SSPC-SP WJ-4NACE WJ-4 2017

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SSPC-SP WJ-4/NACE WJ-4

March 10, 2012

Editorial Revisions January 5, 2017

This SSPC: The Society for Protective Coatings/NACE

International joint surface preparation standard 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, whether he or she has

adopted the standard or not, from manufacturing, marketing,

purchasing, or using products, processes, or procedures not

in conformance with this standard practice. Nothing contained

in this SSPC/NACE standard 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 standard represents minimum requirements and should

in no way be interpreted as a restriction on the use of better

procedures or materials not discussed herein. Neither is this

standard intended to apply in all cases relating to the subject.

Unpredictable circumstances may negate the usefulness of

this standard in specic instances. SSPC and NACE assume

no responsibility for the interpretation or use of this standard

by other parties, and accept responsibility for only those of-

cial SSPC or NACE interpretations issued by SSPC or NACE

in accordance with their governing procedures and policies,

which preclude the issuance of interpretations by individual

volunteers.

Users of this SSPC/NACE standard are responsible for

reviewing appropriate health, safety, and regulatory docu-

ments and for determining their applicability in relation to this

standard prior to its use. This SSPC/NACE standard may not

necessarily address all potential health and safety problems

or environmental hazards associated with the use of mate-

rials, equipment, and/or operations detailed or referred to

within this standard. Users of this SSPC/NACE standard also

are 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 require-

ments prior to the use of this standard.

CAUTIONARY NOTICE: SSPC/NACE joint surface prep-

aration standards are subject to periodic review, and may be

revised or withdrawn at any time in accordance with SSPC/

NACE technical committee procedures. SSPC and NACE

require that action be taken to reafrm, revise, or withdraw this

standard no later than ve years from the date of initial publi-

cation and subsequently from the date of each reafrmation

or revision. The user is cautioned to obtain the latest edition.

Purchasers of SSPC/NACE standards may receive current

information on all standards and other SSPC/NACE joint

publications by contacting the organizations at the addresses

below:

SSPC: The Society for Protective Coatings

800 Trumbull Drive

Pittsburgh PA 15205-4365

+1-412-281-2331

NACE International

15835 Park Ten Place

Houston, TX 77084

+1 281-228-6200

Foreword

This SSPC/NACE joint standard denes the Light Cleaning

degree of surface cleanliness of coated or uncoated metallic

substrates achieved by the use of waterjet cleaning prior to the

application of a protective coating or lining. Waterjet cleaning is

the use of pressurized surface preparation water for removing

coatings and other materials, including hazardous materials,

from a substrate to achieve a dened degree of surface clean-

liness. Waterjet cleaning includes various methods such as

low-pressure water cleaning (LP WC), high-pressure water

cleaning (HP WC), high-pressure waterjetting (HP WJ), and

ultrahigh-pressure waterjetting (UHP WJ).

The four degrees of surface cleanliness achieved by

waterjet cleaning, which are addressed in separate standards,

are as follows:

Degree of Surface Cleanliness Designation

Clean to Bare Substrate WJ-1

Very Thorough Cleaning WJ-2

Thorough Cleaning WJ-3

Light Cleaning WJ-4

Light Cleaning (WJ-4) provides a a lesser degree of

cleaning than Thorough Cleaning (WJ-3).

Waterjet cleaning to achieve the Light Cleaning (WJ-4)

degree of surface cleanliness is used when the objective is

to allow as much of the tightly adherent rust and other corro-

sion products, coating, and mill scale to remain as possible,

but when the extra effort required to remove more of these

SSPC: The Society for Protective Coatings/NACE International

Joint Surface Preparation Standard

Waterjet Cleaning of Metals

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

SSPC-SP WJ-4/NACE WJ-4

March 10, 2012

Editorial Revisions January 5, 2017

materials is determined to be unwarranted. Discoloration of the

surface may be present.

Waterjet cleaning does not provide the primary anchor

pattern on the metallic substrate known as “surface prole.”

The coatings industry uses waterjet cleaning primarily for

recoating or relining projects in which there is an adequate

pre-existing surface prole. The degrees of surface cleanli-

ness cited above to be achieved by waterjet cleaning methods

are not intended to require that a surface prole be present or

dened prior to coating application.

Waterjet cleaning reduces and may completely remove

water-soluble surface contaminants, notably those contami-

nants found at the bottom of pits on the surface of corroded

metallic substrates. Waterjet cleaning also helps remove oil,

grease, rust and other corrosion products, and other foreign

matter (for example, shotcrete spatter) from the surface, and is

used when it is a more feasible method of surface preparation

than, for example, abrasive blast cleaning, power or hand tool

cleaning, or chemical stripping. Waterjet cleaning may be used

when the application of high-performance coatings requires

extensive surface preparation, surface decontamination, or

both.

