casting high quality c12a · ®2011 bradken the intercritical region • perhaps the most common...
TRANSCRIPT
BRADKEN ENERGY PRODUCTS
March 2012
Elaine Thomas, Director of Metallurgy Bradken Tacoma
Valve Manufacturers Association
of America
March 2012
Casting High Quality
C12A
© 2011 BRADKEN®
ASTM A217 C12A and ASME Code case 2197-7
Chemistry
Element wt%
C 0.08 – 0.12
Mn 0.30 – 0.60
Si 0.20 – 0.50
P 0.020
S 0.010
Mo 0.85 – 1.05
Cr 8.0 – 9.5
Nb 0.060 – 0.10
V 0.18 – 0.25
N 0.030 – 0.070
Al .02
Ti .01
Zr .01 2
© 2011 BRADKEN®
CERTIFICATES
• ASME
• ISO 9002:2002
• Det Norske Veritas
• Nuclear Industry Assessment Committee (Audit)
• American Bureau of Shipbuilding
• LLOYDS Registrar
• Boeing D6-56202 4
© 2011 BRADKEN®
EMPLOYEE TRAINING
• Training Manuals for Skilled Positions
• Continuing Education From Professional Society Participation – American Society for Testing and Materials
– Steel Founders Society of America
– American Foundry Society
– American Welding Society
– American Society for Non-destructive Testing
• Continuing Education From National Conferences – Offshore Technical Conference
– Submarine Industrial Base Conference
– Marine Machinery Association
– Hydro Vision
– Power-Gen
• Training Manuals for Skilled Positions
• Continuing Education From Professional Society Participation
– American Society for Testing and Materials
– Steel Founders Society of America
– American Foundry Society
– American Welding Society
– American Society for Non-destructive Testing
• Continuing Education From National Conferences
– Offshore Technical Conference
– Submarine Industrial Base
– Marine Machinery Association
– Hydro Vision
– Power-Gen
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© 2011 BRADKEN®
THE CASTING PROCESS
GRINDING &
WELDING INSPECTION ROUGH
MACHINE
RISER REMOVAL
INITIAL HEAT
TREATMENT
SHAKEOUT & BLAST
POURING PATTERN MAKING
MOLDING CORE MAKING MOLD
CLOSING
ENGINEERING
REVIEW
FINAL INSPECTION SHIPPING
ORDER ENTRY
CONTRACT
REVIEW
HEAT TREATMENT
FOR PROPERTIES HEAT TREATMENT
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© 2011 BRADKEN®
ENGINEERING REVIEW
• Process Simulation (MagmaSoft)
• Process Instruction/Documentation (Process Sheet)
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© 2011 BRADKEN®
MOLDING
Qty:
Cookie Cores Break Off Cores
Rigging
Qty. Qty. Qty. Qty. Qty. Qty.
Qty. Qty. Qty. Qty. Qty. Qty.
4
Qty. Qty. Qty. Qty. Qty. Qty.
Size
Guide: Br=brick, BO=break off core, C=cookie core, D=dome, Nd=neck down, sp=stove pipe, TB=test bar, F=Flange
Size
Eng. Comments:
NO 903
Ht.
Blind
Sand
Chills:
Facing Sand:
Ht.
Eng.
Facing Sand:
n/a
16-8x8x8
si 2 wood lock pieces
2/7/11 Material:
n/a
per cstg
Cast in mold: WC Date:
n/a
Test bar comments:
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Customer:
Tile Size:Gate Type:
Molding TP 4370-1
Pattern No.
CANYON Serial No:
tile 5,4 Quantity:10-3096
LengthWidth
Width Length
168168
Eng. Comments:
Drag
Flask Size
168 48 Chills:
Ht.SizeHt.
Open
Sleeves
Size
Size
Size
Loose Pcs:
Size
Blind
Sleeves
Ht. Ht.
Ht.
18
Size
22-popoff vents sticks
Ht. Ht.
5x5 Spacing:
Size
Loose Pcs:Height
Special Id:
Cheek:
A743 CA6NM
168
Sprue Size
Ht.
Paint popoff vents thoroughly with silver parting. Using 4" tile, risers will interconect with each other, 12" hi into the riser measuring from
the contact surface and form a loop around the center of the part
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Test bar: M
Size
HeightFlask Size
Cope
Open
Sand
standard
Size Ht.
Ht.
Size
SizeSize Ht.
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SizeHt. SizeHt. Ht.Size Ht.
si
SizeHt.
• Mold Ticket
• Process Sheet
• Sign-Off Sheet
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© 2011 BRADKEN®
MELTING • Radioactivity Test on incoming
scrap
• Chemical Analysis
– Traceable to National
Standards
– Internal Proprietary Chemistry
• Gas Analysis
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© 2011 BRADKEN®
ASTM A217 C12A and ASME Code case 2197-7
Chemistry
Element wt%
C 0.08 – 0.12
Mn 0.30 – 0.60
Si 0.20 – 0.50
P 0.020
S 0.010
Mo 0.85 – 1.05
Cr 8.0 – 9.5
Nb 0.060 – 0.10
V 0.18 – 0.25
N 0.030 – 0.070
Al .02
Ti .01
Zr .01 13
© 2011 BRADKEN®
Issues with casting C12A
Nitrogen –
– keeping N in solution
• chemistry
• low turbulence gating
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© 2011 BRADKEN®
POURING • Document Pour Weight, Time, Temperature
• Sign-Off Sheet
• Problem Report
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© 2011 BRADKEN®
HEAT TREATMENT • Heat Treat Procedures
• Furnace Uniformity Survey
• Time & Temperature
• Fans for cooling
Stress prior to Riser removal; Aus/fan Cool + Temper (1350< T <
1450F); PWHT
ASME code being discussed: PWHT would be Aus/fan Cool + Temper
(1350< T < 1450F);
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© 2011 BRADKEN®
INSPECTION
•Personnel
• ASNT qualified inspectors
Level III on staff
Procedure and Acceptance Standards
• ASME, ASTM, Internal Quality Procedures
Visual
Dimensional
Magnetic Particle / Liquid Penetrant
Ultrasonic
Radiography
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© 2011 BRADKEN®
INSPECTION
Which should you choose? • Visual
• Dimensional
• Magnetic Particle / Liquid Penetrant
• Ultrasonic
• Radiography
Choices:
critical areas like areas to be welded,
high stress
fatigue areas
Max feasible volume? what level? (1,2,3,4)
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© 2011 BRADKEN®
Welding C12A
Welding & Hydrogen
Pipe must be welded in dry environment.
