Alloy 400

A single-phase, solid-solution nickel-copper alloy that’s highly resistant to corrosion in a wide variety of temperatures and conditions. While used in many industries and applications, it has been prevalent in the marine and chemical processing industries.

Ball Valve

A quarter-turn valve that uses a hollow, perforated, pivoting ball to control the flow of fluids passing through it. Because of their durability and reliability (even after periods of disuse), they are often utilized in shutdown and control applications.

Bellows Valve

Surrounded on the outside by bellows, these valves are commonly used in applications where preventing leakage is critical. As such, they are common for applications in semiconductor manufacturing, biotechnology, and pharmaceutical industries.

Bleed Valve

Bleed valves isolate (block) the flow of fluid in the system, allowing liquid to be removed from a tank or tube.

Bulkhead Union

A point of connection designed to pass through the sealed wall of a vessel or tank. These fittings are also used as distribution outlets in a piping systems.

Carbon Steel

Steel with carbon content up to 2.1%. While significantly harder and more durable than many materials, carbon steel with higher carbon content is less ductile and weldable.

Calibration Fittings

Hy-Lok calibration fittings for DP transmitters offer quick access for transmitter calibration, saving time and lowering costs. Our calibration fittings are made with straight threads to eliminate galling, and are constructed from 316 stainless steel (SS316) for maximum durability and corrosion resistance.

Check Valve

Any two-port valve that typically allows fluid to flow through it in only one direction. They are a wide variety of check valves, and they can be found in everything from heavy industrial applications to everyday household appliances.

Check Valve

Any two-port valve that typically allows fluid to flow through it in only one direction. They are a wide variety of check valves, and they can be found in everything from heavy industrial applications to everyday household appliances.

Diaphragm Valve

A type of valve that uses a flexing rubber diaphragm to create a seal. Pressure on the upstream side must be higher than on the downstream side (this is known as the pressure differential) for the valve to open. Once positive pressure stops, the diaphragm flexes back to the closed position.

Dielectric Union

These fittings are used to separate two metal pipes made of different metals (such as copper and stainless steel), preventing galvanic corrosion caused by electrolysis.

DIN 2353 Fittings

These ball and non-return valves can handle pressures up to 800 bar at 120° C, and conform to installation standard ISO 8434 part1 and DIN 2353. Hy-Lok offers precision valves made of stainless steel, carbon steel, and brass, constructed to the highest standards of quality and safety.

Excess Flow Valves

A check valve with override control to stop the flow of fluids, regardless of flow direction or pressure.

Ferrule Fittings

A “ferrule” is any object used for fastening, joining, sealing, or reinforcement. Many compression fittings for attaching tubing or piping require ferrules, and are commonly used to create liquid-tight connections. Hy-Lok offers a wide variety of ferrules engineered for every standard and application, as well as the ability to custom-build products to your specifications.

Flare Fittings

A type of compression fitting used with metal tubing (usually soft steel, copper, aluminum, and other ductile metals). A flare nut is used to secure the flared tubing’s tapered end to the fitting, producing a pressure-resistant, leak-tight seal.


A nickel-molybdenum-chromium superalloy designed to have exceptional resistance to corrosion in demanding environments. Hastelloy C276 is the most widely used alloy in most applications.

Heat Exchanger Tube Plugs

Heat exchangers are systems used to transfer heat between two or more fluids. They are commonly found in heating, refrigeration, air conditioning, power stations, chemical plants, the petroleum industry, and sewage treatment. Hy-Lok tube plugs are manufactured to the highest quality and safety standards to ensure a leak-free seal, no matter what the application.

Hose Fittings/Couplings

Hy-Lok hose connectors provide quick and easy installation for soft plastic or rubber hose. Our connectors are durable, fully reusable, and allow your organization to save both time and money on installation and use.

In-Line (Poppet-style) Check Valve

An in-line check valve features a spring that can be lifted off its seat by higher pressure of inlet or upstream fluid to allow flow to the outlet or downstream side. When the upstream pressure subsides, gravity or downstream pressure causes the disc to lower and shut the valve.

Needle Valve

A type of valve with a small port and a threaded, needle-shaped plunger. Because of this shape, needle valves are often used in precision-based applications where high flow rates are not required.

Nitrogen Leak Testing

In order to ensure our products meet the highest quality standards, all Hy-Lok components undergo extensive Nitrogen Leak Testing to ensure a leak-free seal in working conditions.

Pipe Fittings

In addition to valves, Hy-Lok offers a wide variety of fittings for all of your connection needs. With a wide range of materials available and the ability to manufacture fittings to your exact specifications, Hy-Lok is proud to offer a variety of quality products to meet even the most demanding requirements.

Plug Valve

A valve with a cylindrical or cone-shaped plug which can be rotated inside the valve to control flow. Simple and economical, the most common use for this type of valve is as a shutoff valve for household natural gas lines.

Poppet Valve

These valves are typically used to control the timing and quantity of gas and vapour flow. The plug is spring-loaded to help keep it shut and create a seal.

Presetting Tools

Hy-Lok offers a full range of presetting tools to enhance your tube system installations. We offer manual, hydraulic, and electric automatic presetting tools to expedite installation and maximize productivity for your operation.

Quick Connector

Our Q and QF Series quick connectors are designed for use with laboratory and portable test equipment, gauge calibration, biopharmaceutical applications, and gas distribution. Our easy-to-use connectors cannot be over or under-tightened and are resistant to damage from galling or cross-threading.

Relief Valve

A type of safety valve that controls/limits the pressure in a system. A relief valve allows pressurized fluid to flow from an auxiliary passage out of the system, preventing instrument and equipment failure.

SAE J514 Fittings

These fittings are constructed to the standards of SAE International (formerly the Society of Automotive Engineers). These are commonly used in the aerospace, automotive, and commercial vehicle industries.


A material that has electrical conductivity between a conductor (metallic copper, for example) and an insulator (such as glass). Hy-Lok manufactures top-quality semiconductor components for all industries requiring clean, sterile precision parts. All semiconductor components are oxygen-cleaned and vacuum-sealed to ensure sterility for the most demanding applications.

Shutdown Valves

A valve designed to stop the flow of hazardous fluid upon the detection of a dangerous event, such as a leak or dangerous pressure buildup. They are a vital part of any safety instrumented system, especially in the petroleum industry. Typically, ball valves and block and bleed valves are utilized as shutdown valves in most fluid applications.


An austenitic (non-magnetic) stainless steel with added molybdenum to increase corrosion resistance and improve strength at high temperatures. Because of its durability, SS316 is the ideal material for many exhaust, heat exchange, pharmaceutical, cryogenic, and petrochemical systems. (90% of what we sell)

Swing Check Valve

Also known as a tilting disc check valve, these valves use discs mounted on hinges or trunnions to block reverse flow while still allowing forward flow. Most large check valves are swing check valves.

Trunnion Ball Valves

A type of ball valve that has additional anchoring of the ball at the top and bottom, making it suitable for large and high-pressure applications.

Union Bonnet Needle Valves

A valve type in which the bonnet is held together by a union nut with threads on the body. Union bonnet needle valves provide a leakproof seal, and are suitable for applications requiring frequent inspection and/or cleaning.

ZCO Fittings

These fittings are made up of three basic components: the female nut, the gland, and the body. The body contains a viton o-ring as standard, although other materials are available by request. Hy-Lok ZCO O-Ring Face Seal Fittings feature zero clearance, easy installation and maintenance, and perform in a wide variety of temperatures and pressures.