A hydraulic nut splitter tool, also known as rock splitter or Darda splitter is a portable hydraulic device that is used in demolition jobs regarding large, heavy blocks of concrete or rocks. There are various hydraulic or Darda splitters. Some of them are known as piston splitters which are used in large rock demolition sites like underground sites or building foundation sites. The hole size in a splitter requires a larger hole size than the Darda splitter, which is usually around 50 mm. This piston splitter was introduced in Korea whereas large size piston splitter was introduced in Germany.

However, the difference between a piston splitter and Darda splitter are:

• The Darda splitter is constructed of two wedges which screwed inside a pre-drilled hole backed up by a hydraulic power pack. The piston splitter is made of one hydraulic power pack and one or more cylinders which contains one or more pistons on cylinder body and connecting hoses between power pack and the cylinders.
• The application of piston splitters can be found in the demolition of rocks in building a foundation, underground tunnels, shaft digging, trench work, zoo areas and in quarry. Darda splitters are only used in demolition of large blocks of rocks. Piston splitters are more effective because they can be mounted on an excavator for massive demolition.
• The manual type splitters are more performance efficient. The manual type splitters require not more than 20-25 cm space, whereas a piston splitter requires 40-50 cm space. Larger size splitters can be mounted on excavators.

However, when it comes to tube expanders, several are available in the market. Most expanders are heat-treated so they can be used for operation with electric or pneumatic tools. The following tube expanders are:

Mandrel extension and universal joints: these can be supplied according to the lengths and sizes demanded by the consumers. Mandrel extensions are used in cases where sufficient room is not available to use standard expanders with drive unit.

• Standard reversible thrust collar: this increases the possibility of using the collar flush for the front tube sheet because it’s reversible, the collar can be used for rear tube sheet acting as a flow-collar allowing the tube to be drawn outwards.
• Thrust collars: there are different thrust collars available in the market i.e. recessed thrust collar, adjustable recessed thrust collar which bring the tube to the right position according to the tube sheet, small diameter collars for the expansion of the outside row of tubes into water boxes and thin gauge tube to prevent the tube from getting trapped among the rolls and collars.
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Care and maintenance of tube expanders:

The tubing expander tools are frequently used and they need to be maintained and cleaned from time to time. To clean them, one must remove all rust, mill scale and other foreign matter from inside and outside of the tube. If the foreign matter gets embedded within the tube wall they may cause the rolls and mandrels of the tube expanders to start breaking up. Mill scale must be cleaned to prevent the formation of a pressure-tight joint.