Welding followed by hydrogen diffusion cycle.
No evidence (so far) that Castings have the
same issues as pipe. Unlike Pipe, Casting
receive upgrade welds followed by low
temperature PWHT.
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© 2011 BRADKEN®
the intercritical region
• Perhaps the most common problem with Grade
• 91 is post-production exposure to temperatures in
Perhaps the most common problem with Grade 91 is post-production exposure to
temperatures in the intercritical region—where the tempered martensite begins to
transform back into austenite and below the temperature where phase transformation
is complete.
This can happen in the field where thermal blankets are used for PWHT. If not used
properly (e.g. overlapped blankets), regions can get too hot putting the metal into the
intercritical zone.
When Grade 91 is heated into this intercritical region, the material partially reaustenitizes,
and the resulting structure will have substantially reduced creep-rupture strength
In the worst case, this material will have lower creep-rupture strength than that of
traditional Grade 22.
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© 2011 BRADKEN®
Type IV Cracking in Modified 9Cr-1Mo Steel Weld Joint
• Type IV cracking in the heat affected zone (HAZ) of weld joints limits the life
of the component.
• Creep tests performed on the steel and its joint revealed that the type IV
cracking occurs in the inter-critical region of HAZ, which is sandwiched
between relatively higher creep resistant constituents of the joint.
• The constrained localized deformation leads to the pronounced creep
cavitation in the soft intercritical region of HAZ of the weld joint to yield type
IV failure.
• The creep rupture life reduction due to type IV cracking in the weld joint of
the steel was found to depend on the applied stress and test temperature.
• Based on the study, the reductions in 105 hours creep rupture strength of
the steel weld joint are estimated as 18 %, 30 % and 45 % of base metal
strength at 823 K, 873 K and 923 K respectively.
( i.e. 1022F, 1112F, and 1202F)
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© 2011 BRADKEN®
ASME New C12A considerations
• ASME Section I Code Case 2192 permits the use of
A217 C12A and A426 CP91 castings in the construction
of boilers. The case has been revised several times to
tighten requirements to deal with problems encountered
with this grade (in both its cast and wrought product
forms).
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© 2011 BRADKEN®
ASME New C12A considerations
• Volumetric inspection of castings (per S5, RT, or
S7, UT, of A703) has been made mandatory,
with the choice of the inspection method to be at
the discretion of the material manufacturer
unless stipulated otherwise in the PO. – ASME Section I, PG-25 applies an 80% casting quality factor to the allowable stresses
of pressure containing castings; but permits use of a 100% factor if castings are RT
and MT examined.
– Castings with up to a 4½ in. nominal body thickness require partial RT, while larger
castings require 100% RT.
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© 2011 BRADKEN®
ASME New C12A considerations
• A full normalizing and tempering heat
treatment has been made mandatory
following the completion of any major
repair to the casting.
• Type 4 weld failure w.r.t. stress rupture – especially bad in large
welds - Piping issues with thermal blankets which caused
overheating.
• FC+T eliminates the type 4 issues in the weld HAZ
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© 2011 BRADKEN®
ASME New C12A considerations
• It is required that compliance with the
specified temperature ranges during any
heat treatment operation be demonstrated
by thermocouples placed directly on the
casting or batch of castings and that a
record of these operations be provided to
the purchaser.
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© 2011 BRADKEN®
ASME New C12A considerations
• The hardness requirements currently in the two material
specifications, SA-217 and SA-426, have been added to
the Code Case.
• This has been discussed previously in A01.18 and the
185 HB minimum hardness for this grade was
accepted by the ASME committees, even though this
is lower than the 190 HB minimum hardness required of
wrought grade 91.
• The required hardness range is the same as that
required by A217/A217M-11 paragraph 7.2 for C12A and
by Table 3 of A426/A426M for CP91.
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© 2011 BRADKEN®
ASME New C12A considerations
• It has been made mandatory that the location of
all weld repairs on a casting be recorded and
that for major weld repairs the dimensions of the
repair be recorded, and it is required that this
information be documented either on the
Material Test Report, for repairs made by the
material manufacturer, or on the Manufacturer's
Data Report, for repairs performed by the Boiler
Manufacturer.
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© 2011 BRADKEN®
ASME New C12A considerations
This requirement is not relevant to material manufacturer, but
might be relevant to valve and pump manufacturers.
It has been stipulated that in cases where the requirement
to either re-heat treat or replace a portion of the casting
that has been heated above 1470°F is waived due to the
fact that the allowable stress values used are less than
or equal to those used for Grade 9, the use of the waiver
must be recorded on the Manufacturer's Data Report.
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© 2011 BRADKEN®
ASME New C12A considerations
• Some of these proposed changes are unnecessary and
impractical.
• Not all users want or need these restrictions.
• Mapping all weld repairs is impractical. Majors only.
• Re-normalizing and tempering a finish machined casting
is impossible.
– Dimensions will change and/or warp.
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