MIL-STD-767 REV G.pdf

AMSC N/A

INCH-POUND

MIL-STD-767G(SH)

5 September 2012

SUPERSEDING

MIL-STD-767F(SH)

10 November 2000

DEPARTMENT OF DEFENSE

MANUFACTURING PROCESS STANDARD

CONTROL OF HARDWARE CLEANLINESS

FSC 20GP

DISTRIBUTION STATEMENT F: Further dissemination only as directed by Naval Sea Systems Command (Code 09T) or its authorized representative.

MIL-STD-767G(SH)

FOREWORD

1. This Manufacturing Process Standard is approved for use by the Naval Sea Systems Command (NAVSEA) , Department of the Navy, and is available for use within the distribution limitations noted on the cover page.

2. Comments, suggestions, or questions on this document should be addressed to Commander, Naval Sea Systems Command , ATTN: SEA 050, 1333 Isaac Hull Avenue, SE, Stop 5160, Washington Navy Yard DC 20376-5160 or emailedtocommandstandards@navy.mil with the subject line "Document Comment". Since contact information can change, you may want to verify the currency of this address information using the ASSIST Online database at www.dodssp.daps.mil.

ii

CONTENTS

PARAGRAPH PAGE

1. SCOPE

1.1 Purpose

1.2 Applicability

2. APPLICABLE DOCUMENTS

2.1 General

2.2 Government documents

2.3 Non-Government publications

2.4 Order of precedence

3. DEFINITIONS

3.1 Authorized Representative of the Naval Sea Systems Command

3.2 Cleanliness boundary

3.3 Cleanliness cap, cover, plug or seal

3.4 Corrosion resistant material

3.5 Crevice

3.6 Critican surface

3.7 Exposed location

3.8 Final closure

3.9 Final surface

3.10 Foreign material

3.11 Hardware

3.12 Inaccessible area

3.13 Internal surface

3.14 Lint free cloth

3.1 5 Loss of cleanliness

3.16 Loss of cleanliness control

3.17 Noncorrosion-resistant material

3.18 Rust

3.19 Support system

3.20 Thermal treatment

4. GENERAL REQUIREMENTS

4.1 Conflicts

4.2 Procedures

5. CONTROL OF DETRIMENTAL MATERIALS

5.1 Control of Detrimental Materials

6. CLEANING REQUIREMENTS

6.1 Cleaning

6.2 Cleaning restrictions on specific types of hardware

6.3 Cleaning methods

6.4 Rust removal

6.5 Tape residue removal

6.6 Drying

ii i

PARAGRAPH

7. CLEANLINESS INSPECTION

7.1 Introduction

7.2 Cleanliness inspection requirements

7.3 Cleanliness inspection methods and acceptance criteria

8. MAINTAINING CLEANLINESS

8.1 Introduction

8.2 Cleanliness operations

8.3 Sealing and capping hardware openings

8.4 Cleanliness identity

8.5 Tools and equipment cleanliness

8.6 Preventing foreign material from entering hardware

8.7 Tape

8.8 Water requirements

8.9 Support system requirements

9. RECOVERY FROM A LOSS OF CLEANLINESS OR LOSS OF

CLEANLINESS CONTROL

9.1 Procedure

9.2 Inspection for foreign material

9.3 Removal of foreign material

9.4 Verification of cleanliness

9.5 Records

9.6 Hardware acceptance

10. NOTES

10.1 Changes from previous issue

iv

FIGURES PAGE

1 Nonexpandable caps and seals 2 Nonexpandable plugs 3 Expandable plug D-1 Crevicefixture

TABLES

I Cleaning solvents II Solvent temperatures for vapor degreasing 11 1 Water purity IV Required grade of test water A-I Acid cleaning methods A-II IGA depth limits

APPENDICES

A CLEANING METHODS

B FREE IRON DETECTION

C REQUIREMENTS FOR CAPS, COVERS, SEALS AND PLUGS

D QUALIFICATION OF ALTERNATE FINAL CLEANING

SOL VENTS

v

1. SCOPE

1.1 Purpose. The purpose of this standard is to establish uniform requirements for cleaning and maintaining cleanliness of hardware.

1.2 Applicability. This standard , when invoked by contract technical requirements, applies to hardware internal surfaces. The detrimental material control requirements of MIL STD-2041 apply to internal hardware surfaces and external surfaces of pressure boundary parts.

2. APPLICABLE DOCUMENTS

2.1 General. The documents listed in this section are specified in Sections 3 through 9 of this standard . This section does not include documents cited in other sections of this standard or recommended for additional information or as examples. While every effort has been made to ensure the completeness of this list, document users are cautioned that they must meet all specified requirements of documents cited in Sections 3 through 9 of this standard , whether or not they are listed .

2.2 Government documents.

2.2.1 Specifications and standards. The following specifications and standards form a part of this standard to the extent specified herein . Unless otherwise specified , the issues of these documents are those cited in the solicitation or contract.

SPECIFICATIONS

FEDERAL

O-S-642

TT-1-735

MILITARY

MIL-PRF-680

MIL-D-16791

MIL-C-24671

STANDARDS

MILITARY

- Sodium Phosphate, Tribasic, Anhydrous;

Dodecahydrate; and Monohydrate; Technical

- lsopropyl Alcohol

- Dry Cleaning Solvent.

- Detergents, General Purpose (Liquid, Nonionic)

- Cloth , Lint-Free, Flushing and Cleaning

MIL-STD-2041- Control of Detrimental Materials

(Copies of these documents are available online at https://assist.daps.dla.mil/quicksearch/ or www.dodssp.daps.mil or from the Standardization Documents Order Desk, Building 4D, 700 Robbins Avenue, Philadelphia, PA 19111-5094.)

