Specification_15022_R_0.pdf

AIR FORCE RESEARCH LABORATORY (AFRL) 15022: CLEANING OF COMPONENTS, PIPING, VESSELS, AND RELATED

ITEMS FOR OXYGEN SYSTEM SERVICE

AIR FORCE RESEARCH LABORATORY SPECIFICATION: 15022

EDWARDS AFB, CA REVISION: 0

DATE REVISED: 30 DEC 2013

NUMBER OF PAGES: 48

AFRL SPECIFICATION 15022: CLEANING OF

COMPONENTS, PIPING, VESSELS, AND RELATED

PREPARED BY: Print Name Signature

Author/Engineer: Philip Rice

APPROVED BY:

RQRO Branch Chief: Julie Carlile

Revision Notes Prepared By

Complete replacement of “AIR FORCE RESEARCH LABORATORY TEST

STANDS 1D AND 2A SECTION 15019 CLEANING OF PIPING, VESSELS, AND

RELATED COMPONENTS” Revision 5. Change is primarily to modify the specification from one that was written as part of a “turn-key” construction specification/scope of work, to one that covers component and field cleaning of oxygen systems. Changes were also made to address issues of obsolete specifications and allow more flexibility with respect to material selections and processes used by cleaning contractors.

Philip Rice Senior Aerospace Engineer Air Force Research Laboratory

(AFRL/RQRO)

8 Draco Dr., Bldg 8350 Edwards AFB, CA 93524 Phone: (661) 275-5890 Fax: (661) 275-5514 Cell (661) 433-2074 E-Mail: philip.rice.1@us.af.mil

1 PREFACE

This cleaning specification is limited to the cleaning of piping, vessels, and related components, for oxygen service. This specification is not intended for cleaning hydraulic systems or any other fuel or oxidizer service.

This document is written with the explicit intention that it is for subcontract cleaning. It can also be used by the Air Force Research Laboratory (AFRL) for in-house cleaning with the understanding that not all sections are applicable, and that other requirements above and beyond this specification may apply.

This specification does not cover the plethora of materials and component configurations used in an oxygen clean system, or the complexity of the items to be cleaned. It is the responsibility of the AFRL or its designated representative (henceforth referred to simply as the AFRL) and the cleaning Contractor to verify that cleaning processes and procedures are appropriate for the materials being cleaned.

This specification, by its nature, must be accompanied by directions provided in a Scope of Work (SOW), or specified in a Purchase Order (PO). It is the duty of the AFRL Program Manager, responsible Engineer, and Quality Control Engineer to verify that the specific requirements for the cleaning of any components, piping, vessels, and related accoutrements have been defined, and are well understood by the cleaning Contractor prior to performing the cleaning service. In general, an SOW is provided for more complex work that requires detailed instructions and information regarding the nature of the task. Attached in Appendix 2 is a sample of an SOW for performing a specific cleaning task (in this case on-site field cleaning carbon steel vessels for oxygen system pressurization). This appendix is provided for the AFRL personnel as an example of a good SOW to use as a basis for writing an SOW for specific work. (It is also useful to any Contractor that is preparing to be pre-qualified to provide cleaning services to the AFRL so they know what expectations they have to meet). An SOW may also be prepared for routine contracting of component cleaning services on multiple PO’s. However, once a Contractor’s processes and procedures have been reviewed and approved, a PO may be all that is required.

It is not the intent of this specification to dictate the methods and procedures used by the cleaning Contractor to perform the requested cleaning services except as specifically stated within this document. It is however, the responsibility of the AFRL or its designated representative to verify that the cleaning Contractor is qualified to perform the service and has processes and procedures in place that meet the requirements of this document.

2 PURPOSE AND SCOPE

This procedure establishes the cleanliness levels, cleaning, protection, and inspection for piping, vessels, and surfaces of parts, components, assemblies, subassemblies, systems, or other related equipment in contact with oxygen service media. The body of this specification covers general requirements for cleaning, and is applicable to most cleaning tasks specified in an SOW or PO.

However its format and requirements are weighed more towards component cleaning in a shop environment. Field cleaning of systems presents unique requirements beyond those of component cleaning. Therefore, Appendix 1 is presented as a mandatory addendum to this specification specifically to address considerations and requirements for field cleaning. This appendix in no way absolves the Contractor of its obligation to meet the requirements of the main body of this specification. However, it is recognized that exceptions based on applicability of the requirements will be required. These shall be presented in the Contractor’s Cleaning Plan prior to award of the contract.

This procedure is to be used in cleaning equipment for oxygen. It shall be incumbent upon each individual involved to read this document before starting a cleaning, processing, or handling operation.

3 APPLICABLE STANDARDS

In keeping with the purpose and intent of this specification, applicable standards are provided in two categories so as to not overly constrain the cleaning Contractor: 1) Specifications that shall be adhered to, and 2) Specifications that are provided for reference, state good practices, or define process recommendation for cleaning of special materials (such as Monel, Inconel, 440 stainless steel, certain soft goods, etc.), that may require special processes. The latest version of the standards shall be used.

