The Versatility of Spare Parts Hydraulic Connector Adapter Carbon Steel SAE Thread Flange

An SAE thread flange, also called a split flange or SAE J518 flange, is a two-piece carbon steel clamp that seals a hose or tube end to a port using an O-ring and bolted clamp halves. It is the standard high-pressure connection for hydraulic power units and mobile equipment. For the matched sealing face, see our flange gaskets and flange products.

What an SAE Thread Flange Is

The assembly has four parts: two clamp halves (the split flange), a welded or threaded tail (nipple), and an O-ring seated in the groove of the tail. Tightening the bolts squeezes the O-ring between the tail face and the mating port, giving a soft-seal that will not loosen from vibration. Carbon steel is the default material for the pressure range and cost.

Code 61 and Code 62

• Code 61 (SAE J518-1) — 3000 psi working pressure, the common size for most hydraulic circuits.
• Code 62 (SAE J518-2) — 6000 psi working pressure, thicker clamp and larger bolts for high-pressure lines.
• Both share bolt-circle geometry per size, so the halves are interchangeable in footprint but not in rating.

Choosing the Right Code

Why Use a Split Flange

Against NPT or ORFS threaded ports, the split flange wins on large-bore, high-flow lines where threading a hose into a port is slow and leak-prone. The O-ring seal tolerates moderate misalignment and is easy to service: replace the O-ring, not the whole fitting.

Key Benefits

• Leak-free soft seal from the O-ring under pressure and vibration.
• Standardized SAE geometry for cross-brand compatibility and easy spare sourcing.
• Strong carbon steel body that survives shock loads in mobile machinery.
• Simple field assembly — clamp halves, tail, and O-ring only.

Where They Are Used

SAE thread flanges appear wherever hydraulic power moves through hose and tube: construction and agricultural machinery, mining equipment, injection molding and press lines, and offshore and marine hydraulics. They suit stationary power units as well as equipment that runs through heavy duty cycles.

Fitting It Into the Circuit

The flange clamps the hose or tube; the seal lives in the gasket face of the mating port, while the flange carries the line into the manifold or cylinder. Pair the flange code to the port rating so the joint matches the system pressure.

Installation and Care

Weld or thread the tail to the line, slip on the clamp halves, seat a new O-ring, and torque the bolts evenly in a cross pattern to the published value. Inspect the O-ring for nicks and the bolt holes for cracking at each service. Use a compatible O-ring compound for the fluid and temperature, and never mix a Code 61 half with a Code 62 port under pressure.

Frequently Asked Questions

Can Code 61 and Code 62 halves be mixed?

No. The bolt circles match by size, but the pressure ratings differ. Always fit the half to the port code; a 3000 psi half on a 6000 psi port will leak or fail.

Why does my flange still weep?

Usually a cut or hardened O-ring, an uneven bolt torque, or dirt on the sealing face. Replace the O-ring, clean the face, and re-torque in a cross pattern.

Steel or stainless for the flange?

Carbon steel covers most hydraulic service. Choose stainless when the line sees washdown, seawater, or corrosive atmosphere that would rust the clamp.