NPTLOK, Your Reliable Hex Plug Manufacturer
Cast for Low Pressure, Machined for High Pressure
- Cast hex plug: economical one-piece forming
- Machined hex plug: precision threads, up to 6,000 psi
- Stainless steel, brass, and carbon steel available
- NPT, BSP, and metric threads, one supplier, all standards
One Supplier, Two Solutions
NPTLOK makes hex plugs for every pressure range. Cast hex plugs handle 150 psi for water, air, and low-pressure systems, economical and ready to ship. Machined hex plugs handle 3,000 to 6,000 psi for hydraulic and instrumentation applications, precision threads, stainless steel, and full traceability.
NPT, BSP, or metric threads. Solid or hollow. Cast or machined. Stainless steel, brass or carbon steel. One supplier. All your hex plug needs.
Get in touch with us today to request a quote or sample. We have a minimum order quantity of 10 pieces, so why not try us out before placing a larger order?

One-piece forming. 150 psi rating. Economical. Good for water lines, air lines, and general plumbing.

Precision cut threads. 3,000 to 6,000 psi. Stainless steel or brass or carbon steel. Full traceability. MTC with every batch.

These parts have holes for checking pressure, letting air out, or draining liquids. You can get them made in two ways: cast for lower pressure or machined for higher pressure.

Solid hex plug is completely sealed, making it ideal for permanent closure of a port. It comes in two different versions: one that is cast and another that is machined.

SS304 or SS316. Low pressure cast or high pressure machined. Vibration resistant. Heat number stamped.

High pressure machined. Cost-effective. Good for water, air, and general industrial use.

High pressure machined. Strong and economical. Requires coating or plating for rust protection. Good for oil, gas, and hydraulic systems.
Features of Our Hex Plug
One-piece forming. Economical. 150 psi. Or Precision threads. 3,000-6,000 psi.
Permanent seal or pressure tapping.
Vibration resistance or low cost or dry environment.
NPT, BSP, metric. We match your system.
Cast vs Machined, Which Hex Plug Do You Need?
Here’s the simple rule.
Cast hex plug: One-piece forming. 150 psi. Economical. Use it for water lines, air lines, drain ports, and general plumbing where pressure is low.
Machined hex plug: Precision cut threads. 3,000 to 6,000 psi. Use it for hydraulic power units, instrumentation panels, chemical plants, and oil and gas equipment where pressure is high and leaks are not an option.
Not sure? Ask yourself two questions: What’s my pressure? Any vibration? Low pressure and no vibration? Cast. High pressure or with vibration? Machined.
Don’t buy the wrong one. A cast plug on a 3,000 psi line will crack. A machined plug on a water line is a waste of money. Pick right the first time.
If you want both, it’s okay, we make both.


Solid vs Hollow, When Do You Need a Hole?
Solid hex plug: No hole. Use it to seal an unused port permanently. Close it and forget it.
Hollow hex plug: Has a through hole. Use it when you need to tap pressure, vent air, or drain fluid from a low point.
Common hollow plug applications:
- Pressure gauge connection: put a hollow plug under the gauge
- System vent: install at the highest point to let air out
- Drain port: install at the lowest point to drain fluid
Decide whether you need a hole and we can meet all your needs either.
Where Are Hex Plugs Used?

Machined hex plug seals unused ports on valve blocks. 3,000-6,000 psi.

Machined hollow plug for pressure gauge tapping. Precision threads, no leaks.


Machined stainless steel plug. Corrosion resistant. Full traceability. MTC included.

Cast plug. Low pressure. Cheap. Easy to install.

High pressure machined plug. 6,000 psi. Heat number on every piece.
当社についてもっと詳しく知りたい方はこちら
- Machined Hex Plug Catalog
- Cast Hex Plug Catalog
- ISO-9001認証
- MTC
- EAC1
- EAC2
- EAC3
- EAC4
- EAC5









Look at your system’s maximum pressure. 150 psi or less? Cast is fine. 3,000 psi or higher? Machined. If you’re between 150 and 3,000 psi, go with machined to be safe.
NPT is standard in North America. BSPT or BSPP in Europe and Asia. Metric on OEM equipment. Measure the outer diameter. Or send us a photo. We’ll tell you.
1/8″, 1/4″, 3/8″, 1/2″, 3/4″, 1″. Larger sizes on request.
SS, Brass, and Carbon Steel.
Stainless steel for vibration resistance. Brass for water, air, and lower budget. Carbon steel for a dry environment. It needs coating to prevent rust. Pick by your media and budget.







