NACE International

Mousta

Item No. 24232 NACE International Publication 02107

This Technical Committee Report has been prepared by NACE International Task Group 148* on Coatings and Methods of Protection for Threaded Fasteners Used with Structural Steel, Piping, and Equipment.

Coatings for Protection of Threaded Fasteners Used with Structural Steel, Piping, and Equipment

© March 2007, NACE International

This NACE International technical committee report represents a consensus of those individual members who have reviewed this document, its scope, and provisions. Its acceptance does not in any respect preclude anyone from manufacturing, marketing, purchasing, or using products, processes, or procedures not included in this report. Nothing contained in this NACE report is to be construed as granting any right, by implication or otherwise, to manufacture, sell, or use in connection with any method, apparatus, or product covered by Letters Patent, or as indemnifying or protecting anyone against liability for infringement of Letters Patent. This report should in no way be interpreted as a restriction on the use of better procedures or materials not discussed herein. Neither is this report intended to apply in all cases relating to the subject. Unpredictable circumstances may negate the usefulness of this report in specific instances. NACE assumes no responsibility for the interpretation or use of this report by other parties. Users of this NACE report are responsible for reviewing appropriate health, safety, environmental, and regulatory documents and for determining their applicability in relation to this report prior to its use. This NACE report may not necessarily address all potential health and safety problems or environmental hazards associated with the use of materials, equipment, and/or operations detailed or referred to within this report. Users of this NACE report are also responsible for establishing appropriate health, safety, and environmental protection practices, in consultation with appropriate regulatory authorities if necessary, to achieve compliance with any existing applicable regulatory requirements prior to the use of this report. CAUTIONARY NOTICE: The user is cautioned to obtain the latest edition of this report. NACE reports are subject to periodic review, and may be revised or withdrawn at any time without prior notice. NACE reports are automatically withdrawn if more than 10 years old. Purchasers of NACE reports may receive current information on all NACE International publications by contacting the NACE FirstService Department, 1440 South Creek Drive, Houston, Texas 77084-4906 (telephone +1 281/228-6200).

fa Bayoumi - Invoice INV-606124-JJHSQM, downloaded on 11

Foreword

This technical committee report describes current industry practices and gives information on the most commonly used generic coating systems for protection of threaded fasteners used with structural steel, piping, and equipment. The coating system provides a protective barrier between the base metal and the environment to minimize the effect of corrosion. The information presented in this report addresses steel quality, pretreatment processes, coating application, quality assurance/quality control, and test comparisons for evaluating corrosion resistance. This report does not reflect the NACE position on these practices, but rather summarizes existing technology and practices of various manufacturers, applicators, and users. ___________________________

*Chair Brian Willis, Whitford Corporation, Elverson, Pennsylvania.

/20/2012 10:07

This technical committee report was prepared for the use of engineers, purchasing agents, coating inspectors, and project leaders in any industry having corrosion problems with threaded fasteners. The purpose is to provide information on the various generic coating systems currently available for corrosion protection of threaded fasteners.

This technical committee report was prepared by NACE Task Group 148 on Coatings and Methods of Protection for Threaded Fasteners Used with Structural Steel, Piping, and Equipment. It is issued by NACE under the auspices of Specific Technology Group (STG) 02 on Coatings and Linings, Protective: Atmospheric.

:10 AM - Single-user license only, copying and networking prohibited.

NACE International

Moustafa

NACE technical committee reports are intended to convey technical information or state-of-the-art knowledge regarding corrosion. In many cases, they discuss specific applications of corrosion mitigation technology, whether considered successful or not. Statements used to convey this information are factual and are provided to the reader as input and guidance for consideration when applying this technology in the future. However, these statements are not intended to be recommendations for general application of this technology, and must not be construed as such.

