API's New Casting Quality Standards

Faircloth opened his presentation by stating: “As the global supply chain grows, there is a need to develop industry standards to address the special product and processes to assure repeatable quality compliance. A new API standard has been developed to address qualification and production of pressure-containing, pressure-controlling and primary load-bearing castings manufactured from carbon, alloy, stainless, nickel-base alloy steel castings used in the petroleum and natural gas industries.”

While the presentation contained more detail than can be shared in this feature, a few highlights follow:

Visual Inspection

Among the requirements for visual inspection is that all surfaces of a qualification casting are to be visually inspected in accordance with MSS SP-55. No internal chills or permanent metal chaplets are allowed, however, chaplets or core supports made of molding media are allowed. Where these molding media chaplets are used, the hole remaining in the casting wall will need to be welded. Photographs are to be taken of the qualification casting in the “as-received” condition to document surface finish and general appearance. Reference photographs in MSS SP-55 are to be used to determine acceptability of castings. Results are to be documented.

Non Destructive Examination

In this new standard, even the retention of records is itemized. The casting supplier has to establish and maintain documented procedures to control all documents and data required by this standard. Records required by this standard are to be maintained for 10 years from date of manufacture. Documents and data may be in any type of media (hard copy or electronic) and must be legible, retained and readily retrievable, stored in an environment to prevent damage, deterioration or loss, maintained to demonstrate conformance to specified requirements and must be available and auditable by the user/purchaser.

Repair Welding

API also enumerates what repair welding is permitted, and how. Post-weld heat treatment (solution treatment) of repair welds in austenitic stainless steels is neither required nor prohibited except when required by the material specification. The weld area has to be re-examined by the NDE method that originally disclosed the defect. The re-examination by magnetic particle or liquid penetrant methods of a repaired area originally disclosed by magnetic particle or liquid penetrant examination is to be performed after post-weld heat treatment when post-weld heat treatment is performed. The re-examination by radiography or ultrasonic methods of a repaired area originally disclosed by radiography or ultrasonic examination may be performed either before or after post-weld heat treatment. The acceptance standards are to be as in the original examination.

Weld repairs made as a result of radiographic examination are to be radiographed after welding. The acceptance standards for porosity and slag inclusion in welds are to be in accordance with the ASME BPVC, Section VIII, Division 1, UW-51. In this standard, repair welding is not permitted on duplex stainless steel and CSL-4.

Markings

Marking of the castings are also regulated in this standard. Manufacturing drawings have to identify where stamping is appropriate. Marking are to be applied using low-stress (dot, vibration, or rounded V) stamps or by cast-on lettering. Conventional sharp V-stamping is acceptable in low-stress areas, such as raised pads designed for stamping. Sharp V-stamping is not permitted in high stress areas unless subsequently stress-relieved at 590 °C (1100 °F) minimum.

Cast lettering is to be placed on the drag side of the pattern. All cast marking is to be of a size in relationship to the size of the casting. If cast markings are not 100% legible, they shall be ground smooth and reapplied using low stress steel stamping.

In his talk, Faircloth compared the API standard to MSS SP-14X, which is the quality standard for steel castings used in standard-class steel valves, “Sampling Method for Evaluating Casting Quality.” See the following article by Greg Johnson, “The Proposed MSS Standard for ‘Standard-Class’ Castings,” in which Johnson provides insight into the development of MSS SP-14X.

Judy Tibbs is editor in chief of Valve Magazine and Kate Kunkel serves as the magazine’s senior editor.

Rick Faircloth is principal engineer with Cameron Valves & Measurement – Engineered Valves in his native Houston. He has more than 40 years experience in the field of castings, forgings, heat treatment, manufacturing, materials, nondestructive examination, quality, and welding and standards development. Faircloth has held numerous positions in operations, quality management, project management and standards management during his 35 years in standard development for API and 20 years for ISO.