Successful Implementation of Alternatives to ODS For Hand Wipe Cleaning in the Manufacture of Launch Vehicles

The Successful Implementation of Alternatives to ODS For Hand Wipe Cleaning in the Manufacture of Launch Vehicles

Grant H. Moskowitz
Ecolink, Inc.
1481 Rock Mountain Blvd.
Stone Mountain, GA. 30083
800/886-8240
mailto:gmoskowitz@ecolink.com

The sweeping changes in manufacturing processes caused by the ratification of the Montreal Protocol agreement impacted industry and its manufacturing practices throughout the 43 industrialized countries of the world. The Montreal Protocol initially called for the cessation of manufacture of 1,1,1 trichloroethane and CFC-113 by the year 2020 in the worlds’ 43 industrialized countries. Due to compelling evidence unearthed subsequently, the date was moved up to December 31^st, 1995. Virtually every company which performed manufacturing or maintenance, repair or overhaul in the Aerospace industry was impacted.

Alliant Techsystems, formerly Hercules Aerospace, was no exception. As the manufacturers of the solid rocket motors for the Titan, Delta, Trident and Pegasus programs, they used a significant amount of 1,1,1 trichloroethane in a number of applications as well as Freon TA in others. In 1992 they began to examine possible alternatives to these ozone depleting, chlorinated solvents.

APPLICATIONS TO BE ADDRESSED:

Chlorinated solvents, after being in use for almost 50 years, had established themselves as the precision cleaning solvents of choice. Their use at Alliant was no exception, and included:

*Case Winding

*Case Machining

*Hydroproof Testing

*Case Preparation

Liner Application

Cork Application

*Mandrel Assembly and Preparation

*Mix/Case Propellant Bowl Cleaning

*Rocket Motor Assembly

*Tool Cleanup

It will be readily noted that these applications were extremely varied in nature and comprised a great many substrates, soils and quite often, intricate geometries. The evaluation and implementation effort took four years to complete.

HURDLES TO OVERCOME IN THE CHANGEOVER TO ALTERNATIVE SOLVENT TECHNOLOGIES.

FINANCIAL:

This effort required a significant investment on the part of Alliant Techsystems. It is estimated that between $5-8 million dollars was spent to identify and then take steps to implement alternative solvent technology. There was a great deal of work done by in house Process Engineers as well as independent testing laboratories.

CONFIRMATION OF SUBSTRATE COMPATIBILITY:

Due to the variety of substrates involved, it was necessary to test every candidate for compatibility with all of the substrates. As 1,1,1 trichloroethane was so widely used, there was less emphasis placed on substrate compatibilities in days past. This could no longer be the case. It has been shown time and again that there are no "drop in replacements" for 1,1,1 trichloroethane. An alternative solvent or cleaner will very often be compatible with some substrates and effective on some soils, however, none of the alternative choices are as versatile as 1,1,1 and 113 were. This is a primary reason so many new cleaners and solvents have been brought to market over the past few years.

VERIFICATION OF SOLVENT PERFORMANCE:

The next step was to test to verify solvent performance. Procedure included cleaning with the candidate solvent, then confirming that subsequent bond or coatings application demonstrated integrity, equal to or greater than previous cleaning technology. Much of this was performed in the laboratory working closely with the Process Engineering staff, whose ultimate responsibility would be the incorporation of the alternative into day to day processes.

COST OF ALTERNATIVES AND MANUFACTURER INTEGRITY:

A survey was performed which included all of the alternative candidates to assure procurement would be cost effective and the costs would remain stable. Additionally, it was necessary to verify that any alternative being provided by a manufacturer could provide certification to the manufacturing processes of the material, as well as demonstrating the ability to continuously supply the solvent.

CUSTOMER APPROVALS:

Due to the nature of the relationship between Alliant and its customers, a wide range of approvals needed to be secured to proceed with the proposed process changes. Parties to the changes included the U.S. Navy, the U.S. Air Force, NASA, Thiokol, McDonnell Douglas Space Systems, Lockheed Martin and Orbital Sciences. The strategic nature of these launch vehicles demanded that close scrutiny was given to any of the process changes to insure vehicle integrity.