3.1 Mandatory Standards:

IEST-STD-CCI246-D, Product Cleanliness Levels and Contamination Control Program ISO 14644-1 Cleanrooms and associated controlled environments-Part 1: Classification of air cleanliness ISO 14644-2 Cleanrooms and associated controlled environments-Part 2: Specifications for testing and monitoring to prove continued compliance with ISO 14644-1 AFRL PR-W OPERATING INSTRUCTION 99-105 Rev 14-Jun-06 Gaseous and Liquid Oxygen

Systems & Components Cleaning (AFRL use only) AFRL CS-120-2A-9000 Test Stand 2A Component Cleaning (AFRL use only)

American Society for Testing and Materials (ASTM)

ASTM G93, Standard Practice for Cleaning Methods and Cleanliness Levels for Material and

Equipment Used in Oxygen Enriched Environments ASTM G120, Test Method for the Determination of Soluble Residual Contamination in

Materials and Components by Solvent Extraction ASTM G121, Preparation of Test Coupons for Evaluation of Cleaning Agents ASTM G122, Test Method for Evaluation of Effectiveness of Cleaning Agents ASTM G127, Guide for Selection of Cleaning Agents for Oxygen systems ASTM G131, Practice for Cleaning of Materials and Components by Ultrasonic Techniques ASTM G136, Practice for Determination of Soluble Residual Contaminants in Materials by

Ultrasonic Extraction ASTM F331, Standard Test Method for Nonvolatile Residue of Solvent Extract from Aerospace

Components (Using Flash Evaporator) ASTM F312, Standard Test Method for Microscopical Sizing and Counting Particles from

Aerospace Fluids on Membrane Filters ASTM A380 – 06, Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel

Parts, Equipment, and Systems ASTM A967 – 05, Standard Specification for Chemical Passivation Treatments for Stainless

Steel Parts

Compressed Gas Association (CGA)

CGA G-4.4, Industrial Practices for Gaseous Oxygen Transmissions and Distribution Piping

Systems CGA G-4.1, Cleaning Equipment for Oxygen Service CGA P-14, Accident Prevention in Oxygen-Rich and Oxygen- Deficient Atmospheres

3.2 Reference Standards:

Federal Specifications

0-S-642, Trisodium phosphate 0-N-350, Nitric acid 0-0-670, Phosphoric acid 0-H-765, Hydrochloric acid 0-H-795, Hydrofluoric acid PPP-T-60, Tape: Pressure Sensitive Adhesive, Vinyl Plastic Film L-P-378, Plastic Sheet and Strip, Thin Gauge, Polyethylene TT-1-735, Isopropyl Alcohol, Grade A or B Fed-Std-2098, Clean Room and Work Station Requirements

Military Standards

MIL-D-16791, Detergents, General Purpose MIL-P-27401, Propellant, Pressurizing Agent, Nitrogen

American Society for Testing and Materials (ASTM)

ASTM Standards Related to Flammability and Sensitivity of Materials in Oxygen Enriched

Atmospheres (a Collection of 23 ASTM Standards Relating to Oxygen System Design, Material Selection, Cleanliness, and Operation)

ASTM G144, Test Method for Determination of Residual Contamination of Materials and Components by Total Carbon Analysis Using a High Temperature Combustion Analyzer

ASTM D1193, Standard Specification for Reagent Water

Other

Commercial Item Description, A-A-59147, Citric Acid, Technical KSC-C-123, Surface Cleanliness of Fluid Systems, Specification For (NASA) JPG 5322-1, Contamination Control Requirements Manual (NASA) ISO 8573-1 2001, Compressed air -- Part 1: Contaminants and purity classes NASA JSCM5322 Contamination Control Requirements Manual NASA Langley Research Center LHB-1740.5 Procedures for Cleaning of Systems and

Equipment for Oxygen Service

4 DEFINITIONS

4.1 Calibration – Comparison of a measurement standard or instrument of unknown accuracy with another standard or instrument of known accuracy to detect, correlate, report, or eliminate by adjustment any variation in the accuracy of the unknown standard or instrument.

4.2 Cleanroom – A room specially constructed of materials that minimize contaminant introduction, generation and retention, and in which the control of pressure, temperature and relative humidity is provided, and the concentration of airborne particles is controlled to specified limits on a recirculate or once-thru basis by passing the air through HEPA or ULPA filters. Control of air velocity and direction, noise, lighting, vibration, EMI, RFI, etc., may be provided as well.

4.3 Cleanliness Level – An established maximum of allowable contaminants based on size, distribution, or quantity on a given area or in a specific volume or an absence of particulate and non-particulate matter visible under white light and/or UV illumination.

4.4 Contamination – Any impurity, unwanted material or energy that degrades process or product performance or reliability or adversely affects product manufacturability. This contamination may be a solid, liquid or gas and may reach the product through liquid, air or physical transfer.

4.5 Continuous – Uninterrupted (data) updating that occurs on a constant, real-time basis.

4.6 Degreasing Agent – A solvent that removes oil and grease residue from surfaces. Aqueous degreasing agents are preferable and aqueous based fluids must utilize reagent grade water. The reagent water must meet the requirements of ASTM D1193.

4.7 Desiccant – Moisture absorbing material, used to entrap water vapor from components or equipment cleaned and packaged for special service.

4.8 Frequent – Data updating that occurs often, on an interval-of-time basis.

4.9 Gross Cleaning – Washing, wiping, blowing, vacuuming, brushing or rinsing to produce parts that are visibly free of manufacturing residue, dirt, oil, grease, processing debris or other extraneous contamination when viewed under normal lighting conditions using the unaided eye.

This level may be attained in any area where the cleanliness integrity of the article being processed would not be jeopardized.

4.10 Micron – (micrometer), A unit of measurement equal to 1 x 10-6 meters (3.393 x 10-5 inches).

25 microns are equal to approximately one one-thousandth of an inch or one “mil”.