Bayoumi - Invoice INV-606124-JJHSQM, downloaded on

Background

Threaded fasteners are coated to provide corrosion protection and ease of make-up during installation. Given the design and make-up tolerances of most threaded-fastener systems, the allowable coating thickness for proper make-up is a real concern for end users. Overtapping of the nut threads is a viable option to prevent make-up problems such as galling, seizing, fretting, and other thread damage. When the total dry film thickness (DFT) of the coating system is >0.75 mil (18 µm), overtapping of the nuts is a normal practice to prevent make-up problems. With the exception of hot-dip galvanized or mechanical zinc coatings, ASTM(1) A 563M1 requires that overtapping be approved by the purchaser. Many coating systems also reduce the amount of make-up torque (or pretensioning) required by lowering the

2

11/20/2012 10:07:

coefficient of friction (e.g., fluoropolymer coatings). These systems provide lubricity and reduce friction in the make-up/breakout cycle. This helps prevent thread damage (galling). Multiple make-up/breakout cycles are also possible. If the coating system wears or is damaged during use, the degree of corrosion protection can be reduced. The selection of the coating system is important in achieving the desired performance characteristics. Although there are industry standards covering the manufacture and use of threaded fasteners (ASTM, API,(2) ANSI(3)) the specific recommendations for the application and use of coatings, including corrosion control performance, are limited in scope. Only a few coating systems (such as galvanizing and metallic plating) are addressed in current industry standards.

Definitions

Breakout: A violent, forceful loosening of the fabricated threaded fastener system from a restraining condition. (For example, a wrench is usually used to loosen a nut or bolt that has been in service an extended period of time.) Chemical Conversion Coating: An adherent reaction product layer on a metal surface formed by reaction with a suitable chemical to provide greater corrosion resistance to the metal and increase adhesion of coatings applied to the metal. (Example is an iron phosphate coating on steel, developed by reaction with phosphoric acid.) Coating: A liquid, liquefiable, or mastic composition that, after application to a surface, is converted into a solid protective, decorative, or functional adherent film. For the purpose of this technical committee report, the term coating includes metallic coatings applied by galvanizing and electroplating. Coating System: The complete number and types of coats applied to a substrate in a predetermined order. (When used in a broader sense, surface preparation, pretreatments, dry film thickness, and manner of application are included.)

Dry Film Thickness (DFT): The thickness of a dried film, coating, or membrane. It is usually expressed in mils or micrometers (µm). (NOTE: 1.00 mil = 0.001 in. or 25.4 µm). Electroplating: Application of a thin coating of metal by an electrochemical process. Fit: Relationship that exists when an external thread (male) gauges properly and assembles with an internal thread (female) that also gauges properly, according to ANSI Standard B1.1.2

Fluoropolymer Resin-Bonded Coatings: The family of engineering plastics containing fluorine that is characterized by high thermal stability, almost universal chemical resistance, and low coefficients of friction. Function: Characteristic exhibited by a threaded fastener when it is able to perform the physical task it is designed to do (in tension, shear, etc.). Galvanized Coating: A coating of virtually pure zinc applied by various processes including hot dipping and electrolytic and mechanical deposition.

___________________________ (1) ASTM International (ASTM), 100 Barr Harbor Dr., West Conshohocken, PA 19428-2959. (2) American Petroleum Institute (API), 1220 L St. NW, Washington, DC 20005-4070. (3) ANSI International (ANSI), 25 West 43rd St., 4th Floor, New York, NY 10036.

10 AM - Single-user license only, copying and networking prohibited.

NACE International

metal parts.

Moustafa

Galvanizing: Application of a coating of zinc. Gauging: Precisely measuring the dimensions and checking for conformity to ANSI Standard B1.1.2 Galling: Damage to metal surfaces resulting from friction between sliding solid materials, usually involving roughening and creation of protrusions above the original surface. Galling usually causes thread damage and can interfere with the proper function of a threaded-fastener system. Hydrogen Embrittlement: A loss of ductility of a metal resulting from absorption of hydrogen. Kesternich Test: An accelerated test method performed in an enclosed test cabinet with 100% humidity and concentrations of sulfur dioxide (SO2) in cyclic exposures. Test parameters are defined by DIN(4) 500183 with two different volumes (concentration levels) of SO2 introduced into a 300 L chamber. Test method SFW 2.0 S DIN 50018 with a total of 2.0 L of SO2 is the most commonly used concentration, while 0.2 L of SO2 is often used for the least severe exposure. Liquid Metal Cracking (LMC): Cracking of a metal caused by contact with a liquid metal. Make-Up: Mating the internally threaded nut and externally threaded bolt and turning the nut until a predetermined torque or pretensioning of the threaded-fastener system is achieved. Overtapping: Increasing the manufacturing tolerances of the nut to allow for additional coating thickness in the threaded-fastener system to ensure proper make-up. Polytetrafluoroethylene (PTFE): A waxy, opaque-white, thermoplastic fluoropolymer resin that contains four fluorine

