ASTM A1082/A1082M Bolting Specification
ASTM A1082/A1082M (2016 edition) covers high strength stainless steel bolting materials and bolting components, including bars, bolts and nuts, for special purpose applications such as pressure vessels. It lists 14 duplex (ferritic-austenitic) grades and 5 precipitation-hardening grades; selection depends on design, service conditions, mechanical properties and characteristics related to the application. Specification A962/A962M is indispensable and applies in full, but A1082 prevails where the two conflict (clauses 1.2 and 4.1). Inch-pound units apply unless the order specifies the A1082M (SI) designation (clause 1.4). Bars shall be produced in accordance with Specifications A276/A276M, A479/A479M or A564/A564M as applicable. Finish (hot or cold, ground, rough turned, drawn, etc.) shall be at the option of the manufacturer unless otherwise specified in the purchase order or contract.
Ordering and heat treatment. PH bolting ordered to a Type or UNS designation only is supplied solution treated per Table 2; ordered to a Type and Condition (for example Type 630 H1150) it must meet the age-hardened requirements of Table 3 (clause 7.1.1). Duplex bolting is furnished solution annealed per Table 4 (clause 7.2.1). Hardness is tested after all production heat treatment: one test on each mill-treated length for bars 2 in. [50 mm] and over, and on at least 10 % of the lengths under 2 in. (clause 8.4). The certification report gives the chemical analysis, mechanical test results and the heat treatment method (clause 10.1).
Supplementary requirements apply only when the purchaser specifies them individually in the purchase order or contract (clause 1.3).
When S1 is specified, Charpy impact testing is required and the samples shall meet the impact values of Table 3, which lists them for Type 630 from H925 (5 ft-lbf [6.8 J]) to H1150M (55 ft-lbf [75 J]).
With S2, the grade symbol from Table 5 (for example 174A for S17400 in H900) is applied to one end of studs and to the heads of bolts of all sizes. If the area is too small, the grade symbol may go on one end and the manufacturer's identification on the other. Bolts under 1/4 in. [6 mm], studs under 3/8 in. [10 mm] and 1/4 in. [6 mm] studs that need more than three symbols are marked by agreement.
If material is straightened after heat treatment, a stress-relieving operation shall follow, 50 to 100 °F [28 to 55 °C] below the tempering temperature. Mechanical property tests are performed after stress relieving.
Each bar or forged blank of starting material is examined after final heat treatment by eddy current, magnetic particle (wet or dry), liquid penetrant, ultrasonic or visual testing, at the producer's option. With MPI or LPI, linear indications longer than 1/16 in. [1.5 mm] and longer than three times their width are unacceptable. UT and ET reject levels are set by a calibration notch no deeper than 0.012 in. [0.30 mm]. Product for visual testing is pickled first, and visual indications longer than 1/8 in. [3.2 mm] are prohibited. UT personnel are qualified to ASNT SNT-TC-1A (2006 or later) or an agreed national standard.
S5 requires proof load testing of nuts. The number of tests and the proof loads are agreed between purchaser and manufacturer.
S6 requires cross-sectional hardness testing of nuts in accordance with Annex A3 of ASTM A370, with the number of tests agreed between purchaser and manufacturer.
Frequently Asked Questions
What is ASTM A1082/A1082M?
ASTM A1082/A1082M is the Standard Specification for High Strength Precipitation Hardening and Duplex Stainless Steel Bolting for Special Purpose Applications. The current extracted edition is 2016. It covers bolting materials and components such as bars, bolts and nuts for special purpose applications such as pressure vessels, with ASTM A962/A962M as its indispensable general requirements.
Which grades does ASTM A1082 cover?
ASTM A1082/A1082M (2016) Table 1 lists 14 duplex (ferritic-austenitic) grades, S31100, S31260, S31803, S32101, S32202, S32205 (2205), S32304 (2304), S32506, S32550 (255), S32750 (2507), S32760, S32906, S32950 and S39277, and 5 precipitation-hardening grades, S15700 (Type 632), S17400 (Type 630), S17600 (Type 635), S17700 (Type 631) and S35500 (Type 634). Grade selection depends on design, service conditions and the mechanical properties required.
What strength does 17-4 PH (Type 630) reach under ASTM A1082?
Table 3 gives Type 630 minimums from H900 (tensile 190 ksi [1310 MPa], yield 170 ksi [1170 MPa], 10 % elongation) through H1025 (155 ksi [1070 MPa], 145 ksi [1000 MPa]) and H1150 (135 ksi [930 MPa], 105 ksi [725 MPa], impact 30 ft-lbf [41 J]) to H1150M (115 ksi [795 MPa], 75 ksi [520 MPa], impact 55 ft-lbf [75 J]), for sections up to 8 in.
How is ASTM A1082 17-4 PH bolting heat treated?
Solution treatment is 1900 °F [1040 °C] ±25 °F [15 °C] with cooling to below 90 °F [32 °C] (Table 2). Table 3 then gives the suggested ageing: H900 at 900 °F [480 °C] for 1 hour; H925, H1025, H1075, H1100 and H1150 for 4 hours at 925 to 1150 °F [495 to 620 °C]; H1150D, 1150 °F [620 °C] for 4 hours twice; H1150M, 1400 °F [760 °C] for 2 hours then 1150 °F [620 °C] for 4 hours, each air cooled.
What are the super duplex 2507 (S32750) requirements?
Table 4: solution annealed at 1880 to 2060 °F [1025 to 1125 °C], water quenched. Up to and including 2 in.: tensile 116 ksi [800 MPa] and yield 80 ksi [550 MPa] min. Over 2 in.: 110 ksi [760 MPa] and 75 ksi [515 MPa] min. Elongation 15 % min and hardness 33 HRC or 310 HB max for both. The marking grade symbol is 32750 (Table 5).
Can ASTM A1082 bolting be used in sour service (NACE MR0175 / ISO 15156)?
ISO 15156-3 Table A.24 accepts wrought duplex stainless steel for any equipment when it is solution-annealed and liquid-quenched or rapidly cooled, has 35 % to 65 % ferrite and has had no ageing heat treatment. With 30 ≤ PREN ≤ 40 and Mo ≥ 1.5 % the limit is 232 °C (450 °F) and 10 kPa (1.5 psi) H2S partial pressure; with 40 < PREN ≤ 45 it is 232 °C (450 °F) and 20 kPa (3 psi). Table A.27 accepts wrought 17-4 PH (S17400) at 33 HRC max after a double age at 620 °C (1150 °F) or a modified double age, for named wellhead, valve and subsurface components, up to 3.4 kPa (0.5 psi) H2S and pH 4.5 or above.
Which supplementary requirements can be ordered?
Six, each only when the purchaser specifies it (clause 1.3): S1 Charpy impact tests, S2 product marking, S3 stress relieving, S4 non-destructive inspection, S5 proof load testing of nuts and S6 cross-sectional hardness testing of nuts.
