Hollow Hex O-Ring Steel Plug

application scope 

The application scope of Hollow Hex O-Ring Steel Plug is closely related to its structural features: it adopts a hollow design, uses an internal hexagonal drive mechanism, and has end face O-ring sealing. Therefore, it is mainly applied in the following scenarios:

（1）Hydraulic system

It is used to seal the unused process holes or inspection ports on hydraulic valve blocks, pump stations, and oil cylinders.

The hollow structure can be used for pressure relief, exhaust, or as a flow-limiting channel (for example, in situations where a small amount of oil needs to be released or buffering is required).

（2）Pneumatic equipment

In cylinders, pneumatic valves, and air path boards, Hollow Hex O-Ring Steel Plug can be used as sealed plugs to prevent compressed air from leaking.

The hollow design can be used for muffler interfaces or for slow deflation.

（3）Lubrication system

As the end cap in the centralized lubrication pipeline, the hollow hole can accommodate a pressure gauge or sensor (if the thread is compatible).

（4）Automobiles and construction machinery

Sealing of the oiling ports or reserved holes of the gearbox, transfer case, and drive axle.

The hollow screw plugs can also be used as throttling plugs to control the flow of oil.

（5）Instrument and test interface

A temporary connection port for the test equipment is required. It is sealed with a hollow plug when not in use; during use, it can be directly connected to the pressure gauge or the oil sample collection needle valve through the central hole.

Storage and Spare Parts Management

(1) Storing spare Hollow Hex O-Ring Steel Plug

Keep them in a dry place with no dust. If they're made of carbon steel, put a little anti‑rust oil on them or seal them in an anti‑rust bag.

(2) Storing sealing parts

For copper washers, ED rings, and O‑rings, keep them away from light, high heat, and ozone. Rubber parts don't last forever – they usually have a shelf life of about 5 to 10 years.

(3) Storing magnetic Hollow Hex O‑Ring Steel Plugs

Keep them away from strong magnetic fields, high temperatures, and hard impacts. Avoid demagnetization or cracking of the magnets.

FAQ

（1）(1) What is the maximum working pressure of your Hollow Hex O-Ring Steel Plug?

For parallel threaded plugs with sealing rings, the recommended maximum pressure is 63 megapascals. For conical threaded plugs, they can typically withstand up to 140 megapascals in hydraulic applications, depending on the thread size and material.

（2）What torque should be applied during installation?

The torque size depends on the thread size and the material. For the standard M14 × 1.5 steel plug (with copper washer), the recommended torque is 35 to 45.

（3）Can I use a used copper washer again?

We strongly recommend replacing the copper crush washer every time you remove the plug. Copper work‑hardens after compression and will not seal properly when reused. For cost‑saving, you can use an ED ring or O‑ring which can be reused 2–3 times.