3

Bayoumi - Invoice INV-606124-JJHSQM, downloaded on 11/20/2012 10:07

atoms on each ethylene molecule (C2F4)n. It is thermally stable, very resistant to chemicals, and has an extremely low coefficient of friction. Primer: A coating material intended to be applied as the first coat on an uncoated surface. The coating is specifically formulated to adhere to and protect the surface as well as to produce a suitable surface for subsequent coats. (Also referred to as Prime Coat.) Salt Fog Exposure: An accelerated test method performed in an enclosed cabinet to compare the corrosion resistance of various materials. Test methods are defined by ASTM B 117.4

Surface Pretreatment: A thin protective coating or corrosion inhibitor formed on the surface of a base metal, usually by a chemical reaction process. Examples are chemical conversion coatings (e.g., metal phosphates), chromate compounds, and nitrides. Threaded-Fastener System: A threaded mechanical device for holding two or more bodies in definite position with respect to each other. Topcoat: The final coat of a coating system. (Also referred to as Finish Coat.) Torque: A turning or twisting force applied to threaded fasteners to ensure proper make-up or pretensioning. Torque is usually expressed in foot-pounds (ft-lb) (newton-meters [N•m]). Volatile Organic Compound (VOC): Organic-based solvent that vaporizes rapidly into the atmosphere. These organic solvents are used in solvent-based coating formulations and can be used for vapor degreasing various

Coatings Selection

The selection of the proper coating system depends on the intended use. A wide variety of coating systems is available for numerous applications from light atmospheric exposure to severe immersion service (marine environments, chemical exposure to acids or gases, etc.). Most coating manufacturers provide data on the corrosion performance of specific coating systems in various environments. The proper evaluation, selection, and placement in a given environment (atmospheric, marine, industrial, etc.) are critical to successful performance. Some end users conduct laboratory testing, either in-

:

house or by independent laboratories, of various coating systems in specific environments for screening purposes. For proper coating selection, actual field trials and performance evaluation in the specific environment are typically conducted. Many other factors are involved in the coating selection process such as the ease of application, consistency of quality of the finished product, resistance of the coating system to physical damage during handling and use, ease of installation, economics, and overall performance. The application process can influence the selection of the coating system.

Generic Coating Systems

Table 1 lists the commonly used generic coating systems available for threaded fasteners. The DFT range and the

maximum exposure temperature typical for each generic coating system are given.

___________________________ (4) Deutsches Institut fur Normung (DIN) (German Institute for Standardization), Burggrafenstrasse 6, D-10787 Berlin, Germany.

10 AM - Single-user license only, copying and networking prohibited.

NACE International

Moustafa

Manufacturers or suppliers can usually supply accelerated test results. Commonly used accelerated test methods for threaded fasteners are listed in Table 2. Field performance reports (case histories) furnished by suppliers also provide useful information. Within each generic coating system listed in Table 1 are numerous types and brand names, including proprietary coating systems. Each manufacturer or supplier can usually supply detailed performance data for each specific coating system. The generic coating system information provided in Table 1 is a compilation of data from many suppliers and end users. It is provided for comparison purposes only and is not a recommendation for use.

4

Bayoumi - Invoice INV-606124-JJHSQM, downloaded on 11/20/2012 10:07:1

The most commonly used test method for threaded fasteners is ASTM B 117. The data provided are for comparison purposes only. The amount of test data available for the other test methods listed in Table 2 is very limited and not included. The relative cost comparisons are listed to show approximate cost differences between the various generic coating systems. An ASTM A 1935 bare steel stud bolt and two nuts are used for comparison purposes. Costs vary from region to region and between various suppliers. Manufacturers and suppliers can provide accurate, detailed information on each specific threaded-fastener system.

