Comparison of ASTM A479 and ASTM A276 1. Both standards cover the same product forms – hot or cold finished bars including rounds and various shapes. A479 specifically refers to use in boiler and pressure vessel applications. A276 specifically defers bars for reforging and free machining grades to other ASTM standards (A314 and A582/A582M) while A479 is silent on those items and they are presumed to not be covered. 2. Both standards refer to the same reference ASTM documents for general requirements with the following exceptions: A276 – references A314 and A582 A479 – references A262 for IGA testing and E112 for grain size measurements 3. While both standards look for similar basic requirements – alloy, size, finish, the A479 standard provides more definition of additional testing, inspection, certification and packaging requirements. Both reference A484 for general tolerances etc. 4. Both standards allow several conditions A276 has: A – annealed, S – light cold work and B – heavy cold worked. A applies to either hot or cold finished bar while S and B apply to only cold finished bar. Condition A is available for all 650/620 austenitic grades and duplex grades except 2003, 255+ and 2507. Condition B is available for only 304/304L and 316/316L. Condition S is available for only 304/304L, 316/316L, 255 and 2507. A479 has annealed, strain hardened level 1 and strain hardened level 2. (Strain hardened level 1 and level 2 will be similar but not identical to A276 conditions S and B.) Condition A is available for 304/304L, 316/316L and 317 and the duplex grades except 2003, 2304 and 255+. Notably 2304 is not available and 2507 is available. Only four grades are available in either strain hardened level: 304/304L and 316/316L. The differences between A276 and A479 essentially expand the possible alloy/condition combinations available (see mechanical properties). 5. Chemistry There are only two slight variations in chemistry requirements for the API alloys. For 304 nickel is 8 – 11 in A276 and 8-10.5 in A479 For 317 nitrogen is 0.010 max in A276 and not mentioned in A479 Neither difference should result in any disqualification of the alloys based on chemistry as melt Ni is controlled to the range minimum nor will N be more than a trace unless a minimum is specified. A479 does require product check analysis be performed in accordance with ASTM A484 requirements while A276 does not. 6. Mechanical Properties

For the duplex grades the mechanical property requirements are the same for the annealed bars but A276 adds the higher strength condition S for the 255 and Z100 grades. For the austenitic grades the comparison is more difficult primarily due to variations between cold worked strength levels and available conditions. For the annealed condition the requirements are the same for tensile and yield but A479 is lower for elongation and reduction of area. A276 also adds the cold worked and annealed condition with its higher strength levels. A479 level 1 offers a strength level between that of A276 hot worked and annealed and cold worked and annealed material but with higher elongation and RA requirements. A479 level 2 offers property levels equal to A276 condition S. Finally A276 condition B offers an increased level of strength not available in A479.

7. Grain Size A479 requires a grain size evaluation for all austenitic grades but does not set a required size for API grades. 8. Corrosion testing A479 requires an A262 test for all austenitic grades annealed by the alternate method. (The alternate method is working at temperatures above the solution annealing minimum temperature and the direct quenching to room temperature.) 9. Certifications A479 requires certifications while A276 is “upon request”. 10. Product Marking A479 has a complete description of marking requirements while A276 does not. 11. Supplemental Requirements A479 has several supplemental requirements that could apply to API grades: Corrosion tests performed on sensitized 304L or 316L material. Product chemistry analysis. No cold work allowed after annealing for materials to be subjected to stress corrosion cracking environments. Determination of detrimental intermetallic phases for both austenitic and duplex grades. Summary While there are differences between the two specifications those differences do not indicate an inferior product level would be the result of ordering to A276. Actually the addition of A276 to

the API standards would be more likely to increase product diversity and availability. Steps can be taken to maintain the controls present in the A479 through ordering requirements. The added higher strength levels of A276 condition B could be a definite advantage. Also stock availability would be increased by allowing the use of both standards.