API 934-A pdf free download
API 934-A pdf free download.Materials and Fabrication of 2 1 / 4 Cr-1Mo, 2 1 / 4 Cr-1Mo- 1 / 4 V, 3Cr-1Mo, and 3Cr-1Mo- 1 / 4 V Steel Heavy Wall Pressure Vessels for High-temperature, High-pressure Hydrogen Service.
Specified heat treatment (aggregate temperature and time) of test coupons used to simulate the maximum heat treatment exposures on the vessel alloy. Prior to heat treatment, coupons shall be representative of the as- supplied material (i.e. having the same austenitizing and tempering heat treatment). By definition, maximum PWHT includes all fabrication heat treatments above 900 °F (482 °C), e.g. intermediate stress relief (ISR), all PWHT cycles, a PWHT cycle for possible shop repairs, and a minimum of one extra PWHT for possible future use by purchaser. Typically, the ISR and PWHT cycles are aggregated into one single equivalent heat treatment that approximates the sum total effects of time and temperature. Methods to account for the aggregate effects on mechanical properties are discussed in the note below. DHT do not need to be included, as they are at temperatures too low to affect material properties. NOTE To determine the equivalent time at one temperature (within the PWHT range) of heating steps that have temperatures outside the PWHT range, the Larson-Miller Parameter formula (or Hollomon-Jaffe Parameter) may be used; results should be agreed upon by purchaser and manufacturer. At the time of any future repairs, it is the purchaser’s responsibility to determine any changes in properties that may have occurred from high-temperature service, and the affects that any repair welding and PWHT will have on the vessel.
Specified heat treatment (aggregate temperature and time) of test coupons used to simulate the minimum heat treatment exposures on the vessel alloy. Prior to heat treatment, coupons shall be representative of the as-supplied material (i.e. having the same austenitizing and tempering heat treatment). By definition, minimum PWHT includes only the minimum of all fabrication heat treatments above 900 °F (482 °C), e.g. ISR (if any), and one PWHT cycle. Typically, the ISR and PWHT cycles are aggregated into one single equivalent heat treatment that approximates the sum total effects of time and temperature. Methods to account for the aggregate effects on mechanical properties are discussed in the note below. NOTE To determine the equivalent time at one temperature (within the PWHT range) of heating steps that have temperatures outside the PWHT range, the Larson-Miller Parameter formula (or Hollomon-Jaffe Parameter) may be used; results should be agreed upon by purchaser and manufacturer.
The reduction in toughness due to a metallurgical change that can occur in some low-alloy steels as a result of long- term exposure in the temperature range of approximately 650 °F to 1070 °F (343 °C to 577 °C). This change causes an upward shift in the ductile-to-brittle transition temperature as measured by Charpy impact testing. Although the loss of toughness is not evident at operating temperature, equipment that is temper embrittled may be susceptible to brittle fracture during subsequent hydrotests, start-ups, and shutdowns.
4.1 Design and manufacture shall conform to ASME Section VIII, Division 2 and its applicable Code Cases. The latest edition effective through the date of the purchase agreement shall be used. 4.2 The manufacturer’s design report (which includes ASME Code strength calculations, and when applicable, local stress analysis for extra loads and other special design analyses) should show compliance with the purchaser’s design specification and other technical documents.API 934-A pdf download.
