8
12
1 1/4
-
-
-
-
8
8
3/4
12
7/8
12
1 1/4
12
1 1/2
-
-
-
-
10
12
7/8
16
1
16
1 3/8
16
1 5/8
-
-
-
-
12
12
7/8
16
1 1/8
20
1 3/8
20
1 3/4
-
-
-
-
14
12
1
20
1 1/8
20
1 1/2
20
2
-
-
-
-
16
16
1
20
1 1/4
20
1 5/8
20
2 1/4
-
-
-
-
18
16
1 1/8
24
1 1/4
20
1 3/4
20
2 1/2
-
-
-
-
20
20
1 1/8
24
1 1/4
24
1 7/8
24
2 1/2
-
-
-
-
24
20
1 1/4
24
1 1/2
24
2
24
3
-
-
-
-
26
-
-
-
-
-
-
-
-
24
1 1/4
28
1
28
-
-
-
-
-
-
-
-
28
1 1/4
32
1
30
-
-
-
-
-
-
-
-
28
1 1/4
36
1
32
-
-
-
-
-
-
-
-
28
1 1/2
36
1 1/8
34
-
-
-
-
-
-
-
-
32
1 1/2
40
1 1/8
36
-
-
-
-
-
-
-
-
32
1 1/2
44
1 1/8
38
-
-
-
-
-
-
-
-
36
1 1/2
44
1 1/4
40
-
-
-
-
-
-
-
-
36
1 1/2
48
1 1/4
42
-
-
-
-
-
-
-
-
40
1 1/2
52
1 1/4
44
-
-
-
-
-
-
-
-
40
1 3/4
56
1 1/4
46
-
-
-
-
-
-
-
-
44
1 3/4
60
1 1/4
48
-
-
-
-
-
-
-
-
44
1 3/4
60
1 1/2
50
-
-
-
-
-
-
-
-
48
1 3/4
64
1 1/2
52
-
-
-
-
-
-
-
-
52
1 3/4
68
1 1/2
54
-
-
-
-
-
-
-
-
52
1 3/4
72
1 1/2
56
-
-
-
-
-
-
-
-
56
1 3/4
76
1 1/2
58
-
-
-
-
-
-
-
-
56
2
80
1 1/2
60
-
-
-
-
-
-
-
-
60
2
84
1 1/2
Wafer Style: EN 1092-1 Flanges
Standard Note
EN 1092-1 is the dominant standard throughout Europe, superseding older national standards like DIN, BS, and NFE. The data below is applicable for Type 01 (Plate), Type 05 (Blank), and Type 11 (Weld-Neck) flanges. Bolt sizes are metric (M).
Nominal Size (DN)
PN 6
PN 10
PN 16
PN 25
PN 40
Qty.
Size
Qty.
Size
Qty.
Size
Qty.
Size
Qty.