4.11 Nonvolatile Residue (NVR) – Soluble (or suspended) material and insoluble particulate matter remaining after controlled evaporation of a filtered volatile solvent usually measured in milligrams.

4.12 Oxygen compatible lubricants – An inert, nonflammable, non-corrosive and odorless lubricant that has been approved for use in highly reactive liquid and gaseous oxygen services.

4.13 Particle – Matter of miniature size with observable length, width, and thickness usually measured in micrometers. This definition includes fibers, which are particles whose length-to-width ratio is in excess of 10:1. Non-particulate is a film matter without definite boundaries.

4.14 Particle Burden – The number of particles in the relevant size range per unit area.

4.15 Passivation

4.15.1 Passivation of Stainless Steel - Passivation is the treatment of the surface of stainless steels, often with acid solutions (or pastes), to remove contaminants and promote the formation of the passive film on a freshly created surface (e.g. through grinding, machining or mechanical damage). Passivation treatments are sometimes specified, but it is important to consider whether this is strictly necessary or not. Stainless steels cannot be passivated unless the steel surface is clean and free from contamination and scale from welding operations.

4.15.2 Passivation of Carbon Steel - Passivation is the treatment of the surface of carbon steel in an attempt to create an inert, passive layer usually comprised of black oxide (magnetite

- Fe3O4) that is frequently accomplished by the application of strong bases (iron has a natural tendency to oxidize below a pH of ~8.5). Technically, the surface is converted from one oxide layer (rust - Fe2O3 and Fe(OH)2) to another (with desired properties) as opposed to generating a self-sustaining passive film which occurs with stainless steel.

Prior to passivation, the carbon steel surface is pickled in order to remove any debris, particles, undesired oxide scales or any other surface contaminants.

4.16 Pickling

4.16.1 Pickling of Stainless Steel - Pickling is the removal of any high temperature scale and any adjacent low chromium layer of metal from the surface of stainless steel by chemical means. Where the steel has been heated by welding, heat treatments or other means, to the point where a colored oxide layer can be seen, there is a chromium depleted layer on the surface of the steel underneath the oxide layer. The lower chromium content gives lower corrosion resistance. To restore the best corrosion resistant performance, the damaged metal layer must be removed, exposing a fully alloyed stainless steel surface.

Mechanical removal may leave abrasive or other particles embedded (interfering with corrosion performance) or may be impractical, so chemical means are usually employed.

4.16.2 Pickling of Carbon Steel - Pickling is the process of removing the oxide scaling formed during the production of steel and its exposure to air or while in extended operation.

Pickling is performed with strong acids that function both as a solvent and reactant – usually with the addition of inhibitors since the acid will react with carbon steel. This process cleans and primes the surface for eventual passivation.

4.17 Precision Cleaning – Final or fine cleaning accomplished in a controlled environment. Cleaning involves the physical removal of particulate and oils from surfaces. The term “Precision cleaning” is applied to hardware when cleanliness specifications limit maximum permissible contamination to a particle size less than 500 micron or weight of less than 10 milligrams per part. The precision cleaning process requires a cleanroom environment of sufficient air quality that hardware, once cleaned, will remain at that particle and molecular-free state for a reasonable period if left exposed. This is intended to provide sufficient time for visual inspection, verification testing, assembly, and packaging operations.

4.18 Precision-Clean Packaging – Packaging or protection used to preserve precision cleanliness for a specific period and condition.

4.19 Primary Surface – A surface that is in direct contact with the fluid, for example, the inside valve body bore.

4.20 Purchase Order – A purchase order (PO) is a commercial document issued by a buyer to a seller, indicating types, quantities, and agreed prices for products or services the seller will provide to the buyer. Sending a purchase order to a supplier constitutes a legal offer to buy products or services. Acceptance of a purchase order by a seller usually forms a contract between the buyer and seller, so no contract exists until the purchase order is accepted. It is used to control the purchasing of products and services from external suppliers.

4.21 Scope of Work (SOW) – An SOW is an AFRL generated document that provides specific information that frames the scope of the job to be executed by the Contractor and any special requirements or consideration that the Contractor must be aware of or comply with. A SOW may be negotiable prior to establishment of a contract to account for Contractor capabilities and specific processes.

4.22 Secondary Surface – A surface that is not in contact with the product but indirectly affects the product, for example, the valve body exterior.

4.23 Residue – Any substance left on a surface after cleaning.

4.24 Surface Contamination – Any unwanted substance present (in or) on a surface.

4.25 Test – Procedure undertaken in accordance with a defined method to determine the performance of a system or an element thereof.

4.26 VC (Visibly Clean) – The absence of all particulate and non-particulate matter, visible to the unaided eye (except corrected vision).

4.27 (VCI) Breathable Plastic - A specially impregnated plastic, designed to protect metals from moisture and corrosion by forming an inert vapor barrier.

5 MATERIALS

Materials used in the cleaning process shall be identified in the Contractor’s cleaning procedure or Cleaning Plan and submitted to the AFRL for approval prior to starting work. Below is a list of some suggested materials that are used by, or are already approved for use in oxygen clean systems by the AFRL. This is only a suggested materials list, and does not in any way constrain the Contractor from providing other materials that meet the requirements of this specification or relieve the contractor to verify the oxygen compatibility of the material, and their applicability to the cleaning process. Specific grades and part numbers are not provided. The contractor is responsible for providing that information in their procedure. Listing of the materials below does not specify how they are used. Methods for employing the materials shall be detailed in the Contractor’s cleaning procedure.

