MIL-STD-1330-SUP-2 Precision Cleaning and Testing of Shipboard Oxygen, Helium, Helium-Oxygen, Nitrogen, and Hydrogen SystemsThis standard provides the requirements for precision cleaning and testing of oxygen or oxygen-enriched systems and components; oxygen generating plants including nitrogen, hydrogen, and demineralized water support systems and components; and helium, helium-oxygen, and hydrogen life support systems and components. Each activity will implement the applicable requirements of this document through a locally prepared and approved procedure. Activities subject to additional quality assurance requirements such as NAVSEA SS800-AG-MAN-010/P-9290 or NAVSEA SS521-AA-MAN-010 will obtain procedure approval from the applicable certifying activity.

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MIL-STD-1330D(SH)

20 September 1996

5.11  Piping repairs between flask and isolation valve.

5.11.1  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.

5.11.2  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 as specified in

5.10.1.1.  That portion of the system where cutting or grinding will occur shall be depressurized and purged of dangerous gases (such as, oxygen, hydrogen) using helium or nitrogen.  The affected portion of the system where cutting or grinding will occur shall be isolated by shutting the boundary isolation valve.  A convenient bleed point within the affected boundary shall be allowed.  After the affected portion has been depressurized, systems containing oxygen at levels greater than 22 percent or hydrogen at levels greater than 3 percent shall be purged with helium or nitrogen to eliminate fire or explosion hazards as specified in 5.10.1.4.

5.11.3  Maintenance of purge.  During cutting or grinding and when the system is open to the atmosphere, maintain a slight positive helium or nitrogen purge of

about 2 lb/in2

to prevent possible entry of airborne contamination or

contamination from cutting or grinding.

5.11.4  Cutting or 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.

5.11.5  Cleaning.  While maintaining the purge, locally clean the pipe internally and externally where the cutting or grinding occurred as specified in

5.12.4.  If there are any significant delays during fit up and welding, the system shall be packaged as specified in 5.16.1.3.  The purge shall be maintained during welding.  Work shall be planned 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.

5.11.6  Inspection and testing.  In addition to the inspection of the weld in accordance with MIL-STD-278, a liquid penetrant (PT) inspection shall be performed on the root of the weld.  Hydrostatic testing is not required.  Perform a joint tightness test as specified in 5.9.

5.12  Loss of system cleanliness.

5.12.1  Definition.  Contamination of a system which has previously been cleaned as specified by this standard due to other than normal system use is considered a loss of system cleanliness.  Examples include loss of a purge, system degradation causing pieces of material to deposit in the system, and inadvertent exposure of a cleaned surface to an uncontrolled atmosphere.

5.12.2  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 5.13.1.  The boundary of the contamination is determined based on the inspection results.  The following would be considered as unacceptable requiring corrective action as specified in

5.12.3.  This list is for guidance only and does not include all items that may be encountered requiring corrective action.

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