New Products

Round Head Hollow Threaded Plugs with Threaded Fasteners for Metal and Machinery

This product is a round-head stepped hollow screw plug manufactured from high-quality carbon steel with a black oxide finish. It consists of a large flat round head, a stepped shoulder and a fine-pitch threaded body with an axial through hole in the center and a cross hole on the side of the shoulder.

Send Inquiry

Product Description

Product Overview

This product is a round-head stepped hollow screw plug manufactured from high-quality carbon steel with a black oxide finish. It consists of a large flat round head, a stepped shoulder and a fine-pitch threaded body with an axial through hole in the center and a cross hole on the side of the shoulder. The wide round head provides easy gripping and tightening, the center through hole can be used for venting, pressure balancing or the passage of media, and the cross hole on the shoulder assists tightening or can be used with pins as required. Machined to standard thread specifications, it is a practical and reliable threaded fitting for sealing and connecting ports on mechanical equipment.

Product Features

Large round head: The wide, flat head provides a large bearing area for easy manual gripping or tool application, making tightening effortless and the lock reliable.

Stepped shoulder with cross hole: The cross hole on the shoulder allows an auxiliary bar to be inserted for greater tightening torque, and can also be used with pins or safety wire for locking and anti-loosening purposes.

Fine-pitch precision threads: The threads are clearly formed, uniform and complete, ensuring smooth engagement, firm meshing, reliable sealing and stable locking.

Hollow design with through hole: The axial through hole in the center supports functions such as venting, pressure balancing or the passage of media according to the actual application.

Black oxide finish: The black oxide process forms a uniform black protective layer which, together with an anti-rust oil film, provides good corrosion resistance and a clean appearance.

Application Field

This product is widely used for sealing, venting or through-passage on threaded ports in machinery, hydraulic and pneumatic systems, automotive and engineering equipment, such as oil and air circuit plugs and service openings. It is especially suitable for assembly applications with strict requirements on sealing and anti-loosening performance.

Instructions for use

Selection: Choose the appropriate plug size according to the thread specification, hole diameter and sealing requirements of the mounting port, and check that the threads, through hole and cross hole are intact and clear.

Cleaning: Clean the mounting port and the plug threads before installation to remove oil and dirt. For enhanced sealing, wrap PTFE tape around the threads or apply a suitable sealant.

Installation: Screw the plug smoothly into the port. When greater torque is needed, insert an auxiliary bar into the cross hole on the shoulder for leverage, and tighten to the specified torque without over-torquing to avoid damaging the threads.

Inspection: After installation, confirm the plug is fully seated and sealed reliably; in vibrating applications, inspect and re-tighten periodically.

Maintenance

Rust protection: The black oxide surface relies on an oil film for corrosion resistance. Keep the surface lightly oiled and avoid impacts or scratches that may damage the coating; apply anti-rust oil before long-term storage.

Cleaning: Clean oil and dirt from the threads and the center through hole regularly to prevent blockage that may affect venting or passage functions.

Tightness inspection: For installations under long-term load or vibration, check for loosening regularly and re-tighten in time.

Proper use: Always use matching specifications, avoid ports with mismatched thread sizes, and never reuse parts with damaged or deformed threads.

FAQ

Q: What material and surface finish does this screw plug have?

A: It is made of high-quality carbon steel with a black oxide finish. The surface is black with an anti-rust oil film for good corrosion resistance. The specific material grade is subject to the product specification.

Q: What is the function of the center through hole?

A: The center through hole can be used for venting, pressure balancing or the passage of media according to the actual design and application of the product.

Q: What is the function of the cross hole on the shoulder?

A: The cross hole allows an auxiliary bar to be inserted for applying greater torque during tightening, and can also be used with pins or safety wire for locking and anti-loosening purposes.

Q: How to select the right specification?

A: Choose according to the thread specification (diameter and pitch), hole size and sealing requirements of the mounting port. Provide your port parameters for sizing assistance.

Q: How to prevent loosening and rust?

A: Tighten to the specified torque and inspect periodically. Keep the black oxide surface oiled for rust protection, and re-apply anti-rust oil regularly in humid environments.