2.2.2 Other Government documents. drawinqs, and publications. The following other Government documents, drawings, and publications form a part of this standard to the extent specified herein . Unless otherwise specified , the issues of these documents are those cited in the solicitation or contract.

PUBLICATIONS

NAVAL SEA SYSTEMS COMMAND

NAVSEA 250-1500-1 - Welding Standard NAVSEA S9074-AR-GIB-010/278 - Requirements for Fabrication , Welding and

Inspection, and Casting Inspection and Repair for Machinery, Piping , and Pressure Vessel Welds

CODE OF FEDERAL REGULATIONS

Title 27 - Alcohol , Tobacco Products, and Firearms

Chapter 1 - Bureau of Alcohol , Tobacco Products, and Firearms, Department of the Treasury

Part 21 - Formulas for Denatured Alcohol and Rum

(Copies of this document are available on line at www.access.gpo.gov or from the Superintendent of Documents, Government Printing Office, North Capitol & "H" Streets, NW.,Washington , DC 20402-0002.)

OTHER

AAFCSL - Approved Alternate Final Cleaning Solvents List

(Copies of this document are available online at https://logistics.bpmionline.neUconsolidatedaplqpl or from the Manager, Materials Engineering , Bechtel Plant Machinery, Inc., 3500 Technology Drive, Monroeville, PA 15146-2459.)

(Copies of publications and drawings required by contractors in connection with specific acquisition functions should be obtained from the contracting activity or as directed by the contracting activity.)

2.3 Non-Government publications. The following documents form a part of this standard to the extent specified herein. Unless otherwise specified , the issues of these documents are those cited in the solicitation or contract.

AMERICAN CHEMICAL SOCIETY (ACS) SPECIFICATIONS

Reagent Chemicals

(Copies of this document are available from the American Chemical Society, 1155 Sixteenth Street, N. W. , Washington D.C. 20036.)

AMERICAN IRON AND STEEL INSTITUTE (AISI)

Steel Products Manual

(Copies of this document are available from the American Iron and Steel Institute, 1140 Connecticut Avenue, Washington DC 20036.)

AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM)

ASTM D 329 - Standard Specification for Acetone ASTM D 4080 - Standard Specification for Trichloroethylene, Technical and

Vapor-Degreasing Grade ASTM D 4376 - Standard Specification for Vapor-Degreasing Grade

Perchloroethylene

(Copies of these documents are available from the American Society for Testing and Materials, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959 or on line at (www.astm.org .)

SOCIETY OF AUTOMOTIVE ENGINEERS (SAE)

SAE AS8660 - Silicone Compound NA TO Code Number S-736

(Copies of this document are available from the Society of Automotive Engineers, 400 Commonwealth Drive, Warrendale PA 15096-0001 or online at www.sae.org .)

2.4 Order of precedence. In the event of a conflict between the text of th is document and the references cited herein , the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained .

3. DEFINITIONS

3.1 Authorized Representative of the Naval Sea Systems Command:

a. The Commander of a Naval Shipyard, for vendors to the Naval Shipyard .

b. The commercial shipyard , for subcontractors to the commercial shipyard .

c. The direct contractor of the Naval Sea Systems Command, other than a commercial shipyard, who has design and/or procurement responsibility , for all others.

3.2 Cleanliness boundarv. For support systems, a filter arrangement or other device (e.g. , fluid separator) used to separate a portion of the system that is a lower level of cleanliness from a portion of the system with a higher level of cleanliness.

3.3 Cleanliness cap, cover, plug or seal. For open or exposed hardware, temporary equipment or materials that are applied to the hardware to exclude foreign material as necessary until installation .

3.4 Corrosion-resistant material. A metal or alloy that inherently resists oxidation or chemical attack in air and water at ambient temperatures. Examples include chromium-nickel corrosion-resistant steel , nickel base, cobalt base, and copper base alloys, and precipitation hardened corrosion-resistant steel.

3.5 Crevice. Any narrow opening in a surface or any open juncture between mating surfaces in which detrimental solutions or foreign particles can likely be entrapped and not readily observed or removed. Examples include the annular space in threaded connections and socket assemblies, tube-to-tube support joints, and small holes and grooves. Tightly fitting parts with no visible gap need not be considered a crevice with respect to foreign particles.

3.6 Critical surface. A surface which , when corroded or otherwise roughened , can impair the hardware's proper function . Examples include small orifices, bearings, bellows, seal membranes or heat exchanger tubing up to 1/8 inch thick.

3.7 Exposed location . Any opening in hardware which exposes a final cleaned internal surface that is inaccessible.

3.8 Final closure. Any final assembly operation that will prevent visual access to internal surfaces, except that assembly operations that create crevices only are not considered final closures. An example of final closure includes final fitup of piping joints for welding.

3.9 Final surface. A hardware surface that will be subjected to no further metal removal operations.

3.10 Foreign material. Any material or object that should not be on or within clean hardware. Examples include grit, chips , particles, oil , machining coolant, liquid penetrant, dried liquid residue/stains , slag , scale, fibers , tape, tools , and loose articles.

3.11 Hardware. Any article, piece of material , individual part, subassembly, assembly, equipment or system to which this standard applies.

3.12 Inaccessible area. A hardware surface that is not readily accessible for cleaning or visual inspection , wipe cloth inspection or swab inspection ; includes all crevices.

3.13 Internal surface. A surface that contacts system fluid .

3.14 Lint free cloth. A cloth which is free from loose thread , fluff from cloth or yarn , or other particles of a size visible to the unaided eye, and which does not leave any visible residue on the hardware surface. If used for cleaning or inspecting a hardware surface, it shall meet the detrimental material requirements of MIL-STD-2041 .

3.15 Loss of cleanliness. A condition in which a final cleaned surface of hardware does not meet the cleanliness verification criteria of this standard .

