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INTERNATIONAL STANDARD VALVE, INC.

7111 Perimeter Park Drive, Bldg 320Houston, Texas

TM

Valve Manufacturers Association – March 2011 Technical Seminar


Accuracy of Radiography of Castings and New API 20A Draft Standard;

Casting Steel, Stainless Steel and Nickel Base Alloy Castings

Valve Manufacturers Association – March 2011 Technical Seminar

Casting Steel, Stainless Steel and Nickel Base Alloy Castings for use in the Petroleum and Natural Gas Industry

Engin GulgunInternational Standard Valve Houston TX, USA


NDE Evaluation• Surface and Volumetric Nondestructive evaluation (NDE) methods are widelyused to evaluate castings quality.•Surface inspection can be Visual, Magnetic Particle (MP) or Liquid Penetrant(LP).•Volumetric inspection can be radiographic or ultrasonic.•Volumetric inspection can be radiographic or ultrasonic.•These techniques are intended to detect and classify the magnitude ofsurface and internal indications.•ASTM, ISO and other organizations have a series of standards that seek toqualify these indications.•However, the effect of the different quality levels on part performance hasnot been quantified. These standards are commonly referred to as“workmanship standards” and were not developed to predict performance.


NDE Evaluation Accuracy•The NDE method (technique), NDE personnel qualification and the interpretations of the NDE results impacts the accuracy of the NDE results.

•The University of Iowa Department of Mechanical Engineering performed a statistical study to analyze ASTM X-RAY SHRINKAGE rating for steel casting.

•Four foundries cast 3” thick x 6” wide plates, •Four foundries cast 3” thick x 6” wide plates,

• One foundry cast 1” thick x 5.5” wide plates.

•Each foundry cast plates in various lengths in order to select the X-Ray films from RT level 0 to RT Level 5 shrinkage.

•All plates were cast from low alloy steel.

•X-Rays for each plate were performed produced according ASTM E94 and total 128 X-Ray films were produced.


NDE Evaluation Accuracy•Each casting foundry provided initial evaluation of ASTM shrinkage type andlevel (Radiographer 1 involved different NDE personnel).•Then the 128 X-Ray films from all five foundries were sent to otherradiographer for evaluation.•Level III Radiographers 2 and 3 each evaluated the x-ray films two separate•Level III Radiographers 2 and 3 each evaluated the x-ray films two separatetimes.•Level II radiographers 4 and 5 each evaluated the x-ray films once.•All X-ray films were evaluated total of 7 times. (initial foundry evaluationincluded).•The X-ray films from 1” thick plates were evaluated by using referencestandard from ASTM E446.•The X-ray films of 3” thick plates were evaluated using reference radiographsfrom ASTM E186,


NDE Evaluation Accuracy•Occurrence of common agreement between x-ray ratings

Common agreement in shrinkage TYPE

Common agreement in shrinkage LEVEL

Common agreement in shrinkage TYPE and

LEVEL

47/128 (37%)

14 level 07 CA type defect20 CB type defect6 CC type defect

22/128 (17%)

14 Level 01 Level 11 Level 21 Level 35 Level 5

LEVEL

16/128 (12.5%)

14 Level 02 CB type level 5


NDE Evaluation Accuracy•These results indicate that shrinkage type is more readily identifiable than shrinkage level.

•Common agreement on X-Ray defect type occurred in nearly 2 out of every 5 X-Rays, while common agreement on X-Ray level occurred in less than 1 out of every 5 X-Rays.every 5 X-Rays.

•Most of the X-Rays with common level ratings were either Level 0 or Level 5.

•All the X-Rays with both common defect type and level rating were either Level 0 or Level 5.


NDE Evaluation Accuracy•Worst case example for rating


NDE Evaluation Accuracy•Average accuracy for all 128 X-Ray films are about ±1.4 levels.

•The largest variance was found to occur in level 2 and level 3 X-Rays which isabout ± 2 levels.

•The results concerning accept/reject thresholds may be possible for oneradiographer to accept a casting while another rejects the same casting.radiographer to accept a casting while another rejects the same casting.

•In addition one radiographer looking at one X-Ray on two separate occasionsmay give it an acceptable rating at one time and unacceptable rating atanother.

•Valve castings which have more complex shapes than the cast plate parts mayhave different variance on the radiographic rating depending on theradiographic technique used.