Size
50
4
M16
4
M16
4
M16
4
M16
4
M20
65
4
M16
4
M16
4
M16
4
M16
8
M20
80
8
M16
8
M16
8
M16
8
M20
8
M20
100
8
M16
8
M16
8
M16
8
M20
8
M24
125
8
M16
8
M16
8
M16
8
M24
8
M27
150
8
M20
8
M20
8
M20
8
M24
8
M27
200
8
M20
8
M20
12
M20
12
M27
12
M30
250
12
M20
12
M24
12
M24
12
M27
12
M33
300
12
M20
12
M24
12
M24
12
M30
16
M33
350
16
M20
16
M24
16
M27
16
M30
16
M36
400
16
M24
16
M27
16
M27
16
M33
16
M39
450
20
M24
20
M27
20
M30
20
M36
20
M42
500
20
M24
20
M30
20
M30
20
M36
20
M42
600
20
M27
20
M33
20
M33
20
M39
20
M48
700
24
M27
24
M33
24
M36
24
M42
24
M52
800
24
M30
24
M36
24
M39
24
M45
24
M56
900
28
M30
28
M39
28
M42
28
M48
28
M64
1000
28
M33
28
M42
28
M45
28
M52
28
M68
1200
32
M36
32
M48
32
M52
32
M56
-
-
1400
36
M39
36
M52
36
M56
-
-
-
-
1600
40
M42
40
M56
40
M64
-
-
-
-
1800
44
M45
44
M64
44
M68
-
-
-
-
2000
48
M48
48
M68
48
M72
-
-
-
-
2200
52
M52
52
M72
-
-
-
-
-
-
2400
56
M56
56
M76
-
-
-
-
-
-
2600
60
M56
60
M80
-
-
-
-
-
-
2800
64
M60
64
M85
-
-
-
-
-
-
3000
68
M64
68
M90
-
-
-
-
-
-
3200
72
M68
-
-
-
-
-
-
-
-
3400
76
M72
-
-
-
-
-
-
-
-
3600
80
M76
-
-
-
-
-
-
-
-
3800
84
M80
-
-
-
-
-
-
-
-
4000
88
M85
-
-
-
-
-
-
-
-
Wafer Style: JIS B2220 Flanges
Standard Note
JIS (Japanese Industrial Standards) is the primary standard in Japan and widely used in Asia. The data below applies to the most common pressure ratings for butterfly valves.
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Nominal Size (DN)
5K
10K
16K
20K
Qty.
Size
Qty.
Size
Qty.
Size
Qty.
Size
50
4
M12
4
M16
4
M16
8
M16
65
4
M12
4
M16
4
M16
8
M16
80
4
M16
8
M16
8
M16
8
M20
100
8
M16
8
M16
8
M20
8
M20
125
8
M16
8
M16
8
M20
8
M22
150
8
M16
8
M20
8
M22
12
M22
200
8
M20
12
M20
12
M22
12
M24
250
12
M20
12
M22
12
M24
12
M27
300
12
M20
16
M22
16
M24
16
M27
350
12
M22
16
M24
16
M27
16
M30
400
16
M22
16
M24
16
M27
16
M30
450
16
M24
20
M24
20
M30
20
M33
500
20
M24
20
M27
20
M30
20
M33
550
20
M24
20
M27
-
-
-
-
600
20
M24
20
M30
20
M33
20
M36
700
-
-
24
M30
24
M33
-
-
750
24
M27
24
M30
24
M36
24
M39
800
-
-
24
M33
24
M36
-
-
900
-
-
28
M33
28
M39
28
M42
1000
-
-
28
M36
28
M42
28
M45
1100
-
-
32
M36
-
-
-
-
1200
-
-
32
M39
-
-
-
-
1350
-
-
36
M39
-
-
-
-
1500
-
-
36
M42
-
-
-
-
Wafer Style: AS 2129 Flanges
Standard Note
AS 2129 is the Australian standard for flanges, with Tables D and E being common for general purpose and low-pressure applications where butterfly valves are often used.
Nominal Size (DN)
Table D
Table E
Qty.
Size (in)
Qty.
Size (in)
50
4
5/8
4
5/8
65
4
5/8
4
3/4
80
4
5/8
4
3/4
100
4
3/4
8
3/4
125
8
3/4
8
3/4
150
8
3/4
8
7/8
200
8
7/8
8
1
250
8
1
12
1
300
12
1
12
1 1/8
350
12
1
12
1 1/4
400
12
1 1/8
16
1 1/4
450
16
1 1/8
16
1 1/4
500
16
1 1/4
20
1 1/4
600
20
1 1/4
20
1 3/8
750
20
1 1/2
24
1 1/2
900
24
1 1/2
28
1 5/8
1050
28
1 1/2
32
1 3/4
1200
32
1 1/2
36
1 3/4
Lug Style Butterfly Valve Bolt Chart
Data below represents the required Cap Screws for Lug Style valves. The quantity is double the flange bolt hole count, as each flange is bolted to the valve body independently. Ensure cap screw length is appropriate for the flange thickness and thread engagement.
