How to Identify and Measure Fittings
Pipe size is an industry designation, not the actual size. View information about how to measure threaded and unthreaded pipe and pipe fittings.
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Nuts for High-Pressure Nipples for Compressed Gas
Slide a high-pressure hose nipple for compressed gas into one of these nuts to connect a pipe to the inlet of a pressure regulator. They are also known as CGA (Compressed Gas Association) nuts and inlet nuts.
Brass nuts have good corrosion resistance and are softer than 316 stainless steel nuts, so they're easier to thread together. Chrome-plated brass nuts have comparable corrosion and wear resistance to aluminum-plated brass nuts, and have a bright, shiny appearance.
Nuts with a plastic grip can be tightened by hand instead of with a wrench.
Nuts with left-hand threads are identified with a notch.
Note: Nuts have a CGA, BS, or DIN number that corresponds to a specific type of gas. Choose a nut with the same number as your tank and other system components.
For technical drawings and 3-D models, click on a part number.

- Maximum Pressure: See table
- Maximum Temperature: 120° F, except DIN 477 No. 9: 250° F
Number | Thread Size | Thread Type | Thread Direction | Max. Pressure | For Use With | Each | |
Brass | |||||||
---|---|---|---|---|---|---|---|
CGA 300 | 0.830"-14 | NGO | Right Hand | 500 psi @ 72° F | Ethyl Chloride | 000000000 | 00000 |
CGA 320 | 0.830"-14 | NGO | Right Hand | 3,000 psi @ 72° F | Carbon Dioxide | 000000000 | 0000 |
CGA 326 | 0.830"-14 | NGO | Right Hand | 3,000 psi @ 72° F | Nitrous Oxide | 000000000 | 0000 |
CGA 330 | 0.830"-14 | NGO | Left Hand | 3,000 psi @ 72° F | Boron Trifluoride, Carbonyl Sulfide, Hydrogen Bromide, Hydrogen Chloride, Hydrogen Iodide, Hydrogen Sulfide, Methyl Bromide, Silicon Tetrafluoride, Sulfur Tetrafluoride | 000000000 | 00000 |
CGA 346 | 0.830"-14 | NGO | Right Hand | 3,000 psi @ 72° F | Air | 000000000 | 0000 |
CGA 347 | 0.830"-14 | NGO | Right Hand | 4,700 psi @ 72° F | Air | 000000000 | 00000 |
CGA 350 | 0.830"-14 | NGO | Left Hand | 3,000 psi @ 72° F | Carbon Monoxide, Ethane, Ethylene, Hydrogen, Methane, Methyl Fluoride, Natural Gas | 000000000 | 0000 |
Brass with Plastic Grip | |||||||
CGA 320 | 0.830"-14 | NGO | Right Hand | 3,000 psi @ 72° F | Carbon Dioxide | 000000000 | 00000 |
CGA 346 | 0.830"-14 | NGO | Right Hand | 3,000 psi @ 72° F | Air | 000000000 | 00000 |
Chrome-Plated Brass | |||||||
CGA 320 | 0.830"-14 | NGO | Right Hand | 3,000 psi @ 72° F | Carbon Dioxide | 000000000 | 00000 |
CGA 326 | 0.830"-14 | NGO | Right Hand | 3,000 psi @ 72° F | Nitrous Oxide | 00000000 | 00000 |
CGA 346 | 0.830"-14 | NGO | Right Hand | 3,000 psi @ 72° F | Air | 00000000 | 00000 |
CGA 350 | 0.830"-14 | NGO | Left Hand | 3,000 psi @ 72° F | Carbon Monoxide, Ethane, Ethylene, Hydrogen, Methane, Methyl Fluoride, Natural Gas | 000000000 | 00000 |
High-Pressure Threaded Fittings for Compressed Gas
Designed to handle high-pressure welding applications, these fittings are commonly used to connect pressure regulators to compressed gas tanks or cylinders. Fittings are also known as CGA (Compressed Gas Association) fittings. They are brass for good corrosion resistance.
Fittings with left-hand threads are identified with a notch in the nut.
Note: Fittings have a CGA number that corresponds to a specific type of gas. Choose a fitting with the same CGA number as your tank and other system components.
For technical drawings and 3-D models, click on a part number.