What about Radiographic Accuracy in other Applications –Airport TSABased on the ABC News;

•A Houston businessman reported that he flew out of IAH airport with hisloaded .40 caliper gun and TSA screeners missed the loaded gun inside hiscarry –on computer bag.

21%

carry –on computer bag.

•It was reported on the latest tests the failure rate approaches 70 % at somemajor airports.

•TSA's new director said every test gun, bomb part or knife got past screenersat some airports.

•Detection of suspect items in baggage using X-Ray 21% of items missed (UKSynergy Consultants Ltd. report 2003)


What about Radiographic Accuracy in Medical FieldBased on article published in The British Journal of Radiology;•The level of error varies depending on the radiological investigation,….•but the range is 2–20% for clinically significant or major error.


New API Standard Activity API 20A•Title of the standard is “Steel, Stainless Steel and Nickel Base Alloy Castings foruse in the Petroleum and Natural Gas Industry”.•This API standard applies to castings used in the manufacture of pressurecontaining, pressure controlling and primary load bearing components.•Castings manufactured in accordance with this API Standard may be produced•Castings manufactured in accordance with this API Standard may be producedusing any industry standard casting method. (Sand , lost wax etc.)•This API Standard establishes requirements for four Casting SpecificationLevels (CSL).•These four CSL designations define different levels of cast product technical,quality and qualification requirements.•The CSL’s are numbered in increasing levels of severity from 1 to 4 in order toreflect increasing technical quality and qualification criteria.


Material Groups•There are 5 different material groups listed in the draft standard


Qualification Casting•Qualification casting shall be produced, tested and evaluated by castingsupplier.

•Castings shall be produced in accordance with a Manufacturing ProcedureSpecification (MPS).

•MPS shall include as minimum allowable levels for all casting parameters•MPS shall include as minimum allowable levels for all casting parametersincluding process control variables and the heat treatment variables.

•As part of MPS, pattern equipment shall be shown with detailed rigging.

•Weld repair and cosmetic grinding to remove defects is permitted up tocertain levels.

•Weld repair limitation for CSL 1 => no limit, CSL 2=> %25, CSL=> %20, CSL4=>10% (percentage of surface area or wall thickness).


Qualification Casting•Qualification castings are to be in their completed cast form, with theaddition of any specified rough machining and full heat treatment to establishthe final mechanical properties required of the finished product.

•Examination/Testing Requirements for Qualification Casting is as follows;

MechanicalMicro-

Structure Visual Dimensional HardnessSurface

NDEVolumetric

NDESacrificial

CastingCorrosion

Testing

CSL-1 X - X X - - - - -

CSL-2 X - X X X X - - -

CSL-3 X X X X X X X - X (Group D)

CSL-4 X X X X X X X X X (Group D)


Qualification – Visual InspectionAll surfaces of the qualification casting shall be visually inspected in accordancewith MSS-SP-55.

Qualification – Dimensional InspectionQualification – Dimensional Inspection•The casting supplier shall specify and verify critical dimensions.•Acceptance criteria for critical dimensions shall be as required by the castingsupplier’s written specification.

Qualification – Hardness Testing•Brinell and/or Rockwell hardness testing (in accordance with ASTM E10, E110 or E18)shall be performed on external surfaces.


Qualification – Surface Examination Acceptance Criteria•All accessible surfaces of each Group A and Group B ferromagnetic castingshall be magnetic particle inspected per ASTM E709.

•All accessible surfaces of each non-ferromagneticnon-ferromagneticcasting shall be liquid penetrant inspected inaccordance with ASTM E165.


Qualification – Volumetric RT Examination Acceptance CriteriaAs far as practical, the entire volume of each part shall be volumetricallyinspected (radiography or ultrasonic) after heat treatment.


Qualification – Mechanical Test•The mechanical tests shall be performed on qualification test couponsrepresenting the heat and heat treatment lot used in the manufacture of thecasting. Tests shall be performed in accordance with the requirements of ASTM A370, orequivalent national standards, using material in the final heat-treated condition.

•The Size and Shape of the Qualification Test Coupon (QTC) is defined by using•The Size and Shape of the Qualification Test Coupon (QTC) is defined by usingthe Equivalent-Round Method and thicker QTC is used for thicker partqualification.

•QTC shall either be integral with the components they represent, separatefrom the components or be taken from sacrificed production part(s).

•In all cases, test coupons shall be from the same heat as the componentsthey qualify and shall be heat-treated together with the components.


