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Rev. 01

Date 02/04

Notes First Issue

TOPCOR General Specification TSCCP

Page #2

Date 02/04 Rev. 00

1.0 1.1


This specification defines the requirements for the field or shop application of thermal spray coatings of aluminum, zinc or their alloys onto steel surfaces. It defines the minimum requirements for pre-qualification, materials, equipment, surface preparation, application procedures, quality control and repair. "Thermal spray coatings (TSCs) are used extensively for the corrosion protection of steel and iron in a wide range of environments. The corrosion tests carried out by the American Welding Society and the 34 and 44 year marine-atmosphere performance reports of the LaQue Center for Corrosion Technology confirm the effectiveness of flame [and wire-arc] sprayed aluminum and zinc coatings over long periods of time in a wide range of hostile environments. The British Standards Institution code of practice for the corrosion protection of steel specified that only TSCs give protection greater than 20 years to first maintenance for the 19 industrial and marine environments considered and that only sealed, sprayed aluminum or zinc gives such protection in sea water immersion or splash zones." (1) TSCs offer superior corrosion and temperature resistance to fusion bonded and liquid applied coatings and also provide cathodic protection to steel elements in both atmospheric exposure and seawater immersion. In addition to these applications, TSCs offer superior protection to CUI (Corrosion Under Insulation). Another application for TSCs is the cathodic protection of reinforcing steel in concrete structures, primarily in marine environments. The details for such application are covered in a different TOPCOR General Specification.

(1) SSPC Interim Standard C.1.2.B

TOPCOR General Specification TSCCP

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Date 02/04 Rev. 00

1.2 Reference Documents

Standards Reference

ANSI/AWS C2,18-93 ASTM 4541


Guide for the Protection of Steel with Thermal Sprayed Coatings of Aluminum, Zinc, and their Alloys and Composites, American Welding Society, April 1993 Standard test method for pull-off strength of coatings using portable adhesion testers

ASTM C 633 ASTM D 1186

Test Method for Adhesion or Cohesive Strength of Flame-Sprayed Coatings Standard test method for nondestructive measurement of dry film thickness of nonmagnetic coatings applied to a ferrous base Test Method for Indication Oil or Water in Compressed Air

ASTM D 4285

ASTM D 4417

Standard Test Methods for Field Measurement of Surface Profile of Blast-Cleaned Steel Recommended Practices for Metallizing with Aluminum and Zinc for Protection of Iron, American Welding Society Wire, Metallizing Military Standard, Metal Sprayed Coatings for Corrosion Protection aboard Naval Surface Ships, April 1986 Wrought aluminum and aluminum alloys ­ chemical composition and forms of products ­ part 1 : Chemical composition, 1989 Interim specification for the application of thermal spray coatings (metallizing) of aluminum, zinc, and their allows and composites for the corrosion protection of steel Shop, field, and maintenance painting of steel

AWS C2.2

AWS C2.25

DOD-STD-2138A (SH)

ISO 209-1

SSPC-CS Guide 23.00 SSPC-PA 1

SSP-QP 6 (draft) SSPC-SP5 /NACE No. 1

Standard procedure for evaluating qualifications of thermal spray (metallizing) applicators White Metal Blast Cleaning (SSPC/NACE Joint Standard), Steel Structures Painting Council, September 1994 Visual Standard for Abrasive Blast Cleaned Steel, Steel Structures Painting Council, 1989


TOPCOR General Specification TSCCP

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Date 02/04 Rev. 00

2.0 2.1

QUALIFICATIONS Pre-Qualification

The thermal spray process is a relatively sophisticated one and requires specific equipment and experience from the operators and contractors. This section covers the contractor selection and qualification requirements. 2.2 Contractor Qualification

Contractor must provide documentation proving three years of experience applying TSCs by either the flame or wire-arc process. Contractor must also have completed three successful projects applying TSCs. Finally, Contractor must have applied a minimum of 25,000 sq. ft. of TSC onto steel surfaces. 2.3 Contractor Equipment