3.16 Loss of cleanliness control. A condition in which control of proper cleanliness maintenance for a final cleaned surface of hardware is lost. Loss of cleanliness control may or may not involve an actual loss of cleanliness.

3.17 Noncorrosion-resistant material. A material that inherently does not resist oxidation or chemical attack in air or water at ambient temperatures. Examples include carbon steels, low alloy steels, and low chromium martensitic steel (generally AISI 400 and 500 series steels, except for AISI 403 and 410, which are corrosion resistant) .

3.18 Rust. Visible corrosion product consisting of hydrated oxides of iron . Rust usually forms when iron or ferrous alloys are exposed to water, or moisture and oxygen in air.

3.19 Support system. A structure of fluid-handling or gas-handling equipment and/or instrumentation that is temporarily attached to the hardware, which is required to be clean to this standard , that could add fluid or gas to the hardware for the purpose of cleaning, calibrating , flushing , testing, or performance of other specified operations.

3.20 Thermal treatment. Any operation, except vapor degreasing in perchloroethylene, where the temperature of the hardware exceeds 350°F (177°C). Examples include heat treating , welding , brazing , preheating for welding or brazing , hot forming , stress relieving , hot tests, baking for embrittlement relief and hot plant operations. Metal removal (other than thermal cutting) is not a thermal treatment.

4. GENERAL REQUIREMENTS

4.1 Conflicts. Any conflict noted within this standard or between this standard and other contract technical requirements shall be promptly brought to the attention of NAVSEA or its authorized representative, prior to any action by an organization .

4.2 Procedures. Each organization shall develop procedures for hardware cleaning and cleanliness control which satisfy the requirements of this standard. The procedures shall be available for review or approval upon request.

5. CONTROL OF DETRIMENTAL MATERIALS

5.1 Control of Detrimental Materials. The detrimental material control requirements of MIL-STD-2041 apply.

6. CLEANING REQUIREMENTS

6.1 Cleaning . Hardware shall be final cleaned by one or more of the cleaning methods in 6.3, to conform to the acceptance criteria of Section 7. Alternate solvent cleaning methods used in accordance with the restrictions of MIL-STD-2041 may be used for preliminary cleaning of hardware. The cleaning method selected should be effective for removing the particular foreign material present.

6.2 Cleaning restrictions on specific types of hardware.

6.2.1 Hardware surface with a crevice or inaccessible area. Each hardware surface that will be part of a crevice or inaccessible area shall be in a final cleaned condition prior to the assembly operation that creates the crevice or inaccessible area. Once assembled , cleaning of the crevice or inaccessible area requires disassembly or use of a cleaning procedure approved by NAVSEA or its authorized representative .

6.2 .2 Non-metallics. Non-metallic hardware shall not contact any solvent that would degrade it.

6.2 .3 Acid cleaning , blast cleaning , and tumbling . Acid cleaning, blast cleaning , and tumbling shall be used only after obtaining approval of NAVSEA or its authorized representative .

When approved for use, acid cleaning , blast cleaning , and tumbling shall be performed in accordance with the procedure requirements of Appendix A, Sections A.5 , A.6 , and A.7 , respectively.

6.2.4 Seal membranes. The final surfaces of seal membranes shall not be mechanically cleaned by power driven grinding, polishing , or wire brushing .

6.2.5 Tube and pipe. Internal surfaces of tube or pipe that contain no crevices may be final cleaned by swabbing as specified in Appendix A, Section A.4.

6.2.6 Hardware to which thermal insulation will be applied . Before applying thermal insulation , all exterior surfaces of corrosion-resistant steel to which the insulation will be applied shall be cleaned in accordance with 6.3.2.

6.3 Cleaning methods.

6.3 .1 Mechanical cleaning . Examples of mechanical cleaning include grinding , buffing , pol ishing , wire brushing , sanding , filing , rubbing , etc. Mechanical cleaning shall be performed in such a manner that particles will not enter an exposed location of the hardware being cleaned.

All particles resulting from mechanical cleaning operations shall be removed from the hardware.

6.3.2 Solvent cleaning. Only solvents meeting the specifications and conditions listed in Table I shall be used for final cleaning. Except as specified in 6.2, cleaning shall be performed with any of the solvents listed in Table I by immersion , vapor degreasing (as applicable) , or by wiping with a saturated clean , lint-free cloth or swab. After solvent cleaning, hardware shall be thoroughly dried .

6.3.2.1 Solvent cleaning exception . Specific solvents listed on the AAFCSL may also be used for final cleaning hardware in accordance with the restrictions specified (i.e. , for use on all hardware or hardware with no crevices or inaccessible areas). Activities wishing to use a specific solvent not on the list should qualify the solvent to the procedure in Appendix D and request approval for use from NAVSEA or BPMI. For continued use, specific solvents must be requalified for detrimental material content every four years .

TABLE I. Cleaning solvents

Code Solvent Specification Additional requirements

A Acetone ASTM D 329 Unused or redistilled

B Denatured alcohol 27-CFR-21 Denatured ethanol conforming to formula 3-A, 3-C, 23-A or 30 c lsopropyl alcohol TT-1-735 - -

D Grade B water Table Ill For loose particles or water-soluble contaminants

E Perchloroethylene ASTM D 4376 Shall not be used on hardware (T etrachloroethylene) with crevices or inaccessible areas or non-metallic hardware.

F Trichloroethylene ASTM D 4080 Shall not be used on hardware with crevices or inaccessible areas or non-metallic hardware.

G Deleted

H Nonionic detergent MIL-D-16791 Maximum of 1 fluid ounce (28.3 grams [29.6 ml]) per gallon (3.8 liters) of grade C water. Shall not be used on hardware with crevices or inaccessible areas. Cleaning shall be per 6.3.2.3.

