Pipeline and Parts Cleaning

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Pipeline and Parts Cleaning

• Charles W. (Bill) Nuttall - TIS/GC

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Cleanliness - The quality or state of being free
from dirt or filth

• The Shorter Oxford English Dictionary

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Outline of the Presentation

• Historical
• The soils to be removed
• Aims of Cleaning
• Methods of cleaning
• Aqueous
• Organic Solvents
• Test Methods

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Historical

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

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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

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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

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The Main Stages in a Cleaning Process

• Preparation
• Cleaning
• Rinsing
• Drying
• Packaging
• Storage
• Use

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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

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Where does contamination come from?

• Pre-cleaning
• In-cleaning
• Post cleaning

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Pre cleaning

• Manufacturing contamination
• Assembly area
• Personnel
• Environment
• Equipment and machines
• Storage
• Transport

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In -cleaning

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

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Post cleaning

• Clothes and handling
• Inadequate packaging
• Inadequate storage
• Inadequate transport
• Inadequate un-packaging
• Dirty assembly procedures
• AND

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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

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Where are these compounds

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

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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.

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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

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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

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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

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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

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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

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Other Cleaning Techniques

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

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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.

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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

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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

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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.

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The whole system must be addressed

• Pipelines
• Fittings
• Instruments
• Installation
• Use

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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

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What you dont have cant pollute
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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

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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 dont 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

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Cleanliness is, indeed, next to godliness

• John Wesley 1703 - 1791