Technical Guide

SAE Flange Fittings

Code 61 vs Code 62 — the high-pressure connection standard

Complete guide to SAE Code 61 and Code 62 flanges: 3000 PSI vs 6000 PSI, flange size identification, port patterns, and how to select the right flange for your hydraulic system.

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How to Identify an SAE Flange

SAE flanges are used in high-pressure hydraulic lines where a bolted, leak-free connection is required.

Count the Bolt Holes

All SAE flanges use 4 bolt holes in a square pattern around the centre bore. Count the holes: 4 holes = SAE flange (BSP flanges typically have 4 holes too, but the bolt pattern dimensions differ). The hole count alone doesn't distinguish Code 61 from Code 62 — both have 4 holes.

Measure the Bolt Circle Diameter (BCD)

Measure the diameter of the circle passing through the centre of the 4 bolt holes. This is the key distinguishing measurement: Code 61 flange BCD is smaller than Code 62 for the same nominal size. e.g., 1" Code 61: BCD = 52.4mm. 1" Code 62: BCD = 57.2mm. The Code 62 flange also has larger bolt holes.

Measure the Flange Face OD

Code 61: smaller flange OD for a given size. Code 62: larger flange OD and thicker material for higher pressure. At 1" size: Code 61 OD ≈ 63mm; Code 62 OD ≈ 70mm. The Code 62 flange has visibly thicker material and larger bolt holes (M10 vs M8 for 1" size).

Check the Pressure Rating (PSI)

Code 61 (3000 PSI / 207 bar): standard pressure rating. Used for general mobile and industrial hydraulic systems. Code 62 (6000 PSI / 414 bar): high pressure. Used in severe-duty, high-pressure systems — often mining, marine, and heavy construction. Never substitute Code 61 for Code 62 in a high-pressure system.

Identify the Configuration

SAE flanges come in several configurations: Straight (code 61C / 62C): flange connects to port or another flange. 45° Elbow (code 61A / 62A): exits at 45°. 90° Elbow (code 61B / 62B): exits at 90°. The configuration letter is part of the SAE standard designation.

Check the Flange Size

SAE flange size is designated by the nominal bore: size 8 (1/2" bore), size 12 (3/4" bore), size 16 (1" bore), size 20 (1-1/4" bore), size 24 (1-1/2" bore), size 32 (2" bore), size 40 (2-1/2" bore), size 48 (3" bore). Note: the flange size refers to the bore, not the port thread or hose ID.

Technical Specifications

Code 61 — 3000 PSI	Standard pressure series. BCD smaller, flange OD smaller, bolt holes smaller. Used in general mobile hydraulics: excavators, tractors, trucks. Common sizes: 8 to 48.
Code 62 — 6000 PSI	High pressure series. BCD larger, flange OD larger, thicker material, larger bolt holes. Used in severe-duty: mining, marine, high-pressure presses. NOT interchangeable with Code 61.
Flange Size 8	1/2" bore. Code 61 BCD: 40.5mm, OD: 53mm. Code 62 BCD: 40.5mm, OD: 56mm.
Flange Size 12	3/4" bore. Code 61 BCD: 50.8mm, OD: 63mm. Code 62 BCD: 50.8mm, OD: 63mm.
Flange Size 16	1" bore. Code 61 BCD: 52.4mm, OD: 63mm. Code 62 BCD: 57.2mm, OD: 70mm.
Flange Size 20	1-1/4" bore. Code 61 BCD: 58.7mm, OD: 70mm. Code 62 BCD: 66.7mm, OD: 79mm.
Flange Size 24	1-1/2" bore. Code 61 BCD: 70.0mm, OD: 80mm. Code 62 BCD: 79.4mm, OD: 94mm.
Flange Size 32	2" bore. Code 61 BCD: 77.8mm, OD: 88mm. Code 62 BCD: 96.8mm, OD: 101mm.
Config: Straight (C)	Flange face perpendicular to hose axis. Used to connect to a port or in-line connection.
Config: 45° Elbow (A)	Flange face at 45° to hose axis. Used to change direction with minimum bending stress.
Config: 90° Elbow (B)	Flange face at 90° to hose axis. Most common elbow configuration.
BCD / OD Key	BCD = Bolt Circle Diameter (centre-to-centre of opposite bolt holes). OD = Flange Outside Diameter (overall face diameter).
Port Standard	SAE J518 (Code 61/62 flanges). ISO 6162-1 (Code 61). ISO 6162-2 (Code 62). BSPP flange ports also exist (ISO 6164).
Technical Disclaimer	Dimensions shown are representative SAE J518 / ISO 6162 interface dimensions. Actual fitting/component geometry may vary by manufacturer and design. Verify against the applicable manufacturer's drawing before ordering.

How to Identify an SAE Flange

Use this checklist to identify a hydraulic SAE flange: 1. **Measure the nominal bore** — the hose connection size (1/2", 3/4", 1", etc.) 2. **Measure the bolt circle diameter (BCD)** — the diameter through the centre of the 4 bolt holes 3. **Measure the flange outside diameter (OD)** — the overall flange face diameter 4. **Count the bolt holes** — SAE flanges always have 4 bolt holes 5. **Determine Code 61 or Code 62** — compare your BCD and OD measurements against this table 6. **Verify before ordering** — confirm against the equipment manufacturer's flange drawing Not sure which flange you need? Send us a photo via WhatsApp and we can help identify it.

Code 61 vs Code 62 — Key Differences at a Glance

How to Select the Right Flange

Step 1: Identify the pressure requirement → System pressure ≤ 250 bar: Code 61 is sufficient → System pressure 250–350 bar: Check manufacturer spec — Code 61 or Code 62 → System pressure > 350 bar: Code 62 required Step 2: Measure or identify the flange size → Measure the bore of the hose or port connection → Match to SAE flange size (8 = 1/2", 12 = 3/4", 16 = 1", etc.) Step 3: Choose the configuration → Straight: for port connections and in-line runs → 45° Elbow: directional change where 90° is too sharp → 90° Elbow: most common for routing around components Step 4: Specify the hose end → SAE Code 61/62 flange fittings are crimped onto the hose end → Always specify: flange size + configuration + hose type + hose length