I Trisodium phosphate O-S-642 Add 2.3 to 23 ounces (65.2-652 (TSP) - detergent grams) of dodecahydrate TSP solution to 1 gallon (3.8 liters) of solvent H. Shall not be used on hardware with crevices or inaccessible areas. Cleaning shall be per 6.3.2.3.

J

Dry cleaning Solvent MIL-PRF-680 For preliminary degreasing or for (Stoddard solvent) Type I removal of tape adhesive residue only. Shall not be used on hardware with crevices or inaccessible areas.

Note: American Chemical Society reagent grade chemicals , if available for the solvents listed above, may also be used.

6.3.2.2 Vapor degreasing . Vapor degreasing shall be performed as follows:

a. Solvent operating temperatures shall be maintained in accordance with Table II requirements. A solvent shall be replaced if its boiling point exceeds the applicable maximum operating temperature specified in Table II or if it is not degreasing properly.

b. Solvents E and F shall contain a neutral inhibitor to maintain a pH of 6.5 to 7.5.

TABLE II. Solvent temperatures for vapor degreasing

Solvent Operating Temperature, °F (°C) Code

Minimum Maximum

E 248 (120) 258 (126) F 185 (85) 195(91)

6.3.2.3 Trisodium phosphate and detergent cleaning . Trisodium phosphate or detergent cleaning shall be performed as follows:

a. Hardware may be cleaned by scrubbing with or immersion in solvents Hor I. A wetting agent may be added to the solution if necessary. The wetting agent, when diluted to the concentration in the detergent solution , shall conform to the detrimental material requirements of MIL-STD-2041 .

b. Hardware shall be final rinsed with grade B water at a temperature of 120°F (66°C) minimum, until no visible solvent H or I film remains on the surface after drying . Grade C water may be used for an initial rinse , if desired . Final rinsed hardware shall be dried .

c. Solutions of solvent H or I in continuous or intermittent use (e.g., cleaning baths) shall be tested weekly for chloride buildup. Sampling may be suspended during extended periods of non-use but shall be reinitiated prior to putting the solution back in use. A batch of solution shall not be used if its chloride ion concentration exceeds 500 ppm.

6.3.2.4 Ultrasonic cleaning . All of the solvents listed in Table I may be used for ultrasonic cleaning . All applicable restrictions and requirements specified in 6.2 and 6.3 shall be observed .

6.3.2.5 Filter cleaning. Temporary support system cleanliness filters that have not been fabricated to this standard may be cleaned by ultrasonic cleaning (6.3.2 .4) or another method approved by NAVSEA or its authorized representative and then flushed to a type I acceptance criteria (see 7.3.4.7) .

6.3.3 Vacuum cleaning. Hardware surfaces contaminated with dirt, grit, dust, or similar material may be final cleaned by vacuuming .

6.3.4 Flushing . Flushing to establish cleanliness or to remove foreign material to reestablish cleanliness is allowed when the criteria of 9.3.b. have been met. Flushing shall be performed in accordance with the requirements in 7.3.4. Hardware shall not be purposely assembled without cleanliness controls with the intention of cleaning by flushing .

6.4 Rust removal. Rust shall be removed using any mechanical methods of this standard. For carbon and low alloy steels, the stripping procedure of Appendix A, Section A.3 , may be used, observing the hardware restrictions for acid cleaning of Appendix A, Section A.5.

6.5 Tape residue removal. Tape residue shall be removed with any cleaning method allowed in Section 6. In addition , tape residue may be removed with the procedure of Appendix A, Section A.8 provided that then-heptane is used in accordance with MIL-STD-2041 .

6.6 Qr:yjng. When drying of hardware is specified , open flames shall not be used and hardware should not be exposed to damaging temperatures. Drying systems should meet the support system cleanliness requirements of 8.9.

6.6.1 Special drying requirements for noncorrosion-resistant material. Hardware that contains noncorrosion-resistant material shall be dried as soon as practicable after water contacts the noncorrosion-resistant material. Accessible surfaces of dried hardware containing noncorrosion-resistant material shall be visually inspected for residual water and rust.

7. CLEANLINESS INSPECTION

7.1 Introduction. This section provides clean liness inspection requirements , methods, and acceptance criteria to determine that the cleanliness requirements of this standard have been met. Hardware without inaccessible areas that is cleaned to MIL-STD-2041 can be accepted as clean to this standard .

7.2 Cleanliness inspection requirements .

7.2.1 Inspection Requirements. Hardware surfaces shall be inspected for cleanliness at the times and by the personnel specified below.

INSPECTION INDEPENDENT INSPECTION REQUIRED

a. Following entry into clean hardware. a. Yes, for entry that is dirt producing (e.g. , machining , grinding) or potentially dirt producing operations (e.g ., clean cuts of pipe) .

b. Prior to final closure. b. Yes (exception : no for closure of support systems or connection of support systems to clean hardware) .

c. During any operations in which a c. Yes .

loss of cleanliness could occur that is not easily detected and corrected .

d. Reverification of hardware d. Yes.

cleanliness per Section 9.

INSPECTION INDEPENDENT INSPECTION REQUIRED

e. Final inspection following fabrication e. Yes.

of hardware or dirt producing modification to hardware.

f . Prior to and during assembly f. No; however, an independent inspection is operations (including assembly that required prior to final closures (see creates crevices) . inspection b) .

g. Before each thermal treatment. g. No.

h. After each free iron check. h. No.

i. Before and after acid cleaning . i. No.

j . After any test that uses soft metal j . No.

probes or tips ; for example, alloy identity or magnetic particle testing .

k. After removal of a controlled product k. Yes, for internal surfaces of hardware as defined in MIL-STD-2041 . that contains crevices and inaccessible areas.

