Waterjetting—New Standards for Assessing End Condition Cleanliness

Monday, July 9, 2012; 11:00 AM - 12:00 PM (Eastern)

Richard A. BurgessKTA-Tator, Inc.

This presentation will address the new standards, and the value of

experience and training in assessing end conditions and precautions when

specifying cleaning pressures.

Waterjetted Steel Cleaning Levels

• Visual cleanliness• Flash rusting levels• Soluble salt levels

SSPC-SP 12/NACE No. 5, “Surface Preparation and Cleaning of Metals by Waterjetting Prior to Recoating” (2002).

Different than the other SSPC/NACE Joint Surface Preparation Standards. It was comprised of……….

4 Levels of surface cleanliness (WJ-1 through WJ-4)

4 Degrees of flash rust (None, Light, Moderate, Heavy), no single definition of surface cleanliness.

3 Non-Mandatory Levels of Non-Visible Contaminants (NV-1, NV-2, NV-3)

Four new standards exist, one for each of the WJ definitions.

June 25, 2012

NACE International has withdrawn

NACE No. 5/SSPC-SP 12, “Surface Preparation and Cleaning of Metals by Waterjetting Prior to Recoating,”

replaced with four new joint standards……………….

SSPC-SP WJ-1/NACE WJ-1 – Clean To Bare Substrate

2.1 Clean to Bare Substrate (WJ 1): A metal surface after Clean to Bare Substrate, when viewed without magnification, shall have a matte (dull, mottled) finish and shall be free of all visible oil, grease, dirt, rust and other corrosion products, previous coatings, mill scale, and foreign matter.

And, WJ-1

• Thin films of mill scale, rust and other corrosion products, and coating are not allowed.

• The gray to brown-black discoloration remaining on corroded and pitted carbon steel that cannot be removed by further waterjet cleaning is allowed.

• SSPC-VIS 4/NACE VIS 76 or other visual guide or comparator may be specified to supplement….. written standard shall take precedence

SSPC VIS 4: Waterjetting

SSPC-SP WJ 2/NACE WJ-2 – Very Thorough Cleaning

2.1 Very Thorough Cleaning (WJ 2): A metal surface after Very Thorough Cleaning, when viewed without magnification, shall have a matte (dull, mottled) finish and shall be free of all visible oil, grease, dirt, rust, and other corrosion products except for randomly dispersed stains of rust and other corrosion products, tightly adherent thin coatings, and other tightly adherent foreign matter. The staining or tightly adherent matter shall be limited to no more than 5 percent of each unit area of surface and may consist of randomly dispersed stains of rust and other corrosion products or previously applied coating, tightly adherent thin coatings, and other tightly adherent foreign matter.

And, WJ-2

• A unit area of surface is an area approximately 5,800 mm2 [9.0 in2] (i.e., a square 76 mm x 76 mm [3.0 in x 3.0 in].

• Coatings, mill scale, and foreign matter are considered tightly adherent if they cannot be removed by lifting with a dull putty knife.

• The gray to brown-black discoloration remaining on corroded and pitted carbon steel that cannot be removed by further waterjet cleaning is not considered part of the percentage staining.

• SSPC-VIS 4/NACE VIS 75 ……….written standard shall take precedence over the visual guide or comparator.

SSPC-SP WJ 3/NACE WJ-3 – Thorough Cleaning

2.1 Thorough Cleaning (WJ 3): A metal surface after Thorough Cleaning, when viewed without magnification, shall have a matte (dull, mottled) finish and shall be free of all visible oil, grease, dirt, rust, and other corrosion products except for randomly dispersed stains of rust and other corrosion products, tightly adherent thin coatings, and other tightly adherent foreign matter. The staining or tightly adherent matter shall be limited to no more than 33 percent of each unit area of surface and may consist of randomly dispersed stains of rust and other corrosion products or previously applied coating, tightly adherent thin coatings, and other tightly adherent foreign matter.

And, WJ-3

• A unit area of surface is ………..an area approximately ….[9.0 in2] (i.e. [3.0 in x 3.0 in].

• Coatings, mill scale, and foreign matter are considered tightly adherent if they cannot be removed by lifting with a dull putty knife.

• The gray to brown-black discoloration remaining on corroded and pitted carbon steel that cannot be removed by further waterjet cleaning is allowed.

• SSPC-VIS 4/NACE VIS 75 ……….written standard shall take precedence over the visual guide or comparator.

SSPC-SP WJ 4/NACE WJ-4 – Light Cleaning

2.1 Light Cleaning (WJ 4): A metal surface after Light Cleaning, when viewed without magnification, shall be free of all visible oil, grease, dirt, dust, loose mill scale, loose rust and other corrosion products, and loose coating. Any residual shall be tightly adhered to the metal substrate and may consist of randomly dispersed stains of rust and other corrosion products or previously applied coating, tightly adherent thin coatings, and other tightly adherent foreign matter.

And, WJ-4

• Coatings, mill scale, and foreign matter are considered tightly adherent if they cannot be removed by lifting with a dull putty knife.

• The gray to brown-black discoloration remaining on corroded and pitted carbon steel that cannot be removed by further waterjet cleaning is allowed.

• SSPC-VIS 4/NACE VIS 75 ……….written standard shall take precedence over the visual guide or comparator.

SSPC VIS 4: Waterjetting

Are We There Yet?

Who Has the Dull Putty Knife?

