1/4 BSP Male Hex Head Captive Seal

1/4 BSP Male Hex Head Captive Seal is a small part used to block the oil or inspection ports in the hydraulic system. The specification is 1/4 inch BSP external thread (that is, G1/4"), and the head is an external hexagon. It can be tightened by using an ordinary wrench. What's special about it is that it comes with a self-locking sealing ring - this sealing ring is fixed on the end face of the plug and will not fall off or shift.

Technical Specifications

The following parameters related to the 1/4 BSP Male Hex Head Captive Seal are for reference only. The specific data may vary depending on the specifications.

Project	Value
Thread specification	G1/4" (BSPP)
Hexagon edge width	Usually 19 mm
Thread length	Approximately 12–15 mm
Maximum working pressure	Up to 350–400 bar
Operating temperature (NBR)	-40°C to +120°C
Operating temperature (FKM)	-15°C to +200°C
Material	Carbon steel (galvanized / nickel-plated), stainless steel 304/316L, brass

Main features

（1）Hexagonal shape of the head

It can be tightened by using an ordinary open-end wrench or a socket wrench. The operation is simple.

The external hexagonal shape can withstand greater tightening force than the internal hexagonal shape, and it is less likely to slip or damage the head.

（2）Built-in anti-detachment sealing ring

The sealing ring is fixed in the groove on the end face of the 1/4 BSP Male Hex Head Captive Seal and will not fall off or shift.  

No separate gaskets are required during installation, nor is it necessary to wrap the raw material tape or apply sealant.

（3）End face seal, ensuring reliable and leak-proof performance

After being tightened, the sealing ring is pressed tightly between the end face of the 1/4 BSP Male Hex Head Captive Seal and the oil outlet plane, thus forming a seal.

Not affected by the accuracy of the thread.

（4）A wide range of material options

Carbon steel galvanization: Cost-effective.

Stainless steel 304/316L: Corrosion-resistant, suitable for marine, chemical and food environments.

Bronze: Suitable for water, gas or low-pressure oil circuits.

Compliant with international standards

The size conforms to international standards and can be used in conjunction with various mechanical equipment.

（5）Easy to install and maintain

First, screw it in by hand to ensure the threads are aligned properly. Then, use a wrench to tighten it.

After disassembly and assembly, as long as the sealing ring is not damaged, it can be reused.

（6）The identification is clear.

The top surface of the hexagonal head is usually stamped with "G1/4″ or "1/4", which is convenient for on-site identification.