What Is a Pipe Belling Machine?

A Complete Guide to Automatic and Semi-Automatic Pipe Socketing Equipment

In plastic pipe production, extrusion is only part of the manufacturing process. For pipes such as PVC drainage pipes, water supply pipes, and large-diameter sewer pipes, the pipe ends must be expanded into a socket structure so that pipes can be connected reliably.

This is where a Pipe Belling Machine—also known as a Pipe Socketing Machine or Pipe Expanding Machine—becomes essential.

A pipe belling machine is designed to heat and expand the pipe end to form a bell (socket) shape, ensuring secure jointing and sealing performance in pipeline systems.

SGK series pipe belling machine integrated in extrusion line

What Is a Pipe Belling Machine?

A Pipe Belling Machine is a downstream auxiliary machine used in plastic pipe extrusion lines. It forms a socket (bell) on the pipe end by controlled heating and shaping with molds.

According to the product information in the image, the SGK series includes:

Automatic Pipe Belling Machine
Semi-automatic Pipe Belling Machine
Matching mould systems
Integration capability with complete pipe extrusion lines

It can be connected directly to pipe production lines or used independently.

Why Is Belling Necessary in Plastic Pipe Production?

Without a socket structure:

Pipes cannot be easily connected.
Sealing reliability is reduced.
Installation efficiency decreases.
Structural stability of pipeline systems is compromised.

Belling creates:

Tight-fit joints
Sealing ring installation space
Faster on-site installation
Standardized connection systems

For PVC pipes especially, vacuum-type belling ensures dimensional precision.

Types of Pipe Belling Machines

1. Fully Automatic Belling Machine

Integrated heating, forming, cooling
PLC controlled
Suitable for large-scale pipe production lines
High efficiency and consistency

2. Semi-Automatic Belling Machine

Operator-assisted loading
Lower investment
Ideal for small to medium production volumes

Belling Methods

According to the technical data:

Double pipe belling (for smaller diameters)
Vacuum belling type (for larger diameters)
Cooling methods: wind cooling or water cooling

Vacuum belling provides higher precision and smooth socket finish, especially for large-diameter PVC pipes.

Main Technical Standards

Model	Pipe Diameter (mm)	Belling Method	Cooling Type	Heating Power (kW)	Total Power (kW)
SGKS63	Φ20–63	Double Pipe	Wind/Water	4	5.53
SGK250	Φ63–250	Vacuum	Water	4	10.1
SGK315	Φ110–315	Vacuum	Water	7.2	12.1
SGK400	Φ160–400	Vacuum	Water	15.6	22
SGK630	Φ315–630	Vacuum	Water	25.4	36.2
SGK800	Φ630–800	Vacuum	Water	32	60

This range covers pipe diameters from 20mm up to 800mm, suitable for drainage, water supply, and large municipal pipeline systems.

How Does a Pipe Belling Machine Work?

Pipe enters belling station
Pipe end is heated evenly
Mold expands the pipe into socket shape
Vacuum ensures dimensional precision
Cooling stabilizes the structure
Finished pipe exits the machine

Temperature control and forming time are critical factors for socket quality.

Applications of Pipe Belling Machines

PVC drainage pipes
PVC water supply pipes
Large diameter sewer pipes
Electrical conduit pipes
Agricultural irrigation pipes

Automatic vs Semi-Automatic Belling Machine

Feature	Automatic	Semi-Automatic
Labor Requirement	Low	Medium
Production Efficiency	High	Moderate
Investment Cost	Higher	Lower
Recommended For	Continuous extrusion lines	Independent workshops

Engineering Procurement FAQ

Q1: What pipe materials are suitable for belling machines?

Mainly PVC pipes. Some models can be adjusted for other thermoplastic pipes depending on material characteristics.

Q2: What is the maximum pipe diameter available?

Up to Φ800mm according to the SGK series specifications.

Q3: What is the difference between vacuum and double pipe belling?

Vacuum belling provides higher precision and is typically used for medium and large diameter pipes. Double pipe belling improves efficiency for small-diameter pipes.