Request for Spec Clarification 11.docx

N32205-15-R-1009

USNS RAPPAHANNOCK (T-AO 204)

REQUEST FOR SPECIFICATION CLARIFICATION - #011

NAME OF CONTRACTOR:

SPECIFICATION ITEM NO.: 903 & 904

PARAGRAPH / SECTION NO: (WI# 903, Para 7.5.1); (WI# 904, Paras 7.2.4 & 7.2.5)

TITLE: UNDERWATER HULL PRESERVATION

In review of work items 903 & 904 we note the requirement for method of surface preparation is different between each work item.

Work item 903 specifies Ultra High Pressure (UHP) Water Jetting as the method for surface preparation.

7.5.1 Spot Ultra-High Pressure Water Jet the damaged or deteriorated areas of the hull from the keel to the 01 level, and focsle area of the bow, in accordance with reference 2.1.3, Surface Preparation Standard SSPC-SP-12/NACE 5, to a WJ-2 Condition. No more than a light (L) grade flash rust shall be allowed on the steel at the time of coating application. If heavier flash rust is present, the surface shall be pressure washed at 2,500 to 3,000 psi and allowed to air dry in order to restore the surface to a coatable condition. The surface profile achieved shall be angular in nature and within the range set by the manufacturer’s product data sheet for the coating system being applied. Profile shall be determined using a Keane-Tator (or equal) Surface Profile Comparator. Testex (or equal) Replica Tape shall be used at a rate of one (1) reading per 1,000 SF for verification. Replica Tape shall be mounted, identified as to location and included as part of the final paint report.

Converseley WI 904 specifies Grit Blasting as the method for surface preparation.

7.2.4 Abrasive-blast all freeboard surfaces marked by the Port Engineer for spot blasting. These areas shall be abrasive blasted in accordance with Surface Preparation Standard SSPC-SP10/NACE 2, Near White Metal Blast Cleaning. The surface profile achieved shall be angular in nature, and within the range set by the coating manufacturer’s product data sheet for the coating system being applied. Profile shall be determined using a Keane-Tator (or equal) Surface Profile Comparator. Testex (or equal) Replica Tape shall be used at a rate of one (1) reading per 1,000 Square Feet for verification. Replica Tape shall be mounted, identified as to location and included as part of the final paint report. All edges shall be feathered. Contain and dispose of all abrasive blast media in accordance with all national, state and local regulations as a part of this work item.

7.2.5 Sweep blast the remaining freeboard surfaces to remove any lose non-adhering paint on the surface. Any edges shall be feathered. Contain and dispose of all sweep blast media in accordance with all national, state and local regulations as a part of this work item.

QUESTION:

Recommend the method of surface preparation identified in WI#903, paragraph 7.5.1 be revised to “Grit Blasting” method as specified in WI# 904 paragraphs 7.2.4 & 7.2.5 to create uniformity and consistency in surface preparation methods of the ship’s hull.

ANSWER:

The contractor shall perform work in accordance with the Work Item as stated. No changes will be made as a result of this request for specification clarification.

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