Code 61 vs Code 62 Flange Dimensions: Complete SAE & CAT Chart
Dimensions per SAE J518 / J516 standards
Quick answer: Code 61 vs Code 62 flange dimensions come down to head thickness. Measure with a caliper. 0.315″ = Code 61, 0.405″ = Code 62, 0.560″ = CAT style (sizes -12 through -32). Full dimensions for every dash size are below.
Jump to a size: -08 · -12 · -16 · -20 · -24 · -32 · FAQ
Code 61 vs Code 62 Flange Dimensions: Master Reference Chart
Complete dimensional data for SAE Code 61 (3,000 PSI), SAE Code 62 (6,000 PSI), and Caterpillar (CAT) style 4-bolt flanges, dash sizes -08 through -32. All measurements listed in inches with millimeter equivalents. For a full breakdown of pressure ratings and when to use each style, see our Code 61 vs Code 62 comparison guide and How to Identify CAT Flanges vs Code 62.
| Dash Size | Nominal Size | Flange Style | Head O.D. (F) | Head Thickness (C) | Bolt Spacing Length (A) | Bolt Spacing Width (B) | Bolt Size (UNC) |
|---|---|---|---|---|---|---|---|
| -08 | 1/2″ | SAE Code 61 (3,000 PSI) | 1.188″ (30.2 mm) | 0.265″ (6.7 mm) | 1.500″ (38.1 mm) | 0.688″ (17.5 mm) | 5/16″-18 |
| SAE Code 62 (6,000 PSI) | 1.250″ (31.8 mm) | 0.305″ (7.7 mm) | 1.594″ (40.5 mm) | 0.718″ (18.2 mm) | 5/16″-18 | ||
| -12 | 3/4″ | SAE Code 61 (3,000 PSI) | 1.500″ (38.1 mm) | 0.265″ (6.7 mm) | 1.875″ (47.6 mm) | 0.875″ (22.2 mm) | 3/8″-16 |
| SAE Code 62 (6,000 PSI) | 1.625″ (41.3 mm) | 0.345″ (8.8 mm) | 2.000″ (50.8 mm) | 0.938″ (23.8 mm) | 3/8″-16 | ||
| CAT Style (6,000 PSI) | 1.625″ (41.3 mm) | 0.560″ (14.2 mm) | 2.000″ (50.8 mm) | 0.938″ (23.8 mm) | 3/8″-16 | ||
| -16 | 1″ | SAE Code 61 (3,000 PSI) | 1.750″ (44.5 mm) | 0.315″ (8.0 mm) | 2.062″ (52.4 mm) | 1.031″ (26.2 mm) | 3/8″-16 |
| SAE Code 62 (6,000 PSI) | 1.875″ (47.6 mm) | 0.375″ (9.5 mm) | 2.250″ (57.2 mm) | 1.094″ (27.8 mm) | 7/16″-14 | ||
| CAT Style (6,000 PSI) | 1.875″ (47.6 mm) | 0.560″ (14.2 mm) | 2.250″ (57.2 mm) | 1.094″ (27.8 mm) | 7/16″-14 | ||
| -20 | 1-1/4″ | SAE Code 61 (3,000 PSI) | 2.000″ (50.8 mm) | 0.315″ (8.0 mm) | 2.312″ (58.7 mm) | 1.188″ (30.2 mm) | 7/16″-14 |
| SAE Code 62 (6,000 PSI) | 2.125″ (54.0 mm) | 0.405″ (10.3 mm) | 2.625″ (66.7 mm) | 1.250″ (31.8 mm) | 1/2″-13 | ||
| CAT Style (6,000 PSI) | 2.125″ (54.0 mm) | 0.560″ (14.2 mm) | 2.625″ (66.7 mm) | 1.250″ (31.8 mm) | 1/2″-13 | ||
| -24 | 1-1/2″ | SAE Code 61 (3,000 PSI) | 2.375″ (60.3 mm) | 0.315″ (8.0 mm) | 2.750″ (69.9 mm) | 1.406″ (35.7 mm) | 1/2″-13 |
| SAE Code 62 (6,000 PSI) | 2.500″ (63.5 mm) | 0.495″ (12.6 mm) | 3.125″ (79.4 mm) | 1.438″ (36.5 mm) | 5/8″-11 | ||
| CAT Style (6,000 PSI) | 2.500″ (63.5 mm) | 0.560″ (14.2 mm) | 3.125″ (79.4 mm) | 1.438″ (36.5 mm) | 5/8″-11 | ||
| -32 | 2″ | SAE Code 61 (3,000 PSI) | 2.812″ (71.4 mm) | 0.375″ (9.5 mm) | 3.062″ (77.8 mm) | 1.688″ (42.9 mm) | 1/2″-13 |
| SAE Code 62 (6,000 PSI) | 3.125″ (79.4 mm) | 0.495″ (12.6 mm) | 3.812″ (96.8 mm) | 1.750″ (44.5 mm) | 3/4″-10 | ||
| CAT Style (6,000 PSI) | 3.125″ (79.4 mm) | 0.560″ (14.2 mm) | 3.812″ (96.8 mm) | 1.750″ (44.5 mm) | 3/4″-10 |
Code 61 vs Code 62 Bench Benchmarks for Caliper Checks
Standing at the bench with a caliper? Measure the flange head thickness:
- 0.265″–0.375″ (varies by size) = SAE Code 61
- 0.305″–0.495″ (varies by size) = SAE Code 62
- 0.560″ flat = CAT Style (constant across -12 through -32)
CAT Flange Rule: Caterpillar flanges in sizes -12 through -32 share the same head O.D. and bolt hole pattern as SAE Code 62, but use a uniform 0.560″ (14.2 mm) head thickness across every size.
