Welping large-size butt fusion machines are equipped with four clamping rings. Therefore, when this article refers to a “2-piece” or “4-piece” insert design, it means the number of insert pieces used on one clamping ring. A complete machine requires the same insert size to be installed on all four clamping rings, so the total number of insert pieces is four times the quantity used on one ring.

The aluminum construction reduces the weight of each individual piece, making the inserts easier to handle, install and replace on site.

· 2 pieces per clamping ring 

· 8 pieces per complete machine set 

· Relatively light individual pieces 

· Simple installation structure 

· Easy to handle and replace on site 

· Suitable for 160–800 models 

· Steel option: 2 pieces × 4 clamping rings = 8 pieces 

A complete machine therefore requires 16 aluminum insert pieces for one pipe size.

Compared with a 2-piece structure, each section is smaller and lighter, making manual handling, installation and removal easier.

On 1000 and 1200 machines, the inserts themselves are already relatively large. Dividing each insert into four sections helps reduce the weight that needs to be handled at one time.

The aluminum inserts also feature a widened pipe-contact surface, which helps provide stable clamping and maintain pipe alignment.

· 4 pieces per clamping ring 

· 16 pieces per complete machine set 

· Smaller and lighter individual sections 

· Easier piece-by-piece handling and installation 

· Widened pipe-contact surface 

· Suitable for 1000 and 1200 models 

Each clamping ring uses an upper and a lower steel insert section, so one complete machine set requires 8 steel insert pieces.

The steel inserts are made from precision-cut steel and welded into a rigid structure. Anti-slip serrations on the inner surface help increase friction between the insert and the pipe, reducing relative movement during pipe handling and fusion operations.

· 2 pieces per clamping ring 

· 8 pieces per complete machine set 

· Fewer pieces to install 

· Anti-slip serrations on the inner surface 

· Stable pipe holding 

· Suitable for 1000 and 1200 models 

As machine size increases, the inserts become significantly larger and heavier. Dividing the insert into four sections makes handling, installation and removal more practical on site.

At the same time, the steel structure provides the rigidity and stability required for very large clamp inserts.

· 4 pieces per clamping ring 

· 16 pieces per complete machine set 

· Split design for easier handling and installation 

· Suitable for 1400 and larger machines 

· Selected non-standard sizes can be customized for specific projects 

When the machine moves the pipe forward or backward, the larger contact area helps reduce relative movement between the pipe and the clamps. This helps keep the pipe more stable during facing, heating and fusion.

This can be particularly useful in low-temperature working conditions.

At lower temperatures, PE pipe becomes stiffer and may not conform to the clamping surface as easily. The increased contact area and friction provided by the anti-slip pads can help improve holding stability when moving large-diameter pipe.

· Winter construction 

· Large-diameter or heavy pipe 

· Applications with relatively high pipe movement resistance 

If the actual pipe OD differs slightly from the nominal size, the pad position can be fine-tuned to improve contact with the pipe and provide more stable clamping.

· Special project pipe 

· Pipes with minor OD deviation 

· Pipe outside diameter

· Standard or non-standard pipe size

· Whether insert sizes will be changed frequently

· Whether inserts will mainly be handled manually

· Expected working temperature or site conditions

· Whether anti-slip pads are required for 800 / 1000 / 1200 models

With this information, the appropriate clamp insert and pipe-holding configuration can be confirmed before delivery.