There is a point where threaded hydraulic connections stop making sense. Above roughly one inch of bore, the torque needed to seal a threaded joint becomes impractical and the fitting gets enormous. The industry's answer is the split flange.
How a flange connection seals
The tube or hose terminates in a flange head with a groove machined into its face. An o-ring sits in that groove. Two split clamp halves bolt the flange head against a flat port face, compressing the o-ring.
As with ORB and ORFS, the o-ring does all the sealing. The bolts only supply clamping force. This is why flange joints tolerate very large bores and very high flow — you can always add clamping force with more or larger bolts, without needing to twist anything.
Code 61 versus Code 62
Two SAE standards, and they are not interchangeable:
- Code 61 — standard pressure series. The common choice for general hydraulic circuits.
- Code 62 — high pressure series. Thicker flange, larger bolts, tighter bolt pattern for the same nominal bore.
They look similar at a glance and will not mate correctly. Check the bolt spacing and flange thickness before ordering anything. Fitting a Code 61 clamp to a Code 62 head is a failure waiting for pressure.
Correct assembly matters more here
Flange joints are unforgiving of sloppy technique:
- Tighten in a cross pattern, in stages, exactly as you would a cylinder head. Pulling one side down first cocks the flange and pinches the o-ring.
- Seat the o-ring in its groove before offering the flange up. A ring that rolls out during assembly will be crushed at the edge and leak immediately.
- Inspect the port face. Scoring across the sealing area will leak regardless of the o-ring.
The sizes you will actually need
Hydraulic O-Ring Kit for Flange Fittings — 70 pieces across 7 common sizes, Buna-N 90 durometer, compartmented case with sizing chart, covering SAE Code 61 and Code 62.
Contents: 10× each of dash 8 (#210), dash 12 (#214), dash 16 (#219), dash 20 (#222), dash 24 (#225), dash 32 (#228) and dash 40 (#232).
As with all hydraulic service, 90 durometer is the right hardness. Softer material extrudes into the clearance gap under pressure and fails early.
Before you reassemble
Every o-ring in these kits seats better and lasts longer with a food-grade silicone lubricant. Dry o-rings pinch, twist and take a set, which is how a brand-new seal starts weeping within a season. A thin film is all you need.
Aqua Flex Food Grade Silicone Lubricant is what we use and what ships in our kits. Apply it to o-rings only — never to the polished faces of a mechanical shaft seal. Those faces need to run dry and clean against each other, and lubricant on the carbon or ceramic will cause the seal to slip, overheat and leak.
Beaver Island Parts Company is not affiliated with, endorsed by, or sponsored by any equipment manufacturer named on this page. All brand names, model numbers and part numbers are the property of their respective owners and are used here solely to identify the equipment our replacement parts fit.