ASTM A266/A266M Standard Specification for Carbon Steel Forgings for Pressure Vessel Components 

 

1.1 This specification 2 covers four grades of carbon steel forgings for boilers, pressure vessels, and associated equipment.

Note1—Designations have been changed as follows:

Current Formerly

Grade 1 Class 1

Grade 2 Class 2

Grade 3 Class 3

Grade 4 Class 4

1.2 Supplementary requirements are provided for use when additional testing or inspection is desired. These shall apply only when specified individually by the purchaser in the order.

1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance

with the standard.

1.4 Unless the order specifies the applicable “M” specification designation, the material shall be furnished to the inchpound units.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

2.1 ASTM Standards: 

A275/A275M Practice for Magnetic Particle Examination of Steel Forgings

A370 Test Methods and Definitions for Mechanical Testing of Steel Products

A788/A788M Specification for Steel Forgings, General Requirements

A1058 Test Methods for Mechanical Testing of Steel Products—Metric

E112 Test Methods for Determining Average Grain Size

E165/E165M Practice for Liquid Penetrant Examination for General Industry

E381 Method of Macroetch Testing Steel Bars, Billets, Blooms, and Forgings

2.2 Other Standard:

ASME Boiler and Pressure Vessel Code, Section IX 4

3.1 In addition to the ordering information required by Specification A788/A788M, the purchaser shall include with the inquiry and order a detailed drawing, sketch, or written description of the forging.

3.2 Material supplied to this specification shall conform to the requirements of Specification A788/A788M, which outlines additional ordering information, manufacturing requirements, testing and retesting methods and procedures, marking, certification, product analysis variations, and additional supplementary requirements.

3.3 If the requirements of this specification are in conflict with the requirements of Specification A788/A788M, the requirements of this specification shall prevail.

3.4 For hubbed flat heads and tube sheets ordered forASME Boiler and Pressure Vessel Code application, Supplementary Requirement S12 of Specification A788/A788M shall be specified in addition to Supplementary Requirement S8 of this specification.

4.1 The steel shall be made in accordance with the Melting Process Section of Specification A788/A788M. A sufficient discard shall be made to secure freedom from injurious pipe and undue segregation.

4.2 The material shall be forged as close as practical to the specified shape and size.

4.3 The finished product shall be a hot-worked forging as defined by Specification A788/A788M.

5.1 Surfaces shall be machined as designated by the purchaser. Unmachined surfaces shall be sufficiently free of scale to permit inspection.

5.2 Machining may be performed either prior to or after heat treatment at the option of the manufacturer unless specified in accordance with Supplementary Requirement S1.

6.1 After forging and before reheating for heat treatment, the forgings shall be cooled in such a manner as to prevent injury and to accomplish transformation.

6.2 All forgings shall be annealed, normalized, or normalized and tempered, but alternatively may be liquid quenched and tempered when mutually agreed upon between the manufacturer and the purchaser. When tempering is performed, it shall be at a subcritical temperature, but no less than 1100 °F

[595 °C].

6.3 A multiple stage austenitizing procedure may be used whereby the forging is first fully austenitized and liquid quenched, followed by reheating within the intercritical temperature range to partially reaustenitize, and again liquid quenched. On completion of the austenitizing/quenching cycles, tempering at a temperature between 1100 °F [595 °C] and the lower critical temperature shall follow.

Note 2—Although liquid quenching from the austenitizing temperatures is more effective in enhancing impact properties, air cooling from the austenitizing temperatures is also beneficial and may be used instead of the normalizing procedure in 6.2.

7.1 Heat Analysis—The heat analysis obtained from sampling in accordance with Specification A788/A788M shall comply with Table 1 except that the additional features of Supplementary Requirements S11 and S12 shall also apply as individually specified in the ordering information.

7.2 Product Analysis—The purchaser may use the product analysis provision of Specification A788/A788M to obtain a product analysis from a forging representing each heat or multiple heat.

Element	Grade 1	Grade 2	Grade 3	Grade 4
Carbon (C)	0.30-0.35%	0.25-0.29%	0.30-0.35%	0.30-0.35%
Manganese (Mn)	0.80-1.35%	0.80-1.05%	0.80-1.10%	0.80-1.10%
Phosphorus (P)	0.025% max	0.025% max	0.025% max	0.025% max
Sulfur (S)	0.025% max	0.025% max	0.025% max	0.025% max
Silicon (Si)	0.15-0.30%	0.15-0.30%	0.15-0.30%	0.15-0.30%

 

8.1 General Requirements—Except when otherwise specified in accordance with Supplementary Requirement S2, the material shall conform to the requirements for mechanicalmproperties prescribed in Table 2 when tested in accordance with the latest issue of Test Methods and Definitions A370 or Test

Methods A1058 when the M suffix standard has been specified.