Contractor must own its own TSC application equipment and show proof of documented training for operation and repair of this equipment. Contractor must have owned this equipment for the same three years of required TSC experience. 2.4 Operator Qualification

All operators that are to work the specific job must be pre-qualified prior to applying TSCs for the project. Such testing shall include: 2.5 Bend Test

Five carbon steel coupons, 2" x 4" x 0.050" shall be surface prepared per specification and TSC applied at specified thickness. The coupons are then bent 180-degrees around a 0.5" mandrel. The bend test passes if, on the bend radius there is no cracking or spalling or only minor cracking which cannot be lifted from the substrate. The bend test fails if the coating cracks with lifting from the substrate. 2.6 Adhesion Test

One carbon steel plate, 12" x 12", shall be prepared per specification and TSC applied at the specified thickness. Following ASTM D 4541, three pull tests shall be conducted on this plate. The minimum requirements for passing are as follows: Zn Al 85/15 (Zn/Al alloy) 500 psi 1000 psi 700 psi

TOPCOR General Specification TSCCP

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Date 02/04 Rev. 00



3.1 General Weld spatter and other surface defects should be removed by an approved mechanical method prior to blasting. Repairs requiring removal of metal shall be subject to client's approval. Any oil, grease, inspection fluids, or other contaminants should be removed by solvent cleaning per SSPC SP1 before blasting. Ambient conditions during blasting and thermal-spray coating operations should be measured and recorded. 3.2 Blast-cleaning Blast-cleaning shall not be performed when the surfaces to be blasted are wet or are less than 5°F above the dew point temperature. The ambient relative humidity should be less than 85%. Prior to blasting, the surface should be checked for soluble salt contamination. Water-soluble salts, such as chlorides, sulfates and nitrates, contaminate steel surfaces and cause rust bloom and premature coating failure. These soluble salts should be tested for via the Chlor-Test C.S.N. Soluble Salts Kit. Testing rates, at a minimum, should be three (3) tests for the first 1,000 sq. ft. of substrate and one (1) test per each 1,000 sq. ft. thereafter. If detected, remediation should be accomplished via application of Chlor-Rid Soluble Salt Remover until undetectable levels are reached, verified by subsequent testing. Coating operators shall make every effort to prevent the contamination of parts after cleaning and prior to coating. Any blasted surface that has become wet by rain or other moisture shall be re-blasted. 3.3 Surface Finish

Surfaces to be coated shall be blast cleaned to SSPC-SP5/NACE No. 1 (white metal) for marine and immersion services and SSPC-SP10/NACE No. 2 or other applications. Blast-cleaned surface finishes should be verified per SSPC-Vis-89 and ASTM 4417. 3.4 Anchor Profile

The anchor profile shall be determined on representative samples or on the work-piece itself, using a surface profile comparator, replica tape or other suitable method in accordance with ASTM D4417. Anchor profile should be 3-5 mils and should have a sharp angular shape. The measurement of the blast profile should be per ASTM D 4417, Method C. Measurements should be taken every 10 ­ 20 sq. ft. of blasted surface.

TOPCOR General Specification TSCCP

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Angular Blast Media

The angular blast media should be clean and dry. Mineral and slag abrasives shall be selected and evaluated per SSPC-AB 1. Confirm absence of oil contamination with the water sheen test per ASTM D 4940.

