SAE Flange Code 61 vs Code 62 (SAE 3000 / 6000): Selection and Installation
Code 61 (ISO 6162-1) and Code 62 (ISO 6162-2) flanges are not interchangeable, even at the same nominal size: the Code 62 flange head is thicker and…
ISO 6162-1 · ISO 6162-2 · SAE J518
SAE Flange Dimensions (Code 61 and 62)
Bolt spacing, UNC bolts, O-ring sizes and working pressures of SAE J518 / ISO 6162 four-bolt flanges in Code 61 (SAE 3000) and Code 62 (SAE 6000), from 1/2" to 3".
Quick answer
SAE flanges come in two series: Code 61 (ISO 6162-1, "SAE 3000") and Code 62 (ISO 6162-2, "SAE 6000"). The bolt spacings differ for the same nominal size; on a 1" flange they are 52.4 × 26.2 mm for Code 61 and 57.2 × 27.8 mm for Code 62. Under ISO 6162, Code 62 has a working pressure of 420 bar in all sizes, while Code 61 drops by size from 350 bar (1/2" and 3/4") to 160 bar (3"). Both series use the same O-ring but are not interchangeable.
ISO 6162-1 · ISO 6162-2 · SAE J518
Size chart
SAE 4-bolt flange dimensions: Code 61 (ISO 6162-1) and Code 62 (ISO 6162-2)
| Nominal sizein | Series | DN | Dash | Bolt spacing, longmm | Bolt spacing, shortmm | Inch bolt (UNC) | O-ring code (ISO 3601-1 / AS568) | O-ring ID × cross-sectionmm | Max. working pressure, ISO 6162 (standard value)bar | Max. working pressure, SAE J518 (standard value)psi | SAE value in barbar |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Code 61 (ISO 6162-1) | |||||||||||
| 1/2 | Code 61 | DN13 | -8 | 38.1 | 17.5 | 5/16-18 | 210 | 18.64×3.53 | 350 | 5000 | 345 |
| 3/4 | Code 61 | DN19 | -12 | 47.6 | 22.2 | 3/8-16 | 214 | 24.99×3.53 | 350 | 5000 | 345 |
| 1 | Code 61 | DN25 | -16 | 52.4 | 26.2 | 3/8-16 | 219 | 32.92×3.53 | 320 | 5000 | 345 |
| 1-1/4 | Code 61 | DN32 | -20 | 58.7 | 30.2 | 7/16-14 | 222 | 37.69×3.53 | 280 | 4000 | 276 |
| 1-1/2 | Code 61 | DN38 | -24 | 69.9 | 35.7 | 1/2-13 | 225 | 47.22×3.53 | 210 | 3000 | 207 |
| 2 | Code 61 | DN51 | -32 | 77.8 | 42.9 | 1/2-13 | 228 | 56.74×3.53 | 210 | 3000 | 207 |
| 2-1/2 | Code 61 | DN64 | -40 | 88.9 | 50.8 | 1/2-13 | 232 | 69.44×3.53 | 175 | no value | no value |
| 3 | Code 61 | DN76 | -48 | 106.4 | 61.9 | 5/8-11 | 237 | 85.32×3.53 | 160 | no value | no value |
| Code 62 (ISO 6162-2) | |||||||||||
| 1/2 | Code 62 | DN13 | -8 | 40.5 | 18.2 | 5/16-18 | 210 | 18.64×3.53 | 420 | 6000 | 414 |
| 3/4 | Code 62 | DN19 | -12 | 50.8 | 23.8 | 3/8-16 | 214 | 24.99×3.53 | 420 | 6000 | 414 |
| 1 | Code 62 | DN25 | -16 | 57.2 | 27.8 | 7/16-14 | 219 | 32.92×3.53 | 420 | 6000 | 414 |
| 1-1/4 | Code 62 | DN32 | -20 | 66.7 | 31.8 | 1/2-13 | 222 | 37.69×3.53 | 420 | 6000 | 414 |
| 1-1/2 | Code 62 | DN38 | -24 | 79.4 | 36.5 | 5/8-11 | 225 | 47.22×3.53 | 420 | 6000 | 414 |
| 2 | Code 62 | DN51 | -32 | 96.8 | 44.5 | 3/4-10 | 228 | 56.74×3.53 | 420 | 6000 | 414 |
| 2-1/2 | Code 62 | DN64 | -40 | no value | no value | no value | 232 | 69.44×3.53 | 420 | no value | no value |
| 3 | Code 62 | DN76 | -48 | no value | no value | no value | 237 | 85.32×3.53 | 420 | no value | no value |
Chart notes
- Code 61 and Code 62 are not interchangeable: the bolt spacings differ. To avoid mix-ups, measure the bolt pattern to within 1 mm.
- Pressures are the ISO 6162-1/-2 and SAE J518 standard values; the rating of an actual product (flange half, clamp) depends on the bolt grade and the manufacturer's test value.
- The allowable working pressure drops at elevated temperature; for a stainless steel flange connection, take the temperature derating from the flange and bolt manufacturer's values.
- According to ISO 6162, ports and assemblies with inch screws (type 2) should not be used in new designs; type 1 ports with metric screws are marked with the letter 'M'. Confirm the metric screw size with the manufacturer's catalog.
- O-rings are ISO 3601-1 sizes (same numbers as AS568 -210 … -237); both series use the same O-ring for a given size.
- Code 61 sizes 3-1/2", 4" and 5" are limited to low pressure and are not included in the chart.
