MATERIALS Q&A
Q: I have a material
certification for bar material
that indicates compliance with
ASTM A105. Is this forged bar?
Can I use it to make hubbed-flange items?
A: ASTM A105 “Carbon Steel Forgings for Piping Applications” includes
the following requirement:
4. 2 Except as permitted by Section
6 in Specification A961, the finished product shall be a forging as
defined in the Terminology Section
of Specification A788.
Paragraph 61.1 of ASTM A961
“Common Requirements for Steel
Flanges, Forged Fittings, Valves, and
6. 1. 1 Bar - Flanges, elbows, return
bends, tees, and header tees shall
not be machined directly from bar.
Other hollow cylindrical shaped
parts up to, and including, NPS 4
can be machined from bar provided
that the axial length of the part is
approximately parallel to the metal
flow lines of the starting stock.
Therefore, a market for bar (usually
by hot-rolling) meeting A105 chemistry
and mechanical property requirements
exists and can be used for hollow cylindri-
cal machined components falling within
this definition. Note that ASTM A350
“Carbon and Low-Alloy Steel Forgings,
Requiring Notch Toughness Testing for
Piping Components” includes similar
wording, so there is also demand for bar
stock certified to ASTM A350 LF2
Class 1. Many bar manufacturers cur-
rently produce hot-rolled bar per ASTM
A105 and ASTM A350 LF2 Class
requirements. In fact, it is quite common
for certified material test reports
(CMTRs) to indicate compliance with
both A105 and A350 LF2 Class 1, which
is accomplished by ensuring chemistry
and tensile test compliance with both
materials and adding Charpy impact test-
ing to meet the A350 LF2 Class 1
requirements.
WHERE CONFUSION LIES
As this shows, it may be difficult for
someone reviewing a CMTR to determine
if the bar is forged or not.
In addition, if you look at this situa-
tion from the viewpoint of a manufactur-
ing plant or a contract machine shop, you
can see further confusion. Consider the
case of a hubbed-flange valve bonnet
being produced by a contracted machine
shop. The specification for the bonnet is
“Carbon steel per ASTM A105.” If no
further instructions are provided to the
machine shop, personnel will be tempted
to go to bar suppliers and ask what
ASTM A105 material is, and whether
those suppliers can provide it. Since
A105-certified bar material is available,
personnel may purchase the hot-rolled
bar and machine the bonnets. Since the
CMTRs state compliance with ASTM
A105, these bonnets could make it
through all inspection steps and be used
in production assemblies. The inconsis-
tency would only be identified if:
DON BUSH is a principal materials engineer at
Emerson Process Management-Fisher Valve Division ( www.emerson.com). Reach him at
Don.Bush@Emerson.com.