I. Following cleaning of internal I. No; except when performed for a, b, c, d, or surfaces. e, or when crevices or inaccessible areas of hardware are exposed.

m. Following tape removal. m. No.

n. Final inspection of cleanliness plugs. n. No, provided the plugs are assembled from clean parts or subassemblies without crevices or inaccessible areas and if the assembly occurs in a clean room or clean area.

0 . During assembly or disassembly 0 . Yes. Inspector shall monitor joint of joints with thread sealant assembly and disassembly. Where downstream of cleanliness filters practical, the inspector shall verify that per 8.9.4. there is no visible thread sealant on internal surfaces following assembly.

7.2.2 Inspection personnel.

a. Those inspections requiring independent inspection in 7.2.1 shall be performed by personnel not responsible for the cleaning and timely delivery of hardware, unless otherwise approved by NAVSEA or its authorized representative .

Production personnel trained to perform inspections for cleanliness may perform the inspections required by 7.2.1 , if an independent inspection is not required .

b. Personnel performing inspections must possess normal visual acuity (natural or corrected) .

7.2.3 Inspection lighting. During cleanliness inspection, each hardware surface being visually inspected shall be illuminated by at least 50 lumen/square foot (538 lux) .

7.3 Cleanliness inspection methods and acceptance criteria. All hardware shall be cleanliness inspected by one or more of the following methods:

a. Visual Inspection - Applicable to all internal hardware surfaces that are visually accessible. Boroscopes, videoprobes, mirrors, and other aids of sufficient resolution may be used to extend the ranges of visual inspection .

b. Wipe Cloth Inspection - Applicable to physically accessible internal surfaces that cannot be visually inspected .

c. Swab Inspection - Applicable to piping assemblies without crevices .

d. Proof of Cleanliness Flush .

7.3.1 Visual inspection. The surface shall be visibly (without magnification) free of foreign material , except:

a. Small amounts of graphite in isopropanol (where used for assembly) are acceptable.

b. A few discrete lint fibers , each less than 1/4 inch (6.4 millimeters) in length , is acceptable,

c. Rust in accordance with 7.3.1.1 is acceptable.

d. Temper films and oxide films in accordance with 7.3.1.3 are acceptable.

7.3.1.1 Acceptance criteria for rust on new hardware surfaces. The following describes the acceptance criteria for corrosion products on new hardware surfaces.

7.3.1.1 .1 Corrosion-resistant material.

7.3.1.1.1 .1 Rust on critical surfaces. A critical surface shall be free of rust. A critical surface exhibiting rust shall be cleaned in accordance with 6.4 to remove the rust and any rust-producing condition . After rust removal, the surface shall be tested in accordance with test methods I, II , or Ill of Appendix B.

7.3.1.1.1.2 Rust on non-critical surfaces. A non-critical surface exhibiting rust shall be cleaned in accordance with 6.4 unless all the following conditions are satisfied :

a. The rust has no visible thickness.

b. The rusted area does not exceed one percent of any one square foot (929 square centimeters) area.

7.3.1.1.2 Noncorrosion-resistant material.

7.3.1.1 .2.1 Rust. Light superficial rust showing no visible thickness is acceptable on any surface. A tightly adherent oxide deposit that cannot be removed by solvent cleaning is also acceptable. All other rust shall be removed in accordance with 6.4.

7.3.1.2 In-service hardware. For hardware that has been in service and returned for refurbishment, the presence of normally occurring corrosion and wear products are acceptable provided there are no visually apparent unusual debris or substances (determined without magnification). However, readily accessible loose corrosion or wear products should be removed . Except for tanks, filters , and dead legs where sediment may collect, the presence of unusual quantities of wear products and particles exceeding the size criteria of 7.3.4.7 shall be promptly reported to NAVSEA or its authorized representative for information .

7.3.1.3 Metal oxide films. Tightly adherent metal oxide films with no visible thickness , which occur on final cleaned surfaces of hardware from specified thermal treatments, are acceptable, except as specified below:

a. Metal oxide films that can be removed by rubbing with a clean cloth are unacceptable.

b. Variations in temper film/oxide appearance caused by foreign material are unacceptable. Examples of unacceptable variations include (1) distinct outlines,

(2) rough or raised surface areas from tape residue , and (3) dried liquid stains, pools and splashes.

7.3.2 Wipe cloth inspection . Wipe cloth inspection shall be performed by wiping the surface being inspected with a wet or dry lint free cloth . Cleanliness shall be evaluated by comparing the wipe cloth with one used to wipe a visually acceptable surface of similar area and finish which has been cleaned in accordance with Section 6. If the wipe cloth exhibits more entrapped or captured foreign material or more discoloration than the comparison cloth , the hardware surface shall be cleaned in accordance with this standard and reinspected . If a cloth is free of discoloration and foreign material , the cloth is acceptable and a comparison cloth is not required .

7.3.3 Swab inspection . Each tube or pipe that is final cleaned by the swab method of Appendix A, Section A.4 shall be cleanliness inspected in accordance with the following . A comparison swab of the same size as the inspection swab shall be transported through a clean tube of the similar length and diameter. As an alternative, the comparison swab may be rubbed on a visually acceptable surface of similar length. If the inspection swab exhibits more entrapped or captured foreign material or more discoloration than the comparison swab, the tube or pipe shall be cleaned in accordance with th is standard and reinspected . If an inspection swab is free of discoloration and foreign material , the inspection swab is acceptable and a comparison swab is not required .

7.3.4 Flushing .

7.3.4.1 Use of flushing . Flushing to restore cleanliness may be performed only when specified in Section 9. Proof of cleanliness flushes may be performed without approval.

