SSPC Updates PA 2, Revises Waterjetting Standard
Summary of SSPC-PA 2 Revisions 2012
SSPC-PA 2, Procedure for Determining Conformance to Dry Coating Thickness Requirements has been revised. The scope and title of PA 2 have changed to reflect the 2012 revision of ASTM D7091-12 Standard Practice for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to Ferrous Metals and Nonmagnetic, Nonconductive Coatings Applied to Non-Ferrous Metals. ASTM D 7091 committee chair Dave Beamish and SSPC chair Bill Corbett have worked closely together to ensure that the revised standards will not overlap or conflict. The title of the revised PA 2 reflects the modification of its scope.
The technical revisions to SSPC-PA 2 2012 are summarized below:
- Much of the descriptive language about operation of the gages has been eliminated. Descriptions of gages and their operation is included in the revision of the ASTM D 7091 standard. The 2012 revision of PA 2 contains procedures for determining compliance with project requirements for dry coating thickness, and procedures for performing accuracy checks to ensure that the gages are reading accurately.
- The section (Section 9) on determining compliance with specified DFT has been rewritten to allow the specifier to reference a greater or lesser "coating thickness restriction" than the default requirement, which requires that an acceptable spot reading must be within 80% of minimum, 120% of maximum specified DFT).
- New language has been added for determining and documenting extent of nonconforming areas. This language is found in Section 8.2.4 and subsections.
- The nonmandatory note on Overcoating has been modified to allow use of ultrasonic gages that have the ability to distinguish coating layers for measurement of DFT on overcoated structures.
- Two new non-mandatory appendices have been added, one for measuring the DFT of coatings on edges, the other for measuring DFT on coated steel pipe exteriors.
Other revisions are considered editorial clarifications.
SSPC members can download the updated standard for free by logging into their MarketPlace account and downloading from the standards store.
Revision of SSPC/NACE Waterjetting Standards
The 2012 revision of the 2002 version of SSPC-SP 12/NACE No. 5 standard, “Surface Preparation of and Cleaning of Metals by Waterjetting Prior to Coating” divides the standard into 4 separate documents, each addressing a different level of surface cleanliness. The organization of the four resulting standards has been revised to more closely parallel the organization of the dry abrasive blast cleaning standards, and allows the specifier to specify levels of cleanliness for waterjetting by use of separate standards, as is done when specifying levels of dry abrasive blast cleaning.
The titles of the new standards are:
- Waterjet Cleaning of Metals: SSPC-SP WJ-1/NACE WJ-1, Clean to Bare Substrate
- Waterjet Cleaning of Metals: SSPC-SP WJ-2/NACE WJ-2, Very Thorough Cleaning
- Waterjet Cleaning of Metals: SSPC-SP WJ-3/NACE WJ-3, Thorough Cleaning
- Waterjet Cleaning of Metals: SSPC-SP WJ-4/NACE WJ-4, Light Cleaning
Although now contained in separate standards, the definitions of the four surface cleanliness levels have changed very little from the definitions in the 2002 version of the standard. Clarification that permissible staining or tightly adherent matter must be evenly distributed over the surface has been added to WJ 2 and WJ 3. In addition, a clarification of “tightly adherent” (cannot be lifted with a dull putty knife) has been added to WJ 2, WJ 3 and WJ 4 definitions.
Descriptions of three degrees of flash rusting are provided in each of the waterjetting standards. These descriptions are based on the degree to which the rust obscures the carbon steel substrate and the degree of adhesion to the substrate, the color of the rust is no longer addressed. A nonmandatory appendix has been added to each standard describing two methods that may be used to assess the amount of flash rusting present on the surface. Each standard also contains examples of language that can be used in project specifications to establish the maximum amount of flash rust permitted on the surface prior to coating.
Copies of the 2012 Waterjetting standards may be downloaded from the SSPC Marketplace (www.sspc.org). Users may also be interested in obtaining copies of SSPC-VIS 4/NACE VIS 7, Guide and Reference Photographs for Steel Surfaces Prepared by Waterjetting, and Recommended Guidelines for Evaluating Flash Rust. Both of these publications are available only in paper format, and contain color photographs that may be useful supplements to the four waterjetting standards.
SSPC members can download the new standards for free by logging into their MarketPlace account and downloading from the standards store.