fication, shall apply to steel castings for pressure-containing Specification A and SI units for material ordered to parts under each of the following ASTM. Q: A customer has asked whether we can supply carbon and alloy steel valve bodies meeting Supplemental Requirement S23 in ASTM A What is the. ASTM A/AM: Standard Specification for Steel Castings, General Requirements, for Pressure- Containing Parts.
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One tension test shall be made from each heat, and shall conform to the tensile requirements specified.
It is informational only and not an official part of the standard; the full text of the standard itself must be a7703 to for its use and application. Variables That Influence Embrittlement There are a number of variables that influence the potential for this type of embrittlement: One of the elements that is sometimes added as a deoxidizer is aluminum, which adtm a potential for the formation of aluminum nitride.
An analysis of each heat shall be made by the manufacturer to determine the percentages of the elements specified.
A cross-section of the heaviest section of a sacrificial casting A coupon attached aatm the heaviest section A coupon removed from directly under a riser or A coupon from the same heat of material removed from a separately cast test block with a thickness representative of the heaviest section of the casting. Combining values from the two systems may result in nonconformance with the standard.
Castings, Austenitic, for Pressure-Containing. After machining, each casting shall be tested under specified hydrostatic shell test pressures in the applicable steel rating for which the casting is designed.
For heats with aluminum content greater than 0. Ferritic and martensitic steel shall be cooled after pouring to provide substantially complete transformation of austenite prior to heat treatment to enhance mechanical properties.
It has also been found thathigher levels of phosphorus, sulfur,boron, molybdenum and copper inhibitaluminum nitride embrittlement. Preparing for a Plant Outage. The macroetch test specified in Supplemental Requirement S23 in ASTM A is designed aztm detect the occurrence of aluminum nitride embrittlement in castings.
This compound tends to precipitate in the astmm austenite grain boundaries and can result in asstm that display loss of ductility that could result in brittle failure of the casting if it is shock-loaded in service. This specification aa703 steel castings, general requirements, for pressure-containing parts. Work Item s – proposed revisions of this standard.
If fracture occurs, it has a rock-candy appearance due to fracture along the prior austenite grain boundaries. The mold material can also influence the cooling rate.
ViewIn Technology for Mechanical Seals. Therefore, the nitrogen content of the steel is often not known or reported, and it is possible that enough nitrogen is present to form aluminum nitride.
The steel shall be made by open-hearth or electric-furnace process, with or without separate refining such as argon-oxygen-decarburization AODunless otherwise designated by the individual specification. E Reference Radiographs for Heavy-Walled to 12 in. The specifications for the common cast steels used in valve bodies do not require analysis or reporting of nitrogen as a standard astn.
When the metal is poured into the casting mold, the oxygen can come out of the solution and form gas porosity in the castings. Upcoming Valve Industry Events Reprints.
Although some foundries monitor nitrogen levels in their steel, many do not have the necessary equipment to do this. Most foundries have the equipment necessary to analyze and report aluminum content.
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Supplemental Requirement S23 in ASTM A
When steel is melted, oxygen and nitrogen can be dissolved in the molten steel. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other.
The material shall conform to the specified chemical composition requirements. Historical Version s – view previous versions of standard. The mechanical test methods and definitions are presented aztm details. These are provided for use when additional testing or inspection is desired and apply only when specified individually by the purchaser in the order. Steel Castings Suitable for Pressure Service.
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