7.3.4.2 Flushing procedure. Flush ing shall be performed in accordance with a written procedure that includes the following information , as applicable:

a. Hardware to be flushed .

b. Type of flush .

c. Flushing fluid (e.g., grade of water or type of gas).

d. Flow rate of flushing water or gas into the hardware.

e. Total duration of flush .

f. Type of effluent filter.

g. Flow direction or flow path.

h. Flush equipment.

i. Flushing filter location(s).

7.3.4.3 Flushing fluid . Unless otherwise specified , hardware shall be flushed in accordance with the water quality requirements of 8.8. Gas support systems, which are disconnected from hardware controlled by th is standard , may be flushed with filtered air or filtered inert gas.

7.3.4.4 Flushing flow requirements . Except for flushing of instrumentation in accordance with 7.3.4.9, the following requ irements apply to the flow of flush ing fluid :

a. Flow velocity. If practicable, flow velocity during flushing shall equal or exceed the flow velocity during normal operation . If normal flow velocity cannot be achieved during flushing , then, to the maximum practicable extent, flow velocity during flushing shall cause turbulent flow.

b. Flow direction . Flushing material from other parts of the system into large, low velocity flow regions or into clean portions of the hardware shal l be avoided .

c. Flow volume. The minimum volume of the flush shall be equal to the internal volume of the component being flush tested . For piping systems, at least three times the volume of the system being flushed shal l be used. The flow for this volume shall be continuous, if practicable .

7.3.4 .5 Filter cloth . A filter cloth's active filtering area shall be no larger than approximately one square foot (929 square centimeters) and shall conform to the techn ical requirements of MIL-C-24671. Detrimental material testing is not required for cloths used for outflushes.

7.3.4 .6 Flushing filter inspection and acceptance criteria . After the completion of each flush , the effluent filter shall be visually inspected for cleanliness. Flushing is complete when two separate, successive flushes conform to the acceptance criteria . When flushing used support systems or hardware that has been in service and is returned for refurbishment and the material causing rejection of the hardware is corrosion or wear products, flushing may continue until two successive acceptable flushes are obtained . If unusual debris or substances are obtained on flush cloths, recover per Section 9.

7.3.4 .7 Type I flush acceptance criteria . All fl ushes shall meet Type I criteria unless specified otherwise. The flush is acceptable if the general appearance of the effluent filter cloth is that of a clean white cloth showing no more than slight speckling , soiling , or staining and the material on the filter cloth does not exhibit any of the following:

a. Fine hair-like sliver larger than 1/16 inch (1 .6 millimeters) in any dimension.

b. Thin flake-like particle larger than 1 /16 inch (1 .6 millimeters) in any dimension.

c. Particle of other geometry, larger than 1/32 inch (0.8 millimeters) in any dimension.

d. Readily apparent (by visual inspection without magnification) quantities of unusual debris or substances, such as resin beads, abrasive grit, oi l, grease, brazing flux, welding flux, pipe joint sealer, or preservative.

e. Visually apparent lint fibers greater than 1 /4 inch (6.4 millimeters) in length.

7.3.4.8 Type II flush acceptance criteria . The flush is acceptable if the total quantity of material on the effluent filter cloth is less in area and thickness than a 1 O cent piece and the material on the filter cloth does not exhibit any of the following :

a. Fine hair-like sliver larger than 1/8 inch (3.2 millimeters) in any dimension.

b. Thin flake-like particle larger than 1/8 inch (3.2 millimeters) in any dimension.

c. Particle of other geometry, larger than 1/16 inch (1 .6 millimeters) in any dimension.

d. Readily apparent (by visual inspection without magnification) quantities of unusual debris or substances, such as resin beads, abrasive grit, oil , grease, brazing flux , welding flux, pipe joint sealer, or preservative.

e. Visually apparent lint fibers greater than 1 /4 inch (6.4 millimeters) in length .

7.3.4.9 Flushing of instrumentation. A disconnected instrument that cannot be flushed by once-through or recirculating methods shall be flushed by either alternate filling and draining or flowing flu id into the instrument through a small diameter tube. Instrumentation shall be flushed until the effluent is visibly clear when observing a static sample or no visible particles or staining are detected when passed through a filter cloth .

8. MAINTAINING CLEANLINESS

8.1 Introduction. This section provides requirements for maintaining cleanliness of final cleaned internal hardware surfaces. Cleanliness is maintained by preventing foreign material from contacting hardware and from entering hardware.

8.2 Cleanliness operations. Hardware shall not be manufactured with the expectation of cleaning only after completion of fabrication or assembly, except when the finished hardware is completely accessible for cleaning and inspection (i .e., free of crevices and inaccessible areas).

Post assembly flushing is not an acceptable alternative to maintaining hardware cleanliness up to and including assembly. Component parts of hardware shall be cleaned prior to assembly;

thereafter, the assembled hardware shall be maintained in a clean condition . Equipment supplied under this standard shall be suitably clean for installation directly into a piping system without further cleaning. It is extremely important that contamination be kept to a minimum to prevent adverse effects upon the system such as accelerating the corrosion and wear of equipment or chang ing the chemistry of the flu id in the system.

8.3 Sealing and capping hardware openings. All openings in hardware shall be capped , covered , or plugged when not in use. Plugs and seals, including attached lanyards, shall be examined for deterioration before and after each use. Illustrated examples of temporary caps, seals, and plugs for hardware are shown in Figures 1 through 3. Specific requirements for caps, seals, and plugs are located in Appendix C.

8.4 Cleanliness identity. Shipping documents accompanying hardware that conforms to the requirements of this standard shall state that the hardware meets the cleanliness requirements of MIL-STD-767. For hardware fabricated to the requirements of this standard by a sub-tier vendor, the organization receiving the hardware shall maintain clean liness and cleanliness identity of the hardware in accordance with this standard .