Lug Style: ASME / ANSI Flanges
Critical Note on Bolt Quantity
A Lug valve uses two sets of cap screws. For example, a 6" Class 150 Lug valve requires 16 cap screws (8 for the upstream flange, 8 for the downstream flange).
Nominal Size (NPS)
Class 150
Class 300
Class 600
Class 900
B16.47 Ser. A
B16.47 Ser. B
Qty.
Size (in)
Qty.
Size (in)
Qty.
Size (in)
Qty.
Size (in)
Qty.
Size (in)
Qty.
Size (in)
2
8
5/8
16
5/8
16
5/8
16
3/4
-
-
-
-
2.5
8
5/8
16
3/4
16
3/4
16
7/8
-
-
-
-
3
8
5/8
16
3/4
16
3/4
16
7/8
-
-
-
-
4
16
5/8
16
3/4
16
7/8
16
1 1/8
-
-
-
-
5
16
3/4
16
3/4
16
1
16
1 1/4
-
-
-
-
6
16
3/4
24
3/4
24
1 1/8
24
1 1/4
-
-
-
-
8
16
3/4
24
7/8
24
1 1/4
24
1 1/2
-
-
-
-
10
24
7/8
32
1
32
1 3/8
32
1 5/8
-
-
-
-
12
24
7/8
32
1 1/8
40
1 3/8
40
1 3/4
-
-
-
-
14
24
1
40
1 1/8
40
1 1/2
40
2
-
-
-
-
16
32
1
40
1 1/4
40
1 5/8
40
2 1/4
-
-
-
-
18
32
1 1/8
48
1 1/4
40
1 3/4
40
2 1/2
-
-
-
-
20
40
1 1/8
48
1 1/4
48
1 7/8
48
2 1/2
-
-
-
-
24
40
1 1/4
48
1 1/2
48
2
48
3
-
-
-
-
26
-
-
-
-
-
-
-
-
48
1 1/4
56
1
28
-
-
-
-
-
-
-
-
56
1 1/4
64
1
30
-
-
-
-
-
-
-
-
56
1 1/4
72
1
32
-
-
-
-
-
-
-
-
56
1 1/2
72
1 1/8
34
-
-
-
-
-
-
-
-
64
1 1/2
80
1 1/8
36
-
-
-
-
-
-
-
-
64
1 1/2
88
1 1/8
38
-
-
-
-
-
-
-
-
72
1 1/2
88
1 1/4
40
-
-
-
-
-
-
-
-
72
1 1/2
96
1 1/4
42
-
-
-
-
-
-
-
-
80
1 1/2
104
1 1/4
44
-
-
-
-
-
-
-
-
80
1 3/4
112
1 1/4
46
-
-
-
-
-
-
-
-
88
1 3/4
120
1 1/4
48
-
-
-
-
-
-
-
-
88
1 3/4
120
1 1/2
50
-
-
-
-
-
-
-
-
96
1 3/4
128
1 1/2
52
-
-
-
-
-
-
-
-
104
1 3/4
136
1 1/2
54
-
-
-
-
-
-
-
-
104
1 3/4
144
1 1/2
56
-
-
-
-
-
-
-
-
112
1 3/4
152
1 1/2
58
-
-
-
-
-
-
-
-
112
2
160
1 1/2
60
-
-
-
-
-
-
-
-
120
2
168
1 1/2
Lug Style: EN 1092-1 (DIN) Flanges
Critical Note on Bolt Quantity
Lug valves require two independent sets of cap screws. The quantities below are the total number required for one valve (upstream + downstream).
Nominal Size (DN)
PN 6
PN 10
PN 16
PN 25
PN 40
Qty.
Size
Qty.
Size
Qty.
Size
Qty.
Size
Qty.