Qualification – Microstructure ExaminationQualification – Chemical AnalysisQualification – Additional TestingSacrificial Casting – CSL-4 :Section the casting into four (4) roughly sized equal quadrants.Section the casting into four (4) roughly sized equal quadrants.Visually inspect all surfaces of each quadrant for cracks, voids, porosity orother anomalies.Liquid penetrant examine the cut surface of each quadrant per ASTM E165and report results.Macro-etch one quadrant in accordance with ASTM E340.


Qualification – Additional TestingGroup D - Duplex Material Corrosion Testing in accordance withASTM G48, Method A.

•The ferrite content shall be conducted in accordance with ASTM E562. Theferrite content shall be in the range of 35-65% (volume fraction).

•Metallographic Examination Samples shall be etched using ASTM E407 etchant number 98•Metallographic Examination Samples shall be etched using ASTM E407 etchant number 98(K3Fe(CN)4 with KOH or NaOH).


Qualification – Acceptance•Qualification castings failing to meet the acceptance criteria shall be cause for reevaluation of foundry practice and casting design. Requalification is required.

•Results of Qualification shall be documented.


Limits of Casting QualificationsCSL 1: A change in material group from the casting that was previouslyqualified requires requalification.CSL 2: Qualification requirements specified for CSL-1 are required for CSL-2A change in the as-cast thickness and weight range class as shown in thefollowing Table from the casting that was previously qualified requiresrequalification.requalification.CSL 3: Qualification requirements specified for CSL-2 are required for CSL-3.When metal refining steps, such as Argon Oxygen De-Carburization (AOD) orladle refining, are used to produce the qualification casting, the elimination ofany of these steps from the melting/casting practice shall requirerequalification.CSL 4: Qualification requirements specified for CSL-3 are required for CSL-4.A change in the specific material specification/grade from the casting that waspreviously qualified requires requalification of the casting.


Qualification – Limits of Casting Qualification


Production Casting•Prior to the production of castings, the casting supplier shall produce a samplecasting(s).• The casting supplier shall perform all required tests and examinations andcertify that the sample casting(s) meets the requirements of this standard.•The first production run of castings may be considered the sample. In thiscase, at least one of the castings shall be processed as a sample by the castingcase, at least one of the castings shall be processed as a sample by the castingvendor.•A casting shall be deemed a "sample" when one or more of the following events take place:•First use of a pattern on a new order;•A pattern is re-rigged;•A new pattern is made;•A pattern is revised;•A change in processing (i.e., core making, sand control, melt practice);•A pattern is sent to another foundry;•Rejection of a sample;•Upon identification of a recurring defect in a casting released for production.


Sample Casting Acceptance•Upon completion of all required examinations (same as qualificationinspection) and tests, results shall be sent to the purchaser for approval.

•Subsequent castings shall not be made until the sample is approved by thepurchaser.


Production Inspection - Visual•All production castings shall be visually inspected in accordance with MSS-SP-55. •If the purchaser does not provide acceptance criteria for visual examination is same as qualification casting. Results shall be documented..


Production Inspection - Surface NDE•CSL-2 and 3: The casting supplier shall randomly select one casting from eachproduction run of each weight/thickness class and material group for surfaceexamination.

•Failure of the casting to meet the applicable acceptance criteria will require a“hold” to be placed on the production lot and a surface examination“hold” to be placed on the production lot and a surface examinationperformed on two additional sample castings selected at random from thesame production run of castings.

•If the two additional castings fail, the purchaser and the casting supplier shallspecifically agree on the disposition of the production lot.

•CSL-4 : Each CSL-4 casting shall be surface examined in accordance with themethods specified in Qualification Casting Section, as appropriate for material.


Production Inspection - Volumetric NDE•CSL-2 and 3 : The casting supplier shall randomly select one casting from eachproduction run of each weight/thickness class and material group forvolumetric examination.

•Failure of the casting to meet the applicable quality level will require a “hold”to be placed on the production lot and a radiographic examination performedto be placed on the production lot and a radiographic examination performedon two additional sample castings selected at random from the sameproduction run of castings.

•If the two additional castings fail, the purchaser and the casting supplier shallspecifically agree on the disposition of the production lot.

•CSL-4 : Each CSL-4 casting shall be volumetrically examined.


Production Casting – RT Acceptance Criteria


Other API Activities• Spec 20A - Castings• Spec 20B - Open Die Forgings• Spec 20C - Closed Die Forgings• Spec 20N - NDE• Spec 20H - Heat Treat:• Spec 20H - Heat Treat:• Bolting


Thank You

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