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Flange standard size tolerance
Created on 2024.08.06
he maximum deviation of the flange size of DN≤600mm is shown in Table 1, Table 2 and Table 3. The limit deviation of the size of butt welded flanges, flat welded flanges, socket welded flanges, threaded flanges and loose flanges is shown in Table 1; The limit deviation of the size of the flanging short joint for the loose flange is shown in Table 2; The limit deviation of the size of the sealing surface of the ring groove is shown in Table 3. The limit deviation of the flange size of DN>600mm is shown in Table 4.
1. "Table 1" Flange Dimension Tolerances for DN≤600mm (SH3406-1996)"
Table 1" Unit: mm
Flange size | Limit deviation |
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Outside diameter | O | Flange outer diameter≤ 610 | ±1.6 |
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Flange outer diameter> 610 | ±3.2 |
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Neijing | B | Butt weld flange | DN≤250 | ±0.8 |
DN350~400 | ±1.6 |
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DN≥500 | ＋3.2－1.6 |
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Bo | Flat welded flange | DN≤250 | ＋0.80 |
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B | Loose flange | DN≥300 | ＋1.60 |
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Bo | Socket weld flange | DN15~20 | ＋0.30 |
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DN65~80 | ＋0.40 |
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B | DN15~50 | ±0.4 |
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DN65~80 | ±0.8 |
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Fran neck | X | Butt weld flange | X≤610 | ±1.6 |
X>610 | ±3.2 |
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Flat welded flanges, loose flanges, threaded flanges, socket welded flanges | DN≤300 | ＋1.6 －0.8 |
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DN≥350 | ＋3.2－1.6 |
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The outer diameter of the butt weld end | H | DN≤125 | ＋2.4－0.8 |
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DN≥150 | ＋4.0－0.8 |
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Sealing side | R | When the height of the sealing surface boss is 1.6 | ±0.8 |
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When the height of the boss on the sealing surface is 6.4 | ±0.5 |
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Concave and convex surface, tongue and groove surface | K | All nominal diameters | ±0.5 |
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g、u、Z、W | ±0.5 |
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d1 | 0-0.4 |
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h1 | ＋0.40 |
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thickness | Q | DN≤450 | ＋3.20 |
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DN≥500 | ＋4.80 |
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Flange height | Y | Butt weld flange | DN≤250 | ±1.6 |
DN≥300 | ±3.2 |
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Flat welded flanges, loose flanges, threaded flanges, socket welded flanges | DN≤450 | ＋3.2-0.8 |
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DN≥500 | ＋4.8-1.6 |
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Screw hole | C | Diameter of the center circle of the bolt hole | DN≤4300 | ±0.8 |
DN≥350 | ±1.6 |
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spacing | All nominal diameters | ±0.8 |
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h | diameter | All nominal diameters | ±0.5 |
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The inner warp of the flange is eccentric to the center circle of the bolt hole | <0.8 |
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The inner warp of the flange is eccentric to the center circle of the sealing surface | <0.8 |
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2. 《Table 2》 Limit deviation of the size of flanged short sections for looseflanges (SH3406-1996)
《Table 2》 Unit: mm |
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Short section size | Limit deviation |
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The outer diameter of the butt weld end | H | DN15~65 | ±1.6-0.8 |
DN80~100 | ±1.6 |
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DN125~200 | ＋2.4－1.6 |
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DN≥250 | ＋4.0－3.2 |
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Stub Inner Diameter (1) | B | DN15~65 | ±0.8 |
DN80~200 | ±1.6 |
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DN≥250 | ±3.2 |
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Short section length | L | DN15~200 | ±1.6 |
LL | DN≥250 | ±2.4 |
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The outer diameter of the short section sealing surface | R | DN15~200 | 0－0.8 |
DN≥250 | 0－1.6 |
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Fillet radius | r2 | DN15~90 | 0-0.8 |
DN≥100 | 0-1.6 |
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Flanging or groove bottom thickness | T | All nominal diameters | ＋1.60 |
Note: (1) The deviation under the thicknessof the short section should exceed 12.5% of the nominal thickness.
3. 《Table 3》 Limit deviation of the size of the ring groove sealing surface(SH3406-1996)
《Table 3》 Unit: mm |
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Ring groove size | Limit deviation |
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> ring groove depth | >E | >＋0.40 |
> the width of the top of the ring groove | >F | >±0.2 |
> the diameter of the center circle of the ring groove | P | ±0.13 |
Ring groove angle | 23° | ±0.5° |
Ring groove rounded corners | r | 5＝0.1 |
The outer diameter of the sealing surface | K | ±0.5 |
4. 《Table 4》 Nominal diameter DN≥600mm flange size limit deviation (SH3406-1996)
《Table 4》 Unit: mm |
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Flange size | Limit deviation |
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Outside diameter | O | ±4.0 |
Neijing | B | ＋4.0－2.4 |
thickness | Q | ＋4.80 |
The outer diameter of the sealing surface | R | 5＝0.8 |
Length | Y | ±3.2 |
Fran neck | X | ±4.0 |
Outer diameter of the neck end of the flange | H | ＋4.0－0.8 |
Diameter of the center circle of the bolt hole | C | ±1.6 |
Bolt hole spacing | ±0.8 |
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Bolt hole diameter | h | ±0.5 |
The inner warp of the flange is eccentric to the center circle of the bolt hole | <1.0 |
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The inner warp of the flange is eccentric to the center circle of the sealing surface | <1.0 |
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