Size
50
8
M16
8
M16
8
M16
8
M16
8
M20
65
8
M16
8
M16
8
M16
8
M20
8
M20
80
16
M16
16
M16
16
M16
16
M20
16
M24
100
16
M16
16
M16
16
M20
16
M24
16
M24
125
16
M16
16
M16
16
M20
16
M24
16
M27
150
16
M20
16
M20
16
M20
16
M24
16
M27
200
16
M20
24
M20
24
M20
24
M27
24
M30
250
24
M20
24
M24
24
M24
24
M30
24
M33
300
24
M20
24
M24
24
M24
24
M30
24
M36
350
32
M20
32
M24
32
M27
32
M33
32
M39
400
32
M24
32
M27
32
M27
32
M36
32
M42
450
40
M24
40
M27
40
M30
40
M36
40
M45
500
40
M24
40
M27
40
M30
40
M39
40
M48
600
40
M27
40
M30
40
M33
40
M45
40
M52
700
48
M27
48
M30
48
M36
48
M48
48
M56
800
48
M30
48
M33
48
M39
48
M52
48
M60
900
56
M30
56
M36
56
M42
56
M56
56
M64
1000
56
M33
56
M39
56
M48
56
M60
56
M68
1100
64
M33
64
M39
-
-
-
-
-
-
1200
64
M36
64
M42
64
M52
64
M68
-
-
1400
72
M39
72
M48
72
M56
72
M76
-
-
1600
80
M45
80
M52
80
M64
80
M85
-
-
1800
88
M45
88
M56
88
M68
-
-
-
-
2000
96
M45
96
M60
96
M72
-
-
-
-
2200
-
-
104
M64
-
-
-
-
-
-
2400
-
-
112
M64
-
-
-
-
-
2600
-
-
120
M68
-
-
-
-
-
2800
-
-
128
M72
-
-
-
-
-
3000
-
-
136
M76
-
-
-
-
-
3200
-
-
144
M80
-
-
-
-
-
3400
-
-
152
M85
-
-
-
-
-
3600
-
-
160
M90
-
-
-
-
-
3800
-
-
168
M95
-
-
-
-
-
4000
-
-
176
M100
-
-
-
-
-
Lug Style: JIS B2220 Flanges
Nominal Size (DN)
5K
10K
16K
20K
Qty.
Size
Qty.
Size
Qty.
Size
Qty.
Size
50
8
M12
8
M16
8
M16
16
M16
65
8
M12
8
M16
8
M16
16
M16
80
8
M16
16
M16
16
M16
16
M20
100
16
M16
16
M16
16
M20
16
M20
125
16
M16
16
M16
16
M20
16
M22
150
16
M16
16
M20
16
M22
24
M22
200
16
M20
24
M20
24
M22
24
M24
250
24
M20
24
M22
24
M24
24
M27
300
24
M20
32
M22
32
M24
32
M27
350
24
M22
32
M24
32
M27
32
M30
400
32
M22
32
M24
32
M27
32
M30
450
32
M24
40
M24
40
M30
40
M33
500
40
M24
40
M27
40
M30
40
M33
550
40
M24
40
M27
-
-
-
-
600
40
M24
40
M30
40
M33
40
M36
700
-
-
48
M30
48
M33
-
-
750
48
M27
48
M30
48
M36
48
M39
800
-
-
48
M33
48
M36
-
-
900
-
-
56
M33
56
M39
56
M42
1000
-
-
56
M36
56
M42
56
M45
1100
-
-
64
M36
-
-
-
-
1200
-
-
64
M39
-
-
-
-
1350
-
-
72
M39
-
-
-
-
1500
-
-
72
M42
-
-
-
-
Lug Style: AS 2129 Flanges
Nominal Size (DN)
Table D
Table E
Qty.
Size (in)
Qty.
