Pipeline and Parts Cleaning

1. Pipeline and Parts Cleaning Charles W. (Bill) Nuttall - TIS/GC

2. Cleanliness - “The quality or state of being free from dirt or filth” The Shorter Oxford English Dictionary

3. Outline of the Presentation • Historical • The soils to be removed • Aims of Cleaning • Methods of cleaning • Aqueous • Organic Solvents • Test Methods

4. Historical • Mechanical - Wipe, Scrape, Brush etc. • Water • Water plus chemicals (e.g.Fuller’s earth) • Water plus soap (e.g. sodium stearate) • Water plus detergents • Organic solvents • Bake out • Electrical discharge

5. Verification of cleanliness • Water Break and Atomiser • Oil soluble fluorescence • Extraction and analysis • Oil evaporation on watch-glass • Weighing • Surface energy-droplet size-contact angle • X-ray fluorescence • Auger analysis • Indium adhesion test

6. Information Sources • Experience • “A survey of contamination (Its nature, detection and control)” Sandia laboratories - USA • “Critical Process Cleaning & Cleaning Validation” - CFPA, 3 day course • “The Aqueous Cleaning Handbook” , Maclaughlin & Zisman, Morris-Lee publishing group, 1998 ISBN 0-9645356-7-X • “General and Inorganic Chemistry” J. R. Partington, Macmillan, London 1954 • Branson Web pages

7. The Main Stages in a Cleaning Process • Preparation • Cleaning • Rinsing • Drying • Packaging • Storage • Use

8. Contamination Sources - The Nature of Contaminant “When a few dust particles or an invisible film of organic material can cause the best designed components and systems to fail, the word “clean” takes on a new significance. The chief parameters of concern in the assembly of clean, reliable components are the assembly area, the personnel, the equipment, the assembly process and the storage of piece parts and subassemblies”

9. Where does contamination come from? • Pre-cleaning • In-cleaning • Post cleaning

10. Pre cleaning • Manufacturing contamination • Assembly area • Personnel • Environment • Equipment and machines • Storage • Transport

11. In -cleaning • Dirty solvents or detergent baths • Inadequate rinsing • Contact with other materials • Handling • Lint from wipers or cloths • Clothes • Food and drink

12. Post cleaning • Clothes and handling • Inadequate packaging • Inadequate storage • Inadequate transport • Inadequate un-packaging • Dirty assembly procedures • AND

13. Contamination generated by materials used to build systems • Polymers and elastomers • Depolymerisation • Plasticisers • Catalysts, hardeners, accelerators etc • Poor moulding techniques • Machining moulded articles increases outgassing • Fillers • Poor selection of epoxies and compounding errors • Anaerobic polymers (e.g. Loctite) in air • Oils and greases, solid film lubricants • Co-deposited polymers in plating processes

14. Where are these compounds • Detector frames • Tubes • Printed circuit boards • Diaphragms • Joints and O-rings • Instruments • Films and sheets • Etc., etc..

15. Process Sensitivities • Thoroughly assess the contamination effect of each single process and possible effects of process interactions • Establish appropriate and adequate process controls in the light of this assessment • Monitor processes to detect and avoid process variations • The processing of plastics, adhesives and sealants is a major problem area. These products must be properly cured, and all contain volatile constituents which may outgas at elevated temperatures.

16. Where Silicon lurks • Silicone oils and greases • Silicone polymers and elastomers • Silicone potting and encapsulation compounds • Silicone mastics • Silicone fire stops • Silicone release agents and papers • Silicone adhesives • Silicone anti foam agents etc., etc., etc. • Sodium metasilicate from detergent residues • Silica gel in driers • AND

17. Glass and related products • ALL glasses contain silicates • Normal glass contains calcium and sodium silicates etc • Pyrex is rich in SiO2 and with boron trioxide • Glass fibres used for reinforcing resins • Powdered slate (an aluminium silicate) has been used as a cheap filler in resin formulations • Clay (an aluminosilicate) is present in ordinary airborne dust

18. Stages in Cleaning Process • Identify soils • Choose and validate cleaning agent • Choose and validate cleaning process • Choose and validate rinsing process • Choose and validate drying process • Choose and validate packaging, storage and transport processes • Identify and treat safety, environmental and waste product concerns

19. Ultrasonic cleaning • The most practical and most effective cleaning technique, when properly used is ultrasonic cleaning • It has limitations, it will not remove attached burrs or hardened epoxy resins

20. Parameters for effective ultrasonic cleaning: • Tank size • Fill level (at least 20mm above top piece) • Generator power • Frequency • Containers and parts must not touch tank surface • Basket aperture size • Arrangement of piece(s) in basket • Avoid “shadowing” • Change of cleaning fluid. Remove items from bath while still operating • Blow off all adhering cleaning solution. NEVER let it dry

21. Other Cleaning Techniques • Soaking • Mechanical methods by hand or machine • Abrasive cleaning • Spray cleaning • Vapour degreasers • Through flow methods (especially for tubes)

22. The need for training The work discipline for cleaning and clean assembly is sufficiently unique and demanding that training for such work is mandatory. Each person associated with the engineering or production of high reliability components or systems should have sound understanding of clean assembly practices and how they affect the manufacturing process or product.

23. Objectives of training • To develop awareness of the serious effects of contamination on the ultimate quality and reliability of the product • To demonstrate step by step definition of the assembly task • To motivate employees toward proper work habits

24. Who should receive training? Personnel may be divided into three general groups requiring different degrees of education and understanding • Higher management and administrative support personnel • Engineering and Supervisory personnel • Personnel in production and associated operations

25. Where and when should training be given? • In classroom using lectures, films, tapes, videocassettes, mock-ups, demonstrations etc.. • Individual on the job training with emphasis on what not to do and not forgetting the minor details • Reinforcement and refresher training should be scheduled when needed, with visual aids and posters in the work place • Although assignment to a high reliability product does not necessarily bring a higher salary, pride in individual and collective workmanship and association with an important programme can bring great rewards.

26. The whole system must be addressed • Pipelines • Fittings • Instruments • Installation • Use

27. A possible mechanism for Silica deposition on the wires • Fluorinated hydrocarbon (e.g. CF4) is hydrolysed by the water vapour present (e.g. diffusion through plastic pipes) • HF formed reacts with glass to form gaseous silicon fluorides • Silicon Fluoride is hydrolised by water vapour to form gelatinous silica • These reactions are possibly accelerated in the electrical field around the anodes • The gelatinous silica deposits on the anodes

28. What you don’t have can’t pollute

29. Safety and Environmental Considerations • Organic Solvents • Toxic • VOC • Ozone depletion potential • Global warming potential • Aqueous Systems • Pollute water courses • Toxic • Corrosive to human skin and eyes

30. Rinsing • Use same method as for cleaning • Use a different method • Remove adhering cleaning fluid with dry nitrogen (air knife) and NEVER allow it to dry on • First rinse with towns water (gives better rinsing) • Blow off with dry nitrogen and don’t allow to dry • Rinse with high purity demineralised water until specified parameters (e.g. conductivity) are met • Blow off with dry nitrogen and pass to dryer • After drying pass to correct packaging and storage

31. “Cleanliness is, indeed, next to godliness” John Wesley 1703 - 1791