8.5 Tool and equipment cleanliness. Any object or article (such as tools, inspection instruments, hands, and packing and packaging materials) that contacts a final cleaned surface shall be free of foreign material.

8.6 Preventing foreign material from entering hardware. To prevent a loss of clean liness by the inadvertent introduction of foreign material, the following requirements apply.

8.6.1 Clean room and clean area. The fo llowing requirements apply:

a. Operations. The following operations shall be performed only within a clean room or a clean area:

(1) Assembly of hardware or any portion thereof whenever a final cleaned surface will become an internal surface that is not fully accessible for clean ing or visual inspection .

(2) Disassembly of final cleaned hardware with inaccessible areas.

(3) Inspection of internal surfaces of final cleaned hardware with inaccessible areas.

(4) Breaking any seal to an inaccessible area of final cleaned hardware.

b. Cleanliness maintenance of a clean room or clean area . The clean room or clean area and all clean room or clean area equipment and furnishings shall be maintained clean and free of foreign material to the extent necessary to prevent foreign material and detrimental material from contacting hardware. The clean room and clean area shall be maintained in a condition as free of dirt as is practicable except for that being produced by the particular manufacturing operation in progress. Each clean room or clean area shall be visually inspected and cleaned as required to maintain cleanliness.

c. Air supply. Air supplied to a clean room or clean area shall be clean to the extent necessary to ensure that hardware cleanliness is maintained.

d. Personnel. Personnel working in a clean room/clean area shall wear clean head covers and overalls or smocks, whenever such clothing is necessary to maintain acceptable cleanliness of the hardware. Eating , chewing gum, or use of tobacco in any form shall not occur within a clean room/clean area. Drinking water shall be confined to restricted areas within the clean room/clean area.

e. Clean room construction . A clean room shall be a complete, permanent enclosure. Clean room floors, walls , and ceilings shall be hard , smooth , and non-flaking and non-peeling . A clean room door shall be tight fitting unless a positive pressure is created by the clean room ventilation system.

f. Clean area construction. If appropriate for the hardware and the operation, a clean area may consist of a clean plastic bag or sleeve around appropriate parts of the hardware, a clean tent, a partitioned and covered area, or a clean table in an office. All materials of construction shall be designed to prevent their entry into the hardware.

g. Control of outside foreign material. If needed to control clean room clean liness, measures shall be taken to prevent foreign material entry via shoes, such as a clean floor covering or clean shoe covers.

8.6 .2 Unnecessary objects. No unnecessary parts, fittings , tools, or other equipment shall be taken near an exposed location.

8.6.3 Accountability. Accountability provides controls to avoid loss of tools and equipment in hardware with inaccessible areas. Unless all internal surfaces can be visually observed and certified to be clean prior to closure of the hardware, the following requirements apply:

a. A physical boundary shal l be established that is located to prevent inadvertent introduction of foreign material , tools, and other equipment into the hardware.

b. A formal written record shall be maintained for all material (e.g., tools, equipment, temporary plugs and seals, and tape) taken inside the physical boundary that are small enough to fit inside openings in the hardware and do not have lanyards per 8.6.3.c. The record shall describe the material , where it was introduced, and when it was removed . Except for clear parts on eyeglasses and goggles, accountability is required for all clear plastic materials regardless of size.

c. To the maximum extent practical , each object used within the physical boundary wh ich is small enough to fit into any openings in the hardware shall be securely attached with a clean lanyard to the user, an object larger than the hardware opening, or a rigid structure. Lanyards shall conform to the following :

(1) Material. Lanyard material shall be corrosion resistant and flexible .

Examples include nylon cord , wire rope of a corrosion-resistant material , or chain of corrosion-resistant material. A lanyard shall not be coated and shall not contain exposed material that chips, flakes, or peels.

(2) Strength. A lanyard shall remain intact under the load imposed by the attached object if it were to free fall the full length of the lanyard .

(3) Length . A lanyard shall be the shortest practicable length consistent with proper use of the attached object.

d. The accountability record shall be reviewed prior to final closure of the hardware opening . If an object cannot be accounted for , hardware cleanliness has been lost and recovery from a loss of cleanliness shall be conducted in accordance with Section 9.

8.6.4 Shop equipment. Shields and covers (such as metal drip pans and polyethylene splash covers) suitable to prevent uncontrolled release of foreign materials shall be affixed as necessary to all shop equipment (such as cranes and hoists) when located above an exposed location .

8.6.5 Shop structures. All structures (such as platforms, walkways, etc.) near an exposed location shall be maintained free of all loose objects and materials or shall be suitably shielded as necessary to prevent a loose object or material from entering hardware.

8.6.6 Hammers. Hammers and mallets used near an exposed location shall not contain loose material such as metal shot.

8.6. 7 Special tools . All tools for an application near an exposed location shall be designed and constructed to be "fail-safe"; i.e., each part that could fail in use shall be captive so that it will not separate from the rest of the tool if failure does occur.

8.6.8 Other methods of protection . If it is not possible to seal all final cleaned surfaces, crevices or inaccessible areas in accordance with 8.3 during a specific, unique dirt producing operation , then another method of protection , when approved by local engineering , shall be used to prevent foreign materials from contacting these hardware surfaces. Other methods, for example, may include one or more of the following :

a. Pressurizing the hardware with clean gas at a pressure and flow rate sufficient to prevent entry of foreign material.

b. Machining without coolant.

c. Using suction devices in close proximity to the location where the foreign material is generated.

d. Orienting the hardware so that foreign material will not fall into any unsealed opening .

