(a) Additional tests before rejection.- Should any of the original test pieces fail to pass the mechanical tests, two further samples which represent the same casting or castings shall be selected and tested in the same manner. The manufacturer shall have the right, if he so desires to re-heat-treat the castings before the two further samples are selected.

Should the two further tests satisfy the requirements of this standard, castings represented by them shall be accepted. Should either of the re-tests fail, the castings represented shall be liable to rejection.

(b) Hardness test after heat treatment.- The Inspecting Officer may call for hardness testing of the heat-treated castings.

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(c) Non-destructive tests.- The Inspecting Officer may call for radiographic examination or other non-destructive testing of the castings.

Castings found to be unsound may be treated in accordance with regulation 75. If the welding repairs are sanctioned by the Inspecting Officer, they shall be carried out in accordance with regulation 80.

High class casting for which a factor greater than 80% is taken in computation of permissible working stress shall be subject to the following inspection requirements:

(i) Each casting shall be examined by radiographic or ultrasonic methods at all critical locations and found free from harmful defects. All the castings shall be fully machined to such an extent that all critical sections are exposed for full thickness.

(ii) All castings shall be examined at all critical locations using magnetic- particle or penetrant-fluid procedure, or by grinding or machining or etching.

(iii) Castings found to be defective shall be rejected or repaired to the satisfaction of the Inspecting Authority. If repairs by welding are carried out the casting shall be subsequently stress-relieved or heat-treated. Castings found to be unsound may be treated in accordance with regulation 80. Repaired areas of castings shall be re-examined by the Inspecting Officer in accordance with sub-clause (i) and shall be shown to be free from harmful defects.

(iv) Castings to which a quality factor of 0.90 is assigned shall be clearly and permanently marked with a suitable symbol after being examined as above and found satisfactory.

Note:- The provisions of the first paragraph of clause (c) of  regulation 79 shall apply to the castings other than high class castings for which a factor greater than 80% is used in the computation of permissible working stress for shells of Boiler and integral superheater Drums and Headers under regulation  271.