4.0 4.1


Blast cleaned steel shall be thermal-sprayed immediately, preferably, but within 4 hours of blast cleaning. Surfaces showing rust-bloom, surface oxidation or other surface coloration shall be reblasted prior to thermal-spraying. A 1-2 mil flash/primer coat of TSCCP may be applied within this 4-hour window to extend the holding period for up to four additional hours beyond the initial window. The relative humidity should be less than 90% and the steel surface temperature should be at least 5° above the dew point. Compressed air used for coating process should be free of oil and condensed moisture according to ASTM D 4285. 4.2 Thermal Spray Equipment

The thermal-spray equipment should be set up and operated per the manufacturer's instructions and per the QC plan of the TSCCP Applicator. Equipment set-up and spray-parameter set-up should be validated with a bend test at the beginning of each shift or crew change. Thermal spray equipment may be wire-arc or flame spray. 4.3 Thermal Spray Coating Material

The TSCCP coating material should be carefully chosen based on the intended use, service environment and service life (Ref. AWS C2.18-93, Annex B). In general, aluminum or an 85/15 zinc/aluminum alloy is used on steel surfaces and zinc is used on concrete surfaces (generally for cathodic protection of reinforcing steel). The chemical compositions of the various materials that may be specified are listed below. Mill certificates should be provided by the TSCCP Applicator to verify the materials being sprayed meet these requirements. The wire should be shipped in a protective wrapping material. Each box should be clearly labeled with the material, batch number and supplier.

TOPCOR General Specification TSCCP

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Chemical Composition Requirements for Aluminum, Zinc, Alloy Wires AWS Class W-AI1100 W-AI1350 W-Zn-1 W-Zn-2 UNS No. Name 1100 Alum 1350 Alum 99.99 Zinc 99.99 Zinc 98/2 ZincAlum 85/15 ZincAlum AI 99.00 min 99.50 min 0.002 0.01 1.5-2.5 Cr --Cu .05-.20 Fe 0.95 (Fe+Si) 0.4 0.003 0.02 --Composition, Wt% Mn 0.05 Pb --Si 0.95 (Fe+Si) 0.1 ------Sn --Ti --Zn 0.01

A91100 A91350 Z13001 Z15001

0.01 -------

0.05 0.005 0.02 ---

1.01 -------

--0.003 0.03 ---

--0.001 -----

0.02 (V+Ti) -------

0.05 99.99 min 99.99 min rem








TSCCP Coating Thickness

The TSCCP coating thickness should be between 10 ­ 15 mils for aluminum and 6 ­ 10 mils for zinc (unless for concrete reinforcing steel cathodic protection, in which case the thickness for zinc should be 12-15 mils). The thickness of either material should not exceed 20 mils. If upon later inspection, the TSC thickness is less than the contract requirement, then applicator shall apply additional TSC to meet the thickness requirement. This additional thickness shall only be applied to clean and dust-free TSC without any visible substrate oxidation or rust. 4.5 Thermal Spray Application.

TSCCP spray guns should be held as close possible to perpendicular to the surface being coated. The optimum distance from the gun to the coated surface should not exceed 8-10 inches. Successive passes shall overlap approximately 50%. The coating tensile bond strength is greater when spray passes are kept thin. Proper pass thickness should be confirmed with a bend test. Right angle cross passes should be used to minimize thin spots in the final coating. If rust bloom, blistering or a degraded coating appears at any time during the application of the TSCCP or flash/primer TSCCP, the applicator should stop spraying, mark off the acceptable sprayed area, re-prepare the unsatisfactory areas and into the acceptable areas 2-3 inches, and reapply TSCCP to the newly prepared areas, including the overlap into the acceptable material. This same procedure of preparing 2-3 inches of good TSCCP material and overlapping newly sprayed TSCCP into that 2-3 inches should be used whenever new work is being feathered into old.

TOPCOR General Specification TSCCP

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Date 02/04 Rev. 00

TSCCP should be applied to within approximately 1 inch from any area know to be welded. Suitable masking should be used to protect these areas from any coating application.

