Fluid penetration (PT) test: an effective way to detect surface defects

Introduction: Introduction to Fluid Penetrating Testing

Liquid penetration testing (PT) is one of  the most common  non-destructive testing methods for detecting surface defects in various materials. Also known as “paint testing”, this method is widely used in various industries, including aerospace, automotive, power plants, and oil and gas, due  to its simplicity, low cost and high effectiveness.

Scientific principles of fluid penetration testing

Mechanism of action

The physiotherapy test is based on three physical principles:

1. Permeability  : the ability of the fluid to penetrate microscopic surface defects.

2. Vermicelli:  the movement of fluids through narrow spaces.

3. Vision  : Create color contrast for easy identification.

The main steps of the test:

1. Surface cleaning

2. Application of permeable fluid

3. Get rid of excess fluid

4. Developer Actions

5. Inspection & Evaluation

Types of liquid penetration test methods

1. Classification based on sensitivity

2. Classification based on the observation method

•   Visible: Bright red colors

• Fluorescent  : requires ultraviolet light

• Double  purpose: a combination of the two methods

Necessary equipment and materials

List of main ingredients:

1. Detergents  : chlorinated or non-chlorinated solvents

2. Permeable  liquid : water-based or solvent.

3. Cleaning  solvent: to remove excess fluid

4. Developer  : Powder or liquid

Utilities:

• Spray pump

• Soft brush

• UV lamp (for fluorescent type)

• Magnifying glass

Regulations on Physiotherapy Tests

International Standards:

• ASTM E165  : Basic Standard for Fluid Penetrating Test

• ISO 3452  : International Standard for Penetration Testing

• Section V of ASME  : Inspection Requirements in the Power Plant Industry

Industry Standards:

• NAS 410  : For the Aerospace Industry

• EN 1371  : For foundries

• MIL-STD-271  : Military Applications

Industrial Applications of PT Tests

Aerospace and Aerospace Industries:

• Turbine blades inspection

• Airframe Quality Control

• Inspection of welded joints

Oil & Gas Industry:

• Examination of pressure vessels

• Pipe Quality Control

• Equipment Repair Evaluation

Cars:

• Castings Inspection

• Structure Quality Control

• Inspection of brake systems

Advantages and disadvantages of the physiotherapy method

Key benefits:

• Suitable for most non-porous materials.

• The cost of implementation is relatively low

• Does not need complex equipment

• High sensitivity to detect small cracks.

Restrictions:

• Applies only to surface defects.

• The need for high-level cleaning

• Porous surface boundaries

• Time-consuming process

Factors affecting the quality of tests

1. Surface preparation:

• Degree of cleanliness

• Superficial dryness

• No pollution

2. Environmental conditions:

• Room temperature (15-50°C is the ideal temperature)

• Relative humidity

• Ambient light (for visible type)

3. Material parameters:

• Breakout time

• Allergy to penetrating liquids

• Developer Type

Step-by-step procedure for a PT test

Step 1: Surface preparation

1. Primary  cleaning: removal of grease, oils and contaminants.

2. Cleaning with solvents  : use acetone or alcohol.

3. Surface  drying: pneumatic or natural air

Step 2: Apply the penetrating liquid

1. Choose the method of application  : spray, dip or brush.

2. Penetration  time : usually from 5 to 30 minutes.

3. Equal  Coverage: Full Coverage Guarantee

Step 3: Remove excess fluid

1. For liquids containing solvents  : use a lint-free cloth.

2. For water-based  liquids: rinse with water spray.

3. Final  drying: before the developer applied.

Step 4: Developer app

1. Choose Developer  Type : Dry, Wet or Solvent

2. Method of application  : spraying or immersion

3. Development  time : usually between 10 and 60 minutes

Step 5: Inspection and Evaluation

1. Suitable  lighting conditions: white light or ultraviolet rays.

2. Use Zoom  : For small defects

3. Record results  : take pictures or write reports

Safety tips when taking the test

Health considerations:

• Use gloves and masks

• Proper ventilation of the environment

• Avoid  contact  with skin.

Disposal of consumables:

• Chemical waste collection

• Compliance with environmental regulations

• Use of special containers

Interpreting physiotherapy test results

Types of signs:

1. Associated  symptoms: Linear fissures

2. Unrelated  symptoms: surface contamination

3. Non-reproducible  symptoms: caused by runtime error

Acceptance Criteria:

• Symbol length

• Poster view

• Density  of tags

• Poster position

Comparison of PT technology with other non-destructive inspection methods

Recent advances in physiotherapy technology

Material innovations:

• Permeable liquids with increased sensitivity 

• Smart developers

• Environmentally friendly materials

Tool Development:

• Automated Application Systems

• Digital cameras to record results

• Image Analysis Software

Training & Related Certifications

Qualification Levels:

• Level 1  : Executive Technician

• Level 2  : Authorized Operator

• Level 3  : Valuation Specialist

Training Courses:

• Basic principles of physiotherapy

• Interpretation of results

• Advanced methods

Conclusion: the niche of ability tests in the industry

Despite its apparent simplicity,   fluid penetration testing is  a highly   effective and reliable way to detect surface defects. It has been used in various industries for over 70 years and remains  the ideal choice for many surface inspection applications.

Key tips for successful  : implementation

• Choose the right test type for your needs

• Strict adherence to standard guidelines

• Pay attention to the proper preparation of the surface.

• Use of trained and experienced staff

• Accurate recording and documentation of results

By adhering to these principles, you can take advantage of the full potential of this method for non-destructive testing and ensuring the quality and safety of industrial parts and equipment.