Remet and Metzke style rods and threads have dominated the industry since inception and are by far the most popular and reliable. Material used in tool joints, inner tube ends and drill subs are of high quality 4140 alloy steel hardened to about 320 Brinell. The tool joint has an interference fit in the drill rod with a shank length in excess of 100 mm and the weld is preheated and post heated with nickel chrome welding wire as the weld material. The outer drill pipe seamless carbon steel pipe to ASTM A106 grade ST52.0, which has a maximum working pressure of 3020 p.s.i. (19058 kpa at 100C) when new. With the use of air booster systems becoming accepted practice, the class of material is extremely important, as the drill column is classified as an air receiver, and as such comes under certain sections of the Mines Safety and Inspections Act 1994. The inner tube connections have many configurations, each with salient differences that have their own patrons and virtues of design.

Remet have standardised on the established style of 'O' rings on the pin in the box of the rod. The advantages of this configuration is that the driller is able to see the 'O' rings without putting his hand under the rod when suspended. Additionally, the rings will not damaged by hooking, the tool joint does not wear as quickly, as the sample passes through the pin bore with less disruption than a box. The locating lugs are now part of the joint and not welded on as earlier configurations.

The additional length of taper thread on the Remet design enhances the stability and strength of the join, with 4.5" RC Remet drill rods having recently been drilled to a depth of 600 meters using 1200 c.f.m. and 1000 p.s.i. with no hint of separation. The longer contact area between pin and box on the inner tube allows for less wear and when removing circlips prevents exposing the 'O' rings during tube movement.

The Case for Standardisation

There are many pros and cons to support the case for Standardisation, however the most notable advantages can be summarized as follows:

• Standardisation can allow for a reduction in inventory holdings.
• Standardisation can reduce confusion or error when ordering and manufacturing replacement parts.
• Standardisation can lower downtime by having access to like components
• Standardisation can provide for smoother operations as personnel would require experience and familiarity with one set of components
  

While the most notable disadvantage is:

• there can be a cost associated with Standardisation

If the cost of Standardisation can be quantified against the likely benefits identified, on a cost basis over a reasonable period of time, it would be sound business practice to move towards the Standardisation of drilling equipment and components, particularly in larger drilling companies where economic scale can be bought into play.

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