5.0 5.1


TSCCP should be sealed and/or topcoated under certain conditions. These include: -very acidic or alkaline environments -TSCCP is subject to direct contact with aggressive chemicals -additional abrasion resistance is required -certain aesthetics are required -TSCCP is subject to salt water spray or salt water immersion Topcoats are generally used only for aesthetic reasons. 5.2 Sealers

A seal coat should be thin enough to penetrate into the body of the TSCCP and seal the porosity. It is not intended to build film thickness. This seal coat is typically applied at approximately 1.5 mils dft. Sealers should be applied as soon as possible after the application of the TSCCP, and definitely within 24 hours after thermal spray application. If this window is not met, verification that the TSCCP has not been contaminated will be by visual inspection. Typical sealers for applications below 150° F are epoxy and above 150° F are silicone. 5.3 Topcoats

Topcoats are not normally required. A topcoat is basically a full coat of paint. They should be compatible with the sealer. A topcoat should not be applied to unsealed TSCCP. Topcoats will greatly reduce or entirely diminish the cathodic protection effects of the TSCCP in immersion or underground services.

6.0 6.1


All coated surfaces shall be visually inspected. Defective or non-conforming coatings shall be repaired in accordance with section 7.0 of this specification. The surfaces shall be free from lumps, coarse areas, loosely adherent particles, blisters, cracks, or chips.

TOPCOR General Specification TSCCP

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Coating Thickness

The TSCCP coating thickness should be measured and recorded for each coated component in accordance with ASTM D 1186. DFT is determined by the average value of five readings taken in an area of approximately four square inches or in a straight line at one-inch intervals. Thickness gages shall be calibrated using certified coating thickness calibrations standards at the start of each shift in which they are used. 6.2 TSCCP Adhesion

Random adhesion tests shall be performed using a self-aligning adhesion tester and according to ASTM D 4541. This test should be performed on unsealed TSCCP. The minimum adhesion value achieved of any single measurement should be according to those values shown on 2.6. If adhesion measurements fall below the specified minimum value, three additional measurements should be made, one near the failed test area and the other two at random. If any of these tests fail to meet the requirement, then areas with TSCCP applied before and after the failed area should also be tested to determine the extent of the defective areas. If three additional measurements meet or exceed the adhesion requirement then the component is acceptable. Identified areas of defective coatings should be repaired per 7.0 of this specification.

7.0 7.1

REPAIR General

Defective areas identified by visual inspection, adhesion testing, inadequate thickness or damage should be repaired as soon as possible according to the procedures outlined in ANSI/AWS C2.18. 7.2 Procedure

-Solvent clean -Scrape off loose TSCCP -Abrasive blast per 3.0 of this specification -Apply new TSCCP according to this specification and feather into acceptable TSCCP 7.3 Re-Inspection

Coating repairs shall be re-inspected, to ensure compliance with the requirements of this specification.

TOPCOR General Specification TSCCP

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Date 02/04 Rev. 00

8.0 8.1


Detailed records of the coating process shall be maintained, including: -Ambient conditions for the day -Wire certificate(s) of conformance -Surface preparation, including blotter testing of air supply, abrasive cleanliness, anchor profile -Coating application, including surface temperature, coating thickness records, material test results, TSA procedure used, amount of work, operators -Sealers and/or Topcoats -Adhesion Test Results -Thickness measurements Records of work performed shall be maintained in computer data form for an indefinite period. Traceability records showing the materials used shall be maintained, together with manufacturer's certification for materials, where appropriate. 8.2 Non-Conformance

Non-Conformance Reports shall be prepared to document all significant variances and corrective actions. 8.3 Quality Plan

The TSCCP applicator should prepare a written Quality Plan and submit to the owner for approval prior to starting work. This plan should include all pre-qualification, testing and quality control procedures outlined in this specification. 9.0 SAFETY CONSIDERATIONS

Potential thermal spray hazards include exposure to vapors, dust, fumes, gases, noise (from the spray gun), and arc ultraviolet (UV) radiation. The fine aluminum and zinc particles produced in thermal spray may be an extreme explosion hazard. Special precaution shall be taken in confined areas where dust accumulation may occur. Do not use water to extinguish aluminum or zinc fires. Use dry sand or a Class D extinguisher.



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