This standard is intended for use by coating or lining

speciers, applicators, inspectors, or others who have respon-

sibility to dene a standard degree of surface cleanliness to be

achieved by waterjet cleaning methods.

This standard was prepared by SSPC/NACE Joint Task

Group (TG) 278, “Surface Preparation of Metals to WJ-4 (Light

Cleaning) by High-Pressure Waterjetting.” TG 278 is adminis-

tered by Specic Technology Group (STG) 04, “Coatings and

Linings, Protective—Surface Preparation,” and is sponsored

by STG 02, “Coatings and Linings, Protective—Atmospheric,”

and STG 03, “Coatings and Linings, Protective—Immersion

and Buried Service.” This standard is issued by SSPC Group

Committee C.2 on Surface Preparation, and by NACE under

the auspices of STG 04. This standard is one of a set of four

standards on degrees of surface cleanliness to be achieved

by waterjet cleaning that are intended to replace SSPC-SP

12/NACE No. 5,1 which includes all four degrees of surface

cleanliness.

In SSPC/NACE standards, the terms shall, must, should,

and may are used in accordance with Paragraph 2.2.1.8 of

the Agreement between SSPC: The Society for Protective

Coatings and NACE International. The terms shall and must

are used to state mandatory requirements. The term should

is used to state something considered good and is recom-

mended, but is not mandatory. The term may is used to state

something considered optional.

Section 1: General

1.1 This standard denes the Light Cleaning (WJ-4)

degree of surface cleanliness of uncoated or coated metallic

substrates by use of waterjet cleaning. The dened degree

of cleanliness shall be achieved prior to the application of a

specied protective coating or lining system. These require-

ments include the end condition of the surface and materials

and procedures necessary to achieve and verify the end condi-

tion, as determined by visual inspection. This standard also

may be used in situations in which the degree of cleanliness is

required, but protective coatings or linings are not immediately

applied. (Paragraphs A1 and A2 of Appendix A provide addi-

tional information.) Waterjet cleaning does not establish but

may reveal an existing surface prole on a metallic substrate.

If the existing surface prole is not acceptable for subsequent

coating application, alternative surface preparation methods to

create the required surface prole must be considered. (Para-

graph A3 of Appendix A provides additional information.)

1.1.1 Light Cleaning (WJ-4) is essentially equivalent to the

International Organization for Standardization (ISO)(1) 8501-42

degree of cleanliness Wa 4, light cleaning. . ISO 8502-4 notes

the use of various common terms for methods of waterjet

cleaning: water jetting, water blast cleaning, hydrojetting, aqua-

jetting, hydroblasting, aquablasting, and “cleaning by directing

a jet of pressurized water onto the surface to be cleaned.”

1.2 Although carbon steel is the metallic substrate most

frequently cleaned in the eld using waterjetting technology,

waterjet cleaning may be used on metallic substrates other

than carbon steel, including other ferrous substrates such

as alloy steels, stainless steels, ductile iron and cast irons,

nonferrous substrates such as aluminum, and copper alloys

such as bronze. For convenience, the written denitions of the

degrees of surface cleanliness of the metallic substrate use

the general term “rust and other corrosion products.” The term

“rust” is intended to apply to carbon steel substrates and the

term “other corrosion products” (such as surface oxides) is

intended to apply to metallic substrates other than carbon steel

that are being waterjet cleaned. “Flash rust” is an oxidation

product that forms as a wetted carbon steel substrate dries.

The visual guides and comparators referenced for cleanliness

and ash rust only illustrate carbon steel substrates.

1.3 This standard does not address surface preparation of

concrete. Information on surface preparation of concrete can

be found in SSPC-SP 13/NACE No. 6.3

1.4 This standard is limited to requirements for visible

surface contaminants. Information on nonvisible contamina-

tion can be found in Paragraph A8 of Appendix A.

Section 2: Denitions

2.1 Light Cleaning (WJ-4): A metal surface after Light

Cleaning, when viewed without magnication, shall be free

of all visible oil, grease, dirt, dust, loose mill scale, loose rust

and other corrosion products, and loose coating. Any residual

material shall be tightly adhered to the metal substrate and may

consist of randomly dispersed stains of rust and other corro-

sion products or previously applied coating, tightly adherent

thin coatings, and other tightly adherent foreign matter.

1 International Organization for Standardization (ISO), 1 ch. de la Voie-Creuse, Case postale

56, CH-1211 Geneva 20, Switzerland.

