S9074-AR-GIB-010/278
13.1 Impregnation. Only castings of copper-base alloys or alluminum-base alloys shall be considered for approval to inpregnate. Impregnation of castings will be permitted to seal off minor leakage due to micro-porosity or other casting defects only after NAVSEA approval and when the defective castings are shown by radiography to be structurally sound. The suitability of aluminum base alloy casting for impregnation shall be based on review of the individual radiographs. Copper-base alloy castings which conform to the applicable classification of radiographic standards are considered satisfactory for impregnation. Copper-nickel castings shall not be impregnated. Castings of any alloy for oxygen service shall not be impregnated. Welding shall not be permitted on castings which have been impregnated. 13.1.1 Impregnation authority. Authority to impregnate castings shall be obtained from NAVSEA. Requests for authority to impregnate shall be accompanied by radiographs of the defective areas of the particular casting or representative casting in the case of a large lot. together with complete information as to the condition of the castings including marked drawings where applicable, the percentage of castings of each type requiring inpregnation, the service for which intended. the name of the foundry or contractor, and the contract or order number. Approval to impregnate is solely at NAVSEA discretion. In addition to the above requirements approval or disapproval depends upon other considerations such as terperature. pressure. service application (including the need/means for in-service repair) and a comparison of service exposure duration and severity to the conditions in MIL-I17563 qualification tests. 13.1.2 Impregnation procedure when approved by NAVSEA. shall be performed in accordance with MIL-STD-276. Each casting which has been impregnated shall be stamped 'IMP' on the stamping pad or in a conspicuous place that will not impair the strength or serviceability of the casting. 13.2 Repair welding 13.2.1 General. This section contains requirements for repair of weldable castings. In the event of a conflict between requirements specified herein and those contained in casting material specifications. the requirements specified herein shall govern. 13.2.2 Minor repairs. Minor repairs are those repairs which do not exceed the following limits:
Maximum - depth does not exceed 20 percent of the casting thickness or 1-inch depth. whichever is less. and individual repair areas do not involve more than 4 percent of the casting surface. Weld build-up for correction of casting dimensions or machining discrepancies not exceeding 10 percent of the total area of the castings may be made at the discretion of the contractor or foundry when the weld build-up is within the following limitations:
(a)
(b)
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