TABLE 1: Generic Coating Systems for Threaded Fasteners

Generic Coating System DFT, mil (µm)

Maximum Temperature

°F (°C)

ASTM B 117(A) Exposure

Hours

Relative(B) Cost

Comparison

Uncoated (Bare) Steel Stud Bolt and 2 Nuts(B)

Aluminum Plating

Cadmium Plating

Ceramic Metallic

Hot-Dip Galvanizing

Inorganic Zinc-Rich Silicate

Manganese Phosphate, Fluoropolymer

Mechanical Zinc

Zinc Aluminum

Zinc Phosphate

Zinc Phosphate and Oil

Zinc Phosphate, Fluoropolymer

Zinc Plating

Zinc Plating, Fluoropolymer

N/A

0.2 to 0.3 (5 to 8)

0.2 to 0.3 (5 to 8)

0.8 to 1.0 (20 to 25)

1.0 to 2.5 (25 to 63)

1.8 to 2.4 (45 to 60)

1.0 to 1.2 (25 to 30)

0.2 to 2.5 (5 to 63)

0.2 to 0.50 (5 to 13)

0.2 to 0.50 (5 to 13)

0.3 to 0.50 (8 to 13)

1.0 to 1.2 (25 to 30)

0.2 to 0.3 (5 to 8)

1.0 to 1.2 (25 to 30)

N/A

1,000 (540)

500 (260)

1,200 (650)

750 (400)

750 (400)

500 (260)

750 (400)

800 (430)

250 (120)

250 (120)

500 (260)

750 (400)

500 (260)

N/A

1,200

250

1,000

1,500

1,500

750

400

1,000

48

250

500

250

1,000

1.0

1.8

1.6

5.0

2.0

2.0

3.7

2.0

2.0

1.5

1.6

3.7

1.6

3.7

(A) ASTM B 117 end point is the first sign of red rust. (B) ASTM A 193 bare steel stud bolt and two nuts, size 0.625 x 4 in. (16 x 100 mm), are used for cost comparisons.

TABLE 2: Accelerated Test Methods for Threaded Fasteners

Test Method Common Name

ASTM B 117 Salt Fog Exposure (Salt spray environment)

DIN 50018 Kesternich (SO2) Test

ASTM G 1546 Weatherometer QUV (Atmospheric exposure)

ASTM D 5894(A), 7 Cyclic Corrosion/UV (Cyclic salt fog/UV exposure)

(A) ASTM D 5894 is a combination of ASTM G 154 and ASTM B 117.

0 AM - Single-user license only, copying and networking prohibited.

NACE International

Moustafa Bayoumi - Invoice INV-606124-JJHSQM, downloade

Threaded Fastener Quality

Obtaining good quality threaded fasteners is essential in obtaining quality coated fasteners. The ANSI specification (B1.1) for threaded fasteners is the recognized standard in the United States. Machining tolerances are well defined in ANSI B1.1 for type and size. The use of thread gauges

5

d on 11/20/2012 10:07:

prior to coating can prevent the application of a coating to “out of tolerance” threaded fasteners. Gauging threaded fasteners after coating can prevent make-up problems during installation. Fasteners that do not meet ANSI specifications and tolerances are generally avoided.

Surface Preparation

Surface preparation is a major step in the coating application process. Coatings do not adhere adequately to contaminated surfaces. The type and method of cleaning and surface preparation depends on the coating system to be applied (e.g., plating, galvanizing,

1

fluoropolymer coating, ceramic metallic coating). In each case, the user typically refers to the manufacturer’s recommendations. Appendix A describes four basic cleaning methods.

Coating Application

Immediately prior to coating application, surfaces to be coated are typically free of rust, dust, oil, moisture, or any other contaminants. Surfaces that have been allowed to oxidize, become contaminated, or no longer meet the required surface preparation specification are normally recleaned prior to the coating application. Many types of coating systems are available for threaded fasteners. Some are proprietary and have been developed over many years. Within each group of generic coating

systems is a wide range of formulations and coating-system combinations provided by numerous suppliers. The manufacturers and suppliers provide detailed information and recommendations for use. Some application methods can become very important in the selection process. For instance, to prevent hydrogen embrittlement of high-strength bolting (e.g., ASTM A 4908), a special baking process is sometimes necessary to remove absorbed hydrogen.

