rite in the base metal. There is no maximum hardness requirement—both
require the ferrite content in the weld
deposit to be 30 to 70 volume percent.
NACE MR0103 also requires 35 to 65
volume percent ferrite in the base metal.
However, it also imposes a maximum
hardness requirement of 28 HRC,
requires weld deposits and heat-affected
zones to contain 35 to 65 volume percent ferrite and requires a Vickers hardness survey to be performed as a part of
the welding procedure qualification.
Therefore, simply meeting either NACE
MR0175-2003 or NACE MR0175/ISO
15156 does not guarantee compliance
with NACE MR0103.
ant with NACE MR0103. In this case,
the base material requirements for all
of the NACE MR0175 variants and
MR0103 are identical. However,
NACE MR0175/ISO 15156 requires
that all welding be performed using a
procedure that includes a Vickers
hardness survey as part of the proce-
dure qualification. NACE MR0175-
2002 and 2003 and NACE MR0103
do not include this requirement. There-
fore, a CF8M casting produced and
weld-repaired in compliance with
NACE MR0103 is also compliant with
NACE MR0175-2002 and 2003, but
is not necessarily compliant with
NACE MR0175/ISO 15156. One
would need to review the welding
procedure used for repairs to see if it
included the required Vickers hardness
survey before compliance with NACE
MR0175/ISO 15156 can be verified.
Scenario 3. Assume the certification is
for an ASTM A105 NPS 4 Class 300
weld-neck flange. ASTM A105 allows
this flange to be delivered in the as-hot-forged condition, with no subsequent heat treatment. All of the versions of NACE MR0175 specifically
allow ASTM A105 forgings provided
they meet a 187 HBW maximum hardness requirement, which is the standard maximum hardness requirement
listed in ASTM A105. In other words,
all versions of NACE MR0175 provide
a specific waiver of the standard carbon steel heat treatment requirements
for ASTM A105 material. However,
NACE MR0103 does not include this
specific waiver for ASTM A105 material. NACE MR0103 requires the
material be subsequently heat-treated
by annealing, normalizing, normalizing
and tempering, or quenching and tempering. Therefore, without further
information about the heat-treatment
condition, conformance with NACE
MR0103 cannot be verified.
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Scenario 4. Let’s turn this issue
around: Assume an ASTM A351 Grade
CF8M casting is certified to be compli-
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