NOTE: These are suggested for Oxygen Systems only. It is incumbent upon the Contractor to specify only materials that are compatible with the specified service.

5.1 DEGREASING AGENTS:

Alkaline Solution: BLUEGOLD, Modern Chemical (www.gluegoldcleaner.com)

Alkaline Solution: Brulen 815 GD, Brulen Inc. (www.brulen.com)

Solvent: Isopropyl Alcohol: (99% Pure Laboratory Grade Undiluted)

Solvent: Vertrel MCA, Dupont

Solvent: ASAHIKLIN AK225, AGC Chemicals Americas, Inc. (www.AK-225.com)

5.2 OXYGEN COMPATIBLE LUBRICANTS:

Grease: LOX-8, Fluoramics, (www.fluoramics.com)

Grease: Krytox, Dupont, (www.krytox.com)

Oil: Krytox, Dupont, (www.krytox.com)

5.3 PROTECTIVE WRAPPING MATERIALS:

VCI Plastic, Armour Poly Llumaloy, Armor Protective Packaging, (www.armorvci.com)

Polyethylene Terepththalate, Metalized PET Film, CPF Films (www.solutia.com)

Chlorotrifluoroethylene (CTFE), Aclar 22A, Allied Chemical Co. (www.knfcorporation.com)

Nylon and Anti-Static Nylon, Clean Room Products Level 1, KNF Clean Room Products, (www.knfcorporation.com)

Polypropylene, Ultraclean Level I, KNF Clean Room Products, (www.knfcorporation.com)

5.4 LEAK DETECTION SOLUTIONS:

Liquid Solution, TAT’L Leak Detector, Shamrock Specialties, (www.shamrockspecialties.net)

Liquid Solution, Sherlock 5-Second, Winton Products Company Inc., (www.wintonproducts.com)

Liquid Solution, Leak Tec, LOX Compatible, American Gas and Chemical Company, (www.amgas.com)

Liquid Solution, Snoop Liquid Leak Detector, LOX Compatible, Swagelock Inc.

(www.swagelock.com)

5.5 Packaging Tape:

Duct Tape Blue, Spec Tape, Concote, (www.concote.com)

Polyimide Kapton or Polyethylene, Cleanroom Tape, UltraTape, (www.cleanroomtape.com)

Duct Tape: White, Polyken, Berry Plastics (www.berryplastics.com)

5.6 PROHIBITED MATERIALS

Trichloroethane or Freon shall not be used for any purpose.

Isopropyl Alcohol may be used as part of the cleaning process, but shall not be used for final precision cleaning, flushing, and sampling.

6 MATERIAL AND PROCESS TRACEABILITY

6.1 CLEANING PROCESS

The cleaning process, cleanliness verifications, type of lubricant used, packing, gasket and packaging information shall be recorded on a Process Traveler that shall contain information with respect to:

Customer identification and cleaning specification level (e.g. 300A per IEST-STD-

CCI246-D)

Pre-Clean documentation Final cleaning and test reports Packaging and labeling

6.2 FINAL ASSEMBLY AND TESTING

In cases where the AFRL SOW requires final assembly and testing by the cleaning Contractor, the Process Traveler shall also contain information (as applicable) with respect to:

Hydro tests Pneumo tests Leak tests Functional tests

7 DISASSEMBLY AND PRELIMINARY INSPECTION BEFORE CLEANING

7.1 DISASSEMBLY

If required by the SOW or the PO, the Contractor shall disassemble components, piping, and vessels as required and maintain parts and configuration control of the items. Unless otherwise specified, the AFRL will provide a complete set of softgoods or other components required for re-assembly of the components. (see 7.2)

7.2 EXAMINATION

Examine Austenitic Stainless Steel Components for any discoloration that could indicate ferrite contamination.

Examine all materials for gross contamination, damage, or any other potential problems prior to starting cleaning processes. Record the information and inform the AFRL.

8 GENERAL CLEANING REQUIREMENTS AND PROCEDURE FOR STAINLESS STEEL

Practically all finishing operations require that fabricated stainless parts be subjected to some type of cleaning operation. These include painting, enameling, electroplating, metallizing, buffing, and polishing. It is generally necessary to clean after welding, brazing, and machining operations. Heat treating often requires cleaning both before and after that operation.

Methods of cleaning to be employed depend primarily upon the surface contamination present.

Considerations such as mechanical configuration, design, subsequent operations, cleaning equipment required, shop operating conditions, conditions for field cleaning, production volume, cost, and some special precautions.

Scale or Foreign Contamination

Cleaning operations can generally be divided into three categories: (1) gross cleaning methods for removing foreign contamination such as lubricants, paints, shop dust, polishing compounds, etc., (2) methods for removing surface oxide or scale resulting from forging, heat treating, welding, etc. and (3) methods for passivation for removal of exogenous iron or iron compounds from the surface of a stainless steel by means of a chemical dissolution, most typically by a treatment with an acid solution that will remove the surface contamination but will not significantly affect the stainless steel itself.

Gross Cleaning

Gross cleaning involves washing, wiping, blowing, vacuuming, brushing or rinsing to produce parts that are visibly free of manufacturing residue, dirt, oil, grease, processing debris or other extraneous contamination when viewed under normal lighting conditions using the unaided eye.

This level may be attained in any area where the cleanliness integrity of the article being processed would not be jeopardized.

Descaling and Acid Pickling

Both mechanical cleaning and chemical cleaning or a combination of both can be used for removing heavy scale from stainless steel.