DOWNSELECTION:

After the long and arduous path outlined above, it was initially determined that no single product would adequately address all of the manufacturers’ needs. Two alternatives were chosen for incorporation. QED , manufactured by ECOLINK, Inc., and PREPSOLV, which was originally manufactured by Glidco Organics. QED is a high purity aliphatic hydrocarbon solvent, which exhibits properties including: very low (<5 ppm) non volatile residue, (NVR), rapid evaporation and excellent solvency. Due to their high purity, aliphatic hydrocarbons contain no aromatics, which include toxic substances such as benzene and toluene. This material is manufactured in a manner which maintains a very narrow boiling range. This has been identified by the manufacturer as being critical to issues such as dry time.

Many of the solvents being marketed today were originally developed as carriers in other processes, and were never intended to be used in precision cleaning applications. MSDS’s will often list similar characteristics, therefore it is critical that prospective users of aliphatic hydrocarbon solvents examine these aspects of the solvents they contemplate incorporating. . These would include criteria such as flashpoint and vapor pressure.

IMPLEMENTATION STRATEGIES:

It was necessary to incorporate procedural changes in order to properly implement these alternative solvents into their respective processes. Issues that were dealt with included:

*Lower vapor pressure: This equates directly to slower evaporation rate. It was noted that the application gained easier acceptance with technicians on the shop floor if they were instructed to use less of the material than they had previously used when they incorporated high vapor pressure chlorinated solvents. Simply put, the less solvent applied to the substrate, the less residue or unevaporated solvent there was left on the part to remove prior to the next step in the process.

*Use of more than one solvent for a given application: Alliant noted that if a soil was particularly aggressive, there are instances in which two solvents would be utilized. The first solvent would be applied to remove the gross soils, the second for final wipe. QED has been identified as the product of choice for the majority of the final wipe cleaning applications at Alliant Techsystems.

*Implementation of safety procedures: There are two primary issues surrounding the use of alternative solvents over chlorinated material. First, unlike 1,1,1 trichloroethane or CFC-113, solvents such as QED have a flashpoint. The flashpoint of QED is 115° F, TCC. This dictates that reasonable precautions be taken when using this material. QED should not be used around sources of open ignition, and good housekeeping practices such as proper rag disposal and control of spilled material should be incorporated.

*The use of personal protective equipment: Gloves were incorporated to protect workers against skin irritation. At one point early on in the use of QED, one of the technicians reported dermatitis on his knees. It was quickly determined that this individual was allowing some unevaporated QED to soak into his pants, and the continuous contact resulted in skin irritation. Technicians who were at risk to this type of exposure were issued knee pads, which immediately resolved the problem.

*Employee training: New products, as earlier noted, call for new procedures. Starting with the beginning of QED implementation, Alliant trained their technicians in the use of QED to teach them the process changes. This resulted in a relatively seamless transition to this low vapor pressure, Environmentally Preferred, safe solvent.

*Summary of Alliant Techsystems’ important issues included but were not limited to: Low Non Volatile Residue; Tight Product Specification and Consistent Product

ECOLINK AND ITS RELATIONSHIP WITH ITS CUSTOMER

With over ten years invested in the manufacture of Environmentally Preferred Alternative Solvents, ECOLINK brings a number of unique attributes to its relationship with its customers. ECOLINK continues to demonstrate the ability to find cost effective, Environmentally sensible alternatives and procedures to precision cleaning applications. We have helped 1,000’s of companies incorporate successful solvent implementations through our knowledge of Regulatory issues, training of end users and an overall understanding of the demands of precision cleaning. ECOLINK has proven expertise in manufacturing, custom packaging and bar coding. ECOLINK embraces up to the minute technological advances such as EDI capability and E mail communication which make it easier for a customer to do business with us.