The largest obtainable tension test specimen as specified in Test Methods and Definitions A370 or Test Methods A1058, as applicable, shall be used.

8.1.1 Except when otherwise specified in accordance with Supplementary Requirement S2, the longitudinal axis of the specimens shall be parallel to the direction ofmajor working of the forging. For upset-disc forgings, the longitudinal axis ofthe test specimen shall be in the tangential direction.

8.1.1.1 The longitudinal axis of the specimen shall be located midway between the parallel surfaces of the test extension ifadded to the periphery ofdisks or midway between the center and surface of solid forgings. For hollow forgings, the longitudinal axis of the specimens shall be located midway

between the center and outer surfaces of the wall. When separately forged test blocks are employed as defined in 8.1.3, the tension test specimens shall be taken from a location that represents the midwall ofthe heaviest section ofthe production forgings. When specimens are required from opposite ends,

they shall be taken from the diagonal corners of an axial plane.

8.1.2 Except as specified herein, tests for acceptance shall be made after heat treatment has been completed. When the ends of the cylindrical forgings are closed in by reforging, the cylindrical forgings may be annealed, normalized, or normalized and tempered and tested prior to reforging. After

reforging, the entire forging shall be reheat-treated in the same manner and at the same temperature range as employed when the forging was heat-treated prior to certification testing.

8.1.3 When mutually agreed upon between manufacturer and purchaser, test specimens may be machined from a specially forged block suitably worked and heat treated with the production forgings. Such a special block shall be obtained from an ingot, slab, or billet from the same heat used to make the forgings it represents. This block shall receive essentially the same type of hot working and forging reduction as the production forgings; however, a longitudinally forged bar with dimensions not less than Tby Tby 3Tmay be used to represent a ring forging. The dimension T shall be representative of the heaviest effective cross section of the forging. For quenched and tempered forgings for which tests are required at both ends by 8.2.2.3 and 8.2.2.4, separately forged test blocks are not allowed.

N OTE 3—In using separately forged test blocks, attention is drawn to the effect of mass differences between the production forgings and the test blocks.

8.2 Specific Requirements—The number and location of tests are based on forging length, weight, and heat treatment, and shall be as prescribed below. The length and weight to be used for this purpose shall be the shipped length and weight of forgings produced individually or the aggregate shipped length

and weight of all pieces cut from a multiple forging.

8.2.1 Annealed, Normalized, or Normalized and Tempered Steel Forgings:

8.2.1.1 For forgings weighing 5000 lb [2250 kg] or less at the time of heat treatment, one tension test shall be taken from one forging per heat in each heat–treatment charge. When heat treatment is performed in continuous-type furnaces with suitable temperature controls and equipped with recording pyrometers so that complete heat-treatment records are available, a tempering charge may be considered as any continuous run not exceeding an 8-h period.

8.2.1.2 For forgings and forged bars weighing over 5000 lb [2250 kg] at the time ofheat treatment, one tension test shall be taken from each forging.

8.2.2 Quenched and Tempered Forgings:

8.2.2.1 For quenched and tempered forgings weighing 5000 lb [2250 kg] or less at the time of heat treatment, but not exceeding 12 ft [3.7 m] in length, one tension test shall be taken from one forging per heat in each heat–treatment charge. When heat treatment is performed in continuous-type furnaces

with suitable temperature controls and equipped with recording pyrometers so that complete heat-treatment records are available, a tempering charge may be considered as any continuous run not exceeding an 8-h period.

8.2.2.2 For quenched and tempered forgings and forged bars weighing over 5000 lb [2250 kg] to 10 000 lb [4500 kg] at the time of heat treatment, but not exceeding 12 ft [3.7 m] in length, one tension test shall be taken from each forging.

8.2.2.3 For quenched and tempered forgings and forged bars that exceed 12 ft [3.7 m] in length, one tension test shall be taken from each end of each forging.

8.2.2.4 For quenched and tempered forgings and forged bars weighing more than 10 000 lb [4500 kg] at the time of heat treatment, two tension test specimens shall be taken from each forging. These shall be offset 180° from each other except that if the length of the forging, excluding test prolongations,

exceeds 12 ft [3.7 m], then one specimen shall be taken from each end of the forging.

9.1 Repair welding of forgings is permissible only at the option ofthe purchaser. Ifrepair welding is performed, welders and weld procedures shall be qualified in accordance with Section IX of the ASME Boiler and Pressure Vessel Code.

10.1 In addition to the mandatory certification requirements of Specification A788/A788M, the heat treatment cycle data shall be included.

11.1 Each forging shall be identified in accordance with the Marking Section of Specification A788/A788M. In addition, the forging shall be marked following the grade designation by

the letter “A” for annealed, “N” for normalized, “NT” for normalized and tempered, and “S” for liquid quenched and tempered, as applicable.

12.1 pressure vessel service; Carbon steel forgings