Mechanical cleaning methods include dry blasting with cast iron grits, metal shot, cut wire or sand. Wet blasting will provide a better finish but is applicable mainly to small parts or when a light scale is to be removed. Brushing and tumbling might also be included as mechanical descaling methods.

Salt bath descaling methods have been found most advantageous for removing scale from large production lots of stainless steel. These methods involve molten salts operated at temperatures ranging from approximately 700º to 900ºF (371º to 482ºC). The sodium hydride caustic soda process is quite versatile; scale is removed by a reducing process so that base metal is not removed.

Most descaling methods must be followed by acid pickling for the complete removal of surface oxide. Perhaps the most versatile acid bath for removing scale from all types of stainless steel is a solution containing sulfuric acid, with or without an inhibitor. Following a descaling treatment, this sulfuric acid pickling bath will effectively remove scale from most stainless steels, although it will react somewhat slowly with the austenitic stainless grades. A solution of hydrochloric acid (all acids are mixed with water), with or without an inhibitor, will clean all stainless grades considerably faster, although closer control is required.

Sometimes a two-bath operation is used with the austenitic stainless grades. Either the sulfuric or hydrochloric acid pickling solutions are followed by a bath consisting of nitric acid and hydrofluoric acid. The nitric-hydrofluoric pickle bath is used to remove the last traces of scale retained after sulfuric acid pickling processes.

After descaling and between each pickling tank, a water rinse is always used. This may be in the form of a water blast to remove traces of scale and prevent contamination from one bath to the other.

Nearly all pickling operations impart a dark "smutty" surface on stainless steel, which can be removed in a cold nitric acid bath. This final pickling process both brightens and passivates the stainless steel surface.

Pickling can cause "hydrogen brittleness" or "acid brittleness" because of hydrogen absorption.

Some hard and highly stressed parts are susceptible enough to suffer cracking during the pickling process. While hard but not highly stressed parts will seldom crack in the acid bath, they may crack in service when subjected to stress. Consequently, steels should not be "overpickled."

Hardened articles should receive a stress-relieving temper before pickling and "bake" after pickling. The baking process consists of heating the part for several hours to remove hydrogen and restore ductility.

Examples of pickling techniques most likely to cause cracking are hot hydrochloric acid and electrolytic techniques, which liberate large amounts of hydrogen. When employing these methods, high-strength grades such as Type 420 or the 440 series and the precipitation hardenable martensitics should not be exposed for long periods.

Passivating

The non-rusting properties of stainless steels are attributable to a very thin, invisible oxide film that completely covers the surfaces of the parts and prevents corrosion from taking place.

Theoretically, a freshly machined, polished or pickled part will acquire this film rather quickly from the atmosphere. In practice, however, such fabricated parts may be contaminated with small particles of foreign matter, which must be removed to impart full stainless properties. As an example, a slight amount of material worn off the cutting tools may be transferred to the stainless parts during machining. Under certain conditions, a thin coating of rust may appear on the part.

This is corrosion of the tool steel and not the parent metal.

The primary purpose of a passivating treatment is to remove surface contamination, usually iron, so that the optimum corrosion resistance of the stainless steel will be maintained. Passivation is not a scale removal treatment.

Basic procedure in passivating consists of cleaning the work with a commercial degreaser or cleanser, immersing it in a solution containing nitric acid, rinsing and drying it. The importance of cleaning prior to acid bath immersion cannot be over-emphasized. In some instances, this step is omitted, assuming the acid bath will give the necessary cleanness. Cleaning should not be skipped because the acid might not remove all of the residual cutting fluid, resulting in possible chemical reactions with the residual cutting fluid known as "flash attack." These unwanted reactions may cause serious deterioration of the surfaces that passivation is designed to protect.

After degreasing and thorough water rinsing, passivation of the stainless steels should take place.

The addition of sodium dichromate or use of 50% nitric acid solution increases the "passivating potential" of the bath so that undesirable local attack is less likely.

The free-machining grades differ from the regular grades of stainless steels because they contain a large number of nonmetallic inclusions throughout their microstructures which create microscopic discontinuities in the machined part surfaces. Even normally efficient water rinses can leave residual acid in these discontinuities after passivation. This acid can then attack the surface of the part unless it is neutralized or removed. Work in Carpenter's research and development laboratory has shown that the following passivating procedure for free-machining grades will produce resistance to subsequent superficial rusting. This procedure is known as the Alkaline-Acid-Alkaline, or A-A-A, passivation method.

Other Important Considerations

Maintain an effective passivating solution to prevent localized attack. Tap water is usually adequate for diluting the acid, although high chloride contents (greater than several hundred ppm) could be deleterious in a borderline situation. Nitric acid concentration should be checked periodically using a simple titration procedure, which can be provided upon request.

When high production rates cause a heavy flow of material through a passivating bath, it is probably best to maintain a definite schedule for replacing the bath to avoid a significant decrease in the "passivating potential," which can result in corrosive attack of the work piece. You should also use a control sample of the same composition as the material to be passivated to test the bath. If the sample is attacked, it is time to change the bath before additional parts are passivated.

The temperature of the bath should be within the specified temperature range. A room temperature bath has a lower "passivating potential" than a warm bath and is, therefore, more likely to cause local attack. It is good practice to passivate only one grade of stainless steel at a time. Not only can mix-ups be prevented but you can avoid galvanic reactions.

Parts that were improperly heat-treated may lead to attack in a passivating bath. Furthermore, high-carbon, high-chromium grades must be hardened to render them corrosion resistant.

