Material Selection with STAMP

Selecting the right piping material isn’t just about what fits—it’s about what lasts. In industrial applications, improper material selection can lead to premature failures, unplanned shutdowns, safety hazards, and costly repairs.

One proven engineering approach to material selection is the STAMP method—a structured way to ensure your thermoplastic piping system matches the demands of your application, especially when dealing with aggressive chemicals.

In this guide, we will break down the STAMP acronym and explain how to apply it when selecting thermoplastic piping materials for industrial chemical handling.

Hand rule of Material selection - STAMP

What Is STAMP?

STAMP stands for:

• S: Size

• T: Temperature

• A: Application

• M: Media (chemical compatibility)

• P: Pressure

  
  

This technique is widely used in engineering for material specification, particularly for the selection of piping, valves, and fittings in complex environments.

🧪 M — MEDIA (Chemical Compatibility)

This is the most critical step when dealing with aggressive environments like acids, alkalis, solvents, and oxidizers. Choosing the wrong material for your chemical can lead to swelling, brittleness, cracking, or even catastrophic failure.

Key Questions:

• What chemical or chemical mixture is being conveyed?

• What is its concentration?

• Is the media oxidizing, reducing, organic, or inorganic?

• Is there abrasion potential or are there slurries involved?

• Are there cleanliness or purity requirements?

  
  

Selecting Thermoplastics Based on Media:

Thermoplastic	Best For	Avoid With
PP / PPH	Diluted acids, bases, salts	Strong oxidizing agents
PVDF	HF, strong acids, high-purity media	Long exposure to hot caustic solutions
CPVC	General industrial acids and alkalis	Aromatic and chlorinated solvents
ECTFE	Chlorine, bleach, mixed chemical resistance	High cost may be a limiting factor
PFA	Universal chemical resistance	High upfront cost
PE 100	Water, saltwater, mild acids	Solvents, hydrocarbons
PPS	Fuels, organic solvents	Strong mineral acids

Always consult a chemical resistance chart or get third-party validation if handling a novel or mixed chemical process.

🌡 T — TEMPERATURE

Every thermoplastic has a maximum operating temperature. Above this point, it can soften, deform, or chemically degrade. Chemical resistance often decreases at higher temperatures.

Material	Max Continuous Temp.
PP / PPH	~90–100°C
CPVC	~93°C
PVDF	~140°C
ECTFE	~150°C
PFA	~260°C

Important: A material that resists a chemical at room temperature may fail under heat. Always cross-check chemical resistance at the actual process temperature.

⚙️ A — APPLICATION

Understanding the function and environment of the system is critical.

Key Considerations:

• Is this pressure piping, drainage, or ventilation?

• Will there be exposure to UV, abrasion, or mechanical stress?

• Does the application require ultrapure, conductive, or anti-static piping?

  
  

Application Examples:

• Semiconductor ultrapure water – Use PVDF or PFA for high purity and clean welds.

• Waste acid drain line – Choose PP, CPVC, or PE based on operational temperature.

• Electroplating tanks – Opt for PP with fiberglass reinforcement.

  
  

🧩 S — SIZE

While this aspect may seem simple, size is more than just nominal diameter.

Things to Consider:

• Is this a batch or continuous process?

• What are the flow rates and pipe lengths?

• Will thermal expansion affect longer runs?

  
  

Thermoplastics expand more than metals. For example, PVDF and PP may require expansion loops or anchors in above-ground installations.

⚠️ P — PRESSURE

Thermoplastic pressure ratings are typically given at 20°C and should be derated at higher temperatures. For high-pressure systems, always refer to ISO 4427, DIN 8077/8078, or manufacturer data.

Material	Pressure Rating (PN)	Derating At 60°C
PE 100 PN16	16 bar @ 20°C	~10 bar @ 60°C
PVDF PN10	10 bar @ 20°C	~6.3 bar @ 60°C

If you’re dealing with pulsating flow, vacuum, or compressible gases, consider reinforced systems or pressure-rated fittings.

In conclusion, the STAMP approach is an invaluable guide when selecting materials. Remember that each step correlates closely with the application's unique requirements. Following these guidelines ensures a safe, efficient, and cost-effective piping system.