MIL-STD-1622B(SH)
exposed openings by minimizing evolutions such as grinding, painting, and brazing.
5.12 Piping repairs between flask and isolation valve.
5.12.1 Applicability. For repairs of piping between permanently installed flasks and the first flask isolation valve, the following procedure may be employed to eliminate the need for flask removal to hydrostatically test and clean the piping. Local engineering approval is required to employ this procedure.
5.12.2 System Preparation. The area where cutting or grinding will occur and the adjacent piping or equipment shall be externally cleaned to remove loose scale, dust, dirt, oil, grease, and other foreign materials. That portion of the system where cutting or grinding will occur shall be depressurized and isolated by shutting the boundary isolation valve. A convenient bleed point within the affected boundary shall be allowed.
5.12.3 Maintenance of purge. During cutting or grinding and when the system is open to the atmosphere, maintain a slight positive air or nitrogen purge of about 2 lb/in2 to prevent possible entry of airborne contamination or contamination from cutting or grinding.
5.12.4 Cutting/grinding of system. When cutting, cut to the blue line and carefully break the pipe or remove the fitting minimizing the entry of contaminants. When grinding, grind carefully to prevent the entry of contaminants. Exercise extreme caution when performing cuts in vertical pipe runs to prevent introducing contamination. A cut in a horizontal pipe run should precede any vertical cut. Increase purge pressure as necessary during cutting or grinding to prevent the entry of contaminants.
5.12.5 Cleaning. While maintaining the purge, locally clean the pipe internally and externally where the cutting or grinding occurred as specified in 5.13.4. If there are any significant delays during fit up and welding, the system shall be packaged as specified in 5.16.3. The purge shall be
maintained during welding. Work shall be planned so as to minimize the time the system is open to the atmosphere or temporarily packaged. If cleanliness is maintained properly and no contamination is detected, flushing of the piping system is not required. If contamination is detected, the extent and source of the contamination shall be determined and the system shall be cleaned as required to remove the contamination as specified herein.
5.12.6 Inspection and testing. Inspect and tightness test the weld as specified in NAVSEA S9086-RK-STM-010/CH-505 using the procedures for replacing a post repair hydrostatic test with a tightness test. Hydrostatic testing is not required. The joint tightness test shall also satisfy the requirements as specified in 5.10.
5.13 Loss of cleanliness.
5.13.1 Definition. Contamination of a system or component which has previously been cleaned as specified by this standard due to other than normal system use is considered a loss of cleanliness. Examples include oil contamination from a compressor and system degradation causing pieces of material to deposit in the system.
5.13.2 Method for determination of extent of contamination. Whenever loss or suspected loss of cleanliness occurs, the extent of the contamination shall be determined by performing a visual inspection as specified in
5.14.1.1. The boundary of the contamination is determined based on the
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