Stainless steel parts that have been carburized or nitrided should never be passivated. These surface treatments lower the corrosion resistance of stainless steel, thus opening the way to attack in the passivating tank.

A highly detailed discussion of requirements, processes, and procedures for descaling, pickling and passivation can be found in the following documents. These documents will constitute the primary requirements for descaling, pickling, and passivation of stainless steel materials as specified in this document.

ASTM A380 – 06, Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems

ASTM A967 – 05, Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts

9 PICKLING AND PASSIVATION

When required by the Contract Statement of Work, or determined to be necessary by the contactor to meet the specified cleaning level, carbon and stainless steel systems shall be pickled, passivated, and rinsed after cleaning. Pickling and passivation shall be executed per the Contractor’s procedures and the applicable standards defined in the body of the specifications. The Contractor shall determine which acid, the exact proportion of the solution, and identify the process in his Cleaning Plan. Likewise, the length of exposure time and the overall plan for pickling and passivation shall be identified in the Cleaning Plan. For carbon steel, the Contractor shall prepare coupons of the same material to be processed. Those coupons shall be processed per the Contractor’s procedure to demonstrate the effectiveness of their process. Control coupons (pre-pickling/passivation) shall also be provided. Measurements shall be made to determine the amount of material removed in the process. The Contractor’s procedure shall cover all the configurations of the systems to be pickled / passivated (e.g. components, pipe, vessels, tanks, etc.)

9.1 PICKLING AND PASSIVATION OF STAINLESS STEEL MATERIAL

Stainless steel can corrode in service if there is contamination of the surface. Both pickling and passivation are chemical treatments applied to the surface of stainless steel to remove contaminants and assist the formation of a continuous chromium-oxide, passive film. Pickling and passivation are both acid treatments and neither will remove grease or oil. If the fabrication is dirty, it may be necessary to use a detergent or alkaline cleaner before pickling or passivation.

Pickling and passivation when required shall be specified in the AFRL SOW or purchase order. If the cleaning Contractor notes any concerns with regards to surface contamination or lack of the passive oxide surface of any stainless steel item not specifically directed to be pickled or passivated, they shall notify the AFRL.

9.1.1 DESCALING AND PICKLING OF STAINLESS STEEL

9.1.1.1 Normal precautions shall be used when completing this process as nitric (HNO3), hydrofluoric (HF), or other strong acids are used and will cause severe irritation and burns if placed in contact with skin. Consult Materials Safety Data Sheets and product packaging for detailed advice.

9.1.1.2 Procedures incorporating pickling solutions of nitric (HNO3) and hydrofluoric (HF) acids shall remove the scale and the underlying chromium depleted layer and restore the corrosion resistance. Pickling solutions shall also remove contaminants such as ferrous and ferric oxide particles. Pickling solutions other than mixtures of nitric and hydrofluoric acids exist and can be used for specialized applications.

9.1.1.3 Pickling pastes, where the solution is mixed with an inert carrier, may be used to treat selected areas such as welds.

9.1.1.4 Electro-polishing or mechanical polishing may be used as an alternative to pickling. Metal removal is achieved, and usually results in a bright, smooth and more highly corrosion resistant finish.

9.1.1.5 All parts from which rust is removed shall be cleaned / degreased in accordance with the Contractor’s approved procedures.

9.1.1.6 Pickling and descaling procedures shall conform to the following ASTM specifications.

ASTM A380 – 06, Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems

ASTM A967 – 05, Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts

Alternate procedures and materials may be considered in the contactors procedure, but must be approved by the AFRL.

9.1.2 PASSIVATION OF STAINLESS STEEL

9.1.2.1 Normal precautions shall be used when completing this process as strong acids are used and will cause severe irritation and burns if placed in contact with skin.

Consult Materials Safety Data Sheets and product packaging for detailed advice.

9.1.2.2 Procedures and passivation solutions shall be selected to aid in the rapid development of the passive oxide film on the steel's surface. Passivation does not usually result in a marked change in appearance of the steel surface.

9.1.2.3 Passivation procedures shall conform to the following ASTM specifications.

ASTM A380 – 06, Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems

ASTM A967 – 05, Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts

Alternate procedures and materials may be considered in the contactors procedure, but must be approved by the AFRL.

9.2 PICKLING AND PASSIVATION OF CARBON STEEL MATERIAL

Carbon steel will corrode in environments containing oxygen along with water or air moisture - it can also occur anaerobically in the presence of chlorides. When exposed, iron will oxidize to ferrous and ferric species (Fe(II) & Fe(III), respectively) mainly in the form of rust which will flake away and expose an active layer. In order to prevent this from happening, the surface is pickled then passivated. As with stainless steel, both pickling and passivation are chemical treatments of the surface used to create an inert surface, free from further oxidization. Typically carbon steel is treated with acids during the pickling process followed by bases during the passivation stage along with the addition of inhibitors, chelating agents, etc. If gross contaminants and debris are present, it may necessary to pre-clean the surface and in some instances perform abrasive, mechanical removal of deposits. Unlike stainless steel passivation, this process is technically a coating conversion process. For carbon steel, the Contractor shall prepare coupons of the same material to be processed. Those coupons shall be processed per the Contractor’s procedure to demonstrate the effectiveness of their process. Control coupons (pre-pickling/passivation) shall also be provided. Measurements shall be made to determine the amount of material removed in the process. The Contractor’s procedure shall cover all the configurations of the systems to be pickled / passivated (e.g. components, pipe, vessels, tanks, etc.).