8.6.9 Welds.

a. Pipe welding in accordance with NA VS EA 250-1500-1 or NA VS EA S907 4-AR G I B-010/278 of pipe that is verified clean prior to welding is not a dirt producing operation to the internal surfaces of the joined pipe, provided that no events which may compromise cleanliness (e.g. , burnthrough or blowout) occur.

b. Gas Tungsten Arc (GT A) welding on any surface may be considered a non-dirt producing operation.

c. For carbon steel and copper-nickel socket welds and backing ri ng welds performed without a purge, flakes of weld scale or oxidation are acceptable to th is standard if the backside of the weld is not accessible for normal cleaning methods.

8.6.10 Clean pipe cuts. A clean pipe cut is a potentially dirt producing operation but does not require restoration of cleanliness per Section 9 provided the following requirements are met:

a. The cut is performed with a method qualified on hardware of similar size and material to not introduce foreign material. During qualification , the hardware being cut shall be completely visually inspected to demonstrate no foreign material was introduced.

b. The cut is conducted by personnel qualified to perform th is method.

c. The hardware is verified clean after the cut by visual inspection to the maximum extent practical without special equipment.

d. Whenever practical , cut locations should be selected on horizontally oriented pipe to facil itate inspection .

e. If inspection indicates entry of foreign materia l into clean hardware, restore cleanliness per Section 9.

8.7 Tape. Use of tape shall comply with all of the following :

a. Tape shall be visible without mechanical aids (e.g., boroscope or mirror(s)).

b. Tape shall be colored and exposed only to temperatures below the tape's temperature rating . Transparent or metal colored tape is prohibited .

c. Tape alone shall not be used to physically prevent cleanliness plug or seal movement into inaccessible areas of hardware.

d. Tape alone shall not be used as a cleanliness barrier.

e. Tape may be used to seal the crevice between a cleanliness plug or seal and hardware surface provided all internal crevices and inaccessible areas on the taped side of the plug or seal are sealed to prevent tape entry.

f. Tape may be used where it is the only practicable means of accomplish ing the work, provided all internal crevices and inaccessible areas are sealed from the areas where tape is used.

g. Any other use of tape must be approved by NAVSEA or its authorized representative.

8.8 Water requirements .

8.8.1 Water purity. Three grades of water, A, Band C in descending order of purity , may be specified for cleaning, flushing , and testing. The specifications for grades A, B and C water are listed in Table Ill.

TABLE Ill. Water purity

Water grade Water attribute

A B c Chloride ion , ppm (maximum)1/ 0.1 1.0 35

Conductivity , micromhos/cm 2.5 20 550 (maximum) pH (range)2/ 5.7 - 8.0 --- ---

Visual clarity No turbidity, oil , sediment, or resin beads

11 Chloride ion need not be measured if the conductivity of grade B or C water is less than 2.5 micromhos/centimeter.

21 pH need not be measured if the conductivity of grade A water is 0.25 micromhos/centimeter or less.

8.8.1.1 Minimum water samolinq test frequency. Each water source (i.e. , public utility, private ground water supply , bottled water supplier, and organization's water purification equipment and support systems) shall be sampled and tested for conformance to Table Ill at a frequency sufficient to ensure the water quality specifications are not violated . The frequency shall be specified in the organization's cleanliness control procedures.

8.8.2 Water grade requirements for testing . Table IV specifies the minimum grades of water that shall be used for tests of hardware, unless otherwise specified by the equipment specification .

TABLE IV. Required grade of test water

Test temperature, °F (°C) Hardware material Water grade

Less than 150 (66) All , except nickel-chromium- c11 boron (Colmonoy) alloys

Less than 150 (66) Nickel-chromium-boron B (Colmonoy) alloys

150 (66) or above All , except copper alloys and B copper-nickel alloys

150 (66) or above Copper alloys and copper- c 11 ~/ nickel alloys 21

11 Grade C water shall be removed from the hardware as soon as practicable after completion of the test and the hardware shall be rinsed with grade B water.

21 All wetted hardware surfaces shall be copper or copper-nickel.

'JI Grade C water to be used above 150°F (66°C) shall be tested for hardness before use to ensure that a residue is not left on the hardware surface.

S.S.3 Water grade requirements for contact with a final cleaned surface. Unless otherwise specified , if water is used in contact with a final cleaned surface, grade A or grade B water shall be used as a final rinse, and hardware shall be dried following contact.

S.9 Support system requirements .

S.9.1 Support system cleanliness. Unless otherwise authorized by NAVSEA, support systems (see 3.19) shall conform to the cleanliness requirements of the hardware to which they will be temporarily connected . Support systems shall also meet the detrimental material control requirements of MIL-STD-2041 to the extent necessary to prevent detrimental materials from being introduced into hardware. For water support systems, the requirements of MIL-STD-2041 shall be applied as necessary upstream of the SO-micron cleanliness filter (if installed) to preclude transfer of dissolved detrimental materials and impurities.

S.9.2 Cleanliness boundary. If the entire support system is not maintained clean , then a cleanliness boundary shall be established as follows:

S.9.2.1 Water system. A nominal rating size SO micron (or finer) metal filter shall be used. Cleanliness shall be maintained between the hardware and the metal filter.

S.9.2.2 Gaseous system. A nominal rating size SO micron (or finer) metal filter downstream of a nominal rating size 10 micron (or finer) fiber filter capable of removing oil and foreign material shall be used. Cleanliness shall be maintained between the hardware and the metal filter.

S.9.2.2.1 Weld gas. Support systems that deliver weld shield gas or purge gas, which contacts final cleaned internal surfaces of hardware, shall either conform to the support system requirements in S.9.2.2 or all of the following :

a. Purchase the gas to an applicable specification with minimum purity requirements.

b. Use a nominal rating size SO micron (or finer) metal filter in the support system;

and maintain cleanliness between the hardware and the metal filter.

c. Prior to welding or daily, which ever is less frequent, purge…