Rockwell, Brinell and Vickers are the predominant hardness testing methods used in the Oilfield industry. API 6A as an example, specifies Rockwell or Vickers for welding procedures and Rockwell or Brinell for base metal qualifications. NACE MR0175 as an example, bases their requiremnts on Rockwell values wich may be obtained by conversion from other hardness testing methods (Brinell, Vickers...).Many of my customers are specifying Vickers 10Kg only for qualification of welding procedures. Rockwell and Brinell are commonly used as a check on finished parts and equipment because these two methods are much more easily performed using portable equipment.
Hope this helps.
Regards,
Mike
On oil & gas components, (carbon steel vessels, piping, etc.),we get more requests for Brinell hardness testing. Second would be Rockwell C.
We have a portable Brinell machine with a 10mm ball and an Equotip. The Equotip is used when the specs call for readings to be taken in the heat affected zone (it leaves a very small indentation), or if other hardness methods are required. You might what to get a copy of ASTM E-140-02 which is a standard that discusses conversion between the various hardness methods and the errors that may be encountered when converting.