- Maximum Pressure: See table
- Maximum Temperature: 120° F
CGA Number | Tank Connection | Regulator Connection | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Tank | Regulator | Thread Size | Thread Type | Thread Direction | Thread Size | Thread Type | Thread Direction | Max. Pressure | For Use With | Each | |
Brass | |||||||||||
300 | 510 | 0.830"-14 | NGO | Right Hand | 0.880"-14 | NGO | Left Hand | 500 psi @ 72° F | Acetylene, Butane, Cyclopropane, Dimethyl Ether, Ethyl Chloride, Ethylene Oxide, Isobutane, Methane, Methyl Chloride, Natural Gas, Propane, Propylene, Vinyl Bromide, Vinyl Chloride | 0000000 | 00000 |
320 | 580 | 0.830"-14 | NGO | Right Hand | 0.960"-14 | NGO | Right Hand | 3,000 psi @ 72° F | Argon, Carbon Dioxide, Helium, Krypton, Neon, Nitrogen, Xenon | 0000000 | 00000 |
346 | 580 | 0.830"-14 | NGO | Right Hand | 0.960"-14 | NGO | Right Hand | 3,000 psi @ 72° F | Air, Argon, Helium, Krypton, Neon, Nitrogen, Xenon | 0000000 | 00000 |
350 | 580 | 0.830"-14 | NGO | Left Hand | 0.960"-14 | NGO | Right Hand | 3,000 psi @ 72° F | Argon, Carbon Monoxide, Ethane, Ethylene, Helium, Hydrogen, Krypton, Methane, Methyl Fluoride, Natural Gas, Neon, Nitrogen, Xenon | 0000000 | 00000 |

- Maximum Pressure: See table
- Maximum Temperature: 120° F
CGA Number | Tank Connection | Regulator Connection | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Tank | Regulator | Thread Size | Thread Type | Thread Direction | Thread Size | Thread Type | Thread Direction | Max. Pressure | For Use With | Each | |
Brass | |||||||||||
200 | 300 | 0.628"-14 | NGO | Right Hand | 0.830"-14 | NGO | Right Hand | 500 psi @ 72° F | Acetylene, Ethyl Chloride | 0000000 | 000000 |
346 | 540 | 0.830"-14 | NGO | Right Hand | 0.908"-14 | NGO | Right Hand | 3,000 psi @ 72° F | Air, Oxygen | 0000000 | 00000 |

- Maximum Pressure: See table
- Maximum Temperature: 120° F
CGA Number | Tank Connection | Regulator Connection | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Tank | Regulator | Thread Size | Thread Type | Thread Direction | Thread Size | Thread Type | Thread Direction | Max. Pressure | For Use With | Each | |
Brass | |||||||||||
510 | 300 | 0.880"-14 | NGO | Left Hand | 0.830"-14 | NGO | Right Hand | 500 psi @ 72° F | Acetylene, Butane, Cyclopropane, Dimethyl Ether, Ethyl Chloride, Ethylene Oxide, Isobutane, Methane, Methyl Chloride, Natural Gas, Propane, Propylene, Vinyl Bromide, Vinyl Chloride | 0000000 | 000000 |
580 | 320 | 0.960"-14 | NGO | Right Hand | 0.830"-14 | NGO | Right Hand | 3,000 psi @ 72° F | Argon, Carbon Dioxide, Helium, Krypton, Neon, Nitrogen, Xenon | 0000000 | 00000 |
580 | 346 | 0.960"-14 | NGO | Right Hand | 0.830"-14 | NGO | Right Hand | 3,000 psi @ 72° F | Air, Argon, Helium, Krypton, Neon, Nitrogen, Xenon | 0000000 | 00000 |
580 | 350 | 0.960"-14 | NGO | Right Hand | 0.830"-14 | NGO | Left Hand | 3,000 psi @ 72° F | Argon, Carbon Monoxide, Ethane, Ethylene, Helium, Hydrogen, Krypton, Methane, Methyl Fluoride, Natural Gas, Neon, Nitrogen, Xenon | 0000000 | 00000 |
590 | 346 | 0.960"-14 | NGO | Left Hand | 0.830"-14 | NGO | Right Hand | 3,000 psi @ 72° F | Air, Sulfur Hexafluoride | 0000000 | 00000 |