Pickling and passivation when required shall be specified in the AFRL SOW or purchase order. If the cleaning Contractor notes concern with regards to executing the work, they shall notify the

AFRL.

9.2.1 PICKLING OF CARBON STEEL

9.2.1.1 Normal precautions shall be taken when completing this process as hydrochloric acid (HCl), nitric acid (HNO3) and sulfuric acid (H2SO4) are commonly used and will at the minimum cause severe irritation and burns if mishandled. Consult Material Safety Data Sheets (MSDS) before using.

9.2.1.2 Procedures incorporating pickling solutions (of the above mentioned acids) shall remove the scale in order to make the surface active and ready for passivation.

9.2.1.3 All parts from which rust was removed shall be cleaned/degreased in accordance with the Contractor’s approved procedures.

9.2.2 PASSIVATION OF CARBON STEEL

9.2.2.1 Normal precautions shall be used when completing this process as sodium hydroxide (NaOH), sodium nitrite (Na2NO2), sodium nitrate (Na3NO3), or other bases and oxidizers are commonly used and will at a minimum cause severe irritation and burns if mishandled. Consult Material Safety Data Sheets (MSDS) before using.

9.2.2.2 Procedures and passivation solutions shall be selected to aid in the rapid development of the passive oxide film on the steel's surface.

10 CLEANING PROCEDURE

The Contractor shall submit a detailed cleaning procedure to the AFRL prior to award of contract. As a The Contractor shall submit a detailed cleaning procedure and / or plan to the AFRL prior to award of contract. As a minimum, the procedure shall address all of the items within this specification and include sections detailing the following:

10.1 PRECLEANING

Pre-cleaning/gross cleaning that address methods for removing gross contamination such as dirt, debris, grease, oil, surface rust, etc. prior to pickling, passivation, or precision cleaning.

10.2 PRECISION CLEANING

Precision cleaning procedures that address clean room protocols, tooling and fixtures, clothing, equipment, materials, solvents, etc. necessary to assure successful cleaning, final rinsing, drying, and examination.

All precision cleaning, inspection, sampling and analysis, assembly, and packaging shall be performed in a certified clean room or controlled work area appropriate for the level of cleanliness of the item being cleaned.

10.3 INSPECTION

The effectiveness of visual inspection for particles on surfaces depends on the physical characteristics of the particles and the contrast with background surfaces, the wavelength and intensity of the light source, the angle of incidence of both the light source and the viewer, and the experience of the operator. With an unaided eye such an inspection is effective in viewing particles greater than 50 microns in diameter. Inspection/verification and bagging of components shall be performed in a contamination controlled area (minimum allowable ISO 7 or better) if the hardware meets any of the following criteria:

Requires a visual cleanliness verification Requires a numerical particulate cleanliness level as defined in IEST-STD-CC1246D Requires an NVR cleanliness level as defined in IEST-STD-CC1246D

10.3.1 Visual Inspection (Qualitative)

Visual inspections are made of hardware in order to verify a surface to be free of all particles including fibers and lint. The Contractor’s procedure shall address processes and equipment necessary to perform this work, such as lighting levels, use of ultraviolet light, inspector qualifications, etc.

10.3.2 Particulate and NVR Verification (Quantitative)

For cleanliness levels defined by the AFRL per IEST-STD-CC1246D, verification will be provided by taking direct measurements off the hardware unless an exception is justified by the physical constraints of the hardware. Direct measurements off the hardware are to be taken by standard contamination sampling techniques such as solvent rinsing or flushing and filtering for particulate and molecular measurements. The final flush and verification fluids are to be analyzed for particulate and / or NVR to determine compliance with the stipulated specification requirements.

Note: There is no direct correlation between qualitative visual inspection and the quantitative cleanliness levels defined in IEST-STD-CC1246D.

10.3.3 Verification Sequence

After gross cleaning visually inspect components to ensure that no moisture is evident on the part and that all scale, rust, slag, dirt, oil or grease has been removed. No evidence of oil, grease, water, solvents, paints, ink, dirt, metal chips, labels, preservatives, or other foreign matter shall be permitted.

Following precision cleaning and visual inspection, an analysis of particulate and non-volatile residue (NVR) shall be performed in accordance with the Contractor’s standard and approved analytical procedures.

10.3.4 Good Cleanliness Protocol

Parts that have been cleaned and inspected shall be stored in cleanliness verified containers and /or covered or bagged to ensure no contamination occurs prior to reassembly. If parts have been stored for more than 3 days, they shall be inspected prior to being assembled and re-cleaned if necessary.

10.3.5 Surveillance

Surveillance may be performed at the discretion of the AFRL to verify compliance of the work with all specifications and regulations. The AFRL reserves the right to observe any aspect of the cleaning and inspection related work identified herein. The AFRL may make a visual inspection of all cleaned components and systems prior to the Contractor closing/sealing the component or system. The visual inspection may include the use of a boroscope or similar device.

