Now abbreviated HBW. A
designation of hardness, usually of steel, performed by pressing a
10 mm spherical tungsten carbide ball against a clean prepared surface using a 3000
Kilogram force, producing an
impression, measured and given a special numerical value. This
numerical value relates to steel tensile strength. API Spec 6A specifies minimum Brinell
Hardness requirements for different material designations. NACE Standard MR0175
references maximum hardness in determining steel’s suitability for use in
H2S
Service.
A measured factor that
reasonably predicts the amount metal will resist abrasion and bending,
as well as indicating
Ultimate Strength.
Most commonly expressed as Brinell Hardness
and Rockwell Hardness. ASTM E140
provides a guide for comparing hardness determined by different methods
and expressed on different scales.
(Sometimes RB)
An abbreviation for Rockwell Hardness measured
on the B scale. The abbreviation usually appears after a number, e.g. 83 HRB. See:Rockwell
B Hardness.
(Sometimes RC)
An abbreviation for Rockwell Hardness measured
on the C scale. The abbreviation usually appears after a number, e.g. 22 HRC. See:Rockwell C Hardness.
Abbreviation for Hardness Vickers. The
Vickers hardness testing method represents another method of testing by
indenting the test material under a specified load and measuring the
size of the indention and comparing it to a number table. This method
has gained greater use in testing of weld samples to meet
NACE requirements.
The
chemical commonly abbreviated H2S. This deadly poison also
has a destructive effect on high strength low alloy steels when the
hardness of these steels exceeds a hardness of 22 Rockwell
C.
A
hardened pointed or rounded contact object used to impress an indentation into the surface of
steel (or other metal) parts in order to obtain a
Hardness measurement of that part.
See HBW, HRC, and
HRB.
A document published by
the National Association of Corrosion
Engineers defining the specific limits of chemistry,
hardness and microstructure of
Materials used to
make equipment to contain or control
well production fluids that include hydrogen sulfide.
A designation of hardness of
metallic materials measured by pressing a
small rounded indenter against a clean prepared
surface with a specific force. The machine making the indention also measures the depth of the
indention and provides a numerical value for that depth.
The Rockwell B scale expresses more accuracy in the
hardness measurement of metallic materials softer than HRC 20. To
convert hardness numbers between measuring methods and scales, see
Hardness Number Conversion Chart.
A
designation of hardness, usually of steel or
Corrosion Resistant Alloys, measured by pressing a specially shaped indenter against a clean prepared
surface with a specific force. The machine making the indention also measures the depth of the
indention and provides a numerical value for that depth. This numerical
value relates to steel
Tensile Strength and NACE Standard MR0175
references hardness in determining steel’s suitability for use in
H2S
Service. To convert hardness numbers between
measuring methods and scales, see
Hardness Number Conversion Chart.
22 RC, 99 RB, 237 HBW (read 235 in table), and 248 HV
represent the important upper hardness limit for non austenitic steel
for H2S service specified in NACE MRO175 and referenced in API Spec 6A.
Some authorities may offer slightly different equivalent hardness
numbers.
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