- Empty cells are values that could not be verified; for these sizes, refer to the current standard or the manufacturer's catalog.
Reference standards
- ISO 6162-1
- Code 61 flange connections (3.5–35 MPa)
- ISO 6162-2
- Code 62 flange connections (42 MPa)
- SAE J518
- 4-bolt hydraulic flange connections
Values are nominal; for critical applications, verify against the current standard and the manufacturer's catalog.
Description
Description
SAE flange connections (SAE J518 / ISO 6162) replace threaded fittings on large-bore hydraulic lines: the flange head is bolted to the port with four bolts, and an O-ring in the flange head makes the seal. There are two series: Code 61 (ISO 6162-1, "SAE 3000") and Code 62 (ISO 6162-2, "SAE 6000"). The chart gives the bolt spacing, inch bolt, O-ring size and working pressures for sizes from 1/2" to 3".
How to read the chart
- Nominal size, DN and dash are three ways of writing the same size: 1" = DN25 = -16.
- Bolt spacing is the long and short distance between bolt hole centers; it is measured on the port.
- The inch bolt is a UNC-threaded SAE grade 8 bolt (type 2). Type 1 ports with metric bolts are marked with the letter "M"; confirm the metric bolt size from the port drawing.
- The O-ring is the same for both series; the code is the ISO 3601-1 / AS568 number, and the cross-section is 3.53 mm in all sizes.
- The pressure columns are ISO 6162 (bar) and SAE J518 (psi) values; if the two differ, use the lower one. Values that could not be verified are left empty (—) in the chart.
What do SAE 3000 and SAE 6000 mean?
These are series names, not the working pressure of every size. Under ISO 6162-1, the Code 61 working pressure is 350 bar at 1/2" and 3/4", 320 bar at 1", 280 bar at 1-1/4", 210 bar at 1-1/2" and 2", 175 bar at 2-1/2" and 160 bar at 3". Under ISO 6162-2, Code 62 is 420 bar in all sizes. SAE J518 gives 6000 psi (414 bar) for Code 62 from 1/2" to 2".
How to tell Code 61 from Code 62
At the same nominal size the two series look similar, but their bolt spacings differ, and the difference is small: on a 1/2" flange, Code 61 is 38.1 × 17.5 mm and Code 62 is 40.5 × 18.2 mm; on a 1" flange, 52.4 × 26.2 mm and 57.2 × 27.8 mm. ISO 6162-1 recommends measuring the bolt pattern to within 1 mm so that the two series are not mixed up. Code 62 has a thicker flange head and uses larger bolts from 1" up. A split flange or clamp from one series won't grip the flange head of the other correctly; if the joint is forced, the O-ring gets crushed.
Assembly and O-ring
Place the O-ring in the groove without twisting it; the default material is NBR 90, and if the fluid and temperature require it, choose a suitable material such as FKM. Tighten the bolts gradually in a cross pattern and check that the flange head sits parallel to the port face. The pressure of the connection cannot exceed the rating of the weakest part in the assembly: the flange half, clamp and bolt grade are assessed together.
Temperature derating on stainless steel flanges
On a stainless steel flange connection the allowable working pressure drops at elevated temperature; take the derating from the temperature-dependent values given by the flange, clamp and bolt manufacturer. The 2-1/2" and 3" Code 62 sizes are defined at 420 bar in ISO 6162-2; for these sizes, confirm the bolt spacing and bolt from the port drawing.
FAQ
Frequently asked questions
If your question isn't answered here, message us on WhatsApp with dimensions or a photo, and our technical team will answer directly.
What is the difference between SAE 3000 and SAE 6000 flanges?
SAE 3000 is the Code 61 series (ISO 6162-1) and SAE 6000 the Code 62 series (ISO 6162-2). At the same nominal size, Code 62 has a larger bolt spacing and a thicker flange head, and it uses larger bolts from 1" up. Under ISO 6162, Code 62 has a working pressure of 420 bar in all sizes, while Code 61 ranges from 350 bar to 160 bar depending on size.
What are the SAE flange O-ring sizes?
Code 61 and Code 62 use the same O-ring; the cross-section is 3.53 mm in all sizes. Inside diameters: 18.64 mm for 1/2" (210), 24.99 mm for 3/4" (214), 32.92 mm for 1" (219), 37.69 mm for 1-1/4" (222), 47.22 mm for 1-1/2" (225) and 56.74 mm for 2" (228). The material is chosen to suit the fluid and temperature; NBR 90 is the default.
Can a Code 61 flange be fitted to a Code 62 port?
No. The bolt spacings differ; at 1", Code 61 is 52.4 × 26.2 mm and Code 62 is 57.2 × 27.8 mm. In small sizes the difference is only a few millimeters, so measure the bolt pattern carefully. If the joint is forced, the flange head won't sit evenly and the O-ring gets crushed.
How many bar is 3000 psi?
3000 psi is about 207 bar, 5000 psi about 345 bar and 6000 psi about 414 bar (1 bar = 14.504 psi). On SAE flanges these values are used as series names; the working pressure of each size should be checked separately in the chart.
Is the pressure rating reduced on stainless steel SAE flanges?
Yes. On a stainless steel flange connection the allowable working pressure drops at elevated temperature; take the derating from the manufacturer's temperature-dependent values. The rating of the product also depends on the flange half, clamp and bolt grade.
From chart to quote
Need a stainless steel fitting in this size?
Tell us the thread standard, size and quantity; we'll quote price and lead time for an AISI 316/316L stainless steel fitting from stock or made to order.