SSPC-SP WJ-4/NACE WJ-4

March 10, 2012

Editorial Revisions January 5, 2017

2.1.1 Coatings, mill scale, and foreign matter are consid-

ered tightly adherent if they cannot be removed by lifting with a

dull putty knife. (Paragraphs A4 and A5 of Appendix A provide

additional information.)

2.1.2 The gray to brown-black discoloration remaining on

corroded and pitted carbon steel that cannot be removed by

further waterjet cleaning is allowed.

2.1.3 SSPC-VIS 4/NACE VIS 74 or other visual guide or

comparator may be specied to supplement the written deni-

tion. In any dispute, the written standard shall take precedence

over the visual guide or comparator. (Paragraph A6 of Appendix

A provides additional information.)

Section 3: Additional Technical Considerations

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 ash rust. Metals other than

carbon steel can manifest discoloration as well. Degrees of

ash rust may be qualitatively described as follows:

3.1.1 No ash rust: A carbon steel surface that, when

viewed without magnication, exhibits no visible ash rust.

3.1.2 Light (L) ash rusted surface: A carbon steel

surface that, when viewed without magnication, 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.

3.1.3 Moderate (M) ash rusted surface: A carbon steel

surface that, when viewed without magnication, 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.

3.1.4 Heavy (H) ash rusted surface: A carbon steel

surface that, when viewed without magnication, 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 signicant marks on a cloth that is lightly wiped over

the surface.

(Paragraphs A6, A9, and A10 of Appendix A provide addi-

tional information. Appendix B provides additional information

on methods of assessing the degree of ash rust.)

3.2 Appearance Variations

3.2.1 Acceptable variations in appearance that do not

affect the degree of surface cleanliness dened in Paragraph

2.1 include variations caused by composition of the metallic

substrate, original surface condition, thickness of the metal,

weld metal, mill or fabrication marks, heat treating, heat-

affected zones, and differences resulting from the initial

abrasive blast cleaning abrasives or the abrasive blast pattern

if previously blast cleaned, or waterjet cleaning pattern.

3.2.1.1 Carbon steel surfaces cleaned by waterjet cleaning

initially exhibit a matte nish with a color that can range from

light gray to dark brown-black but immediately acquires a

golden hue unless a corrosion inhibitor or environmental

controls are used. The matte nish on older carbon steel

surfaces that have areas from which coating was removed and

areas that were coating-free at the time of cleaning varies even

when all visible surface material has been removed.

3.2.2 Metallic substrates show variations in texture,

shade, color, tone, pitting, aking, and mill scale that should be

considered during the waterjet cleaning process. (Paragraph

A6 of Appendix A provides additional information.)

3.2.3 Direct correlation to existing dry abrasive

blasting standards and visual comparators is inaccurate or

inappropriate.

Section 4: Associated Documents

4.1 Documents associated with this standard and cited in

its mandatory sections include:

Document Title

SSPC-SP 7/NACE No. 45“Brush-Off Blast Cleaning”

SSPC-SP 13/NACE No. 6 “Surface Preparation

of Concrete”

SSPC-VIS 4/NACE VIS 7

“Guide and Visual Reference

Photographs for Steel Cleaned

by Waterjetting”

SSPC-SP 16 “Solvent Cleaning”

4.2 If there is a conict between the requirements of any

of the documents listed in Paragraph 4.1 and this standard, the

requirements of this standard shall govern.

Section 5: Procedures Before Waterjet Cleaning

5.1 Precleaning: Visible deposits of oil, grease, foreign

matter, and other contaminants shall be removed by waterjet

cleaning, by methods in accordance with SSPC-SP 1, or as

specied. (Paragraphs A4, A5, and A10 of Appendix A and

Paragraph C2.6 of Appendix C provide additional information.)

5.2 Prior to beginning waterjet cleaning, surface imper-

fections such as sharp ns, sharp edges, weld spatter, or

burning slag shall be addressed to the extent required by the

procurement documents (project specications). (Paragraph

A12 of Appendix A provides additional information.)

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摘要：

SSPC-SP WJ-4/NACE WJ-4 2017 是由美国防护涂料协会（SSPC）与国际腐蚀工程师协会（NACE）联合发布的表面处理标准规范，专门针对水力或湿磨料喷射清理技术。该标准定义了使用水与磨料混合的喷射方法去除钢材表面涂层、锈蚀及其他污染物的工艺要求，适用于需要减少粉尘、控制基材温度或处理易燃环境的高效表面准备场景。文档详细规定了清理后的表面清洁度等级、水溶性盐残留限制、湿喷操作参数及验收标准，强调在满足工业涂装前表面粗糙度要求的同时，避免因水引入导致的闪锈风险。该版本整合了201

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