Code 61 vs. Code 62 O.D. Rule: For any given dash size, a Code 62 flange head is always 1/8″ (0.125″) larger in outside diameter than a Code 61 flange head.
Fitting a CAT-style flange?
Don’t forget the matching hardware: Caterpillar-style thick split flange halves and extended bolt kits (standard bolts are too short for the 0.560″ head thickness).
CAT flanges also need a CAT D-ring, not a standard round O-ring. We stock the full range: FF90319-12 (-12), FF90319-16 (-16), FF90319-20 (-20), and FF90319-24 (-24). See the FF90319-20 product page for full specs on the D-ring itself.
Decoding a Flange Fitting Part Number
Part numbers encode the flange style, dash size, and configuration. Using 6S20CTB20 as an example:
| Segment | Example | What it means |
|---|---|---|
| Prefix | 6S | Hose/fitting series and wire construction (e.g., 6-wire spiral compatible) |
| Dash size (first) | 20 | Hose dash size — 20 = 1-1/4″ nominal |
| Flange style | CTB | Configuration code (e.g., CAT-style flange, bent/angled head) |
| Dash size (second) | 20 | Flange end dash size, confirming end-to-end match |
Exact prefix and style codes vary by manufacturer (Aeroquip, Parker, Gates, Danfoss) — always confirm against the brand’s own catalog before ordering. See the Danfoss cross‑reference tool for common substitutions.
O-Ring & D-Ring Reference
SAE Code 61 and Code 62 flanges use standard round SAE AS568 series O-rings:
- -08 → AS568-210
- -12 → AS568-214
- -16 → AS568-219
- -20 → AS568-222
- -24 → AS568-225
- -32 → AS568-228
CAT-style flanges are different: they seal with a D-shaped Nitrile (Buna-N) D-ring, not a round O-ring. We stock all four common sizes:
- -12 → FF90319-12
- -16 → FF90319-16
- -20 → FF90319-20
- -24 → FF90319-24
Frequently Asked Questions
What’s the difference between Code 61 and Code 62 flanges?
Code 61 is rated to 3,000 PSI and Code 62 is rated to 6,000 PSI. For the same dash size, Code 62 has a thicker head and a larger outside diameter (typically 1/8″ larger) than Code 61, along with larger bolts on bigger sizes.
Are CAT flanges interchangeable with Code 62?
CAT-style flanges share the same head O.D. and bolt hole pattern as Code 62 in sizes -12 through -32, so the flange halves will physically line up. However, CAT flanges use a thicker 0.560″ head, so you need CAT-specific (extended) bolts — standard Code 62 bolts will be too short to properly seat and torque.
How do I tell Code 61, Code 62, and CAT flanges apart without a spec sheet?
Measure head thickness with a caliper: 0.265″–0.375″ is Code 61, 0.305″–0.495″ is Code 62, and a flat 0.560″ across every size is CAT style.
Why is my Code 62 flange loose on a Caterpillar machine?
This usually means a Code 62 flange was installed where a CAT-style flange is needed. Because CAT flanges are thicker (0.560″ vs up to 0.495″ for Code 62), a Code 62 flange and standard bolts won’t clamp down fully against a CAT-style mating surface, leaving it loose or prone to leaking.
What size hose works with a -20 flange?
A -20 dash size corresponds to 1-1/4″ nominal inside diameter hose. Confirm your hose series (e.g., SAE 100R15 4-wire or 6-wire spiral) matches your system pressure before crimping. Note that if you are using a -20 Caterpillar-style flange (like a 4S20CT20 fitting), it requires a specialized Caterpillar D-Ring seal such as Danfoss part number FF90319-20 rather than a standard round SAE O-ring.
Reviewed by: James Westervelt, Hydraulic Hoses Near Me LLC / J&N Equipment Repair — Fluid Power Association Certified
Last updated: August 30, 2026