Size (in)
50
8
5/8
8
5/8
65
8
5/8
8
3/4
80
8
5/8
8
3/4
100
8
3/4
16
3/4
125
16
3/4
16
3/4
150
16
3/4
16
7/8
200
16
7/8
16
1
250
16
1
24
1
300
24
1
24
1 1/8
350
24
1
24
1 1/4
400
24
1 1/8
32
1 1/4
450
32
1 1/8
32
1 1/4
500
32
1 1/4
40
1 1/4
600
40
1 1/4
40
1 3/8
750
40
1 1/2
48
1 1/2
900
48
1 1/2
56
1 5/8
1050
56
1 1/2
64
1 3/4
1200
64
1 1/2
72
1 3/4
Other National Standards
Beyond the major global standards, many countries maintain national or industry-specific flange standards. Butterfly valve bolt patterns must align with these if specified.
The Universal Principle
Regardless of the standard, the core principle remains: The valve's drilling pattern must exactly match the flange's drilling pattern. This includes the bolt circle diameter (BCD), number of holes, and hole diameter.
Common Regional and Industrial Standards
GOST (ГОСТ - Russian Federation & CIS): Russian national standards, such as GOST 33259, define flange dimensions. These are not interchangeable with ASME or EN standards without specific adapters or dual-drilled flanges. Bolt requirements must be sourced from the specific GOST standard being used.
GB/T (China): Guobiao standards are the national standards for China. Standards like GB/T 9113 (for integral steel pipe flanges) and others dictate flange dimensions. While some are harmonized with ISO, direct compatibility with ASME/EN is not guaranteed.
HG/T (China - Chemical Industry): These are Chinese standards specific to the chemical industry, such as HG/T 20592. They often define flange requirements for specific applications and pressures within this sector and must be adhered to for relevant projects.
SABS / SANS (South Africa): The South African Bureau of Standards issues standards like SANS 1123, which specifies dimensions for pipe flanges. These are often based on BS or ISO standards but require explicit confirmation.
The Rule for "Other" Standards
When encountering a non-ASME/EN/JIS/AS standard, it is mandatory to obtain the technical specification sheet for both the valve and the mating flange to perform a manual verification of:
Bolt Circle Diameter (BCD)
Number of Bolt Holes
Diameter of Bolt Holes
Never assume compatibility based on nominal pipe size alone.
Golden Rules of Bolt & Cap Screw Selection
Mistakes in bolting are costly and dangerous. Adhering to these rules prevents installation failure, leaks, and safety incidents.
1 Rule 1: Always Verify the Mating Flange Standard.
This is the most critical step. Before consulting any chart, you must know the exact standard, pressure class, and size of the flange your valve will be installed between. A "DN150" flange can be PN10, PN16, ASME Class 150, or JIS 10K—each with different bolting.
2 Rule 2: Differentiate Wafer vs. Lug.
Wafer valves use fewer, longer through-bolts that clamp the entire assembly. Lug valves use twice as many shorter cap screws, bolting each flange to the valve body independently. Using the wrong chart will result in incorrect bolt quantity and type.
3 Rule 3: Bolt Length is Critical and is NOT in These Charts.
These charts provide the quantity and diameter, not the length. For Wafer Valves: Length = (Flange 1 Thickness) + (Valve Body Thickness) + (Flange 2 Thickness) + (2 x Gasket Thickness) + (2 x Nut Height) + (Extra Thread Projection). For Lug Valves: Length depends on flange thickness and required thread engagement in the valve body (typically 1 to 1.5 times the bolt diameter). Always calculate length based on the specific assembly components.
4 Rule 4: Match Bolt Material to Service Conditions.
The bolt material must be compatible with the fluid temperature, pressure, and environment. Common choices include ASTM A193 B7 for standard carbon steel applications and A193 B8/B8M for stainless steel or corrosive services. Mismatched materials can lead to corrosion or mechanical failure.
5 Rule 5: The Manufacturer's Datasheet is the Final Authority.
While these charts are comprehensive references based on standards, slight variations can exist between manufacturers. The valve manufacturer's certified dimensional drawing and installation manual are the ultimate source of truth. Use these charts for planning, but ALWAYS confirm with the manufacturer's official documentation before final procurement or fabrication.
JRVAL
Aug 01 2025