Surface Pretreatments

Chemical conversion coatings such as iron, zinc, and manganese phosphates provide corrosion protection if topcoated to prevent reoxidation of the surface. These very thin conversion coatings are typically used to increase lubricity, reduce galling, and protect against underfilm corrosion without altering design dimensions. Topcoats such as epoxies, epoxy-phenolics, fluoropolymers, and others provide good protection for more corrosive environments (e.g., marine, acid or alkali exposure, acid rain, hydrogen sulfide [H2S], carbon dioxide [CO2], SO2). Another advantage of phosphate

pretreatment is enhanced adhesion. The crystalline structure of the metal phosphate promotes improved anchoring of the topcoat system. Other surface pretreatments such as phosphoric acid provide an enhanced corrosion barrier. Most of these “wet” processes have environmental guidelines for use and disposal. The primary reasons for using surface pretreatments are to enhance adhesion, improve corrosion resistance, and prevent underfilm corrosion when the coating system is subjected to damage in handling and use.

Electroplating

Cadmium and zinc electroplating have been successfully used for threaded-fastener coatings for many years. Both have been used as surface pretreatments for various topcoats to enhance the corrosion resistance and lubricity of the total coating system. Environmental concerns and the cost of waste abatement have reduced the use of cadmium plating over the past 10 years. No one system exactly duplicates all of the beneficial performance characteristics of cadmium plating. Alloy plating such as zinc-nickel and zinc-cobalt have been substituted, usually at a higher cost, with enhanced corrosion performance,

but reduced mechanical performance. Systems that are environmentally friendly and cost effective are currently being pursued. Caution is typically exercised when selecting zinc- or cadmium-electroplated fasteners, or other types of zinc-coated fasteners. The zinc on coated carbon steel fasteners can cause LMC of nearby austenitic stainless steels under certain high-temperature conditions. Also, cadmium electroplated fasteners may cause LMC of low-alloy steels (e.g., UNS(5) G41300, G41400, G43400) at temperatures near 450°F (230°C).

___________________________ (5) Metals and Alloys in the Unified Numbering System, a joint publication of ASTM International (ASTM), 100 Barr Harbor Dr., West Conshohocken, PA 19428-2959, and SAE International (SAE), 400 Commonwealth Drive, Warrendale, PA 15096-0001.

0 AM - Single-user license only, copying and networking prohibited.

NACE International

Moustafa Bayoumi - Invoice INV-606124-JJHSQM, downloade

Fluoropolymer Coatings

The fluoropolymers used in threaded-fastener coating formulations typically consist of a granular PTFE dispersed in a binder resin. The amount of PTFE relative to the binder resin dictates the amount of lubricity versus corrosion protection achieved. Lubricity increases with the amount of PTFE loading. Corrosion resistance increases with the amount of binder resin. Fluoropolymers provide good corrosion resistance when combined with a sacrificial base coat or primer.9 Base coats such as phosphate conversion coatings, cadmium plating, zinc plating, zinc-rich primers, aluminizing, nickel plating,

6

d on 11/20/2012 10:07

aluminum plating, chrome plating, and ceramic-metallics have been used successfully. A common fastener system consists of 0.3 to 0.5 mil (8 to 13 µm) of zinc plating with 0.7 to 0.9 mil (18 to 23 µm) of fluoropolymer topcoat. VOC compliance is an ongoing problem for all solvent-borne coating formulations. Water-borne fluoropolymer systems are now available when low VOC emissions are required. Research and development in water-borne coatings technology is advancing rapidly

Zinc-Coated Threaded Fasteners

Hot-dip galvanizing for structural bolts has been an effective corrosion protection system for atmospheric exposure for many years. Because a heavier film thickness is necessary to obtain the desired corrosion protection, the nuts are typically oversized after galvanizing (usually 0.016 to 0.050 in. [410 to 1,300 µm], depending on fastener size) to achieve proper make-up as specified in ASTM A 563 – 04a,10 Section 7.

When lower film thickness is required, alternative corrosion barrier systems using aluminum or zinc-aluminum combinations are typically used.11, 12

Mechanical zinc coating processes13 provide a thin, consistent, uniform coating thickness. These processes are environmentally friendly. However, if acid pickling, electrocleaning, or certain surface pretreatments precede the coating application, hydrogen embrittlement may occur.