Pressures for Cleaning with Water• Low-pressure water cleaning (LP WC): less

than 5,000 psi (34 MPa)• High-pressure water cleaning (HP WC): 5,000

to 10,000 psi (34 to 70 MPa)• High-pressure waterjetting (HP WJ): 10,000 to

30,000 psi (70 to 210 MPa)• Ultrahigh-pressure waterjetting (UP WJ):

above 30,000 psi (210 MPa)

WJ-1, WJ-2, WJ-3, WJ-4 each state that:

This standard is intended for use by coating or lining specifiers, applicators, inspectors, or others who have responsibility to define a standard degree of surface cleanliness to be achieved by waterjet cleaning methods.

3.1 Flash Rust

Flash rust is an additional consideration when a carbon steel substrate is subjected to waterjet cleaning. Gray or brown-black discoloration remaining in the pits of waterjet cleaned carbon steel is not the same as flash rust. Metals other than carbon steel can manifest discoloration as well. Degrees of flash rust may be qualitatively described as follows:

No Flash Rust:

A carbon steel surface that, when viewed without magnification, exhibits no visible flash rust.

Light (L) Flash Rusted Surface:

A carbon steel surface that, when viewed without magnification, exhibits small quantities of a rust layer through which the carbon steel substrate may be observed. The rust or discoloration may be evenly distributed or present in patches, but it is tightly adherent and not easily removed by lightly wiping with a cloth.

Moderate (M) Flash Rusted Surface:

A carbon steel surface that, when viewed without magnification, exhibits a layer of rust that obscures the original carbon steel surface. The rust layer may be evenly distributed or present in patches, but it is reasonably well adherent and leaves light marks on a cloth that is lightly wiped over the surface.

Heavy (H) Flash Rusted Surface:

A carbon steel surface that, when viewed without magnification, exhibits a layer of heavy rust that hides original carbon steel surface completely. The rust may be evenly distributed or present in patches, but it is loosely adherent, easily comes off, and leaves significant marks on a cloth that is lightly wiped over the surface.

Heavy

Moderate,

Light

Requirements for Flash Rust

Flash rust shall be mitigated in accordance with the requirements of the procurement

documents.

An example of a specification statement is provided in Paragraph A10 of Appendix A.

A10.1 The specifier should use the degree of surface cleanliness and one of the degrees of flash rust to specify the required end condition. The following are examples of a specification statement:

“All surfaces to be recoated shall be waterjet cleaned to SSPC-WJ 2L /NACE WJ-2L, Very Thorough Cleaning, Light Flash Rust.” “At the time of the recoating, the degree of flash rust shall be no greater than moderate (M).”

TABLE B1ASSESSMENT OF DEGREE OF FLASH RUST—TAPE PULL TEST

___________________________________________________________________Degree of Flash Appearance of 10th Tape Appearance of Test Area

Rust (after final pull from test area) (after 10th tape pull) __________________________________________________________________

Light No rust on tape No change, or only slight change in test area appearance

___________________________________________________________________Moderate Slight, localized red-brown Significant change of

test rust on tape area appearance, showing

localized areas of black rust____________________________________________________________________

Heavy Significant, uniform red-brown Significant change of test rust on tape also showing area appearance, showing

grains of black rust localized areas of black rust

The existing surface profile shall be assessed to determine conformance with the requirements of the procurement documents.

(Paragraphs A3 and A14 of Appendix A provide additional information.)

Absent from the New StandardsTable A1: Description of Nonvisible Surface Cleanliness Definitions(A)

(NV) Term Description of Surface

NV-1 An NV-1 surface shall be free of detectable levels of soluble contaminants…NV-2 An NV-2 surface shall have less than 7 μg/cm2 of chloride contaminants, less than 10 μg/cm2 of soluble ferrous ion or less than 17 μg/cm2 of sulfate contaminants…NV-3 An NV-3 surface shall have less than 50 μg/cm2 of chloride or sulfate contaminants… (…verified by field or laboratory analysis using reliable, reproducible test methods.)

____________________________

(A) Additional information on suitable procedures for extracting and analyzing soluble salts is available in NACE Publication 6G186,8 and SSPC-TU 4.9

WJ-1, WJ-2, WJ-3, WJ-4 each state that:

This standard is limited to requirements for visible surface contaminants. Information on

non-visible contamination can be found in Paragraph A8 of Appendix A.

Prior to beginning waterjet cleaning, surface imperfections such as sharp fins, sharp edges, weld spatter, or burning slag shall be addressed to the extent required by the procurement documents (project specifications). (Paragraph A12 of Appendix A provides additional

information.)

Immediately prior to coating application, the entire surface shall comply with the degree of surface cleanliness specified herein, and to the extent

established, the procurement document (project specification) requirements, and degree of flash

rust.

Soluble Salts

Soluble Salts, Non-MandatoryA8.6 The following is an example specification for salt

contamination based on concentration measurements:

“Immediately prior to the application of the coating, the surface extract shall not contain more than xx μg/cm2 of the specific contaminant (e.g., chloride) when tested with a specified method.”

A8.7 The following is an example specification for saltcontamination based on conductivity measurements:

“Immediately prior to the application of the coating, the conductivity of the surface extract shall not exceed xx μS/cm when tested with a specified method.”

Job Site Security

Q&ACopies of the 2012 Waterjetting Standards

Download from SSPC Marketplace (www.sspc.org) Also consider

SSPC-VIS 4/NACE VIS 7 “Guide and Reference Photographs for Steel Surfaces Prepared by

Waterjetting” and

“Recommended Guidelines for Evaluating Flash Rust”

Available only in hardcopy contain color photographs useful as supplements to the four new waterjetting standards.