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BALLAST TANK

Ballast Tank

General Overview
Submarine ballast tanks are subjected to immersion conditions in an environment extremely receptive to corrosion. These tanks are used for diving and surfacing operations by filling with seawater and emptying with compressed air.

Ballast tanks are coated with high performance anti-corrosive and anti-fouling coatings to protect the steel from the seawater and marine growth. Shipyard/depot level personnel perform preservation work during major industrial availabilities. Larger areas of coating failure should receive a near white metal abrasive blast (SSPC-SP 10) and fresh coating. Environmental controls must be maintained during all preservation work in order to ensure coating longevity. Only coatings listed in MS 6310-081-015, the Submarine Maintenance Standard (Submarine Preservation) may be utilized. Submarine ballast tanks are critical structures and contain equipment crucial to the safety of the submarine.

In the last decade, represervation of shipboard tanks represented the #1 annual maintenance cost to the fleet. In particular, seawater ballast tank coating systems are failing prematurely. In some cases, five to seven year design life expectancy systems are lasting only one to three years in service. There are over 2900 ballast tanks in the U.S. Navy inventory, and represervation of these tanks costs the fleet roughly $75M annually. Analysis of fleet failures indicated two key contributors to premature failures.

  • Lack of adequate surface preparation prior to coating installation (both new construction and repair);
  • Coating systems' inability to build to the desired dry film thickness at sharp edges, sharp corners, weld seams and other imperfections.

The U.S. Navy has embarked on a major program to improve the reliability of tank coatings. This program involves new coatings, enhanced surface preparation requirements and strict process oversight/controls, along with improved QA. The program's goal is to increase the life expectancy for ballast tank coatings to 20+ years.

Note
The Submarine Maintenance Standard (SMS) and NSTM 631 undergo frequent changes and should be checked for up-to-date, accurate information.


New Technology Areas
(Only NAVSEA Approved Coatings approved for use on submarines may be applied.)

Edge-Retentive, Surface-Tolerant, High-Solids Coatings
Tremendous success has been achieved in this area by shifting from solvent-based coating systems to new technology edge-retentive, surface-tolerant, high-solids coating systems. These new systems provide an improvement over traditional coatings. First, due to their high solids content and design, the coatings do not pull back from sharp edges during curing. These edge-retentive systems are capable of retaining a large percentage of the flat plate paint thickness on edges. This is an important feature, since it eliminates many of the areas where coating failures begin. These coatings are also environmentally friendly. They are solvent-free or nearly so, which reduces volatile organic compound (VOC) emissions during painting evolutions. In submarines, these coatings must be applied over SSPC-SP 11 prepared surfaces.

Improved Surface Preparation
Enhanced surface preparation has been instituted, including strict adherence to surface preparation and cleanliness standards (SSPC/NACE/ASTM).

Quality Assurance
Independent third party QA oversight of key checkpoints and in-house (first party) monitoring of the entire preservation process by NACE or NBPI-qualified inspectors is considered vital to achieving the design life expectancy of these new systems. Government oversight should not replace in-house QA process monitoring by NACE or NBPI-qualified inspectors.


U.S. Navy Coating Application Process Repair Requirements
(Submarine Maintenance Standard MS NO. 6310-081-015 "Submarine Preservation" (Official Use Only))
SMS for submarine preservation is the governing technical document for submarine preservation and maintenance. This document consolidates requirements into a single standard and is dedicated to the proper application and maintenance of coatings on U.S. Navy submarines. Requirements listed in the SMS provide guidance for Intermediate Maintenance Activities (IMAs), Naval Shipyards, and contractors.

The Submarine Maintenance Standard does not supersede NSTM 631, but in instances where requirements specified conflict, the Submarine Maintenance Standard governs. This also applies to DDGOS, MRCs, MSs, and individual ships' Paint Schedule requirements.

Submarine Maintenance Standard MS NO. 6310-081-015 shall be referred to for all application and QA/QC requirements and all information for submarine preservation shall be verified per application documents prior to any work being performed.

Applicable Coatings Specifications and Approved Coatings


Table I: Main Ballast Tanks
Applicable Coatings Specifications and Approved Coatings for Main Ballast Tanks
  • MIL-PRF-23236/QPL-23236 Type VII, Class 7 high solids epoxy
    • 2 coats plus stripe coat
  • MIL-PRF-24647Antifouling Paint
    • 2-4 coats as specified from bottom centerline to 2' vertically above height of highest flood louver over a tack coat of Formula 150
  • MIL-DTL-24441/QPL-24441) Type IV (Approved for repair and touch up ONLY)
    • 1 coat Formula 150
    • 1 coat Formula 152 or 151
  • MIL-PRF-24647/QPL-24647 Antifouling Paint
    • 2-4 coats as specified from bottom centerline to 2' vertically above height of highest flood louver over a tack coat of Formula 150
Note
For specific details on system application, refer to the Submarine Maintenance Standard MS NO. 6310-081-015 "Submarine Preservation" (For Official Use Only).

Table II: Piping in Main Ballast Tanks
Non-Ferrous and CRES piping above residual waterline Non-Ferrous and CRES piping below residual waterline
Unpainted
  • 2 coats of the anti-corrosive paint system applied in tank
AND
  • 2 coats MIL-PRF-24647 Anti-Fouling paint listed on QPL-24647
Note
For specific details on system application, refer to the Submarine Maintenance Standard MS NO. 6310-081-015 "Submarine Preservation" (For Official Use Only).

Table III: Auxiliary Variable Ballast Tanks/ Variable Ballast Tanks
Applicable Coatings Specifications and Approved Coatings for Auxiliary Variable Ballast Tanks/ Variable Ballast Tanks

Note
For specific details on system application, refer to the Submarine Maintenance Standard MS NO. 6310-081-015 "Submarine Preservation" (For Official Use Only).

Naval Ships' Technical Manual (NSTM)
The NSTM is referenced in the Submarine Maintenance Standard for various preservation requirements. The applicable Chapters for preservation are listed below.
Naval Ships' Technical Manual (NSTM) Chapter 631

  • Volume 1  Preservation of Ships in Service

Additional Ballast Tank Requirement References

  • UIPI 6311-460
  • Provides application guidance for high-solids coating systems

Submarine Maintenance Engineering, Planning and Procurement Activity (SUBMEPP)
SUBMEPP provides centralized life-cycle maintenance solutions and support for U.S. Navy submarines and submersibles. SUBMEPP is under the Submarine Directorate of the Naval Sea Systems Command (NAVSEA).

SUBMEPP
Fred Puchlopek
P.O. Box 7002
Portsmouth, NH 03802-7002

The Naval Sea Systems Command (NAVSEA 05) is the technical authority for in-service submarine preservation-related work.

Point of Contact
Ms. Karen Furrer
Naval Sea Systems Command, SEA 05U7T
1333 Isaac Hull Ave., SE
Washington Navy Yard
Washington, DC 20376
(202) 781-4341