:1

Liquid-applied inorganic zinc-rich silicate coating systems also provide viable corrosion protection for threaded-fastener systems. These are generally water-borne silicate systems dispersed with fine particle high-quality zinc dust or flake. The water-borne inorganic zinc-silicate systems are environmentally friendly (low VOCs). Liquid-applied organic zinc-silicate coating systems that meet U.S. Environmental Protection Agency (EPA)(6) guidelines are also available. Another important feature of zinc-rich coatings is their ability to cathodically or galvanically protect the metal substrate when damaged in use. Some zinc-rich coating systems have a high friction coefficient that can make proper fastener make-up difficult. A water-borne PTFE or silicone dispersion coating is available to reduce the coefficient of friction for proper make-up.

Ceramic-Metallic Coatings

Ceramic-metallic coated fastener systems perform well in saltwater environments and offshore (deep water) applications. They also have good high-temperature resistance and ultraviolet (UV) stability, and can be conductive. A ceramic-metallic coating works well as a primer for a fluoropolymer topcoat. Common applications include aerospace/aircraft-type fasteners (MIL-C-8175114) and high-temperature steam-process fasteners. One of the limitations of ceramic-metallic coatings is thickness. A maximum DFT of 1.0 mil (25.4 µm) is normally specified

by manufacturers. In addition, these coatings have poor lubricity. Galling can occur on ceramic-metallic coated fasteners without supplemental lubrication. Ceramic-metallic coated fasteners do not perform well in acid environments. The selection of an acid-resistant topcoat can improve performance. A mechanical burnishing secondary process is typically used to ensure electrical continuity. Accelerated corrosion is possible if proper electrical continuity is not achieved.

Quality Assurance/Quality Control

Examination of quality is important at each step in the coating application process. In-process record keeping allows for the verification of compliance to standards. Parameters such as time, temperature, chemical

concentration, current density, film thickness, and visual appearance are in-process measurements typically used to verify conformance to standards. Final inspection criteria typically include visual examination, thickness

___________________________ (6) U.S. Environmental Protection Agency (EPA), 1200 Pennsylvania Avenue NW, Washington, DC 20460.

0 AM - Single-user license only, copying and networking prohibited.

NACE International

Moustafa B

measurements, adhesion checks, curing tests, and other specific requirements of the various processes involved. Proper fit and function of the fastener system is normally verified to prevent installation problems. A total quality

7

ayoumi - Invoice INV-606124-JJHSQM, downloaded on 11/20/2012 10:07

management system, such as ISO(7) 9000,15 provides for the above-cited inspections and can yield consistent high-quality fastener coatings.

Performance Evaluation

Actual field exposure is a common method for predicting performance. Several accelerated test methods have been used as screening tests to select the best-performing coatings in those specific test environments. In most cases, there has not been a direct correlation between accelerated test performance (usually expressed in hours duration or test cycles) and estimation of service life in a given environment.

Commonly used accelerated test methods for threaded fasteners are listed in Table 2. The most commonly used

test method for the accelerated testing of threaded fasteners is ASTM B 117 (salt fog exposure). For atmospheric exposure, ASTM D 5894 (cyclic salt fog/UV exposure) is typically preferred by end users.

Coatings can be damaged during shipping, handling, and installation. Damage can reduce performance. Fastener suppliers usually can provide field repair procedures and recommendations to help prevent damage and subsequent performance problems.

References

1. ASTM A 563M (latest revision), “Standard Specification for Carbon and Alloy Steel Nuts [Metric]” (West Conshohocken, PA: ASTM). 2. ANSI B1.1 (latest revision), “Unified Inch Screw Threads (UN and UNR Thread Form)” (New York, NY: ANSI). 3. DIN 50018 (latest revision), “Testing in a saturated atmosphere in the presence of sulfur dioxide” (Berlin, Germany: DIN). 4. ASTM B 117 (latest revision), “Standard Practice for Operating Salt Spray (Fog) Apparatus” (West Conshohocken, PA: ASTM). 5. ASTM A 193/A 193M (latest revision), “Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for High Temperature or High Pressure Service and Other Special Purpose Applications” (West Conshohocken, PA: ASTM). 6. ASTM G 154 (latest revision), “Standard Practice for Operating Fluorescent Light Apparatus for UV Exposure of Nonmetallic Materials” (West Conshohocken, PA: ASTM). 7. ASTM D 5894 (latest revision), “Standard Practice for Cyclic Salt Fog/UV Exposure of Painted Metal, (Alternating Exposures in a Fog/Dry Cabinet and a UV/Condensation Cabinet)” (West Conshohocken, PA: ASTM).

