Stainless Steel Hydraulic Fittings

Stainless steel hydraulic fittings are the basic connection components, such as nipples, elbows, tees, adapters and bulkhead fittings, that connect tube and hose lines to the pump, valve block and cylinder, and to each other. In Turkey these parts are often called and written "rekor" in the field, while the correct Turkish name is "rakor"; in a quote request, both spellings refer to the same product. Thread size alone is not enough when selecting a fitting: the thread standard, line pressure, fluid type, temperature, installation orientation and sealing method must be evaluated together. Mismatched standards lead to leaks, thread damage and premature servicing.

Types of stainless steel hydraulic fittings

This group includes four sub-families. Which one you need is usually determined by the tube type and the standard of the port being connected.

Selection by thread standard and line conditions

• Thread standard: The BSP family has a 55° thread profile, while the NPT and UNF families have a 60° profile. Even if they look similar, the angle, pitch and sealing method differ; the outside diameter measured with a caliper is not enough on its own, so the thread pitch gauge and the seal face are checked together.
• Pressure and vibration: At points subject to pressure spikes and vibration, or that are disconnected frequently, parallel-thread connections sealed by a washer or a cone give more repeatable results than tapered threads.
• Fluid and temperature: The O-ring and seal material is selected according to the fluid and the operating temperature.
• Installation orientation and space: In tight spaces, an elbow or a swivel-nut fitting allows the hose or tube to be connected without strain.

Material: 316 or 316L?

The fittings are machined on CNC lathes from AISI 316/316L round bar and hex bar stock; the thread profile, sealing cones and wrench flats are inspected against the tolerances on the technical drawing. Low-carbon 316L is preferred for parts that will be welded. Because both grades contain molybdenum, they are noticeably more resistant than 304 in chloride environments.

Installation notes and common mistakes

Stainless steel threads are prone to galling. Keep the threads clean, use a suitable anti-seize compound, and if a connection runs in freely for a few turns and then suddenly tightens, do not force it; recheck the standard. Connecting tubes and hoses with misalignment or under tension is also a common cause of hidden leaks.

Which industries use them?

On marine and offshore lines exposed to saltwater and vibration, in food plants that use chloride-based cleaning chemicals, in chemical plants handling corrosive fluids, and on rolling mill and board mill lines where maintenance downtime is costly, stainless steel fittings offer a longer service life than carbon steel fittings. Standard sizes in stock are typically ready within 1-3 business days, standard production within 5-10 business days, and custom sizes within 10-20 business days after technical approval.