10.4 ASSEMBLY

10.4.1 If the AFRL SOW or PO requires components to be reassembled, the Contractor shall follow established cleanroom protocols during assembly of cleaned components to maintain their cleanliness. Good protocols include but are not limited to:

10.4.1.1 Before assembly gather / kit all components

10.4.1.2 Unbag components only when ready for assembly

10.4.1.3 Minimize the quantity of lubricant used and ensure that the lubricant meets requirements for the service (e.g., oxygen compatible)

10.4.1.4 Limit assembly and disassembly generated contamination and ensure that sealants and lubricants do not extend into the flow path

10.4.2 Lubrication, if necessary, shall be restricted to the oxygen compatible lubricants approved by the AFRL.

10.5 PRESSURE / LEAK TESTING

10.5.1 Pressure testing, shall be specified in the AFRL SOW or PO if required, along with their requirements.

10.6 FUNCTIONAL TESTING

10.6.1 Functional testing shall be specified in the AFRL SOW or PO if required, along with their requirements.

10.7 PACKING / PACKAGING

To maintain cleanliness and prevent recontamination while handling clean film and packaging parts, these precautions shall be taken: Packaging shall take place in an environment of the same or greater level of cleanliness as that in which the final cleaning and inspection of critical parts will be conducted. Packaging or sealing materials that come into contact with the clean component or equipment shall exhibit a certified level of equivalent cleanliness.

Plastic and poly shall not come into contact during packing process with any component surface that sees process fluid. Use approved materials as a barrier.

All threaded connections shall be plugged or capped. NO plastic plugs or caps are allowed on any surface that sees process fluid.

Flange faces shall where possible be covered with a bolted or clamped cover of approved material and adequate size and strength to prevent damage to the face during shipment and handling. Where the cover may be exposed to the clean surface, the covers shall be cleaned to the same requirement as the component, piping, vessels, etc. Otherwise, they shall be protected by multiple layers of approved barrier materials and protected from damage or loss of integrity.

All fittings or other openings leading to precision-cleaned inner surfaces shall be capped, plugged, or otherwise sealed.

Closures shall mate with and be tightened to sealing surfaces to preclude breathing of the sealed item.

Cap, plug or flange material shall be compatible with system fluids and cleanliness levels.

Items containing openings leading to precision-cleaned inner surfaces, which cannot be sealed with caps or plugs, shall have each opening overlaid with two sheets or bags of the appropriate inner and outer packaging material.

Each sheet or bag shall be secured in place by at least two tight wraps of tape. The tape shall not contact the item.

Each item with sealed openings shall be completely overwrapped with an appropriate outer packaging material. The overwrap shall be secured with tape or heat sealed where practicable.

In any case, sealing of items that may be exposed to temperature variations during transport and storage shall be adequate to prevent the internal volumes of the item from breathing.

All components shall be wrapped in a minimum of one layer of approved oxygen compatible packaging film / bag, and a second layer consisting of a minimum of one layer of cleanroom film / bag such as clean polyethylene or nylon.

10.7.1 Smaller components, fittings, piece parts, etc. shall be contained in heat sealable bags made from approved oxygen compatible packaging film /bag, and a second layer of cleanroom film / bag such as clean polyethylene or nylon or as specified by the AFRL in the SOW or PO.

10.7.2 Consideration for inclusion of desiccant bags between packaging layers shall be made based on packaging methods and storage requirements

10.7.3 All packages, large and small will be purged with clean dry (-45 F due point) oil free filtered nitrogen before final heat sealing.

10.8 MARKING AND TAGGING

10.8.1 Each double-bagged, cleaned component, fitting, or piece part will be identified by exterior tags or decals attached to the outside of the inner film / bag and outer film / bag stating:

"CLEANED FOR OXYGEN SERVICE TO LEVEL ______ PER SPECIFICATION ______"

or as required per AFRL instructions. A warning not to unwrap the article prematurely shall also be included on the tags or decals, such as "DO NOT remove packaging and desiccant bags until ready for installation or in a controlled cleanroom environment".

Cleaning certifications shall include items such as: Level of Cleanliness, Cleaning specification, Item Description, Item drawing number, Serial number or part number, Customer Name, Customer Purchase Order Number, Cleaning / Verification Date, Job Number and the signature / stamp of the inspector and date of final inspection and shall be traceable back to each packaged item.

Gross cleaned hardware does not require a cleanliness certification sticker, since protective contamination control packaging is not required.

10.8.2 If cleaning for other critical service applications, the item will be identified as cleaned for that specific service.

10.9 TRAINING

10.9.1 Operators performing cleaning and verification shall be trained in cleanroom protocols and personnel garmenting, cleaning procedures and verification / inspection processes and all such training is to be documented and recorded.

10.10 SHIPPING

10.10.1 Ship per AFRL instructions as specified in the SOW or PO.

AIR FORCE RESEARCH LABORATORY

AFRL TBD CLEANING OF COMPONENTS, PIPING, VESSELS AND RELATED COMPONENTS

APPENDIX 1

FIELD CLEANING OF PIPING AND VESSELS AT THE AFRL

1 GENERAL WORK

This appendix deals specifically with field cleaning. All sections of the main body of the cleaning specification shall be adhered to as applicable. This appendix excludes all cleaning of hydraulic systems.

Work Included: The work shall be defined in an SOW. See Appendix 2 for an example of a field cleaning SOW. In the event that this field cleaning specification conflicts with the SOW, the SOW shall take precedence.

The Contractor shall furnish all chemicals, equipment, and technical personnel to complete the work.

Disposal of waste materials shall be the responsibility of the Contractor.

GN2 or other purge gases shall be furnished by the Contractor. When required, purges left in place for preservation of cleanliness shall be initially charged, and K-bottles (or other suitable apparatus) shall be used to maintain the purge. This equipment shall be left in place by the Contractor until released by the AFRL.

2 OXYGEN SYSTEMS CLEANLINESS

2.1 QUALITY ASSURANCE

2.1.1 Submittals

All submittals shall be…