:

8. ASTM A 490 (latest revision), “Standard Specification for Structural Bolts, Alloy Steel, Heat Treated, 150 ksi Minimum Tensile Strength” (West Conshohocken, PA: ASTM). 9. E.K. Griggs Jr., R.F. Klein, S.F. Ogden, “An Evaluation of Bolt Coating Materials Currently Used for Corrosion Protection in Offshore Services,” Offshore Technology Conference (OTC) (Houston, TX: Society of Petroleum Engineers [SPE],(8) 1982). 10. ASTM A 563 – 04a (latest revision), “Standard Specification for Carbon and Alloy Steel Nuts” (West Conshohocken, PA: ASTM). 11. ASTM F 1428 (latest revision), “Standard Specification for Aluminum Particle-Filled Basecoat/Organic or Inorganic Topcoat, Corrosion Protective Coatings for Fasteners” (West Conshohocken, PA: ASTM). 12. ASTM F 1136 (latest revision), “Standard Specification for Zinc/Aluminum Corrosion Protective Coatings for Fasteners” (West Conshohocken, PA: ASTM). 13. ASTM B 695 (latest revision) “ Standard Specification for Coatings of Zinc Mechanically Deposited on Iron and Steel” (West Conshohocken, PA: ASTM). 14. Military Standard MIL-C-81751 (latest revision), “Coating, Metallic-Ceramic” (Philadelphia, PA: Department of Defense Single Stock Point [DODSSP(9)].

.

___________________________ (7) International Organization for Standardization (ISO), 1 rue de Varembe, Case Postale 56, CH-1121 Geneva 20, Switzerland. (8) Society of Petroleum Engineers (SPE), PO Box 833836, 222 Palisades Creek Dr., Richardson, TX 75083-3836. (9) Department of Defense Single Stock Point (DODSSP), Document Automation and Production Services, 700 Robbins Ave., Bldg. 4D, Philadelphia, PA 19111-5094.

10 AM - Single-user license only, copying and networking prohibited.

NACE International

Moustafa

15. ISO 9000 (latest revision), “Quality Management and Quality Assurance Standards” (Geneva, Switzerland: ISO).

8

Bayoumi - Invoice INV-606124-JJHSQM, downloaded on 11/20/2012 10:07

16. NACE No. 1/SSPC-5 (latest revision), “White Metal Blast Cleaning” (Houston, TX: NACE, and Pittsburgh, PA: SSPC).

Appendix A: Basic Cleaning Methods

Vapor Degreasing:(A) A solvent is heated, condenses on the work piece, vaporizes, and removes organic contaminants from the metal. VOCs are used.

Chemical Cleaning:(B) Alkaline solutions such as sodium hydroxide or trisodium phosphate are used to degrease fasteners, usually in a multistep “wet” process. Inhibited acid solutions are used to neutralize the alkaline cleaning solutions and chemically etch the surface for improved adhesion.

Thermal Degreasing:(C) An oven is used to remove organic contaminants, generally from two to six hours at 600 to 800°F (316 to 427°C). This is a dry process.

Abrasive Blasting:(D) To establish a well-defined surface profile (anchor pattern) for adhesion, fasteners are usually blasted to a white metal blast cleaned surface in accordance with NACE No. 1/ SSPC-SP 5.16 This is a dry process. The height of the surface profile is important.

For ultra-thin film coatings (1.5 mil [38 µm] or less) the surface profile height is usually limited to 0.50 mil (13 µm) or less. For small fasteners, a tumble blast machine is commonly used for cleaning and to establish the surface profile.

Environmental Notes: (A) VOC emissions are regulated by U.S. Environmental Protection Agency (EPA), state, and local environmental guidelines. (B) Hazardous chemical wastes require special permits for disposal. (C) Thermal ovens may require thermal oxidizers to meet current environmental guidelines in noncompliance metropolitan areas. (D) Abrasive blast operations require control of dust and proper disposal of spent abrasive.

:10 AM - Single-user license only, copying and networking prohibited.